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Sample records for concrete floor slabs

  1. CAISSON TYPE HOLLOW FLOOR SLABS OF MONOLITHIC MULTI-STOREYED BUILDINGS

    Directory of Open Access Journals (Sweden)

    Malakhova Anna Nikolaevna

    2016-06-01

    Full Text Available One of the disadvantages of building structures made of reinforced concrete is their considerable weight. One of the trends to decrease the weight of concrete structures, including floor slabs, is the arrangement of voids in the cross-sectional building structures. In Russian and foreign practice paper, cardboard and plastic tubes has been used for creation of voids in the construction of monolithic floor slabs. Lightweight concretes were also used for production of precast hollow core floor slabs. The article provides constructive solutions of precast hollow core floor slabs and solid monolithic slabs that were used in the construction of buildings before wide use of large precast hollow core floor slabs. The article considers the application of caisson hollow core floor slabs for modern monolithic multi-storeyed buildings. The design solutions of such floor slabs, experimental investigations and computer modeling of their operation under load were described in this article. The comparative analysis of the calculation results of computer models of a hollow slabs formed of rod or plastic elements showed the similarity of calculation results.

  2. Impact sound insulation improvement of wooden floors on concrete slabs

    DEFF Research Database (Denmark)

    Rasmussen, Birgit; Hoffmeyer, Dan; Hansen, Rói

    2014-01-01

    renovating housing. In Denmark, there are about 1 million dwellings in multi-storey housing. About half of the dwellings are built with timber floors, and the other half with wooden floors on concrete slabs, either in-situ cast or prefabricated hollow-core elements. In a project including mapping of sound......Improvement of impact sound insulation is one of the major challenges, when renovating housing. In Denmark, building regulations for impact sound in new-build were strengthened 5 dB in 2008, implying a main requirement L’n,w ≤ 53 dB between dwellings. The same value should also be a goal, when...... insulation in the Danish housing stock and investigation of improvement possibilities, a pilot laboratory study of wooden floors on concrete was carried out. The laboratory study included impact sound improvement measurements of full-scale samples (10 m2) fulfilling the conditions in EN ISO 10140...

  3. CAISSON TYPE HOLLOW FLOOR SLABS OF MONOLITHIC MULTI-STOREYED BUILDINGS

    OpenAIRE

    Malakhova Anna Nikolaevna

    2016-01-01

    One of the disadvantages of building structures made of reinforced concrete is their considerable weight. One of the trends to decrease the weight of concrete structures, including floor slabs, is the arrangement of voids in the cross-sectional building structures. In Russian and foreign practice paper, cardboard and plastic tubes has been used for creation of voids in the construction of monolithic floor slabs. Lightweight concretes were also used for production of precast hollow core floor ...

  4. TECHNOLOGY FOR INSTALLATION OF REINFORCED CONCRETE FLOOR SLABS LIGHTENED BY CORE DRIVERS WITH PRELIMINARY REINFORCEMENT STRESS

    OpenAIRE

    S. N. Leonovich; I. I. Peredkov

    2015-01-01

    The paper presents technology for installation of floor slabs lightened by plastic core drivers which are preliminary stressed under construction conditions.  Efficiency of such constructive solution is justified by the action of preliminary concrete compression in the tensile zone while reducing structure dead weight due to void arrangement.  The paper provides classification of systems for preliminary stress and contains recommendations on selection of the system depending on peculiariar fe...

  5. TECHNO-ECONOMIC ANALYSIS IN A SUPERSTRUCTURE OF A MULTIPLE FLOORS BUILDING (THREE, FIVE, SEVEN AND NINE FLOORS IN REINFORCED CONCRETE AND RIBBED SLABS WITH RECTANGULAR FORM AND DIFFERENT COMPRESSIVE STRENGTH VALUES

    Directory of Open Access Journals (Sweden)

    E. F. S. Moraes

    2017-12-01

    Full Text Available Adapting “fck" values between 25 MPa to 40 MPa, in three, five, seven and nine floor buildings for places under winds of up to 30 m/s, this research calculated the cost and inputs of these variations. The results have as a goal to improve multiple floors building design in reinforced concrete and ribbed slabs, and to contribute to economic gains. The results were analysed in five stages. (I Architectural design definition in a 1:1 proportion, (II structural conception, (III structural design, (IV cost composition and (V techno economic parameters. To sum up, the results showed that lower “fck” has presented more viability to few flooring. In addition, with the increase of floors also the “fck” raised, causing higher cost around 16,54% in the beams and 11,16% in the slabs. Moreover, the pillars showed a saving of 28,89% in the cost, ranging by up to 11,93% in the average thickness and 6,29% in the concrete form expenditure per m³. Therefore, the research showed an economic achievement of 5,14% in the overall cost between the number of floor.

  6. Numerical Analysis of Prefabricated Steel-Concrete Composite Floor in Typical Lipsk Building

    Directory of Open Access Journals (Sweden)

    Lacki Piotr

    2017-12-01

    Full Text Available The aim of the work was to perform numerical analysis of a steel-concrete composite floor located in a LIPSK type building. A numerical model of the analytically designed floor was performed. The floor was in a six-storey, retail and service building. The thickness of a prefabricated slab was 100 mm. The two-row, crisscrossed reinforcement of the slab was made from φ16 mm rods with a spacing of 150 x 200 mm. The span of the beams made of steel IPE 160 profiles was 6.00 m and they were spaced every 1.20 m. The steelconcrete composite was obtained using 80×16 Nelson fasteners. The numerical analysis was carried out using the ADINA System based on the Finite Element Method. The stresses and strains in the steel and concrete elements, the distribution of the forces in the reinforcement bars and cracking in concrete were evaluated. The FEM model was made from 3D-solid finite elements (IPE profile and concrete slab and truss elements (reinforcement bars. The adopted steel material model takes into consideration the plastic state, while the adopted concrete material model takes into account material cracks.

  7. The Design of a Semi-Prefabricated LVL-Concrete Composite Floor

    Directory of Open Access Journals (Sweden)

    David Yeoh

    2012-01-01

    Full Text Available This paper describes the design of a novel semi-prefabricated LVL-concrete composite floor that has been developed in New Zealand. In this solution, the floor units made from LVL joists and plywood are prefabricated in the factory and transported to the building site. The units are then lifted onto the supports and connected to the main frames of the building and to the adjacent units. Finally, a concrete topping is poured on top of the units in order to form a continuous slab connecting all the units. Rectangular notches cut from the LVL joists and reinforced with coach screws provide the composite action between the concrete slab and the LVL joists. This system proved to be an effective modular solution that ensures rapid construction. A design procedure based on the use of the effective flexural stiffness method, also known as the “gamma method” is proposed for the design of the composite floor at ultimate and serviceability limit states, in the short and long term. By comparison with the experimental results, it is shown that the proposed method leads to conservative design. A step-by-step design worked example of this novel semi-prefabricated composite floor concludes the paper.

  8. Prefabricated floor panels composed of fiber reinforced concrete and a steel substructure

    DEFF Research Database (Denmark)

    Lárusson, Lárus H.; Fischer, Gregor; Jönsson, Jeppe

    2013-01-01

    This paper reports on a study on prefabricated composite and modular floor deck panels composed of relatively thin fiber reinforced concrete slabs connected to steel substructures. The study focuses on the design, manufacturing, structural improvements and behavior of the floor systems during...

  9. Long-life slab replacement concrete.

    Science.gov (United States)

    2015-03-01

    This research was initiated following reports of high incidence of cracking on FDOT concrete pavement replacement : slab projects. Field slabs were instrumented for data acquisition from high-early-strength concrete pavement : replacement slabs place...

  10. A Preliminary Experimental Study on Vibration Responses of Foamed Concrete Composite Slabs

    Science.gov (United States)

    Rum, R. H. M.; Jaini, Z. M.; Ghaffar, N. H. Abd; Rahman, N. Abd

    2017-11-01

    In recent years, composite slab has received utmost demand as a floor system in the construction industry. The composite slab is an economical type of structure and able to accelerate the construction process. Basically, the composite slab can be casting by using a combination of corrugated steel deck and normal concrete in which selfweight represents a very large proportion of the total action. Therefore, foamed concrete become an attractive alternative to be utilized as a replacement of normal concrete. However, foamed concrete has high flexibility due to the presence of large amount of air-void and low modulus elasticity. It may result in vibration responses being greater. Hence, this experimental study investigates the vibration responses of composite slab made of corrugated steel deck and foamed concrete. The specimens were prepared with dimension of 750mm width, 1600mm length and 125mm thickness. The hammer-impact test was conducted to obtain the acceleration-time history. The analysis revealed that the first natural frequency is around 27.97 Hz to 40.94 Hz, while the maximum acceleration reaches 1.31 m/s2 to 1.88 m/s2. The first mode shape depicts normal pattern and favourable agreement of deformation.

  11. Seismic analysis and design of steel beam - thick slab floor systems

    International Nuclear Information System (INIS)

    Reed, P.W.

    1981-01-01

    This paper presents a method for seismic analysis and design of floor systems composed of thick reinforced concrete slabs supported by steel beams. The response spectrum modal analysis is used to determine the dynamic response of an orthotropic finite element model. An approximate approach to find the fundamental frequency is explained, allowing an actual acceleration to be determined. The fundamental mode is found to be a major portion of the overall response, whereas the secondary modes are shown to result in a very small portion of the overall response. Dynamic multipliers for the fundamental mode and significant secondary modes are given for several typical floor layouts. These would be used to find equivalent static stress resultants which are used to design the floor. (orig.)

  12. Method for Bubbledeck Concrete Slab with Gaps

    Directory of Open Access Journals (Sweden)

    Sergiu Călin

    2009-01-01

    Full Text Available The composite slabs are made of BubbleDeck type slab elements with spherical gaps, poured in place on transversal and longitudinal directions. By introducing the gaps leads to a 30...50\\% lighter slab which reduces the loads on the columns, walls and foundations, and of course of the entire building. BubbleDeck slab elements are plates with ribs on two directions made of reinforced concrete or precast concrete with spherical shaped bubbles. These slab elements have a bottom and an upper concrete part connected with vertical ribs that go around the gaps.

  13. TECHNOLOGY FOR INSTALLATION OF REINFORCED CONCRETE FLOOR SLABS LIGHTENED BY CORE DRIVERS WITH PRELIMINARY REINFORCEMENT STRESS

    Directory of Open Access Journals (Sweden)

    S. N. Leonovich

    2015-01-01

    Full Text Available The paper presents technology for installation of floor slabs lightened by plastic core drivers which are preliminary stressed under construction conditions.  Efficiency of such constructive solution is justified by the action of preliminary concrete compression in the tensile zone while reducing structure dead weight due to void arrangement.  The paper provides classification of systems for preliminary stress and contains recommendations on selection of the system depending on peculiariar features of the designed construction.  Main products and materials required for execution of works , requirements to stressed wire rope reinforcement, its main characteristics have been considered in the paper.Principal diagram of the lightened preliminary stressed slab stipulates arrangement of so called  dummy caisson. Strands of reinforcement ropes are located within the framework of bars passing over supporting structures (over vertical bearing structures of  the framework and voids are formed in the cells between bars by laying hollow plastic items joined together by a cage. The paper presents technological sequence of operations required for arrangement of the lightened preliminary stressed slab, schemes for equipment arrangement and characteristics of the applied devices and units (pushing device for reinforcement ropes, hydraulic jack with delivery hydraulic pump, mixing station, injection pump and others.  Recommendations have been given for execution of works in cold weather. The paper considers problems pertaining to control quality of the materials and items which are supplied to a construction site and directly execution of works on preliminary stress of a cellular slab.The executed analysis of technology permits to conclude that it is characterized by high level of applicability for import substitution. It is necessary to consider the possibility to apply the technology at objects of various application while comparing it with other

  14. Effect of kenaf fiber in reinforced concrete slab

    Science.gov (United States)

    Syed Mohsin, S. M.; Baarimah, A. O.; Jokhio, G. A.

    2018-04-01

    The effect of kenaf fibers in reinforced concrete slab with different thickness is discusses and presented in this paper. Kenaf fiber is a type of natural fiber and is added in the reinforced concrete slab to improve the structure strength and ductility. For this study, three types of mixtures were prepared with fiber volume fraction of 0%, 1% and 2%, respectively. The design compressive strength considered was 20 MPa. Six cubes were prepared to be tested at 7th and 28th day. A total of six reinforced concrete slab with two variances of thickness were also prepared and tested under four-point bending test. The differences in the thickness is to study the potential of kenaf fiber to serve as part of shear reinforcement in reinforced concrete slab that was design to fail in shear. It was observed that, addition of kenaf fiber in reinforced concrete slab improves the flexural strength and ductility of the reinforced concrete slab. In the slab with reduction in thickness, the mode of failure change from brittle to ductile with the inclusion of kenaf fiber.

  15. Assessing the effectiveness of slab flooring as a barrier to soil gas and radon infiltration

    International Nuclear Information System (INIS)

    Williamson, A.D.; Fowler, C.S.; McDonough, S.E.

    1995-01-01

    Experimental studies on the entry of soil gas and radon into slab-on-grade buildings have been carried out in instrumented, single-zone test structures. This work, as part of the Florida Radon Research Program, focused on the effectiveness of slab flooring variants as barriers to soil gas/radon entry. A second objective was the study of the role of subslab fill soil as both a potential source of and barrier to radon entry. Studies were made in well-sealed (∼ 600 mm 2 ELA) unoccupied test buildings placed on well-characterized, radium-bearing sandy fill soil. The buildings were instrumented with data acquisition systems to continuously monitor indoor radon concentrations, differential pressures at several subsurface locations, weather conditions, and soil moisture. The response of the structures to mechanical depressurization as well as natural driving forces was measured. Limited measurements were made regarding direct diffusive transport of radon through apparently intact concrete slabs, as well as transport through cracks in the floor structure

  16. Repairing reinforced concrete slabs using composite layers

    International Nuclear Information System (INIS)

    Naghibdehi, M. Ghasemi; Sharbatdar, M.K.; Mastali, M.

    2014-01-01

    There are several strengthening methods for rehabilitation of RC structural elements. The efficiency of these methods has been demonstrated by many researchers. Due to their mechanical properties, using fibrous materials in rehabilitation applications is growing fast. Therefore, this study presents rehabilitation of slabs in such a way that plain concrete layers on top, on bottom, on the entire cross section are replaced by reinforced concrete layers. In order to reinforce the concrete, Polypropylene (PP) and steel fibers were used by 0.5%, 1% and 2% fiber volume fractions. Nineteen slabs were studied under flexural loadings and fibrous material effects on the initial crack force, the maximum loading carrying capacity, absorbed energy and ductility were investigated. The obtained results demonstrated that increasing the fiber volume fraction or using reinforced concrete layer on top, bottom, or at the entire cross section of the slabs not only always leads to improvement in the slab performance, but also sometimes debilitates the slab performance. Hence, this study will propose the best positioning of reinforced concrete layer, fiber volume fraction and fiber type to achieve the best flexural performance of slabs. - Highlights: • Using PP fibers at the bottom layer led to the best slab performance in bending. • Using steel fiber at the top layer and entire cross-section led to the best slab performance. • Maximum increase in the initial crack force and loading were obtained at 2% steel fiber. • Maximum increase in the initial crack force and loading were obtained at 1% PP fiber

  17. EFFECTIVE KEYED CONNECTIONS OF HOLLOW-CORE FLOOR SLABS WITH WALLS IN MODERN LARGE-PANEL HOUSE BUILDING

    Directory of Open Access Journals (Sweden)

    O. A. Dovzhenko

    2018-01-01

    Full Text Available The paper considers large-panel constructive system of multi-storey buildings and its industrial basis creates conditions for intensive volume growth in house construction. Application of hollow-core panels are recommended as floor slabs that allows to increase a distance between bearing walls, to improve planning solutions, and also significantly to increase thermal and sound protection properties of floor discs (coatings. Keyed joints having the highest resistance to shearing forces are used to ensure joint action of the slabs with wall panels. A supporting unit of floor elements in the precast-monolithic constructive system ARKOS by means of concrete keys is considered as a prototype of the considered joint. In order to increase a bearing capacity and improve reliability of joints it is envisaged to reinforce keys with space frames. Improvement of joint units is possible to carry out with due account of total number of the factors influencing on strength. Poltava National Technical University named after Yuri Kondratyuk has developed a general methodology for assessment of bearing capacity in keyed joints which is based on the variational method in the theory of concrete plasticity and reflects specificity of stress-strain state of the failure zone. For experimental verification of this methodology investigations have been carried out with the purpose to test operation of keys when they are reinforced in mid-height and reinforcement is distributed in two tiers. The observed experimental fracture pattern in the specimens has confirmed kinematic schemes accepted for calculations and comparative analysis of experimental and theoretical values points to their closeness. Two-level reinforcement significantly improves plastic properties of concrete keys and excludes brittle failure. The proposed design of the joint unit for floor slabs with wall panels is characterized by the ratio of key dimensions and shape of reinforcing cages in the form of

  18. Dynamic Eigenvalue Problem of Concrete Slab Road Surface

    Science.gov (United States)

    Pawlak, Urszula; Szczecina, Michał

    2017-10-01

    The paper presents an analysis of the dynamic eigenvalue problem of concrete slab road surface. A sample concrete slab was modelled using Autodesk Robot Structural Analysis software and calculated with Finite Element Method. The slab was set on a one-parameter elastic subsoil, for which the modulus of elasticity was separately calculated. The eigen frequencies and eigenvectors (as maximal vertical nodal displacements) were presented. On the basis of the results of calculations, some basic recommendations for designers of concrete road surfaces were offered.

  19. Influence of slab connection in case of expanded concrete pavements

    OpenAIRE

    Deluka-Tibljaš, Aleksandra; Prager, Andrija; Rukavina, Tatjana

    2002-01-01

    Load transfer from the stressed slab to the neighboring unstressed slab is analyzed in order to establish possibilities for stress reduction in concrete. The contact between slabs is established by means of reinforcing steel shear studs while the influence of friction in the concrete to concrete contact is neglected. The influence of slab thickness, slab cross-section and spacing of shear studs is analyzed, and the expansion joint movement due to change in temperature is studied. Conditions e...

  20. Discussion on the installation checking method of precast composite floor slab with lattice girders

    Science.gov (United States)

    Chen, Li; Jin, Xing; Wang, Yahui; Zhou, Hele; Gu, Jianing

    2018-03-01

    Based on the installation checking requirements of China’s current standards and the international norms for prefabricated structural precast components, it proposed an installation checking method for precast composite floor slab with lattice girders. By taking an equivalent composite beam consisted of a single lattice girder and the precast concrete slab as the checking object, compression instability stress of upper chords and yield stress of slab distribution reinforcement at the maximum positive moment, tensile yield stress of upper chords, slab normal section normal compression stress and shear instability stress of diagonal bars at the maximum negative moment were checked. And the bending stress and deflection of support beams, strength and compression stability bearing capacity of the vertical support, shear bearing capacity of the bolt and compression bearing capacity of steel tube wall at the bolt were checked at the same time. Every different checking object was given a specific load value and load combination. Application of installation checking method was given and testified by example.

  1. Long-life slab replacement concrete : [summary].

    Science.gov (United States)

    2015-04-01

    Concrete slab replacement projects in Florida have demonstrated a high incidence of : replacement slab cracking. Causes of cracking have not been reliably determined. University of South Florida researchers : sought to identify the factors or : param...

  2. Use of fiber reinforced concrete for concrete pavement slab replacement.

    Science.gov (United States)

    2014-03-01

    Unlike ordinary concrete pavement, replacement concrete slabs need to be open to traffic within 24 hours (sooner in : some cases). Thus, high early-strength concrete is used; however, it frequently cracks prematurely as a result of high : heat of hyd...

  3. Concrete mixtures with high-workability for ballastless slab tracks

    Directory of Open Access Journals (Sweden)

    Olga Smirnova

    2017-10-01

    Full Text Available The concrete track-supporting layer and the monolithic concrete slab of ballastless track systems are made in-situ. For this reason the concrete mixtures of high workability should be used. Influence of the sand kind, the quartz microfiller fineness and quantity as well as quantity of superplasticizer on workability of fresh concrete and durability of hardened concrete is shown. The compositions of the high-workability concrete mixtures with lower consumption of superplasticizer are developed. The results of the research can be recommended for high performance concrete of ballastless slab track.

  4. Optimal Material Layout - Applied on Reinforced Concrete Slabs

    DEFF Research Database (Denmark)

    Dollerup, Niels; Jepsen, Michael S.; Damkilde, Lars

    2015-01-01

    This paper introduces a general, finite-element-based optimisation tool for improving the material layout of concrete structures. The application presented is general and exemplified by material optimisation of reinforced concrete slabs. By utilising the optimisation tool, it is possible to deter......This paper introduces a general, finite-element-based optimisation tool for improving the material layout of concrete structures. The application presented is general and exemplified by material optimisation of reinforced concrete slabs. By utilising the optimisation tool, it is possible...... to determine the optimal material layout of a slab in the ultimate load state, based on simple inputs such as outer geometry, boundary conditions, multiple load cases and design domains. The material layout of the optimal design can either be fully orthotropic or isotropic, or a combination with a predefined...

  5. Moisture transfer in a concrete slab

    International Nuclear Information System (INIS)

    Huang, C.L.D.; Siang, H.H.; Kirmser, P.G.

    1979-01-01

    A diffusion theory with a linear or a nonlinear coefficient of diffusivity is insufficient for the characterization of the drying behaviour of hydrated concrete slabs. A general mathematical model, based on nonequilibrium, irreversible flows of heat and mass, yields a set of nonlinear partial differential equations of parabolic type. Implicit finite difference calculations for a concrete slab yield moisture, temperature, and pressure histories as well as global average drying rates. Graphs show that during the pendular state of dessication, diffusion, capillary, and evaporation-condensation processes are the governing mechanisms in drying. (orig.)

  6. 0-6722 : spread prestressed concrete slab beam bridges.

    Science.gov (United States)

    2014-08-01

    The Texas Department of Transportation uses : precast prestressed concrete slab beam bridges for : shorter-span bridges of approximately 3050 ft in : length. Conventional slab beam bridges have slab : beams placed immediately adjacent to one anoth...

  7. 9 CFR 91.26 - Concrete flooring.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Concrete flooring. 91.26 Section 91.26... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.26 Concrete flooring. (a) Pens aboard an ocean vessel shall have a 3 inch concrete pavement, proportioned and mixed to give 2000 psi...

  8. Reinforcement of the concrete base slab of the ATLAS cavern

    CERN Multimedia

    Maximilien Brice

    2002-01-01

    Photo 02: UX15 cavern, preparation for concreting of base slab first lift. Photo 05: UX15 cavern, placing of reinforcement for base slab first lift. Photo 07: UX15 cavern, preparation for concreting of base slab first lift. Photo 09: UX15 cavern, placing of reinforcement for base slab first lift. Photo 10: UX15 cavern, view into PX14 shaft above. Photo 12: UX15 cavern, temporary access platform of RB16 tunnel. Photo 15: UJ17 chamber, invert excavation.

  9. Structural behavior of lightweight bamboo reinforced concrete slab with EPS infill panel

    Science.gov (United States)

    Wibowo, Ari; Wijatmiko, Indradi; Nainggolan, Christin Remayanti

    2017-09-01

    Eco-friendly, green, and natural materials have become increasingly important issues in supporting sustainable development, for the substitution of nonrenewable materials such as steel. Bamboo has been considered in many studies to replace steel in reinforced concrete elements. Further investigation has been carried out to obtain lightweight and eco-friendly reinforced concrete slabs by using bamboo bars as reinforcement and recycled materials such as EPS (expanded polystyrene) as infill panel. The flexural loading test on full scale one-way slabs test has been conducted. The results showed that the flexural strength of specimens decreased marginally of about 6% but with the weight advantage of 27% less compared with those of steel rebar reinforced concrete slab with the same dimension. Two type shear-connectors comprising of concrete and bamboo studs were also investigated which showed that the bamboo stud provided better ductility compared to that of slab with concrete as shear connector. Overall, the reinforced concrete slab with bamboo reinforcement and EPS infill panel showed reasonably good performance compared to slabs with steel rebar.

  10. Analysis of the Behaviour of Composite Steel and Steel Fiber Reinforced Concrete Slabs

    Directory of Open Access Journals (Sweden)

    Mindaugas Petkevičius

    2011-04-01

    Full Text Available There was a pending influence of steel fiber on the strength and stiffness of composite steel–concrete slabs under statical short–time load. Steel profiled sheeting and steel fiber reinforced concrete were used for specimens. Four composite slabs were made. Experimental investigations into the behaviour and influence of steel fiber reinforced concrete in composite slabs were conducted. Transverse, longitudinal, shear deformation and deflection of the slab were measured. The results indicated that the use of steel fiber in composite slabs was effective: strength was 20–24 % higher and the meanings of deflections under the action of the bending moment were 0,6MR (where MR is the bending moment at failure of the slabs and were 16–18 % lower for slabs with usual concrete. Article in Lithuanian

  11. Cost Effectiveness of Precast Reinforced Concrete Roof Slabs

    Science.gov (United States)

    Parskiy, N. D.; Molodtsov, M. V.; Molodtsova, V. E.

    2017-11-01

    Engineers always seek to free interior space from intermediate supporting elements. Nowadays plants, being at the forefront of technology, produce a new generation of exclusive patented prefabricated reinforced concrete elements with a high load-bearing capacity, excellent heat resistance characteristics combined with the aesthetics and beauty. It is a system of Seagull Gabbiano prestressed roof slabs for the spans of 12m - 40m. The article shows the advantages of the Seagull slabs over conventional precast reinforced concrete and metal roof trusses. It also gives the analysis of the technical and economic indices of design and construction of a building with the Seagull slabs depending on the size of spans to cover. The use of structural systems with increased spans allows for the modern buildings and structures of prefabricated reinforced concrete with enhanced functionality and aesthetics alongside with a wide range of planning solutions.

  12. Cost analysis of reinforced concrete slabs and columns

    OpenAIRE

    Spuś, Piotr

    2013-01-01

    The construction industry is increasingly looking for solutions that are both simple and effective and that provide cost savings, speed and flexibility of execution. Two-way slabs are a form of construction unique to reinforced concrete comparing with the other major structural materials. It is an efficient, economical, and widely used structural system. The present dissertation aims to analyze and compare costs between four types of slabs: waffle slab with recuperate molds, flat slabs wit...

  13. Behavior of one-way reinforced concrete slabs subjected to fire

    Directory of Open Access Journals (Sweden)

    Said M. Allam

    2013-12-01

    Full Text Available A finite difference analysis was performed to investigate the behavior of one-way reinforced concrete slabs exposed to fire. The objective of the study was to investigate the fire resistance and the fire risk after extinguishing the fire. Firstly, the fire resistance was obtained using the ISO834 standard fire without cooling phase. Secondly, the ISO834 parametric fire with cooling phase was applied to study the effect of cooling time. Accordingly, the critical time for cooling was identified and the corresponding failure time was calculated. Moreover, the maximum risk time which is the time between the fire extinguishing and the collapse of slab was obtained. Sixteen one-way reinforced concrete slabs were considered to study the effect of important parameters namely: the concrete cover thickness; the plaster; and the live load ratio. Equations for heat transfer through the slab thickness were used in the fire resistance calculations. Studying the cooling time revealed that the slabs are still prone to collapse although they were cooled before their fire resistance. Moreover, increasing the concrete cover thickness and the presence of plaster led to an increase in the maximum risk time. However, the variation in the live load ratio has almost no effect on such time.

  14. CONCRETE PROPERTIES IMPROVEMENT OF SLAB TRACKS USING CHEMICAL ADDITIVES

    Directory of Open Access Journals (Sweden)

    V. V. Pristinskaya

    2015-11-01

    Full Text Available Purpose. On the Railways of Ukraine a very large number of slab tracks are operated with cracks. Many scientific works of previous years are dedicated to improving the design of slab tracks. The main causes of defects are: poor exploitation of the track; insufficient physic-mechanical characteristics of concrete; poor quality of initial materials. It is therefore necessary to develop an optimum concrete mix for the manufacture of these concrete products. Methodology. To assess the impact of individual factors and effects of their interactions on properties of concrete mix and concrete method of experimental and statistical modeling was used. At this, methodological fundamentals of mathematical experiment planning in concrete technology and modern methods of optimization of composite materials were taking into account. Based on the obtained data during the planned experiment conducting, including15 studies and using the computer program MathCad, were obtained the regression equations, which describe the relevant physical and mechanical properties of concrete. On the basis of the equations with the help of computer program MATLAB R2012b the graphs were drawn, illustrating the dependences of system response from the changes of two factors at a fixed value of the third factor. Findings. Firstly was the analysis of cracks that occur in the process of operation in the constructions of slab tracks. Further reasons of possible occurrence of these cracks were presented. In the process of the conducted research the author has concluded that for rational concrete mix development it is necessary to conduct the planned experiment with the use of quality materials. It was established that to increase the strength, chemical additives should be added in to concrete mix, it will let reduce cement amount. Originality. Experiments proved the usage of modern chemical additives in order to improve the properties of concrete. Models were developed, reflecting

  15. Modelling of the bending behaviour of double floor systems for different contact surfaces

    Directory of Open Access Journals (Sweden)

    Attila PUSKAS

    2014-07-01

    Full Text Available In the practice of prefabricated concrete structures considerable surfaces of intermediate floors are constructed using double floor systems with prefabricated bottom layer and upper layer. This second layer is cast on site. The quality of the prefabricated concrete is often of superior class with respect to the monolithic layer. In the service state of the double floor system, important compressive stresses appear in the upper concrete layer. On the other hand, the bond quality between the concrete layers cast in successive stages raises questions especially in the case of hollow core floor units with no connecting reinforcement in-between. The paper presents results of the numerical models prepared for double floor elements having different thicknesses for the top and bottom layers, subjected to bending. Three situations have been studied: stepped top surface of the prefabricated slab with no connecting reinforcement, broom swept tracks on the prefabricated slab with no connecting reinforcement and broom swept tracks on the prefabricated slab with stirrups connecting the concrete layers. For each situation two different ratios of the thicknesses of the layers have been considered. The results are emphasizing the critical regions of the elements, the differences in crack development and in the behaviour resulting from surface preparation and use of connecting reinforcements.

  16. MEMBRANE ACTION IN PROFILED STEEL SHEETING DRY BOARD (PSSDB FLOOR SLAB SYSTEM

    Directory of Open Access Journals (Sweden)

    MAHMOOD SERAJI

    2013-02-01

    Full Text Available Profiled steel sheeting dry board (PSSDB system is a lightweight composite structural system that made of the profiled steel sheeting (PSS connected to the dry board (DB by self-drilling and self-tapping screws. The objective of this paper is to study the effect of membrane action in improving the flexural capacities of the PSSDB system. According to the literatures, common failure of the PSSDB floor is due to local buckling in the top flanges of steel sheeting at the centre of a simply supported slab. Restraining the horizontal movement at supports may develop the membrane action (MA in the slab that can remarkably enhance the flexural rigidities of the floor. Experimental tests were conducted along with developing nonlinear finite element model to explore the effect of MA in the PSSDB floor. Experimental results of the PSSDB panel with simply end support were exploited to verify the nonlinear finite element results. The developed finite element model was then modified by restraining the horizontal movement of the slab at the supports. The obtained results disclosed that the developed compressive membrane action enhanced the stiffness of the slab at serviceability load by about 240%.

  17. Concrete mixtures with high-workability for ballastless slab tracks

    OpenAIRE

    Olga Smirnova

    2017-01-01

    The concrete track-supporting layer and the monolithic concrete slab of ballastless track systems are made in-situ. For this reason the concrete mixtures of high workability should be used. Influence of the sand kind, the quartz microfiller fineness and quantity as well as quantity of superplasticizer on workability of fresh concrete and durability of hardened concrete is shown. The compositions of the high-workability concrete mixtures with lower consumption of superplasticizer are developed...

  18. Prediction of punching shear capacities of two-way concrete slabs reinforced with FRP bars

    Directory of Open Access Journals (Sweden)

    Ibrahim M. Metwally

    2013-08-01

    Full Text Available Where corrosion of steel reinforcement is a concern, fiber-reinforced polymer (FRP reinforcing bar or grid reinforcement provides an alternative reinforcement for concrete flat slabs. The existing provisions for punching of slabs in most international design standards for reinforced concrete are based on tests of steel reinforced slabs. The elastic stiffness and bonding characteristics of FRP reinforcement are sufficiently different from those of steel to affect punching strength [1]. This paper evaluates the punching shear strength of concrete flat slabs reinforced with different types of fiber-reinforced polymer (FRP. A total of 59 full-size slabs were constructed and tested collected from the literature of FRP bars reinforced concrete slabs. The test parameters were the amount of FRP reinforcing bars, Young’s modulus of FRP bars, slab thickness, loaded areas and concrete compressive strength. The experimental punching shear strengths were compared with the available theoretical predictions, including the ACI 318 Code, BS 8110 Code, ACI 440 design guidelines, and a number of models proposed by some researchers in the literature. Two approaches for predicting the punching strength of FRP-reinforced slabs are examined. The first is an empirical new model which is considered as a modification of El-Gamal et al. [2] model. The second is a Neural Networks Technique; which has been developed to predict the punching shear capacity of FRP reinforced concrete slabs. The accuracies of both methods were evaluated against the experimental test data. They attained excellent agreement with available test results compared to the existing design formulas.

  19. Composite slab behavior and strength analysis under static and dynamic loads

    Directory of Open Access Journals (Sweden)

    Florin Radu HARIGA

    2012-07-01

    Full Text Available Steel-framed buildings are typically constructed using steel-deck-reinforced concrete floor slabs. The in-plane (or diaphragm strength and stiffness of the floor system are frequently utilized in the lateral load-resisting system design. This paper presents the results of an experimental research program in which four full size composite diaphragms were vertically loaded to the limit state, under static or dynamic loads. Two test specimens were provided with longitudinal steel-deck ribs, and the other two specimens with cross steel-deck ribs. Typical composite diaphragm limit states are described, and the controlling limit state for each of the full size tests is indicated. The interaction effects between the reinforced concrete slab and the steel girder on the composite slab strength and stiffness were mainly studied.

  20. Ultimate deformation capacity of reinforced concrete slabs underblast load

    NARCIS (Netherlands)

    Doormaal, J.C.A.M. van; Weerheijm, J.

    1996-01-01

    In this paper a test method to determine the deformation capacity and the resistance-deformation curve of blast-loaded slabs is described. This method was developed at TNO-PML. The method has been used to determine the ultimate deformation capacity of some simply supported reinforced concrete slabs

  1. Theoretical Investigations on the Structural Behavior of Biaxial Hollow Concrete Slabs

    Directory of Open Access Journals (Sweden)

    Nazar Kamel Ali Oukaili

    2015-06-01

    Full Text Available This paper presents a numerical analysis using ANSYS finite element program to simulate the reinforced concrete slabs with spherical voids. Six full-scale one way bubbled slabs of (3000mm length with rectangular cross-sectional area of (460mm width and (150mm depth are tested as simply supported under two-concentrated load. The results of the finite element model are presented and compared with the experimental data of the tested slabs. Material nonlinearities due to cracking and crushing of concrete and yielding of reinforcement are considered. The general behavior of the finite element models represented by the load-deflection curves at midspan, crack pattern, ultimate load, load-concrete strain curves and failure modes shows good agreement with the experimental data.

  2. Behaviour of reinforced concrete slabs with steel fibers

    Science.gov (United States)

    Baarimah, A. O.; Syed Mohsin, S. M.

    2017-11-01

    This paper investigates the potential effect of steel fiber added into reinforced concrete slabs. Four-point bending test is conducted on six slabs to investigate the structural behaviour of the slabs by considering two different parameters; (i) thickness of slab (ii) volume fraction of steel fiber. The experimental work consists of six slabs, in which three slabs are designed in accordance to Eurocode 2 to fulfil shear capacity characteristic, whereas, the other three slabs are designed with 17% less thickness, intended to fail in shear. Both series of slabs are added with steel fiber with a volume fraction of Vf = 0%, Vf = 1% and Vf = 2% in order to study the effect and potential of fiber to compensate the loss in shear capacity. The slab with Vf = 0% steel fiber and no reduction in thickness is taken as the control slab. The experimental result suggests promising improvement of the load carrying capacity (up to 32%) and ductility (up to 87%) as well as delayed in crack propagation for the slabs with Vf = 2%. In addition, it is observed that addition of fibers compensates the reduction in the slab thickness as well as changes the failure mode of the slab from brittle to a more ductile manner.

  3. MODELING OF TRANSIENT HEAT TRANSFER IN FOAMED CONCRETE SLAB

    Directory of Open Access Journals (Sweden)

    MD AZREE OTHUMAN MYDIN

    2013-06-01

    Full Text Available This paper reports the basis of one-dimensional Finite Difference method to obtain thermal properties of foamed concrete in order to solve transient heat conduction problems in multi-layer panels. In addition, this paper also incorporates the implementation of the method and the validation of thermal properties model of foamed concrete. A one-dimensional finite difference heat conduction programme has been developed to envisage the temperature development through the thickness of the foamed concrete slab, based on an initial estimate of the thermal conductivity-temperature relationship as a function of porosity and radiation within the voids. The accuracy of the model was evaluated by comparing predicted and experimental temperature profiles obtained from small scale heat transfer test on foamed concrete slabs, so that the temperature history of the specimen calculated by the programme closely matches those recorded during the experiment. Using the thermal properties of foamed concrete, the validated heat transfer program predicts foamed concrete temperatures in close agreement with experimental results obtained from a number of high temperature tests. The proposed numerical and thermal properties are simple yet efficient and can be utilised to aid manufacturers to develop their products without having to conduct numerous large-scale fire tests.

  4. GEOMETRIC AND MATERIAL NONLINEAR ANALYSIS OF REINFORCED CONCRETE SLABS AT FIRE ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Ayad A. Abdul -Razzak

    2013-05-01

    Full Text Available In the present study a nonlinear finite element analysis is presented  to predict the fire resistance of reinforced concrete slabs at fire environment. An eight node layered degenerated shell element utilizing Mindlin/Reissner thick plate theory is employed. The proposed model considered cracking, crushing and yielding of concrete and steel at elevated temperatures. The layered approach is used to represent the steel reinforcement and discretize the concrete slab through the thickness. The reinforcement steel is represented as a smeared layer of equivalent thickness with uniaxial strength and rigidity properties.Geometric nonlinear analysis may play an important role in the behavior of reinforced concrete slabs at high temperature. Geometrical nonlinearity in the layered approach is considered in the mathematical model, which is based on the total Lagrangian approach taking into account Von Karman assumptions.Finally two examples for which experimental results are available are analyzed, using the proposed model .The comparison showed good agreement with experimental results. 

  5. Experimental sensitivity analysis of subsoil-slab behaviour regarding degree of fibre-concrete slab reinforcement

    Science.gov (United States)

    Hrubesova, E.; Lahuta, H.; Mohyla, M.; Quang, T. B.; Phi, N. D.

    2018-04-01

    The paper is focused on the sensitivity analysis of behaviour of the subsoil – foundation system as regards the variant properties of fibre-concrete slab resulting into different relative stiffness of the whole cooperating system. The character of slab and its properties are very important for the character of external load transfer, but the character of subsoil cannot be neglected either because it determines the stress-strain behaviour of the all system and consequently the bearing capacity of structure. The sensitivity analysis was carried out based on experimental results, which include both the stress values in soil below the foundation structure and settlements of structure, characterized by different quantity of fibres in it. Flat dynamometers GEOKON were used for the stress measurements below the observed slab, the strains inside slab were registered by tensometers, the settlements were monitored geodetically. The paper is focused on the comparison of soil stresses below the slab for different quantity of fibres in structure. The results obtained from the experimental stand can contribute to more objective knowledge of soil – slab interaction, to the evaluation of real carrying capacity of the slab, to the calibration of corresponding numerical models, to the optimization of quantity of fibres in the slab, and finally, to higher safety and more economical design of slab.

  6. Influence of transverse reinforcement on perforation resistance of reinforced concrete slabs under hard missile impact

    International Nuclear Information System (INIS)

    Orbovic, Nebojsa; Sagals, Genadijs; Blahoianu, Andrei

    2015-01-01

    This paper describes the work conducted by the Canadian Nuclear Safety Commission (CNSC) related to the influence of transverse reinforcement on perforation capacity of reinforced concrete (RC) slabs under “hard” missile impact (impact with negligible missile deformations). The paper presents the results of three tests on reinforced concrete slabs conducted at VTT Technical Research Centre (Finland), along with the numerical simulations as well as a discussion of the current code provisions related to impactive loading. Transverse reinforcement is widely used for improving the shear and punching strength of concrete structures. However, the effect of this reinforcement on the perforation resistance under localized missile impact is still unclear. The goal of this paper is to fill the gap in the current literature related to this topic. Based on similar tests designed by the authors with missile velocity below perforation velocity, it was expected that transverse reinforcement would improve the perforation resistance. Three slabs were tested under almost identical conditions with the only difference being the transverse reinforcement. One slab was designed without transverse reinforcement, the second one with the transverse reinforcement in form of conventional stirrups with hooks and the third one with the transverse reinforcement in form of T-headed bars. Although the transverse reinforcement reduced the overall damage of the slabs (the rear face scabbing), the conclusion from the tests is that the transverse reinforcement does not have important influence on perforation capacity of concrete slabs under rigid missile impact. The slab with T-headed bars presented a slight improvement compared to the baseline specimen without transverse reinforcement. The slab with conventional stirrups presented slightly lower perforation capacity (higher residual missile velocity) than the slab without transverse reinforcement. In conclusion, the performed tests show slightly

  7. Lifetime Reliability Assessment of Concrete Slab Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    A procedure for lifetime assesment of the reliability of short concrete slab bridges is presented in the paper. Corrosion of the reinforcement is the deterioration mechanism used for estimating the reliability profiles for such bridges. The importance of using sensitivity measures is stressed....... Finally the produce is illustrated on 6 existing UK bridges....

  8. Use of wet concrete spraying in building technology of reinforced-concrete fiber slabs according to «Monofant» system

    OpenAIRE

    BUGAYEVSKIY S.

    2016-01-01

    Technology of cementation of reinforced-concrete slabs with non-extractable-liners for the «Monofant» system, using wet concrete spraying is implemented. A compression test for obtained columns made of fiber concrete is carried out.

  9. Shear strength of end slabs of prestressed concrete reactor vessels

    International Nuclear Information System (INIS)

    Cheung, K.C.; Gotschall, H.L.; Liu, T.C.

    1975-01-01

    Prestressed concrete reactor vessels (PCRV's) have been adopted for primary containments in most large high-temperature gas-cooled reactor installations. The most common configuration for PCRVs is a right-vertical cylinder with thick end slabs. In order to assess the integrity of a PCRV it is necessary to predict the ultimate strength of the end slabs. The complexity of the basic mechanism of shear failure in the PCRV end slabs has thus far prohibited the development of a completely analytical solution. However, many experimental investigations of PCRV end slabs have been conducted over the past decade. This information makes it possible to establish empirical formulae for the ultimate strength of PCRV end slabs. The basis and development of an empirical shear-flexure interaction expression is presented. (Auth.)

  10. Simulation analysis of impact tests of steel plate reinforced concrete and reinforced concrete slabs against aircraft impact and its validation with experimental results

    International Nuclear Information System (INIS)

    Sadiq, Muhammad; Xiu Yun, Zhu; Rong, Pan

    2014-01-01

    Highlights: • Simulation analysis is carried out with two constitutive concrete models. • Winfrith model can better simulate nonlinear response of concrete than CSCM model. • Performance of steel plate concrete is better than reinforced concrete. • Thickness of safety related structures can be reduced by adopting steel plates. • Analysis results, mainly concrete material models should be validated. - Abstract: The steel plate reinforced concrete and reinforced concrete structures are used in nuclear power plants for protection against impact of an aircraft. In order to compare the impact resistance performance of steel plate reinforced concrete and reinforced concrete slabs panels, simulation analysis of 1/7.5 scale model impact tests is carried out by using finite element code ANSYS/LS-DYNA. The damage modes of all finite element models, velocity time history curves of the aircraft engine and damage to aircraft model are compared with the impact test results of steel plate reinforced concrete and reinforced concrete slab panels. The results indicate that finite element simulation results correlate well with the experimental results especially for constitutive winfrith concrete model. Also, the impact resistance performance of steel plate reinforced concrete slab panels is better than reinforced concrete slab panels, particularly the rear face steel plate is very effective in preventing the perforation and scabbing of concrete than conventional reinforced concrete structures. In this way, the thickness of steel plate reinforced concrete structures can be reduced in important structures like nuclear power plants against impact of aircraft. It also demonstrates the methodology to validate the analysis procedure with experimental and analytical studies. It may be effectively employed to predict the precise response of safety related structures against aircraft impact

  11. Investigation on reinforced concrete slabs subjeted to impact loading

    International Nuclear Information System (INIS)

    Freiman, M.; Krutzik, N.J.; Tropp, R.; Zorn, N.F.

    1984-01-01

    A comparison of experimental and computational results for tests of reinforced concrete slabs subjected to soft missile impact is presented. Numerical simulation techniques were employed to predict the target response. The objective of the calculations was to validate the material model for reinforced concrete implemented in a finite difference code. The computational results regarding displacements or strains in the reinforcement conform satisfactorily with the experimental values. (Author) [pt

  12. EXPERIMENTAL RESEARCH OF THE THREE-DIMENSIONAL PERFORMANCE OF COMPOSITE STEEL AND CONCRETE STRUCTURES

    Directory of Open Access Journals (Sweden)

    Zamaliev Farit Sakhapovich

    2012-12-01

    steel-concrete slabs limits their use in the construction of residential housing. This article describes the composition, geometry, reinforcement, and anchors to enable the use of concrete slabs and steel beams. The article contains photographs that illustrate the load distribution model. Methods of testing of fiber strains of concrete slabs and steel profiles, deflections of beams, shear stresses in the layers of the "steel-to-concrete" contact area that may involve slab cracking are analyzed. Dynamics of fiber deformations of concrete slabs, steel beams, and layers of the "steel-to-concrete" contact areas, deflection development patterns, initial cracking and crack development to destruction are analyzed. The author also describes the fracture behavior of the floor model. Results of experimental studies of the three-dimensional overlapping of structural elements are compared to the test data of individual composite beams. Peculiarities of the stress-strain state of composite steel and concrete slabs, graphs of strains and stresses developing in sections of middle and external steel-and-concrete beams, deflection graphs depending on the loading intensity are provided. The findings of the experimental studies of the three-dimensional performance of composite steel-and-concrete slabs are provided, as well.

  13. Development and Evaluation of Cement-Based Materials for Repair of Corrosion-Damaged Reinforced Concrete Slabs

    OpenAIRE

    Liu, Rongtang; Olek, J.

    2001-01-01

    In this study, the results of an extensive laboratory investigation conducted to evaluate the properties of concrete mixes used as patching materials to repair reinforced concrete slabs damaged by corrosion are reported. Seven special concrete mixes containing various combinations of chemical or mineral admixtures were developed and used as a patching material to improve the durability of the repaired slabs. Physical and mechanical properties of these mixes, such as compressive strength, stat...

  14. What Is Low Profile Access Flooring and Why More Businesses Need It

    OpenAIRE

    NetfloorUSA

    2017-01-01

    Low profile access flooring is being commonly used in a variety of businesses today. To understand why more businesses, need this type of flooring, it is essential that we take the time to first understand what is low profile flooring actually is. What Is Low Profile Access Flooring A low profile access floor is a floor that is designed to sit above the original concrete slab flooring installed in any home, business, or public building. The higher floor height creates a space between ...

  15. Numerical Analysis of Effectiveness of Strengthening Concrete Slab in Tension of the Steel-Concrete Composite Beam Using Pretensioned CFRP Strips

    Directory of Open Access Journals (Sweden)

    Jankowiak Iwona

    2017-12-01

    Full Text Available One of the methods to increase the load carrying capacity of the reinforced concrete (RC structure is its strengthening by using carbon fiber (CFRP strips. There are two methods of strengthening using CFRP strips - passive method and active method. In the passive method a strip is applied to the concrete surface without initial strains, unlike in the active method a strip is initially pretensioned before its application. In the case of a steel-concrete composite beam, strips may be used to strengthen the concrete slab located in the tension zone (in the parts of beams with negative bending moments. The finite element model has been developed and validated by experimental tests to evaluate the strengthening efficiency of the composite girder with pretensioned CFRP strips applied to concrete slab in its tension zone.

  16. Numerical Analysis of Effectiveness of Strengthening Concrete Slab in Tension of the Steel-Concrete Composite Beam Using Pretensioned CFRP Strips

    Science.gov (United States)

    Jankowiak, Iwona; Madaj, Arkadiusz

    2017-12-01

    One of the methods to increase the load carrying capacity of the reinforced concrete (RC) structure is its strengthening by using carbon fiber (CFRP) strips. There are two methods of strengthening using CFRP strips - passive method and active method. In the passive method a strip is applied to the concrete surface without initial strains, unlike in the active method a strip is initially pretensioned before its application. In the case of a steel-concrete composite beam, strips may be used to strengthen the concrete slab located in the tension zone (in the parts of beams with negative bending moments). The finite element model has been developed and validated by experimental tests to evaluate the strengthening efficiency of the composite girder with pretensioned CFRP strips applied to concrete slab in its tension zone.

  17. Timber floors strengthened with concrete

    NARCIS (Netherlands)

    Blass, H.J.; Linden, M.L.R. van der; Schlager, M.

    1998-01-01

    Timber-concrete composite (tcc) beams may be used for the renovation of old timber floors. Although these systems are not new (Pokulka, 1997) and form a simple and practical solution, they are not widely adopted. One of the reasons for this is the Jack of uniform design rules. In this research

  18. Timber-concrete composite floor systems

    NARCIS (Netherlands)

    Linden, M.L.R. van der; Blass, H.J.

    1996-01-01

    Timber-concrete composite (tcc) beams may be used for the renovation of old timber floors. Although these systems are a simple and practical solution, they are not widely adopted. One of the reasons for this is the lack of uniform design mies. In this research programme shear tests on four different

  19. Behaviour of fiber reinforced concrete slabs under impact loading

    International Nuclear Information System (INIS)

    Huelsewig, M.; Stilp, A.; Pahl, H.

    1982-01-01

    The behaviour of steel fiber reinforced concrete slabs under impact loads has been investigated. The results obtained show that fracturing and spallation effects are reduced to a large extend due to the high energy absorption and the increased yield strength of this material. Crater depths are comparable to those obtained using normal concrete targets. Systematic tests using different fiber types and dimensions show that the terminal ballistic behaviour is strongly dependent on these parameters. (orig.) [de

  20. Structural response of reinforced concrete slabs to impulsive loads

    International Nuclear Information System (INIS)

    Florence, A.L.

    1977-01-01

    The structure treated here is a clamped circular slab of reinforced concrete. The loading is a rectangular pulse uniformly distributed over a central area. The practical value of this problem is that it probably represents a most severe loading case for bending response among more realistic cases, because it replaces the local loaded area with a circular area at the slab center, and because it replaces the pulse with a rectangular pulse of the same peak pressure and impulse. In the theoretical treatment the pulse is assumed to produce plastic deformations large enough to neglect elastic deformation but small enough to neglect membrane action. Yielding of the reinforced concrete slab is assumed to be governed by the Johansen criterion and the associated flow rule. For simplicity, the analysis is restricted to isotropic slabs with top and bottom steel reinforcement arranged to provide the same yield moment magnitude for positive and negative curvature changes. A consequence of the assumed rigid-perfectly plastic behavior is that the deformation modes may be considered as simple mechanism governed by a yield circle. Moreover, the yield circle is stationary while the constant pressure is being applied and expands to the support once the pressure is removed. After the yield circle has arrived at the support, the remaining deformation occurs in the static collapse mode. The principal results are explicit simple formulas for permanent central deflection in terms of pressure, duration, loaded area radius, and plate properties (radius, density, yield moment)

  1. Radon exhalation study from cement, cement slabs and concrete slabs with variation in fly ash

    International Nuclear Information System (INIS)

    Sharma, Nisha; Singh, Jaspal

    2012-01-01

    Fly ash is a waste product from coal-fired power plants. Fly ash has become a subject of world-wide interest in recent years because of its diverse uses, e.g. in the manufacture of concrete for building purposes, for the filling of underground cavities, or as a component of building material. The fly ash may contain enhanced levels of the natural radionuclides in the uranium and thorium series and by using the fly ash in building materials, the radiation levels in houses may thus be technologically enhanced. Because of its relatively high radionuclide contents (including 226 Ra), fly ash may, however, present a potential hazard to the population through its radon emanation, which would be highly undesirable. Since fly ash is frequently used as a building material, the idea of the experiment was to mix fly ash in different proportions in the cement in the powder form, cemented slabs and concrete slabs to study the combined behaviors. Alpha sensitive LR-115 type II plastic track detector, commonly known as Solid State Nuclear Track Detectors (SSNTDs), were used to measure the radon concentration. The alpha particles emitted from the radon causes the radiation damaged tracks. The chemical etching in NaOH at 60°C for about 90 minutes was done to reveal these latent tracks, which were then scanned and counted by an optical microscope of suitable magnification. By calculating the track density of registered tracks, the radon concentrations were determined. In case of cement in the powder form and in cemented slab, starting from the pure cement, fly ash was added up to 70% by weight. In this case the radon exhalation rate has increased by addition of fly ash in the cement and in case of concrete slabs by the addition of fly ash in the cement the radon exhalation increases up to 60% and then decreases. Therefore, on the basis of our investigations we concluded that in general radon exhalation rate increases with the addition of fly ash. (author)

  2. Smart concrete slabs with embedded tubular PZT transducers for damage detection

    Science.gov (United States)

    Gao, Weihang; Huo, Linsheng; Li, Hongnan; Song, Gangbing

    2018-02-01

    The objective of this study is to develop a new concept and methodology of smart concrete slab (SCS) with embedded tubular lead zirconate titanate transducer array for image based damage detection. Stress waves, as the detecting signals, are generated by the embedded tubular piezoceramic transducers in the SCS. Tubular piezoceramic transducers are used due to their capacity of generating radially uniform stress waves in a two-dimensional concrete slab (such as bridge decks and walls), increasing the monitoring range. A circular type delay-and-sum (DAS) imaging algorithm is developed to image the active acoustic sources based on the direct response received by each sensor. After the scattering signals from the damage are obtained by subtracting the baseline response of the concrete structures from those of the defective ones, the elliptical type DAS imaging algorithm is employed to process the scattering signals and reconstruct the image of the damage. Finally, two experiments, including active acoustic source monitoring and damage imaging for concrete structures, are carried out to illustrate and demonstrate the effectiveness of the proposed method.

  3. Evaluation of precast concrete slabs using a heavy vehicle simulator

    CSIR Research Space (South Africa)

    Kohler, E

    2008-10-01

    Full Text Available Precast slabs are considered an attractive pavement option for rehabilitation or reconstruction cases where traffic closures of less than eight hours are required. Benefits include long life expectancy of concrete cast in factory...

  4. Thermal and strength performance of reinforced self-compacting concrete slabs mixed with basalt and PVA fibers in high intensity fire

    Directory of Open Access Journals (Sweden)

    Mohd Jani Noraniza

    2017-01-01

    Full Text Available Fibers addition to concrete and the innovation of self-compacting concrete technology lead to the development of high-performance concrete. However, high intensity fire may adversely affect the performance of this type of concrete. A series of fire resistance test experiments to evaluate the performance of fiber reinforced self-compacting concrete (FR-SCC slabs consisting of various mix of basalt and PVA fibers were carried out by subjecting the concrete slabs as an element of construction to high intensity Hydrocarbon fire heating condition. The fire testing condition was in accordance with the standard time-temperature fire curve for 120 minutes up to 1100°C heating temperature. The temperatures on the surface and within the concrete slabs were recorded and the performance of each type of FRSCC slabs were evaluated. The performance of Basalt FR-SCC was found to be more resistant to fire in comparison to PVA FRSCC. There residual compressive strength of core samples were tested and SEM analysis were carried out to determine the effect of high intensity fire on the basalt and PVA FR-SCC slabs.

  5. Numerical Investigation on Detection of Prestress Losses in a Prestressed Concrete Slab by Modal Analysis

    Science.gov (United States)

    Kovalovs, A.; Rucevskis, S.; Akishin, P.; Kolupajevs, J.

    2017-10-01

    The paper presents numerical results of loss of prestress in the reinforced prestressed precast hollow core slabs by modal analysis. Loss of prestress is investigated by the 3D finite element method, using ANSYS software. In the numerical examples, variables initial stresses were introduced into seven-wire stress-relieved strands of the concrete slabs. The effects of span and material properties of concrete on the modal frequencies of the concrete structure under initial stress were studied. Modal parameters computed from the finite element models were compared. Applicability and effectiveness of the proposed method was investigated.

  6. Calculations of concrete containment tight loss: Studies of a reinforced concrete slab with non uniform thickness

    International Nuclear Information System (INIS)

    Jamet, P.; Berriaud, C.; Humbert, J.M.; Millard, A.; Nahas, G.

    1983-01-01

    A study was carried out in order to investigate the validity of a concrete model including tensile fracture and strain-softening under compressive loading. Triaxial tests were performed on micro-concrete specimens, and the post-peak behaviour of the material was characterized. The parameters required by the model were therefore obtained. The case of a circular slab loaded up to failure was then considered, in order to compare the numerical results obtained by a finite elements analysis including the concrete model, to the experimental data. (orig.)

  7. Calculations of concrete containment tight loss: studies of a reinforced concrete SLAB with non uniform thickness

    International Nuclear Information System (INIS)

    Jamet, P.

    1983-08-01

    A study was carried out in order to investigate the validity of a concrete model including tensile fracture and strain-softening under compressive loading. Triaxial tests were performed on micro-concrete specimens, and the post-peak behaviour of the material was characterized. The parameters required by the model were therefore obtained. The case of a circular slab loaded up to failure was then considered, in order to compare the numerical results obtained by a finite elements analysis including the concrete model, to the experimental data

  8. Identification of Delamination in Concrete Slabs by SIBIE Procedure

    International Nuclear Information System (INIS)

    Yamada, M.; Yagi, Y.; Ohtsu, M.

    2017-01-01

    The Impact-Echo method is known as a non-destructive testing for concrete structures. The technique is based on the use of low-frequency elastic waves that propagate in concrete to determine the thickness and to detect internal flaws in concrete. The presence and locations of defects in concrete are estimated from identifying peak frequencies in the frequency spectra, which are responsible for the resonance due to time-of-flight from the defects. In practical applications, however, obtained spectra include so many peak frequencies that it is fairly difficult to identify the defects correctly. In order to improve the Impact-Echo method, Stack Imaging of spectral amplitudes Based on Impact-Echo (SIBIE) procedure is developed as an imaging technique applied to the Impact-Echo data, where defects in concrete are identified visually at the cross-section. In this study, the SIBIE procedure is applied to identify the delamination in a concrete slab. It is demonstrated that the delamination can be identified with reasonable accuracy. (paper)

  9. Differential dose albedo for high-energy X-rays on concrete slab

    International Nuclear Information System (INIS)

    Kato, Hideki

    2006-01-01

    We computed the differential dose albedo (α D ) for high-energy X-rays on a concrete slab when the incident angle, reflection angle, and azimuth angle were changed, by means of Monte Carlo simulation. We found that α D changed with incident, reflection, and azimuth angles to the concrete slab. On the whole, the larger the incident angle, the larger α D tended to become. If the incident angle and reflection angle were the same, the larger the azimuth angle, the smaller α D tended to become. When the incident, reflection, and azimuth angles were the same, the smaller the X-ray energy was, the larger α D became, in the order of 10 MV, 6 MV, and 4 MV X-rays. (author)

  10. The Impact of Concrete Pavement Field Floor to Vehicle Missile Launching Process

    Directory of Open Access Journals (Sweden)

    Wei Xinlin

    2017-01-01

    Full Text Available The conception and evaluation indices of the bearing capacity of the concrete pavement field floor are analyzed in this paper. In order to get the damage process of the concrete panel, its tension and compression injury factors are derived, and a field floor structural dynamic model with concrete damage constitutive relation is built based on ABAQUS, and the influence of thickness and Young’s modulus of the concrete panel to the vehicular missile launching is comparatively analyzed.

  11. Documentation for Calculations of Standard Fire Resistance of Slabs and Walls of Concrete with Expanded Clay Aggregate

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl

    A number of full-scale tests are made in order to document calculation methods for fire-exposed slabs and walls derived during a previous project on fire exposed light-weight aggregate concrete constructions. The calculation methods are derived, and thus have a logical connection with the calcula......A number of full-scale tests are made in order to document calculation methods for fire-exposed slabs and walls derived during a previous project on fire exposed light-weight aggregate concrete constructions. The calculation methods are derived, and thus have a logical connection...... with the calculation methods used for other load cases. In addition the methods are shown to be valid for heavy concrete constructions by cooperation with tests for beams and columns, and a few slabs and walls. The two test series phase 1 and 2 of this report can therefore be seen as a necessary supplement to show...... that the methods are applicable for slabs and walls of light weight aggregate concrete. It is shown that the temperatures for standard fire exposed cross sections can be calculated, that the ultimate moment capacity can be calculated for slabs, and that the anchorage capacity and the shear tension capacity can...

  12. Prestressing of reinforcing bars in concrete slabs due to concrete expansion induced by Alkali-Silica Reaction

    DEFF Research Database (Denmark)

    Gustenhoff Hansen, Søren; Antonio Barbosa, Ricardo; Hoang, Linh Cao

    2017-01-01

    Alkali-silica reactions (ASR) in concrete bridges have been a major concern worldwide for many decades. In Denmark, several bridges are severely damaged due to ASR and over 600 bridges have the potential to develop ASR in the future. The majority of these bridges are slab-bridges. Despite the many...... cases, experimental research on structural safety and residual load carrying capacity of ASR-damaged bridges is limited. As ASR causes severe cracks in the concrete, which may affect the concrete compressive and tensile strength, concerns have been directed towards the residual shear capacity. Yet...

  13. Transport of radon through cracks in a concrete slab

    Energy Technology Data Exchange (ETDEWEB)

    Landman, K A; Cohen, D S

    1983-03-01

    A model involving the use of line sources is developed to describe the transport of radon through the cracks or gaps which appear in concrete slabs used in building foundations. The strength of these sources is determined from the results of the diffusion model proposed by Landman in a previous work. Once the strength of the source is known, additional transport mechanisms can be treated in a simple manner. Pressure differences across the slab and in the underlying soil are discussed. The rate of exhalation through a portion of the cracked slab is determined and compared to the rate of exhalation from the same surface area of bare soil. In typical cases, their ratios vary from 0.25 to 0.50. Therefore, these transport mechanisms account for a larger portion of the levels of radon found in many houses than do previous models.

  14. Causes of Early-Age Thermal Cracking of Concrete Foundation Slabs and their Reinforcement to Control the Cracking

    Science.gov (United States)

    Bilčík, Juraj; Sonnenschein, Róbert; Gažovičová, Natália

    2017-09-01

    This paper focuses on the causes and consequences of early-age cracking of mass concrete foundation slabs due to restrained volume changes. Considering the importance of water leaking through cracks in terms of the serviceability, durability and environmental impact of watertight concrete structures, emphasis is placed on the effect of temperature loads on foundation slabs. Foundation slabs are usually restrained to some degree externally or internally. To evaluate the effect of external restraints on foundation slabs, friction and interaction models are introduced. The reinforcement of concrete cannot prevent the initiation of cracking, but when cracking has occurred, it may act to reduce the spacing and width of cracks. According to EN 1992-1-1, results of calculating crack widths with local variations included in National Annexes (NAs) vary considerably. A comparison of the required reinforcement areas according to different NAs is presented.

  15. Nondestructive analysis of alkali-silica reaction damage in concrete slabs using shear waves

    Science.gov (United States)

    Khazanovich, Lev; Freeseman, Katelyn; Salles, Lucio; Clayton, Dwight

    2018-04-01

    Alkali-silica reaction (ASR) is the chemical reaction that occurs in concrete. It is caused by the interaction of alkalis in Portland cement and silica in aggregates and results in microcracks within the material. This type of damage has been the focus of nondestructive evaluation efforts in recent history, but no work was done on in-situ structures or large-scale samples. To address these limitations, an ultrasonic linear array device, MIRA, was utilized for this research. An experimental investigation was performed on four slabs with various levels of alkali-silica reaction at the Electric Power Research Institute (EPRI) [1]. One-period impulses with a target of 50kHz center frequency were selected in this study. We propose the use of the Hilbert Transform Indicator (HTI) for quantification of ASR damage [2]. A higher HTI value would be indicative of damaged concrete, while a low value represents sound concrete. In general, values below 90 are regarded as an indicator of sound concrete while values above 100 indicate the presence of damage [3]. The ability of the HTI values to distinguish between areas of damaged concrete was evident via the production of color intensity maps. The maps show that the control specimen, was in good condition, while other slabs exhibited higher levels of damage as indicated by the HTI values. It should be noted that extreme damage conditions were not present in any of the slabs. Evaluation of migration-based reconstructions can give a qualitative characterization of large scale or excessive subsurface damage. However, for detection of stochastic damage mechanisms such as freeze-thaw damage, evaluation of the individual time-history data can provide additional information. A comparison of the spatially diverse measurements on several concrete slabs with varying freeze-thaw damage levels is given in this study. Signal characterization scans of different levels of freeze-thaw damage at various transducer spacing is investigated. The

  16. Causes of Early-Age Thermal Cracking of Concrete Foundation Slabs and their Reinforcement to Control the Cracking

    Directory of Open Access Journals (Sweden)

    Bilčík Juraj

    2017-09-01

    Full Text Available This paper focuses on the causes and consequences of early-age cracking of mass concrete foundation slabs due to restrained volume changes. Considering the importance of water leaking through cracks in terms of the serviceability, durability and environmental impact of watertight concrete structures, emphasis is placed on the effect of temperature loads on foundation slabs. Foundation slabs are usually restrained to some degree externally or internally. To evaluate the effect of external restraints on foundation slabs, friction and interaction models are introduced. The reinforcement of concrete cannot prevent the initiation of cracking, but when cracking has occurred, it may act to reduce the spacing and width of cracks. According to EN 1992-1-1, results of calculating crack widths with local variations included in National Annexes (NAs vary considerably. A comparison of the required reinforcement areas according to different NAs is presented.

  17. Shear strength of end slabs of prestressed concrete nuclear reactor vessels

    International Nuclear Information System (INIS)

    Reins, J.D.; Quiros, J.L. Jr.; Schnobrich, W.C.; Sozen, M.A.

    1976-07-01

    The report summarizes the experimental and part of the analytical work carried out in connection with an investigation of the structural strength of prestressed concrete reactor vessels. The project is part of the Prestressed Concrete Reactor Vessel Program of the Oak Ridge National Laboratory sponsored by ERDA. The objective of the current phase of the work is to develop procedures to determine the shear strength of flat end slabs of reactor vessels with penetrations

  18. Impact resistance performance of green construction material using light weight oil palm shells reinforced bamboo concrete slab

    International Nuclear Information System (INIS)

    Muda, Z C; Usman, F; Beddu, S; Alam, M A; Thiruchelvam, S; Sidek, L M; Basri, H; Saadi, S

    2013-01-01

    This paper investigate the performance of lightweight oil palm shells (OPS) concrete with varied bamboo reinforcement content for the concrete slab of 300mm x 300mm size reinforced with different thickness subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.2 kg drop at 1 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance against the amount of bamboo reinforcement and slab thickness. A linear relationship has been established between first and ultimate crack resistance against bamboo diameters and slab thickness by the experiment. The linear relationship has also been established between the service (first) crack and ultimate crack resistance against the bamboo reinforcement diameter for a constant spacing for various slab thickness using 0.45 OPS and 0.6 OPS bamboo reinforced concrete. The increment in bamboo diameter has more effect on the first crack resistance than the ultimate crack resistance. The linear relationship has also been established between the service (first) crack and ultimate crack resistance against the various slab thickness. Increment in slab thickness of the slab has more effect on the crack resistance as compare to the increment in the diameter of the bamboo reinforcement.

  19. Damage detection in concrete precast slabs: a quick assessment through modal tests

    Directory of Open Access Journals (Sweden)

    Leal Pimentel Roberto

    2015-01-01

    Full Text Available The use of modal tests for detecting damage in reinforced concrete precast slabs is evaluated. A set of eight slabs were tested, each belonging to flats constructed for residential use. Two groups of slabs were identified and, in each group, both cracked and uncracked slabs were found. This made it possible to compare the responses of the slabs when subjected to modal tests. The tests were carried out employing an instrumented hammer and heel drops as excitation sources. Responses were measured using an accelerometer. The lowest natural frequencies of the slabs could be identified and after filtering the results, plots indicating the variation of the lowest natural frequency versus the number of cycles of free decay were obtained for each slab. Such a plot is of more general use than the value of the natural frequency by itself, as it does not depend on slab configuration. It was observed that the cracked slabs presented a similar pattern of variation of the natural frequencies throughout the decay, being distinctive from the pattern observed for their uncracked counterparts. This provided evidence that a quick assessment of the structural condition of such slabs through the use of the tests were feasible.

  20. structural behavior of fibrous reinforced concrete hollowcore one-way slabs strengthening by C.F.R.P

    Directory of Open Access Journals (Sweden)

    wassif khudair majeed

    2016-02-01

    Full Text Available Abstract A reinforced concrete hollow core one-way slab is one of the types of slabs used widely around the world in residential and industrial buildings to take advantage of them Economic and thermal insulation as well as to reduce the self weight of the construction . The aim of the present study is to examine the structural behavior of the reinforced concrete hollow core one-way slabs  reduce failure using the normal concrete and fibrous concrete and then strengthened using carbon fiber(CFRP This study include molding of ( 6 specimens differ in terms of the voids volume (Vv , volumetric percentage of steel fibers ( , and then strengthened by using fibers of carbon , with the aim of rehabilitation by fibers, carbon polymer (CFRP is to find out how efficient element structural when treated after the occurrence of the failure and the validity of its use in the event of a failure has occurred entirely or partly in the roof, and re- examined using the same method and conditions that were examined ceilings is affected through it, knowing that these ceilings have been addressed and strengthened in the same way , the results of the tests of the models that have been rehabilitated using carbon fiber (CFRP, compared with the same models before strengthening and examined reduce failure, increased very high susceptibility endurance extreme , with the increase ranging from (51.6% to ( 96.2% , as has been observed decrease in deflection value of models after strengthening by (CFRP. It is concluded through this study the possibility of using its concrete hollow core one-way slab as a roofing system for buildings also proved the highly efficient for this slab after rehabilitation using carbon fiber (CFRP .

  1. Characteristics of Recycled Concrete Aggregates from Precast Slab Block Buildings

    Science.gov (United States)

    Venkrbec, Václav; Nováková, Iveta; Henková, Svatava

    2017-10-01

    Precast slab block buildings (PSBB) typically and frequently occur in Central and Eastern Europe, as well as elsewhere in the world. Some of these buildings are currently used beyond their service life capacity. The utilization of recycled materials from these buildings with regard to applying the principles of sustainable construction and using recycled materials will probably be significant in the following years. Documentation from the manufacturing processes of prefabricated blocks for precast slab block buildings is not available, and also it is difficult to declare technological discipline during the construction of these buildings. Therefore, properties of recycled concrete aggregates (RCA) produced from construction and demolition waste (C&DW) of precast slab block buildings build between 1950s to 1990s are not sufficiently known. The demolition of these buildings is very rare today, but it can be assumed an increase in demolitions of these buildings in the future. The use of RCA in new concrete requires verification/testing of the geometrical and physical properties of RCA according to the EN 12 620+A1 standard. The aim of the contribution is to present a case study of the demolition of slab block building with emphasis on RCA usage. The paper presents the results of the tests according to European standards for determining selected geometrical and physical properties of the RCA. The paper describes and evaluates tests such as determination of particle size distribution - Sieve Analysis, content of fine particles, determination of density and water absorption. The results of the properties testing of RCA are compared with the properties of natural aggregate. The general boundary conditions of RCA particular tests are presented.

  2. Empirical Strengths of Concrete Roof Slabs After 34 Years Service ...

    African Journals Online (AJOL)

    The results were compared with those from standard compressive strength machine in the laboratory, and subjected to statistical analysis. The final results showed that the lowest slab compressive strength was 14 N/mm2 below the minimum concrete grade of 25N/mm2; and percentage defective was 29.5% more than the ...

  3. Analytical model for shear strength of end slabs of prestressed concrete nuclear reactor vessels

    International Nuclear Information System (INIS)

    Abdulrahman, H.O.; Sozen, M.A.; Schnobrich, W.C.

    1979-04-01

    The results are presented of an investigation of the behavior and strength of flat end slabs of cylindrical prestressed concrete nuclear reactor vessels. The investigation included tests of ten small-scale pressure vessels and development of a nonlinear finite-element model to simulate the deformation response and strength of the end slabs. Because earlier experimental studies had shown that the flexural strength of the end slab could be calculated using intelligible procedures, the emphasis of this investigation was on shear strength

  4. Total Strain FE Model for Reinforced Concrete Floors on Piles

    NARCIS (Netherlands)

    Hofmeyer, H.; Bos, van den A.A.

    2008-01-01

    A finite element (FE) model using a total strain material model has been developed to predict the behavior of warehouse reinforced concrete floors on piles. The material model (not the FE model itself) was calibrated to material tests. The FE model for the floor structure was checked with full-scale

  5. Thermal protection system for the concrete core support floor at Fort St. Vrain

    International Nuclear Information System (INIS)

    Jones, H.; Hedgecock, P.D.

    1976-01-01

    A unique feature of the Fort St. Vrain HTGR is its steel jacketed concrete core support floor. The construction of this floor generally resembles that of the prestressed concrete reactor vessel, but its location immediately below the core hot gas outlets generates some particularly severe thermal protection requirements. A thermal barrier is used over the entire outer surface of the floor and in the twelve hot gas ducts which convey the primary coolant through the floor to the steam generators. A cooling water system of square tubes welded to the inside of the steel jacket is used to remove that heat which does pass through the thermal barrier and to maintain the concrete at acceptable temperatures. The design approach to the floor itself and to the thermal barriers and cooling system will be described, but the main emphasis of the paper will be on the total experience gained during construction and pre-operational testing. A particular problem experienced during construction was leakage from some cooling tubes, after their embedment in concrete. The solution to that problem was to develop a method for injecting catalyzed epoxy into the leaking tube. This method, which has general usefulness for in-service repairs, will be described. (author)

  6. Embodied Energy Optimization of Prestressed Concrete Slab Bridge Decks

    Directory of Open Access Journals (Sweden)

    Julián Alcalá

    2018-04-01

    Full Text Available This paper presents one approach to the analysis and design of post-tensioned cast-in-place concrete slab bridge decks. A Simulated Annealing algorithm is applied to two objective functions: (i the economic cost; and (ii the embodied energy at different stages of production materials, transport, and construction. The problem involved 33 discrete design variables: five geometrical ones dealing with the thickness of the slab, the inner and exterior web width, and two flange thicknesses; concrete type; prestressing cables, and 26 variables for the reinforcement set-up. The comparison of the results obtained shows two different optimum families, which indicates that the traditional criteria of economic optimization leads to inefficient designs considering the embodied energy. The results indicate that the objectives are not competing functions, and that optimum energy designs are close to the optimum cost designs. The analysis also showed that the savings of each kW h of energy consumed carries an extra cost of 0.49€. The best cost solution presents 5.3% more embodied energy. The best energy solution is 9.7% more expensive than that of minor cost. In addition, the results have showed that the best cost solutions are not the best energy solutions.

  7. Structural Behavior of Fibrous Reinforced Concrete Hollow Core One-Way Slabs Strengthening by C.F.R.P

    Directory of Open Access Journals (Sweden)

    وصيف مجيد

    2016-02-01

    Full Text Available A reinforced concrete hollow core one-way slab is one of the types of slabs used widely around the world in residential and industrial buildings to take advantage of them Economic and thermal insulation as well as to reduce the self-weight of the construction. The aim of the present study is to examine the structural behavior of the reinforced concrete hollow core one-way slabs reduce failure using the normal concrete and fibrous concrete and then strengthened using carbon fiber(CFRPThis study include molding of ( 6 specimens differ in terms of the voids volume (Vv , volumetric percentage of steel fibers (ا, and then strengthened by using fibers of carbon , with the aim of rehabilitation by fibers, carbon polymer (CFRP is to find out how efficient element structural when treated after the occurrence of the failure and the validity of its use in the event of a failure has occurred entirely or partly in the roof, and re- examined using the same method and conditions that were examined ceilings is affected through it, knowing that these ceilings have been addressed and strengthened in the same way , the results of the tests of the models that have been rehabilitated using carbon fiber (CFRP, compared with the same models before strengthening and examined reduce failure, increased very high susceptibility endurance extreme , with the increase ranging from (51.6% to (96.2%, as has been observed decrease in deflection value of models after strengthening by (CFRP.It is concluded through this study the possibility of using its concrete hollow core one-way slab as a roofing system for buildings also proved the highly efficient for this slab after rehabilitation using carbon fiber (CFRP.

  8. Modeling of Combined Impact and Blast Loading on Reinforced Concrete Slabs

    Directory of Open Access Journals (Sweden)

    P. Del Linz

    Full Text Available Abstract Explosive devices represent a significant threat to military and civilian structures. Specific design procedures have to be followed to account for this and ensure buildings will have the capacity to resist the imposed pressures. Shrapnel can also be produced during explosions and the resulting impacts can weaken the structure, reducing its capacity to resist the blast pressure wave and potentially causing failures to occur. Experiments were performed by the Defence Science and Technology Agency (DSTA of Singapore to study this combined loading phenomenon. Slabs were placed on the ground and loaded with approximately 9 kg TNT charges at a standoff distance of 2.1 m. Spherical steel ball bearings were used to reproduce the shrapnel loading. Loading and damage characteristics were recorded from the experiments. A finite element analysis (FEA model was then created which could simulate the effect of combined shrapnel impacts and blast pressure waves in reinforced concrete slabs, so that its results could be compared to experimental data from the blast tests. Quarter models of the experimental concrete slabs were built using LS-Dyna. Material models available in the software were employed to represent all the main components, taking into account projectile deformations. The penetration depth and damage areas measured were then compared to the experimental data and an analytical solution to validate the models.

  9. Vibration behaviour of foamed concrete floor with polypropylene and rise husk ash fibre

    Science.gov (United States)

    Azaman, N. A. Mohd; Ghafar, N. H. Abd; Ayub, N.; Ibrahim, M. Z.

    2017-11-01

    In the history of the construction industry, lightweight concrete or foamed concrete is a special concrete which can very useful in the construction sector because it is very lightweight and it can compact by itself at each angle of foamwork. Foamed concrete is one of lightweight concrete which widely used for floor construction due to its light weight and economic. The significant challenges in the floor design process are considering the vibration that needs improvements for the poor dynamic behaviour insulation. An alternative material to replace sand with certain amount of rice husk ash (RHA) and polypropylene was introduced. Research was determine the dynamic behavior of foam-polypropylene and foam-RHA concrete by using impact hammer test. The natural frequency for normal foamed concrete, 0.5 % of Polypropylene and 15% of RHA is 29.8 Hz, 29.3 Hz and 29.5 Hz respectively.

  10. Cathodic protection of concrete ground floor elements with mixed in chloride

    NARCIS (Netherlands)

    Schuten, G.; Leggedoor, J.; Polder, R.B.

    1999-01-01

    Corrosion of reinforcement in precast concrete ground floor elements containing mixed in chloride can cause considerable damage. This is a major problem in the Netherlands concerning a large number of privately owned houses. Conventional concrete repair is not acceptable because it does not provide

  11. Flexural performance of steel fiber reinforced concrete (SFRC) ribbed slab with various topping thicknesses

    Science.gov (United States)

    Rahman, Fadhillah Abdul; Bakar, Afidah Abu; Hashim, Mohd Hisbany Mohd; Ahmad, Hazrina

    2017-11-01

    Ribbed slab provides lighter slab than an equivalent solid slab which helps in reducing the weight with its voids. However, in order to overcome the drawbacks in the construction process, the application of steel fibre reinforcement concrete (SFRC) is seen as an alternative material to be used in the slab. This study is performed to investigate the behaviour of SFRC as the main material in ribbed slab, omitting the conventional reinforcements, under four-point bending test. Three equivalent samples of ribbed slabs were prepared for this study with variations in the topping thickness of 100, 75 and 50 mm. The flexural strength of ribbed slab with 100 mm topping shows similar loading carrying capacity with the 75mm topping while 50 mm gave the lowest ultimate loading. First cracks for all slabs occurred at the topping. The cracks began from the external ribs and propagates toward the internal rib. Incorporation of steel fibres help in giving a longer deflection softening than a sudden brittle failure, thus proves its ability to increase energy absorption capacity and improving cracking behaviour.

  12. Numerical analysis of pipe impact on reinforced concrete structures

    International Nuclear Information System (INIS)

    Prinja, N.K.

    1990-01-01

    This paper presents the methodology and the results of numerical analyses carried out by using the computer code DYNA3D to analyse pipe impacts on a reinforced concrete slab, a floor beam and a column. Modelling techniques employed to represent various features of typical reinforced concrete (RC) structures and the details of a soil and crushable foam type of material model used to represent concrete material behaviour are described. The results show that a reasonable prediction of global behaviour of reinforced concrete structures under impact loading can be obtained by this numerical method. (author)

  13. Impact resistance of sustainable construction material using light weight oil palm shells reinforced geogrid concrete slab

    International Nuclear Information System (INIS)

    Muda, Z C; Usman, F; Beddu, S; Alam, M A; Mustapha, K N; Birima, A H; Sidek, L M; Rashid, M A; Malik, G; Zarroq, O S

    2013-01-01

    This paper investigate the performance of lightweight oil palm shells (OPS) concrete slab with geogrid reinforcement of 300mm × 300mm size with 20mm, 30mm and 40 mm thick casted with different geogrid orientation and boundary conditions subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.2 kg drop at 1 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance the slab thickness, boundary conditions and geogrid reinforcement orientation. Test results indicate that the used of the geogrid reinforcement increased the impact resistance under service (first) limit crack up to 5.9 times and at ultimate limit crack up to 20.1 times against the control sample (without geogrid). A good linear relationship has been established between first and ultimate crack resistance against the slab thickness. The orientation of the geogrid has minor significant to the crack resistance of the OPS concrete slab. OPS geogrid reinforced slab has a good crack resistance properties that can be utilized as a sustainable impact resistance construction materials.

  14. Study of fire-resistance of reinforced concrete slab of a new type

    Directory of Open Access Journals (Sweden)

    Kalmykov Oleg

    2017-01-01

    Full Text Available Reinforced concrete structures with complex inner geometry under the effect of high temperatures considering void former materials were examined. The analysis of strain-stress state of new type of architectural and construction system ‘Monofant’ under the effect of high temperature heating in standard fire mode, considering the change of design pattern was carried out. Numerical study of concrete slab with given reinforcement and complex inner geometry was carried out with use of software packages based on finite element method. Temperature fields throughout the depth of cross section of the slab of new type of architectural and construction system ‘Monofant’ upon heating in standard fire mode for time interval 0-240 min. were obtained. The carrying capacity of sections exposed to high temperatures was determined by deformation method. Offered the algorithm that considers the transformation of design patterns depending on temperature values and excessive pressure in thermal insulation cavities taking into account influence of deformation fields on temperature distribution.

  15. Non-linear finite element analysis of reinforced concrete members and punching shear strength of HSC slabs

    Directory of Open Access Journals (Sweden)

    Nassim Kernou

    2018-01-01

    Full Text Available A rational three-dimensional nonlinear finite element model (NLFEAS is used for evaluating the behavior of high strength concrete slabs under monotonic transverse load. The non-linear equations of equilibrium have been solved using the incremental-iterative technique based on the modified Newton-Raphson method. The convergence of the solution was controlled by a load convergence criterion. The validity of the theoretical formulations and the program used was verified, through comparison with results obtained using ANSYS program and with available experimental test results. A parametric study was conducted to investigate the effect of different parameters on the behavior of slabs which was evaluated in terms of loaddeflection characteristics, concrete and steel stresses and strains, and failure mechanisms. Also, punching shear resistance of slabs was numerically evaluated and compared with the prediction specified by some design codes.

  16. Experimental and analytical studies on the vibration serviceability of long-span prestressed concrete floor

    Science.gov (United States)

    Cao, Liang; Liu, Jiepeng; Li, Jiang; Zhang, Ruizhi

    2018-04-01

    An extensive experimental and theoretical research study was undertaken to study the vibration serviceability of a long-span prestressed concrete floor system to be used in the lounge of a major airport. Specifically, jumping impact tests were carried out to obtain the floor's modal parameters, followed by an analysis of the distribution of peak accelerations. Running tests were also performed to capture the acceleration responses. The prestressed concrete floor was found to have a low fundamental natural frequency (≈ 8.86 Hz) corresponding to the average modal damping ratio of ≈ 2.17%. A coefficients β rp is proposed for convenient calculation of the maximum root-mean-square acceleration for running. In the theoretical analysis, the prestressed concrete floor under running excitation is treated as a two-span continuous anisotropic rectangular plate with simply-supported edges. The calculated analytical results (natural frequencies and root-mean-square acceleration) agree well with the experimental ones. The analytical approach is thus validated.

  17. New Transition Wedge Design Composed by Prefabricated Reinforced Concrete Slabs

    OpenAIRE

    Real-Herráiz, Julia; Zamorano-Martín, Clara; Real-Herráiz, Teresa; Morales-Ivorra, Silvia

    2016-01-01

    [EN] Important track degradation occurs in structure-embankment transitions, in which an abrupt change in track vertical stiffness arises, leading to a reduction in passengers comfort and safety. Although granular wedges are suggested by different railroad administrations as a solution to avoid these problems, they present some disadvantages which may affect track long-term performance. In this paper, a new solution designed with prefabricated reinforced concrete slabs is proposed. The aim of...

  18. Need to Identify Parameters of Concrete in the Weakest Zone of the Industrial Floor

    Science.gov (United States)

    Stawiski, Bohdan; Radzik, Łukasz

    2017-10-01

    The ways in which industrial floors are exploited leads to the requirement for the highest strength of their upper zone. Physical phenomena occurring during the compaction and hardening of the concrete cause different strength distributions. In the top zone of industrial floors, the strength is significantly lower (over a dozen MPa) than the strength in the bottom zone (several dozen MPa). Standard tests of control samples do not detect this fact. Processes for the application and finishing of embedded mineral-aggregate hardeners (dry shakes) can be regarded as uncontrolled. The effects of the use of dry shakes are not evaluated. In combination with the phenomenon of bleeding, they often fail by delamination. This paper presents the results of industrial floor testing. The ultrasonic pulse velocity method with dry point contact transducers was used. The results show how upper layer strength was reduced, and how dry shakes application affected the strength of the floor. The strength distribution in hardened concrete, which delaminated from the rest of the floor was presented as well. The extension of compulsory control tests of concrete samples was proposed. In the authors’ opinion, particular attention should be paid to 3 centimetres of the upper layer.

  19. The Electret Radon Sniffer as a diagnostic tool for optimizing the efficiency of sub-slab ventilation systems and/or sealing

    International Nuclear Information System (INIS)

    Yates, J.H.; Kotrappa, P.

    1990-01-01

    In this paper a method for the measurement and interpretation of radon levels beneath a poured concrete slab floor is presented, along with application strategies intended to guide the mitigator in his efforts to effect an optimally efficient sealing or sub-slab mitigation system installation in the structure so measured. Case studies are presented for illustrative purposes, and cautions and uncertainties in this method are detailed, along with related areas of inquiry. The presumed greatest utility of this method is in attacking radon in structures evidencing poor sub-slab communication

  20. Dowel Behavior of Rebars in Small Concrete Block for Sliding Slab Track on Railway Bridges

    Directory of Open Access Journals (Sweden)

    Seong-Cheol Lee

    2018-01-01

    Full Text Available In recent years, several studies have investigated the sliding slab track for railway bridges. In the design of sliding slab tracks, one of the most important considerations is to evaluate the shear capacity of the lateral supporting concrete blocks in which dowel rebars are embedded. The predictions of the dowel behavior of rebars by existing models are considerably different. Therefore, in this study, the actual dowel behavior of the rebars embedded in a small concrete block was extensively investigated through experiments. Test variables were concrete compressive strength, dowel rebar diameter and yield strength, specimen thickness, and dowel rebar spacing. Existing model predictions were considerably different from test results. The maximum dowel force increased as concrete compressive strength and dowel rebar diameter increased, while it did not increase considerably with other test variables. Unlike in existing models, the shear slip at the maximum dowel force decreased as the dowel rebar diameter increased. Existing models significantly underestimated the maximum dowel force of the dowel rebars with small diameters and overestimated it for the dowel rebars with large diameters. This work can be useful for developing a more rational model to represent the actual dowel behavior of the rebars embedded in small concrete blocks.

  1. Lightweight self-compacting concrete reinforced with fibres for slab rehabilitation

    International Nuclear Information System (INIS)

    Klein, N. S.; Fuente, A. de la; Aguado, A.; Maso, D.

    2011-01-01

    The slabs of some buildings in Barcelona are formed by unidirectional beams, with a ceramic arch in between, which are filled with broken pottery or construction waste. These structures often present problems such as displacement of the tiles arranged over it due to the lack of stiffness of the filling material. This supposes a risk to the user and could also cause durability problems. In order to rehabilitate it, a lightweight self-compacting concrete reinforced with fibres (HLACF) has been designed to be used as a filling material, improving the stiffness of the structure. This paper presents a structural analysis of a standard case and the results of an experimental campaign. The concrete showed a density of 1665 kg/m3, a slump flow of 605 mm and a compressive strength of 22.3 MPa, at 28 days. These results are in agreement with the requirements, overcoming common lightweight concrete segregation problems. (Author) 24 refs.

  2. Soft projectile impacts analysis on thin reinforced concrete slabs: Tests, modelling and simulations

    International Nuclear Information System (INIS)

    Pontiroli, C.; Rouquand, A.; Daudeville, L.; Baroth, J.

    2012-01-01

    Numerical simulations of reinforced concrete structures subjected to high velocity impacts and explosions remain a difficult task today. For 10 years and more now, the CEA-Gramat has maintained a continuous research effort with the help of different French universities in order to overcome encountered difficulties in modelling the behaviour of concrete structures under severe loading. To get more data on aircraft impact problems and then validate numerical models, soft projectile impacts tests at small scale on thin reinforced concrete slabs has been carried out at CEA-Gramat. Numerical simulations of these tests have been carried out and compared with experimental results to validate our numerical approach. (authors)

  3. Development of concrete mix proportions for minimizing/eliminating shrinkage cracks in slabs and high performance grouts : final report.

    Science.gov (United States)

    2017-02-01

    The two focus areas of this research address longstanding problems of (1) cracking of concrete slabs due to creep and shrinkage and (2) high performance compositions for grouting and joining precast concrete structural elements. Cracking of bridge de...

  4. Tritium contamination of concrete walls and floors in tritium-handling laboratory

    International Nuclear Information System (INIS)

    Kawano, T.; Kuroyanagi, M.; Tabei, T.

    2006-01-01

    relation between surface contamination obtained with the smear method and inner contamination obtained with the direct-immersion method. The results revealed that surface contamination did not correspond to inner contamination. This means that contamination of the concrete walls and floors themselves cannot be evaluated from data on surface contamination. We also evaluated the dependence of tritium contamination in concrete walls and floors on depth. Maximum contamination was frequently found inside walls and floors. It could be inferred that tritium existed in the chemical form of hydrogen molecules (tritium gas) that crept into deeper locations within concrete walls or floors, changed its form to water through an isotope exchange reaction, and remained there. (authors)

  5. Experimental Investigation of Properties of Foam Concrete for Industrial Floors in Testing Field

    Science.gov (United States)

    Vlcek, Jozef; Drusa, Marian; Scherfel, Walter; Sedlar, Bronislav

    2017-12-01

    Foam concrete (FC), as a mixture of cement, water, additives and technical foam, is well known for more than 30 years. It is building material with good mechanical properties, low thermal conductivity, simple and even high technological treatment. Foam concrete contains closed void pores, what allows achieving low bulk density and spare of raw materials. Thanks to its properties, it is usable as a replacement of conventional subbase layers of the industrial floors, the transport areas or as a part of the foundation structures of the buildings. Paper presents the preparation of the testing field (physical model) which was created for experimental investigation of the foam concrete subbase layer of the industrial floor in a real scale.

  6. Behavior of hybrid high-strength fiber reinforced concrete slab-column connections under the effect of high tempera

    Directory of Open Access Journals (Sweden)

    Reham H. Ahmed

    2016-04-01

    Full Text Available Concrete can be modified to perform in a more ductile form by the addition of randomly distributed discrete fibers in the concrete matrix. The combined effect of the addition of two types of fibers (steel fiber and polypropylene fiber with different percentages to concrete matrix, which is called hybrid effect is currently under investigation worldwide. The current research work presents the conducted experimental program to observe the behavior of hybrid high strength reinforced concrete slab-column connections under the effect of high temperature. For this purpose, ten slab-column connections were casted and tested. The experimental program was designed to investigate the effect of different variables such as concrete mixture, column location and temperature fighting system. All specimens were exposed to a temperature of 500 °C for duration of two hours. To observe the effect of each variable, specimens were divided into four groups according to the studied parameters. The test results revealed that using hybrid high strength concrete HFHSC produced more strength in punching failure compared with high strength concrete HSC when exposed to elevated temperature. Fighting by air had higher initial crack load compared with that for without fighting and fighting by water. On the other hand, fighting by water decreased the ultimate load.

  7. Analysis of DCI cask drop test onto reinforced concrete pad

    International Nuclear Information System (INIS)

    Ito, C.; Kato, Y.; Hattori, S.; Shirai, K.; Misumi, M.; Ozaki, S.

    1993-01-01

    In a cask-storage facility, a cask may be subjected to an impact load as a result of a free drop onto the floor because of cask mishandling. We performed drop tests of casks onto a reinforced concrete (RC) slab representing the floor of a facility as well as simulation analysis [Kato et al]. This paper describes the details of the FEM analysis and calculated results and compares them with the drop test results. (J.P.N.)

  8. Properties of water leakage through concrete slabs with a parallel gap

    International Nuclear Information System (INIS)

    Shimooka, Kenji; Abe, Mikiya

    1988-10-01

    This paper describes the experimental results of water flow in concrete crack, in order to get the fundamental data on the barrier effect of the concrete material on the nuclide migration. Concrete slabs with a parallel gap, instead of the unidentified native cracks were used in the experiment and the water leakage through the certain gap was studied in detail. It is recognized that the water flow through cracks can be generally treated as a laminar flow, thus the theoretical equation derived from Navier-Stokes equation can be applied in the flow analysis. According to the theory, the amount of water flow through the crack is described to be proportional both to the third power of crack width and to the pressure gradient, and also to be inversely proportional to the coefficient of water viscosity. We have confirmed that the equation can be applied to the water flow through even 0.01 cm width gap in concrete by the experiments, measurement of the water flow under the conditions of constant head and gradually changing temperatures and also at the constant temperatures. (author)

  9. Loading capacities and failure modes of various reinforced concrete slabs subjected to high-speed loading

    International Nuclear Information System (INIS)

    Saito, H.; Imamura, A.; Takeuchi, M.; Okamoto, S.; Kasai, Y.; Tsubota, H.; Yoshimura, M.

    1993-01-01

    The objective of this study was to clarify experimentally and analytically the loading capacities, deformations and failure modes of various types of reinforced concrete structures subjected to loads applied at various loading rates. Flat slabs, slabs with beams and cylindrical walls were tested under static, low-speed and high-speed loading. Analysis was applied to estimate the test results by the finite element method using a layered shell element. The analysis closely simulated the experimental results until punching shear failure occurred. (author)

  10. Radon reduction techniques for suspended timber floors and pressure field extension assessment of hardcore specifications

    International Nuclear Information System (INIS)

    Gregory, T.J.; Stephen, R.K.

    1994-01-01

    This paper comprises two case studies. The first describes a series of mitigation measures carried out in a small primary school fitted with a suspended timber floor. Radon levels had been successfully reduced but the floor subsequently collapsed due to an outbreak of dry-rot. The floor was replaced with a ground-bearing concrete slab fitted with a typical example of one of 200 or so sump-and-fan systems fitted by Cornwall County Council (CCC). Following consultation with the Building Research Establishment (BRE) a network of small bore pipes was fitted below the floor during construction to record variations in radon levels and pressures. The second case study describes the floor replacement at a second, similar school but with a permeable layer of material under the concrete slab and more pressure measurement points. The pressure measurements and their subsequent analysis are described and the performance of the two installations compared. Using BRE and CCC expertise, this technique is now being applied to a number of other replacement floors in order to assess pressure field extension in a variety of hardcore and blinding materials. It is hoped that by careful selection of hardcore and blinding specifications the increased pressure field extension obtained could result in a new-build properties requiring fewer underfloor suction points and/or a reduction in fan power consumption with a greater degree of confidence of success than at present. The selection and design of suction systems to date has been on a very pragmatic basis. (author)

  11. Punching shear in reinforced concrete flat slabs with hole adjacent to the column and moment transfer

    Directory of Open Access Journals (Sweden)

    D. C. Oliveira

    Full Text Available The structural behavior and the ultimate punching shear resistance of internal reinforced concrete flat slab-column connections, with one hole adjacent to the column, with or without flexural moment transfer of the slab to the column was investigated. Main variables were: the existence whether or not hole, flexural reinforcement layout and ratio, the direction and sense of the moment transferred and the eccentricity of the load (M (moment transferred to column / V (shear ratio at the connection - 0,50 m or 0,25 m. Seven internal slab-column joining were tested and ultimate loads, cracking, deflections, concrete and reinforcement strains were analyzed. The existence of hole adjacent to the smaller column dimension, the hole dimension, flexural reinforcement rate and placing, the variation of relation Mu/Vu in function of the load, and, than, of eccentricity of the load, influenced the slabs behavior and rupture load. Test results were compared with the estimations from CEB-FIP/MC1990 [7], EC2/2004 [12], ACI-318:2011 [1] and NBR 6118:2007 [5]. ACI [1] and EC2 [12] presented most conservative estimates, although have presented some non conservative estimates. Brazilian NBR [5], even though being partly based in EC2 [12], presented smaller conservative estimates and more non conservative estimates. A modification on all codes is proposed for taking in account the moment caused by the eccentricity at the critical perimeter for slabs with holes.

  12. Fracture Failure of Reinforced Concrete Slabs Subjected to Blast Loading Using the Combined Finite-Discrete Element Method

    Directory of Open Access Journals (Sweden)

    Z. M. Jaini

    Full Text Available Abstract Numerical modeling of fracture failure is challenging due to various issues in the constitutive law and the transition of continuum to discrete bodies. Therefore, this study presents the application of the combined finite-discrete element method to investigate the fracture failure of reinforced concrete slabs subjected to blast loading. In numerical modeling, the interaction of non-uniform blast loading on the concrete slab was modeled using the incorporation of the finite element method with a crack rotating approach and the discrete element method to model crack, fracture onset and its post-failures. A time varying pressure-time history based on the mapping method was adopted to define blast loading. The Mohr-Coulomb with Rankine cut-off and von-Mises criteria were applied for concrete and steel reinforcement respectively. The results of scabbing, spalling and fracture show a reliable prediction of damage and fracture.

  13. Flexible concrete link slabs used as expansion joints in bridge decks

    DEFF Research Database (Denmark)

    Lárusson, Lárus Helgi; Fischer, Gregor

    2011-01-01

    of water through the expansion joint and subsequent corrosion of girders and girder bearings. Investigations on joint-less superstructures using conventional steel reinforcement in so-called concrete link slabs indicate improved performance and economic feasibility. However, this concept requires...... relatively large amounts of steel reinforcement for crack control purposes and consequently provides a relatively large flexural stiffness and negative moment capacity at the joint between the spans. These contradicting requirements and effects in existing replacement concepts for damaged mechanical bridge...... joints are currently unresolved. In the proposed system described in this paper, a ductile cement-based composite section reinforced with Glass Fiber Reinforced Polymers (GFRP) replaces the damaged expansion joint. The combination of this ductile concrete together with corrosion resistant GFRP...

  14. Experimental Tests on Bending Behavior of Profiled Steel Sheeting Dry Board Composite Floor with Geopolymer Concrete Infill

    Directory of Open Access Journals (Sweden)

    Mohd Isa Jaffar

    Full Text Available Abstract Profiled Steel Sheet Dry Board (PSSDB system is a lightweight composite structure comprises Profiled Steel Sheeting and Dry Board connected by self-drilling and self-tapping screws. This study introduced geopolymer concrete, an eco-friendly material without cement content as an infill material in the PSSDB floor system to highlight its effect onto the PSSDB (with full and half-size dry boards floor system's stiffness and strength. Experimental tests on various full scale PSSDB floor specimens were conducted under uniformly distributed transverse loads. Results illustrate that the rigidity of the panel with geopolymer concrete infill with half-size dry board (HBGPC increases by 43% relative to that of the panel with normal concrete infill with full-size dry board (FBNC. The developed finite-element modeling (FEM successfully predicts the behavior of FBGPC model with 94.8% accuracy. Geopolymer concrete infill and dry board size influence the strength panel, infill contact stiffness, and mid-span deflection of the profiled steel sheeting/dry board (PSSDB flooring system.

  15. Spread prestressed concrete slab beam bridges.

    Science.gov (United States)

    2015-04-01

    TxDOT uses prestressed slab beam bridges for short-span bridges ranging from approximately 3050 ft in : length. These bridges have precast, pretensioned slab beams placed immediately adjacent to one another : with a cast-in-place slab made composi...

  16. Area Factor Determinations for an Industrial Worker Exposed to a Concrete Slab End-State

    International Nuclear Information System (INIS)

    Jannik, G. Timothy; Lee, Patricia L.; Farfan, Eduardo B.; Roach, Jesse L.

    2008-01-01

    The U.S. Department of Energy's (DOE) Savannah River Site (SRS) is decommissioning many of its excess facilities through removal of the facility structures leaving only the concrete-slab foundations in place. Site-specific, risk-based derived concentration guideline levels (DCGLs) for radionuclides have been determined for a future industrial worker potentially exposed to residual contamination on these concrete slabs as described in Jannik. These risk-based DCGLs were estimated for an exposure area of 100 m 2 . During deactivation and decommissioning (D and D) operations at SRS, the need for area factors for larger and smaller contaminated areas arose. This paper compares the area factors determined for an industrial worker exposed to a concrete slab end-state for several radionuclides of concern at SRS with 1) the illustrative area factors provided in MARSSIM, 2) the area correction factors provided in the U.S. Environmental Protection Agency's (EPA) Soil Screening Guidance, and 3) the hot spot criterion for field application provided in the RESRAD User's Manual. The purpose of this site-specific assessment is to determine if any of the recommended area factors provided in the guidance documents could be utilized at SRS for field applications of the industrial worker DCGLs. Results show the area factors that were determined for an SRS industrial worker exposed to concrete slab end-states for the common radionuclides provided in the referenced guidance documents. In addition to the SRS site-specific area factors, the following area factors are provided for comparison: - Illustrative examples of outdoor area dose factors (MARSSIM); - Area correction factors as a function of source area (Soil Screening Guidance). Note: the area correction factors were inverted to correspond to a DCGL area factor. - Recommended area correction factors as a function of source area (Soil Screening Guidance); - Ranges for hot spot multiplication factors (RESRAD). As it can be seen

  17. Heat transfer within a concrete slab with a finite microwave heating source

    International Nuclear Information System (INIS)

    Lagos, L.E.; Li, W.; Ebadian, M.A.; Grubb, R.G.

    1995-01-01

    In the present paper, the concrete decontamination and decommissioning process with a finite microwave heating source is investigated theoretically. For the microwave induced heating pattern, a multilayer concrete slab, which includes steel reinforcement mesh, is assumed to be exposed to a finite plane microwave source at normal incidence. Two-dimensional heat transport within the concrete is also considered to evaluate the variations of temperature with heating time at different frequencies with and without the presence of the reinforcement bars. Four commonly used industrial microwave frequencies of 0.896, 2.45, 10.6 and 18.0 GHz have been selected. The results revealed that as the microwave frequency increases to, or higher than 10.6 GHz, the maximum temperature shifts toward the front surface of the concrete. It was found that the presence of a steel reinforcement mesh causes part of the microwave energy to be blocked and reflected. Furthermore, it was observed that the temperature distribution is nearly uniform within the dimensions of the microwave applicator for a high microwave power intensity and a short heating time. (author)

  18. Determination of the ultimate load in concrete slabs by the yield line finite element method

    International Nuclear Information System (INIS)

    Vaz, L.E.; Feijo, B.; Martha, L.F.R.; Lopes, M.M.

    1984-01-01

    A method for calculating the ultimate load in reinforced concrete slabs is proposed. The method follows the finite element aproach representating the continuum slab as an assembly of rigid triangular plates connected along their sides through yield line elements. This approach leads to the definition of the displacement configuration of the plate only as a function of the transversal displacement at the nodes of the mesh (1 DOF per node) reducing significantly the number of DOF's in relation to the conventional formulation by means of the finite element method (minimum of 3 DOF per node). Nonlinear behaviour of the reinforced concrete section is considered in the definition of the moment rotation curve of the yield lines. The effect of the in plane forces acting in the middle surface of the plate is also taken into account. The validity of the model is verified comparing the numerical solutions with the results of the classical yield line theory. (Author) [pt

  19. Slab replacement maturity guidelines : [summary].

    Science.gov (United States)

    2014-04-01

    Concrete sets in hours at moderate temperatures, : but the bonds that make concrete strong continue : to mature over days to years. However, for : replacement concrete slabs on highways, it is : crucial that concrete develop enough strength : within ...

  20. Numerical Simulation on Slabs Dislocation of Zipingpu Concrete Faced Rockfill Dam during the Wenchuan Earthquake Based on a Generalized Plasticity Model

    Directory of Open Access Journals (Sweden)

    Bin Xu

    2014-01-01

    Full Text Available After the Wenchuan earthquake in 2008, the Zipingpu concrete faced rockfill dam (CFRD was found slabs dislocation between different stages slabs and the maximum value reached 17 cm. This is a new damage pattern and did not occur in previous seismic damage investigation. Slabs dislocation will affect the seepage control system of the CFRD gravely and even the safety of the dam. Therefore, investigations of the slabs dislocation’s mechanism and development might be meaningful to the engineering design of the CFRD. In this study, based on the previous studies by the authors, the slabs dislocation phenomenon of the Zipingpu CFRD was investigated. The procedure and constitutive model of materials used for finite element analysis are consistent. The water elevation, the angel, and the strength of the construction joints were among major variables of investigation. The results indicated that the finite element procedure based on a modified generalized plasticity model and a perfect elastoplastic interface model can be used to evaluate the dislocation damage of face slabs of concrete faced rockfill dam during earthquake. The effects of the water elevation, the angel, and the strength of the construction joints are issues of major design concern under seismic loading.

  1. Analysis of the impact of an aircraft crash on underground concrete ducts with protective slab at reactor buildings

    International Nuclear Information System (INIS)

    Kotulla, B.; Hansson, V.

    1977-01-01

    In this paper different types of idealization for a dynamic analysis of underground concrete ducts with protective slab are discussed and compared. Ducts between reactor and control building of a nuclear power plant are to be designed for loadings produced by an aircraft crash. These ducts have a height of about three to four meters and are two to eight meters wide. They are designed with a protective slab about 1.5 m in thickness at ground level and with an intermediate layer of earth of about one meter in thickness. An analysis has to take into account the combined effects of a protective slab with a relatively thin intermediate layer of earth and the underlaying duct and layer of soil with the nonlinear behavior of concrete due to cracking. For describing this behavior two types of idealization were made. One type is a continuum type calculation which describes the slab, the soil and the duct by finite elements. In the other type of idealization a model consisting of springs and lumped masses is used. The protective slab and the intermediate layer of earth may be described as a plate on elastic foundation. The behavior of the cracked part of the plate and the part of earth layer beneath and loads transferred to the uncracked part of the slab and the surrounding soil may be described by parallel springs. Spring and mass of this part of the model have to take into account the cracking of the upper slab which leads to a nonlinear characteristic of the spring. In addition the location of the loading in relation to the duct has to be considered. The duct may be described by a beam on elastic foundation which is loaded locally. From this model representative mass and spring have to be determined

  2. Construction of foundation slab of Temelin reactor building

    International Nuclear Information System (INIS)

    Lebr, P.; Vyleta, M.

    1988-01-01

    The concreting is described of the foundation slab under the WWER-1000 reactor in the Temelin nuclear power plant. The slab area is 68x68 m and thickness 2.4 m. For ease of concreting, the slab was divided in 12 blocks with vertical partition walls of steel mesh. The total thickness was concreted in three stages in which the partial thicknesses slightly differed for operating reasons. The first two partial thicknesses were concreted in layers of 0.45 m each, the third thickness consisted of two layers of 0.30 m each. The reinforcement was completely cleaned of the concrete residues from the previous stages in the break between the second and the third stages. Totally, 11,050 m 3 concrete were used. Briefly described is quality control during concreting and experiences and recommendations are summed up for other concreting jobs. (Z.M.). 19 figs

  3. Composite structures of steel and concrete beams, slabs, columns, and frames for buildings

    CERN Document Server

    Johnson, R P

    2008-01-01

    This book sets out the basic principles of composite construction with reference to beams, slabs, columns and frames, and their applications to building structures. It deals with the problems likely to arise in the design of composite members in buildings, and relates basic theory to the design approach of Eurocodes 2, 3 and 4.The new edition is based for the first time on the finalised Eurocode for steel/concrete composite structures.

  4. A real case of steam-cured concrete track slab premature deterioration due to ASR and DEF

    Directory of Open Access Journals (Sweden)

    Kunlin Ma

    2017-06-01

    Full Text Available Deterioration mechanisms of some premature damaged steam-cured concrete track slabs (CTS in Chinese railway less than 4 years were investigated. Field investigation, raw materials test and suspicious products analysis were carried out. Results show that steam-cured heat damage (SCHD of concrete takes place in steam-cured process. Expansion products are ettringite in hydrated products and alkali-silica gels between the interface of hydrated products and coarse aggregate. SCHD makes CTS surface layer loose, porous and more micro-cracks. Long-term fatigue load from high-speed train acting on CTS enlarges concrete microcracks, leading to water penetrating into concrete easily in moist and rainy environment. In the process of water ingression, alkali-silica reaction (ASR and delayed ettringite formation (DEF take place, hence resulting in CTS cracking and premature deterioration.

  5. Development of Flexible Link Slabs using Ductile Fiber Reinforced Concrete

    DEFF Research Database (Denmark)

    Lárusson, Lárus Helgi

    Civil engineering structures with large dimensions, such as multi-span bridges, overpasses and viaducts, are typically equipped with mechanical expansion joints. These joints allow the individual spans of the structure to undergo unrestrained deformations due to thermal expansions and load......-deformation response and crack development of representative sections of the reinforced composites, and iv) detailing, designing and testing of large scale prefabricated link slab elements. In addition, an application of ductile Engineered Cementitious Composite (ECC) in prefabricated floor panels is presented...... crack widths and crack spacing measurements are obtained, which can characterize the tensile behavior of ECC. In chapter 3 on interfacial bond, the bond slip behavior and crack development, between the reinforcement and surrounding cementitious matrix is investigated in a unique test setup with special...

  6. Finite-Element Investigation of the Structural Behavior of Basalt Fiber Reinforced Polymer (BFRP- Reinforced Self-Compacting Concrete (SCC Decks Slabs in Thompson Bridge

    Directory of Open Access Journals (Sweden)

    Lingzhu Zhou

    2018-06-01

    Full Text Available The need for a sustainable development and improved whole life performance of concrete infrastructure has led to the requirement of more durable and sustainable concrete bridges alongside accurate predictive analysis tools. Using the combination of Self-Compacting Concrete (SCC with industrial by-products and fiber-reinforced polymer (FRP, reinforcement is anticipated to address the concerns of high carbon footprint and corrosion in traditional steel-reinforced concrete structures. This paper presents a numerical investigation of the structural behavior of basalt fiber-reinforced polymer (BFRP-reinforced SCC deck slabs in a real bridge, named Thompson Bridge, constructed in Northern Ireland, U.K. A non-linear finite element (FE model is proposed by using ABAQUS 6.10 in this study, which is aimed at extending the previous investigation of the field test in Thompson Bridge. The results of this field test were used to validate the accuracy of the proposed finite element model. The results showed good agreement between the test results and the numerical results; more importantly, the compressive membrane action (CMA inside the slabs could be well demonstrated by this FE model. Subsequently, a series of parametric studies was conducted to investigate the influence of different parameters on the structural performance of the deck slabs in Thompson Bridge. The results of the analyses are discussed, and conclusions on the behavior of the SCC deck slabs reinforced by BFRP bars are presented.

  7. Constructive solutions for beamless capitalless floors with prestressed reinforcement

    Directory of Open Access Journals (Sweden)

    Bardysheva Yuliya Anatol'evna

    2014-07-01

    Full Text Available In the article the authors present advanced constructions of prestressed reinforced concrete flat ceiling, where high-strength ropes in elastic shell are used as stressed reinforcement. The novelty of the solution lays in diagonal arrangement of hard valves and use of high-strength ropes in a flexible shell of "Monostrand" type. This type of prestress, in our opinion, is the most acceptable from technical point of view for selective reinforcement of separate tense rods or cables. The use of pre-stressed reinforcement in the form of individual rods or cables increases the rigidity and crack resistance of concrete beamless slabs. The use of high-strength ropes in the monostrand-type shell makes it possible to prestress in frames of single cell plate or floor in general and to reduce labour input for stressing armature. The paper presents original solution with diagonal position of the valve. The authors suggest the use of prestressed diagonal valves as in all cells of the floor with the cells of the same or only slightly different size and in separate cells of the floor (for roofs with different cells. The diagonal location of stressed reinforcement proposed in the work is an efficient solution for extending the range of dimensions and loads size.

  8. Environmental Impact Optimization of Reinforced Concrete Slab Frame Bridges

    DEFF Research Database (Denmark)

    Yavari, Majid Solat; Du, Guangli; Pacoste, Costin

    2017-01-01

    The main objective of this research is to integrate environmental impact optimization in the structural design of reinforced concrete slab frame bridges in order to determine the most environmental-friendly design. The case study bridge used in this work was also investigated in a previous paper...... focusing on the optimization of the investment cost, while the present study focuses on environmental impact optimization and comparing the results of both of these studies. Optimization technique based on the pattern search method was implemented. Moreover, a comprehensive Life Cycle Assessment (LCA......) methodology of ReCiPe and two monetary weighting systems were used to convert environmental impacts into monetary costs. The analysis showed that both monetary weighting systems led to the same results. Furthermore, optimization based on environmental impact generated models with thinner construction elements...

  9. Studi Komparasi Antara Pracetak Masif Dan Fly Slab Studi Kasus : Struktur Gedung Rusunawa Surakarta

    OpenAIRE

    Wirawan, Aria; Wicaksono, Budi; Nuroji, Nuroji; Partono, Windu

    2013-01-01

    Fly slab is one of the precast concrete slab technological development that has been researched and patented by Ir . Sulistyana in 2011. The concept is how to reduce the mass of precast concrete slab with makes ribs on the concrete slab. To minimize the volume of concrete plate and while maintaining tensile area to makes the style transfer mechanism of concrete to reinforcement or otherwise, are expected to reduce the mass of the structure without reducing strength.Comparative study will be c...

  10. DESIGN OF A CONCRETE SLAB FOR STORAGE OF SNF AND HLW CASKS

    International Nuclear Information System (INIS)

    J. Bisset

    2005-01-01

    This calculation documents the design of the Spent Nuclear Fuel (SNF) and High-Level Waste (HLW) Cask storage slab for the Aging Area. The design is based on the weights of casks that may be stored on the slab, the weights of vehicles that may be used to move the casks, and the layout shown on the sketch for a 1000 Metric Ton of Heavy Metal (MTHM) storage pad on Attachment 2, Sht.1 of the calculation 170-C0C-C000-00100-000-00A (BSC 2004a). The analytical model used herein is based on the storage area for 8 vertical casks. To simplify the model, the storage area of the horizontal concrete modules and their related shield walls is not included. The heavy weights of the vertical storage casks and the tensile forces due to pullout at the anchorages will produce design moments and shear forces that will envelope those that would occur in the storage area of the horizontal modules. The design loadings will also include snow and live loads. In addition, the design will also reflect pertinent geotechnical data. This calculation will document the preliminary thickness and general reinforcing steel requirements for the slab. This calculation also documents the initial design of the cask anchorage. Other slab details are not developed in this calculation. They will be developed during the final design process. The calculation also does not include the evaluation of the effects of cask drop loads. These will be evaluated in this or another calculation when the exact cask geometry is known

  11. Effect of floor type (dirt or concrete on litter quality, house environmental conditions, and performance of broilers

    Directory of Open Access Journals (Sweden)

    VMN Abreu

    2011-06-01

    Full Text Available This study was conducted with the objective of evaluating the use of concrete or hard-packed dirt floor in broiler houses. This experiment was carried out in two different phases. The following performance parameters were studied: live weight, feed intake, feed conversion ratio, and mortality. Litter moisture, pH and temperature were measured. Litter residual contamination after cleaning and disinfection was also evaluated. A dry bulb thermometer, a wet bulb thermometer, and a black bulb thermometer were placed inside each broiler house at bird height and outside the broiler house for data collection. Environmental data were collected at 3h intervals from 00:00 to 24:00 hours during weeks 4, 5, and 6 of the grow-out. Based on the collected data, air relative humidity (RH was determined, after which wet bulb globe temperature (WBGT and Radiant Heat Load (RHL were calculated. There were no differences in live performance parameters. However, total mortality and sudden death were higher in birds raised on dirt floor. On days 0, 14 and 35, litter pH was higher in the dirt floor as compared to the concrete floor, but at the end of the grow-out, this difference disappeared. There was a cubic effect of bird age on litter moisture, which increased up to day 28, and then stabilized or decreased. Litter coliform contamination was higher at the end of the grow-out as compared to that found at housing, but it was not influenced by floor type. The general thermal comfort of broiler raised on dirt floor was similar to that of broilers raised on concrete floor.

  12. Construction method with prestressed connection of precast prestressed concrete using composite slab with multi-round opening web. Bibai factory office building of Dopi Kensetsu Kogyo Co; Web bu ni renzoku enkei kaiko wo yusuru PC gosei yukaita wo mochiita PC kumitate koho. Dopi kensetsu kogyo (kabu) Bibai kojo jimushoto shinchiku koji

    Energy Technology Data Exchange (ETDEWEB)

    Kuramochi, H.; Nakai, J.; Arai, S.; Toriya, T.

    1997-07-31

    This report summarizes the experimental result on the structural performance of precast prestressed concrete (PC) composite slab work, and a construction method with prestressed connection of PC. Although a double T type precast PC slab (DT board) is frequently used as buried form for slabs, it requires extremely complex bar arrangement and complicated works. The reinforcement method of supports using deformed hair pin type bars was thus devised which has a structural performance higher than that of the previous methods as well as simple bar arrangement and superior workability. For the reinforced DT board (DP slab) and the composite slab construction method using the DP slab, the structural safety and retained use environment were confirmed by structural performance test and construction test. The foundation and footing beam of the Bibai factory office building were constructed by the conventional method considering the construction method, while the column, beam and floor by this method using PCa members. The upper building frame was thus completed for as short as 23 days. 5 refs., 15 figs., 4 tabs.

  13. Nonlinear analysis of end slabs in prestressed concrete reactor vessels

    International Nuclear Information System (INIS)

    Abdulrahman, H.O.

    1978-01-01

    A procedure for the nonlinear analysis of end slabs is prestressed concrete reactor vessels (PCRVs), based on the finite element method, is presented. The applicability of the procedure to the ultimate load analysis of small-scale models of the primary containment of nuclear reactors is shown. Material nonlinearity only is considered. The procedure utilizes the four-node linear quadrilateral isoparametric element with the choice of incorporating the nonconforming modes. This element is used for modeling the vessel as an axisymmetric solid. Concrete is assumed to be an isotropic material in the elastic range. The compressive stresses are judged according to a special form of the Mohr-Coulomb criterion. The nonlinear problem was solved using a generalized Newton-Raphson procedure. A detailed example problem of a pressure vessel with penetrations is presented. This is followed by a summary of the other cases studied. The solutions obtained match very closely the measured response of the test vessels under increasing internal pressure up to failure. The procedure is thus adequate for the assessment of the ultimate load behavior and failure of actual pressure vessels with a moderate demand on human and computational resources

  14. Reliability analysis of reinforced concrete grids with nonlinear material behavior

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Rodrigo A [EESC-USP, Av. Trabalhador Sao Carlense, 400, 13566-590 Sao Carlos (Brazil); Chateauneuf, Alaa [LaMI-UBP and IFMA, Campus de Clermont-Fd, Les Cezeaux, BP 265, 63175 Aubiere cedex (France)]. E-mail: alaa.chateauneuf@ifma.fr; Venturini, Wilson S [EESC-USP, Av. Trabalhador Sao Carlense, 400, 13566-590 Sao Carlos (Brazil)]. E-mail: venturin@sc.usp.br; Lemaire, Maurice [LaMI-UBP and IFMA, Campus de Clermont-Fd, Les Cezeaux, BP 265, 63175 Aubiere cedex (France)

    2006-06-15

    Reinforced concrete grids are usually used to support large floor slabs. These grids are characterized by a great number of critical cross-sections, where the overall failure is usually sudden. However, nonlinear behavior of concrete leads to the redistribution of internal forces and accurate reliability assessment becomes mandatory. This paper presents a reliability study on reinforced concrete (RC) grids based on coupling Monte Carlo simulations with the response surface techniques. This approach allows us to analyze real RC grids with large number of failure components. The response surface is used to evaluate the structural safety by using first order reliability methods. The application to simple grids shows the interest of the proposed method and the role of moment redistribution in the reliability assessment.

  15. Development of a Leave-in-Place Slab Edge Insulating Form System

    Energy Technology Data Exchange (ETDEWEB)

    Marc Hoeschele; Eric Lee

    2009-08-31

    Concrete slabs represent the primary foundation type in residential buildings in the fast-growing markets throughout the southern and southwestern United States. Nearly 75% of the 2005 U.S. population growth occurred in these southern tier states. Virtually all of these homes have uninsulated slab perimeters that transfer a small, but steady, flow of heat from conditioned space to outdoors during the heating season. It is estimated that new home foundations constructed each year add 0.016 quads annually to U.S. national energy consumption; we project that roughly one quarter of this amount can be attributed to heat loss through the slab edge and the remaining three quarters to deep ground transfers, depending upon climate. With rising concern over national energy use and the impact of greenhouse gas emissions, it is becoming increasingly imperative that all cost-effective efforts to improve building energy efficiency be implemented. Unlike other building envelope components that have experienced efficiency improvements over the years, slab edge heat loss has largely been overlooked. From our vantage point, a marketable slab edge insulation system would offer significant benefits to homeowners, builders, and the society as a whole. Conventional slab forming involves the process of digging foundation trenches and setting forms prior to the concrete pour. Conventional wood form boards (usually 2 x 10's) are supported by vertical stakes on the outer form board surface, and by supporting 'kickers' driven diagonally from the top of the form board into soil outside the trench. Typically, 2 x 10's can be used only twice before they become waste material, contributing to an additional 400 pounds of construction waste per house. Removal of the form boards and stakes also requires a follow-up trip to the jobsite by the concrete subcontractor and handling (storage/disposal) of the used boards. In the rare cases where the slab is insulated (typically custom

  16. Assessment of structural reliability of precast concrete buildings

    Directory of Open Access Journals (Sweden)

    Koyankin Alexandr

    2018-01-01

    Full Text Available Precast housing construction is currently being under rapid development, however, reliability of building structures made from precast reinforced concrete cannot be assessed rationally due to insufficient research data on that subject. In this regard, experimental and numerical studies were conducted to assess structural reliability of precast buildings as described in the given paper. Experimental studies of full-scale and model samples were conducted; numerical studies were held based on finite element models using “Lira” software. The objects under study included fragment of flooring of a building under construction, full-size fragment of flooring, full-scale models of precast cross-beams-to-columns joints and joints between hollow-core floor slabs and precast and cast-in-place cross-beams. Conducted research enabled to perform an objective assessment of structural reliability of precast buildings.

  17. Diseño de losas de hormigón con geometría optimizada Design of concrete pavement with optimized slab geometry

    Directory of Open Access Journals (Sweden)

    Juan Pablo Covarrubias V.

    2012-12-01

    condiciones de cargas mecánicas y térmicas en diferentes posiciones. El agrietamiento de las losas se determina calculando la fatiga del hormigón y los modelos utilizados por la guía de diseño AASHTO del año 2007 y mediante calibración en secciones de prueba a gran escala. La nueva metodología diseña losas de hormigón que en promedio son 7 cm más delgadas para vías de alto tráfico en relación con el diseño tradicional de pavimentos AASHTO (1993. El método de diseño también es capaz de diseñar de manera eficiente pavimentos de hormigón para vías de menor volumen de tráfico que no son cubiertos con los actuales métodos de diseño de pavimento dando una alternativa a soluciones en asfalto.A new technology has been developed to design concrete pavements, which reduces slabs' thickness and optimizes their sizes, because of trucks axles' geometry. The design is supported by a gravel base treated with concrete or asphalt. It assumes there is no adherence between the base (existing pavement and the concrete slab. The core principle of this design method consists of designing a slab size, so that no more than one wheel set stays on a given slab, thus minimizing the critical tensile stress on the surface. Test segments have been built on a large scale and they have been tested under accelerated loads, with concrete thickness of 8, 15 and 20 cm, all of them having a gravel base and non-adhered asphaltic layers. Tests demonstrated that a reduced-size slab, of low thickness, might bear a considerable amount of equivalent axles before cracking takes place. Concrete slabs on gravel bases with 20 cm thickness did not suffer from cracking, in spite of being tested under more than 50 millions of equivalent axles. Slabs of 15 cm thickness suffered from cracking when tested under an average of 12 millions equivalent axles, while slabs of 8 cm thickness endured 75,000 equivalent axles before the first cracking took place. Besides the executed tests demonstrated that fiber

  18. Finite Element Modeling of GFRP-Reinforced Concrete Interior Slab-Column Connections Subjected to Moment Transfer

    Directory of Open Access Journals (Sweden)

    Ahmed Gouda

    2015-10-01

    Full Text Available A finite element model (FEM was constructed using specialized three-dimensional (3D software to investigate the punching shear behavior of interior slab-column connections subjected to a moment-to-shear ratio of 0.15 m. The FEM was then verified against the experimental results of full-scale interior slab-column connections reinforced with glass fiber reinforcement polymer (GFRP bars previously tested by the authors. The FEM results showed that the constructed model was able to predict the behavior of the slabs with reasonable accuracy. Afterward, the verified model was used to conduct a parametric study to investigate the effects of reinforcement ratio, perimeter-to-depth ratio, and column aspect ratio on the punching shear behavior of such connections. The test results showed that increasing the tested parameters enhanced the overall behavior of the connections in terms of decreasing deflections and reinforcement strain and increasing the ultimate capacity. In addition, the obtained punching shear stresses of the connections were compared to the predictions of the Canadian standard and the American guideline for FRP-reinforced concrete structures.

  19. Odua Weston Jambi Hotel’s Structural Building Design with Prestressed Concrete Slab System Approach

    Science.gov (United States)

    Bayuaji, R.; Darmawan, M. S.; Rofiq, M. A.; Santoso, S. E.; Hardiyanto, E.

    2017-11-01

    Odua Weston Jambi Hotel is an eight-floor hotel and located in a prone to earth-quake area. This building used conventional concrete to its structural beam and column. This research’s purpose was to maximize the second-floor’s function by modifing its architectural design. Special Moment Resisting Frame System (SMRFS) approach was used in the structural design, referred to SNI 03-2847-2013 dan SNI 1726-2012 and to compensate the needs of a spacious hall without any column in the centre of the hall, so therefore, prestressed concrete plate is used to solve this problem.

  20. New Transition Wedge Design Composed by Prefabricated Reinforced Concrete Slabs

    Directory of Open Access Journals (Sweden)

    Julia Real-Herráiz

    Full Text Available Abstract Important track degradation occurs in structure-embankment transitions, in which an abrupt change in track vertical stiffness arises, leading to a reduction in passengers comfort and safety. Although granular wedges are suggested by different railroad administrations as a solution to avoid these problems, they present some disadvantages which may affect track long-term performance. In this paper, a new solution designed with prefabricated reinforced concrete slabs is proposed. The aim of this solution is to guarantee a continuous and gradual track vertical stiffness transition in the vicinity of structures, overcoming granular wedges disadvantages. The aim of this study is to assess the performance of the novel wedge design by means of a 3-D FEM model and to compare it with the current solution.

  1. Micro-deformation measurement on the concrete roadway surface slabs using Fiber Bragg Grating and analysis by computational simulation

    Energy Technology Data Exchange (ETDEWEB)

    Serpa, C M; Gomez, N D [Instituto Tecnologico Metropolitano Institucion Universitaria (ITM), Medellin A. A. 54954 (Colombia); Velez, F J, E-mail: claudiaserpa@itm.edu.co [Universidad EAFIT, Medellin (Colombia)

    2011-01-01

    This work shows a non-invasive method for micro-deformation measurements on concrete structures using Bragg grating sensors in optical fibers adhered to the surface. We present the measurements on roadway slabs under a load of 10 kN, and we find an approximated ratio of 2:1 between the deformation registered by the sensors and the values from a computational simulation with the finite element method. We propose the use of these sensors for structural monitoring of the slabs and this installation shape for avoiding bends that can damage the edges in the optical fiber in embebed sensors in vertical shape.

  2. Soft impact testing of a wall-floor-wall reinforced concrete structure

    Energy Technology Data Exchange (ETDEWEB)

    Vepsä, Ari, E-mail: ari.vepsa@vtt.fi; Calonius, Kim; Saarenheimo, Arja; Aatola, Seppo; Halonen, Matti

    2017-01-15

    Highlights: • A wall-floor-wall reinforced concrete structure was built. • The structure was subjected to three almost identical soft impact tests. • Response was measured with accelerometers, displacement sensors and strain gauges. • Modal tests was also carried out with the same structure in different conditions. • The results are meant to be used for validation of computational methods and models. - Abstract: Assessing the safety of the reactor building of a nuclear power plant against the crash of an airplane calls for valid computational tools such as finite element models and material constitutive models. Validation of such tools and models in turn calls for reliable and relevant experimental data. The problem is that such data is scarcely available. One of the aspects of such a crash is vibrations that are generated by the impact. These vibrations tend to propagate from the impact point to the internal parts of the building. If strong enough, these vibrations may cause malfunction of the safety-critical equipment inside the building. To enable validation of computational models for this type of behaviour, we have conducted a series of three tests with a wall-floor-wall reinforced concrete structure under soft impact loading. The response of the structure was measured with accelerometers, displacement sensors and strain gauges. In addition to impact tests, the structure was subjected to modal tests under different conditions. The tests yielded a wealth of useful data for validation of computational models and better understanding about shock induced vibration physics especially in reinforced concrete structures.

  3. Synthetic rubber surface as an alternative to concrete to improve welfare and performance of finishing beef cattle reared on fully slatted flooring.

    Science.gov (United States)

    Brscic, M; Ricci, R; Prevedello, P; Lonardi, C; De Nardi, R; Contiero, B; Gottardo, F; Cozzi, G

    2015-08-01

    The aim of this study was to compare a fully slatted concrete floor (concrete slatted (CS)) with the same floor on which synthetic rubber slats were placed on the concrete slats (rubber slatted (RS)) as housing solution for finishing beef cattle. The present study involved five commercial beef cattle farms in which the floor of at least three pens was kept as fully slatted, and in an equal number of pens a rubber cover was placed on the floor, tightly matching the gap profile of the concrete slats to allow the drainage of manure. A total of 326 finishing beef bulls were used (153 on CS and 173 on RS), and regardless of the floor treatment animals were housed in groups of 6 to 12 bulls/pen with a space allowance of 3.1 ± 0.2 m2/bull. Bulls had similar initial live weights (422.3 kg on CS and 425.0 kg on RS), but bulls on RS were heavier at the end of the finishing period with a higher average daily gain than bulls kept on CS (1.53 v. 1.46 kg/day; Pfloor on growth performance and welfare of finishing beef cattle, although compromising cleanliness and hoof overgrowth.

  4. Floors number influence on the instability parameter of reinforced concrete wall- or core-braced buildings

    Directory of Open Access Journals (Sweden)

    R. J. Ellwanger

    Full Text Available This work aims to investigate the floors number influence on the instability parameter limit α1 of buildings braced by reinforced concrete walls and/or cores. Initially, it is showed how the Beck and König discrete and continuous models are utilized in order to define when a second order analysis is needed. The treatment given to this subject by the Brazilian code for concrete structures design (NBR 6118 is also presented. It follows a detailed analytical study that led to the derivation of equations for the limit α1 as functions of the floors number; a series of examples is presented to check their accuracy. Results are analyzed, showing the precision degree achieved and topics for continuity of research in this field are indicated.

  5. Structural Test and Analysis of RC Slab After Fire Loading

    International Nuclear Information System (INIS)

    Chung, Chulhun; Im, Cho Rong; Park, Jaegyun

    2013-01-01

    In the present study the behavior of fire and the residual strength of fire-ignited RC slabs are investigated by experimental tests and numerical simulations. The fire tests of RC slabs were carried out in a furnace using the ISO 834 standard fire. The load capacity of the cooled RC slabs that were not loaded during the fire tests was evaluated by additional 3 point bending tests. The influence of the proportion of PP (polypropylene) fibers in the RC slabs on the structural behavior of the RC slabs after the fire loading was investigated. The results of the fire tests showed that the maximum temperature of concrete with PP fiber was lower than that of concrete without PP fiber. As the concrete was heated, the ultimate compressive strength decreased and the ultimate strain increased. The load-deflection relations of RC slabs after fire loading were compared by using existing stress-strain-temperature models. The comparison between the numerical analysis and the experimental tests showed that some numerical analyses were reliable and therefore, can be applied to evaluate the ultimate load of RC slabs after fire loading. The ultimate load capacity after cooling down the RC slabs without PP fiber showed a considerable reduction from that of the RC slabs with PP fiber

  6. Structural Test and Analysis of RC Slab After Fire Loading

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chulhun; Im, Cho Rong; Park, Jaegyun [Dankook Univ., Yongin (Korea, Republic of)

    2013-04-15

    In the present study the behavior of fire and the residual strength of fire-ignited RC slabs are investigated by experimental tests and numerical simulations. The fire tests of RC slabs were carried out in a furnace using the ISO 834 standard fire. The load capacity of the cooled RC slabs that were not loaded during the fire tests was evaluated by additional 3 point bending tests. The influence of the proportion of PP (polypropylene) fibers in the RC slabs on the structural behavior of the RC slabs after the fire loading was investigated. The results of the fire tests showed that the maximum temperature of concrete with PP fiber was lower than that of concrete without PP fiber. As the concrete was heated, the ultimate compressive strength decreased and the ultimate strain increased. The load-deflection relations of RC slabs after fire loading were compared by using existing stress-strain-temperature models. The comparison between the numerical analysis and the experimental tests showed that some numerical analyses were reliable and therefore, can be applied to evaluate the ultimate load of RC slabs after fire loading. The ultimate load capacity after cooling down the RC slabs without PP fiber showed a considerable reduction from that of the RC slabs with PP fiber.

  7. Estimation of RC slab-column joints effective strength using neural networks

    Directory of Open Access Journals (Sweden)

    A. A. Shah

    Full Text Available The nominal strength of slab-column joints made of highstrength concrete (HSC columns and normal strength concrete (NSC slabs is of great importance in structural design and construction of concrete buildings. This topic has been intensively studied during the last decades. Different types of column-slab joints have been investigated experimentally providing a basis for developing design provisions. However, available data does not cover all classes of concretes, reinforcements, and possible loading cases for the proper calculation of joint stresses necessary for design purposes. New numerical methods based on modern software seem to be effective and may allow reliable prediction of column-slab joint strength. The current research is focused on analysis of available experimental data on different slab-to-column joints with the aim of predicting the nominal strength of slabcolumn joint. Neural networks technique is proposed herein using MATLAB routines developed to analyze available experimental data. The obtained results allow prediction of the effective strength of column-slab joints with accuracy and good correlation coefficients when compared to regression based models. The proposed method enables the user to predict the effective design of column-slab joints without the need for conservative safety coefficients generally promoted and used by most construction codes.

  8. Performance and damages of R.C. slabs in fire

    DEFF Research Database (Denmark)

    Giuliani, Luisa; Gentili, Filippo

    2015-01-01

    Contrary to a common misconception, concrete structures are particularly vulnerable to fire, as witnesses by several cases of fire-induced collapses of buildings with a primary concrete structural system. Even when no collapse occurs, concrete elements are permanently damaged by the fire and may...... on the vulnerability of the slab to the fire action and can be used for optimizing the design on the basis of the required class of resistance or for choosing between different slab alternatives....

  9. Application of a global plasticity model to determine the ultimate strength of a reinforced concrete slab

    International Nuclear Information System (INIS)

    Hoffmann, A.; Millard, A.; Nahas, G.

    1983-08-01

    In order to predict the behaviour of composite beams and shells loaded up to failure, a global method has been developped. This method is based on a generalized stress approach, formulated in terms of moment-curvature relations. The case of a reinforced concrete slab subjected to uniform pressure has been considered. It is shown that numerical results compare fairly well with experimental data. Some improvements to the model are also suggested

  10. Introductory guide to floors and flooring

    CSIR Research Space (South Africa)

    Billingham, PA

    1977-01-01

    Full Text Available not make use of the warming and cooling effects of direct contact with the ground. Indeed the precautions that are necessary to protect such floors against damp and decay may actually reduce the comfort levels within a house. This is because there is a... with resultant discomfort and extra heating costs. Today, in South Africa, most modern homesareof singlestorey con- struction with aconcrete floor slab in direct contact with theground which once again makes its full contribution to the comfort and structural...

  11. TEMPERATURE HETEROGENEITY OF TRAVELLING FIRE AND ITS INFLUENCE ON COMPOSITE STEEL-CONCRETE FLOOR

    Directory of Open Access Journals (Sweden)

    Kamila Horová

    2016-04-01

    Full Text Available In order to follow modern trends in contemporary building architecture, which is moving off the limits of current fire design models, assumption of homogeneous temperature conditions used for structural fire analysis needs to be revised. In this paper fire dynamics of travelling fire is investigated experimentally by conducting fire test in two-storey experimental building. To evaluate the impact of travelling fire on the mechanical behaviour of a structure, the spatial and temporal evolution of the gas temperature calculated in NIST code FDS, which was validated to experimental measurements, is applied to the composite floor of dimensions 9.0 m by 9.0 m. Mechanical behaviour of the composite slab highly affected by regions of high temperatures and areas with only elevated temperatures is solved in code Vulcan. To highlight the severity of spreading fire causing non-uniform temperature conditions, which after-effects differ from traditional methods, a comparison of both methods is introduced. The calculation of mechanical behaviour of the composite floor is repeated in a series of three different thermal loading cases. Results of all cases are then compared in terms of vertical displacement and axial force in several positions of the composite floor.

  12. Characterization of radon penetration of different structural domains of concrete. Final project report

    International Nuclear Information System (INIS)

    Nielson, K.K.; Rogers, V.C.

    1996-05-01

    This report documents the research activities by Rogers and Associates Engineering Corporation on grant DE-FG03-93ER61600 during the funded project period from August 1993 to April 1996. The objective of this research was to characterize the mechanisms and rates of radon gas penetration of the different structural domains of the concrete components of residential floor slabs, walls, and associated joints and penetrations. The research was also to characterize the physical properties of the concretes in these domains to relate their radon resistance to their physical properties. These objectives support the broader goal of characterizing which, if any, concrete domains and associated properties constitute robust barriers to radon and which permit radon entry, either inherently or in ways that could be remediated or avoided

  13. Requalification analysis of a circular composite slab for seismic load

    International Nuclear Information System (INIS)

    Srinivasan, M.G.; Kot, C.A.

    1993-01-01

    The circular roof slab of an existing facility was analyzed to requalify the structure for supporting a significant seismic load that it was not originally designed for. The slab has a clear span of 66 ft and consists of a 48 in. thick reinforced concrete member and a steel liner plate. Besides a number of smaller penetrations, the slab contains two significant cutouts. The dominant load for the slab came from seismic excitation. It was characterized by a response spectrum with a peak spectral acceleration of 0.72 g in the vertical direction. The first part of the analysis showed that the nature of attachment between the liner plate and the reinforced concrete (RC) slab would justify assuming composite action between the two. A finite clement analysis, with the ANSYS code, was made to investigate the region surrounding the openings. As the reinforcement in the slab was quite inhomogeneous, it was necessary to determine the stresses in other areas of the slab also. These were obtained with closed form expressions. Finally it is shown that the strength design provisions of the Code Requirements for Nuclear Safety Related Concrete Structures were met by the reinforced concrete slab and the allowable stress provisions of the American National Standard for safety related steel structures in nuclear facilities were met by the liner plate. The composite action between the RC slab and the liner plate provides for the additional strength required to support the enhanced seismic load. The issues that complicated the analysis of this nontypical structure, i.e., composite action and nonlinear stiffness of RC sections, are discussed. It was possible to circumvent the difficulties by making conservative and simplifying assumptions. If design codes incorporate guidelines on practical methods for dynamic analysis of RC structures, some of the unneeded conservatism could be eliminated in future designs

  14. Chlorine signal attenuation in concrete.

    Science.gov (United States)

    Naqvi, A A; Maslehuddin, M; Ur-Rehman, Khateeb; Al-Amoudi, O S B

    2015-11-01

    The intensity of prompt gamma-ray was measured at various depths from chlorine-contaminated silica fume (SF) concrete slab concrete specimens using portable neutron generator-based prompt gamma-ray setup. The intensity of 6.11MeV chloride gamma-rays was measured from the chloride contaminated slab at distance of 15.25, 20.25, 25.25, 30.25 and 35.25cm from neutron target in a SF cement concrete slab specimens. Due to attenuation of thermal neutron flux and emitted gamma-ray intensity in SF cement concrete at various depths, the measured intensity of chlorine gamma-rays decreases non-linearly with increasing depth in concrete. A good agreement was noted between the experimental results and the results of Monte Carlo simulation. This study has provided useful experimental data for evaluating the chloride contamination in the SF concrete utilizing gamma-ray attenuation method. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Monitoring the distributed impact wave on a concrete slab due to the traffic based on polarization dependence on stimulated Brillouin scattering

    International Nuclear Information System (INIS)

    Bao Xiaoyi; Zhang Chunshu; Li Wenhai; Eisa, M; El-Gamal, S; Benmokrane, B

    2008-01-01

    For the first time to our knowledge, distributed impact waves due to the highway traffic on concrete slabs reinforced with FRP bars are monitored in real time using stimulated Brillouin scattering. The impact wave is caused by the traffic passing on the highway pavement at high speed (>100 km h −1 ), which induced pressure on the concrete slabs, and in turn created a local birefringence change, leading to variation of the local state of polarization change (SOP). The pump and probe waves of the stimulated Brillouin scattering 'see' the SOP change and react with a decrease of the Brillouin gain or loss signal, when the pump and probe waves have the same input polarization state. The frequency difference between the pump and probe waves are locked at the static-strain-related Brillouin frequency. Optical fiber was embedded throughout the concrete pavement continuously reinforced with FRP bars in Highway 40 East, Montréal, Quebec to detect impact waves caused by cars and trucks passing on these pavements at a sampling rate of 10 kHz. A spatial resolution of 2 m was used over a sensing length of 300 m

  16. An investigation of Crater Diameter on Plain Slab Foamed Concrete Rice Husk Ash (FCRHA Exposed to Low Impact Loading

    Directory of Open Access Journals (Sweden)

    Hadipramana Josef

    2017-01-01

    Full Text Available As sustainable material building and construction, the foamed concrete (FC in this investigation was modified by adding the Rice Husk Ash (RHA as sand replacement to increase its strength. Furthermore, this modification material (is called FCRHA treated on impact loading. This investigation was motivated when the plain slab of FCRHA subjected to small impactor, then the nose impactor over all would penetrate into slab target due to porosity of FCRHA. The experimental produced plain slabs FCRHA and FC (as a control with 1400 kg/m3 and 1600 Kg/m3 of densities. In impact test all plain slabs exposed by 40 mm steel blunt nose impactor with various impact velocities. The result showed the crater which produced by impact loading was not found spalling, scabbing, radial crack and widely cratering. This local damage occurred when porosity of FCRHA took over the impact loading. The nose impactor over all considered have been successful penetrated into slab of FCRHA and FC. Therefore, the diameter of crater equals to diameter of impactor. With this certainty, the prediction penetration depth on plain slab FCRHA (also FC can be determined in future investigation. In addition, the penetration of impactor on FCRHA with low impact velocity give the same impression on penetration impactor with high impact velocity on FC.

  17. Locomotion and claw disorders in Norwegian dairy cows housed in freestalls with slatted concrete, solid concrete, or solid rubber flooring in the alleys.

    Science.gov (United States)

    Fjeldaas, T; Sogstad, A M; Osterås, O

    2011-03-01

    This study was part of a cross-sectional project on freestall housing, and the aim was to compare locomotion and claw disorders in freestall dairy cattle herds with slatted concrete, solid concrete, or solid rubber flooring in the alleys. The final population for studying claw disorders consisted of 66 dairy herds with 2,709 dry or lactating cows, whereas the population for studying locomotion consisted of 54 herds with 2,216 cows. All herds used Norwegian Red as the main breed. The herds were visited by 15 trained claw trimmers one time during the period from the beginning of February to summer let-out onto pasture in 2008. The trimmers assessed locomotion scores (LocS) of all cows before trimming. At trimming, claw disorders were diagnosed and recorded in the Norwegian Claw Health Card. Estimates describing locomotion and claw disorders in the hind feet were identified by use of multivariable models fit with LocS and each claw disorder as dependent variables, respectively. Herd nested within claw trimmer was included in the model as random effects. The odds ratio (OR) of having LocS >2 and LocS >3 was 1.9 and 2.1, respectively, on slatted concrete compared with solid concrete. Fewer cases of dermatitis were found on slatted than solid concrete (OR=0.70) and a tendency was observed for fewer heel horn erosions on slatted concrete than solid rubber (OR=0.47). Hemorrhages of the white line and sole were more prevalent in herds housed on slatted and solid concrete than in those housed on solid rubber (OR=2.6 and OR=2.1, respectively). White line fissures were also more prevalent in herds housed on slatted and solid concrete than in those housed on solid rubber (OR=2.1 and OR=2.0, respectively). Double soles were more prevalent on solid concrete than solid rubber (OR=4.4). However, sole ulcers were less prevalent in herds with slatted and solid concrete than solid rubber (OR=0.39 and OR=0.53, respectively). Fewer corkscrewed claws were found on slatted concrete than

  18. Slab replacement maturity guidelines.

    Science.gov (United States)

    2014-04-01

    This study investigated the use of maturity method to determine early age strength of concrete in slab : replacement application. Specific objectives were (1) to evaluate effects of various factors on the compressive : maturity-strength relationship ...

  19. Study of deflection and crack interrelation that use deck slab's automatic measurement

    International Nuclear Information System (INIS)

    Park, Sung Woo; Park, Yung Suk; Joo, Kwon Yong

    2004-01-01

    Reinforce concrete slab executes finish work if 6 - 8 hours pass since concrete placing. Specially, because minimize process composition slab occasion early space-time that use structure deck plate, concrete strength revelation is very important. The reason is that when strength revelation is not made, fine shock and deflection can provoke concrete crack. Executed radio automatic measure to prevent these crack initiation cause in the advance. Apply radio automatic measure is il-san culture center building and pasta measure period 03/09/06 - 03/10/08.

  20. Coffered slabs as a perspective type of the reinforced concrete structures

    OpenAIRE

    Kibkalo Anton; Volkov Mikhail; Vodolagina Anna; Murgul Vera

    2016-01-01

    The article discusses coffered slabs. In this paper considered the technology of arrangement of this slabs. Cast-in-place and precast ways of construction of coffered slab are reviewed. Сast-in-place and precast coffered slabs has been analysed in this article. Among other things construction of coffered slabs has an economical and technical advantages.

  1. Coffered slabs as a perspective type of the reinforced concrete structures

    Directory of Open Access Journals (Sweden)

    Kibkalo Anton

    2016-01-01

    Full Text Available The article discusses coffered slabs. In this paper considered the technology of arrangement of this slabs. Cast-in-place and precast ways of construction of coffered slab are reviewed. Сast-in-place and precast coffered slabs has been analysed in this article. Among other things construction of coffered slabs has an economical and technical advantages.

  2. Transmission of neutrons in serpentine mixed and ordinary concrete a comparative study

    International Nuclear Information System (INIS)

    Ravishankar, R.; Bhattacharyya, Sarmishtha; Bandyopadhyay, Tapas; Sarkar, P.K.

    2002-01-01

    Full text: In particle accelerator facilities, for radiation shielding, concrete is commonly used for its effectiveness in attenuating neutrons in addition to its good structural and mechanical properties. Neutron attenuation depends largely on the water content in the concrete. Serpentine mixed concrete is reported to retain better water content than ordinary concrete. Experiments have been carried out to compare neutron attenuation properties of Serpentine mixed concrete slabs and ordinary concrete slabs of different thickness. Transmission of neutrons from a 185 GBq Pu-Be neutron source has been studied using NE-213 liquid scintillator detector, along with the associated electronics to discriminate neutron from gamma using pulse shape discrimination techniques. The energy differential neutron spectra transmitted through the concrete slabs and the corresponding dose have been obtained by unfolding the pulse height spectra using the FERDOR-U computer code and proper response matrix data of the NE-213 detector. The neutron transmission factors through both Serpentine and Ordinary concrete slabs have been studied. The results show serpentine mixed concrete slabs can attenuate more neutrons of varying energies compared to ordinary concrete slabs of equal dimensions. From the trend, it has been found out, with the increase in slab thickness, the gain in neutron attenuation increases. This is due to increase in quantity of serpentine with the increase in thickness of, concrete. A Monte Carlo simulation carried out, for theoretical analysis of the results, has been found to be in order

  3. Transmission of neutrons in serpentine mixed and ordinary concrete- a comparative study

    International Nuclear Information System (INIS)

    Ravishankar, R.; Bhattacharyya, Sarmishtha; Bandyopadhyay, Tapas; Sarkar, P. K.

    2002-01-01

    In particle accelerator facilities, for radiation shielding, concrete is commonly used for its effectiveness in attenuating neutrons in addition to its good structural and mechanical properties. Neutron attenuation depends largely on the water content in the concrete. Serpentine mixed concrete is reported to retain better water content than ordinary concrete. Experiments have been carried out to compare neutron attenuation properties of Serpentine mixed concrete slabs and ordinary concrete slabs of different thickness. Transmission of neutrons from a 185 GBq Pu-Be neutron source has been studied using NE-213 liquid scintillator detector, along with the associated electronics to discriminate neutron from gamma using pulse shape discrimination techniques. The energy differential neutron spectra transmitted through the concrete slabs and the corresponding dose have been obtained by unfolding the pulse height spectra using the FERDOR-U computer code and proper response matrix data of the NE-213 detector. The neutron transmission factors through both Serpentine and Ordinary concrete slabs have been studied. The results show serpentine mixed concrete slabs can attenuate more neutrons of varying energies compared to ordinary concrete slabs of equal dimensions. From the trend, it has been found out, with the increase in slab thickness, the gain in neutron attenuation increases. This is due to increase in quantity of serpentine with the increase in thickness of concrete. A Monte Carlo simulation carried out, for theoretical analysis of the results, has been found to be in order

  4. Effect of Temperature Variation on Modal Frequency of Reinforced Concrete Slab and Beam in Cold Regions

    Directory of Open Access Journals (Sweden)

    Hanbing Liu

    2016-01-01

    Full Text Available Changes of modal frequencies induced by temperature variation can be more obvious than those caused by structural damage, which will lead to the false damage identification results. Therefore, quantifying the temperature effect on modal frequencies is a critical step to eliminate its interference in damage detection. Due to the nonuniform and time-dependent characteristics of temperature distribution, it is insufficient to obtain the reliable relationships between temperatures and modal frequencies using temperatures in air or at surface. In this paper, correlations between measured temperatures (air temperature, surface temperature, mean temperature, etc. and modal frequencies for the slab and beam are comparatively analyzed. And the quantitative models are constructed considering nonuniform temperature distribution. Firstly, the reinforced concrete slab and beam were constructed and placed outside the laboratory to be monitored. Secondly, the correlation coefficients between modal frequencies and three kinds of temperatures are calculated, respectively. Thirdly, simple linear regression models between mean temperature and modal frequencies are established for the slab and beam. Finally, five temperature variables are selected to construct the multiple linear regression models. Prediction results reveal that the proposed multiple linear regression models possess favorable accuracy to quantify the temperature effect on modal frequencies considering nonuniform temperature distribution.

  5. Net joint kinetics in the limbs of pigs walking on concrete floor in dry and contaminated conditions

    DEFF Research Database (Denmark)

    Thorup, Vivi M.; Laursen, Bjarne; Jensen, Bente Rona

    2008-01-01

    In pigs (Sus scrofa), joint disorders are frequent leg problems, and inappropriate pigpen floors and slippery floor conditions may contribute to these problems. Therefore, this study first aimed to quantify the net joint kinetics (net joint moments and net joint reaction forces) in the forelimbs...... and hindlimbs of healthy pigs walking on solid concrete floors. Second, this study aimed to examine the effect of floor condition on the net joint kinetics. Kinematic (50-Hz video recordings) and kinetic (1-kHz force plate measurements) data were collected from 30 pigs and combined with body segment parameters...... from a cadaver study. Net joint kinetics was calculated by using a 2-dimensional inverse dynamic solution. Inverse dynamics have, to our knowledge, not been applied in pigs before. Dry, greasy, and wet floor conditions were tested with 10 pigs each. In the forelimbs, peak joint moment was less (P

  6. Heavy vehicle simulator testing on pre-cast concrete panels

    CSIR Research Space (South Africa)

    Du Plessis, L

    2007-07-01

    Full Text Available commonly found in California, pre-cast concrete slabs are considered to be a very suitable repair material for extending the service life of intermittently distressed concrete pavements. This is because of the long life expectancy of concrete slabs cast...

  7. Radon Sub-slab Suctioning System Integrated in Insulating Layer

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn

    2013-01-01

    This poster presents a new radon sub-slab suctioning system. This system makes use of a grid of horizontal pressurised air ducts located within the lower part of the rigid insulation layer of the ground floor slab. For this purpose a new system of prefabricated lightweight elements is introduced...

  8. Experimental validation of optimum resistance moment of concrete ...

    African Journals Online (AJOL)

    Experimental validation of optimum resistance moment of concrete slabs reinforced ... other solutions to combat corrosion problems in steel reinforced concrete. ... Eight specimens of two-way spanning slabs reinforced with CFRP bars were ...

  9. Deflection of resilient materials for reduction of floor impact sound.

    Science.gov (United States)

    Lee, Jung-Yoon; Kim, Jong-Mun

    2014-01-01

    Recently, many residents living in apartment buildings in Korea have been bothered by noise coming from the houses above. In order to reduce noise pollution, communities are increasingly imposing bylaws, including the limitation of floor impact sound, minimum thickness of floors, and floor soundproofing solutions. This research effort focused specifically on the deflection of resilient materials in the floor sound insulation systems of apartment houses. The experimental program involved conducting twenty-seven material tests and ten sound insulation floating concrete floor specimens. Two main parameters were considered in the experimental investigation: the seven types of resilient materials and the location of the loading point. The structural behavior of sound insulation floor floating was predicted using the Winkler method. The experimental and analytical results indicated that the cracking strength of the floating concrete floor significantly increased with increasing the tangent modulus of resilient material. The deflection of the floating concrete floor loaded at the side of the specimen was much greater than that of the floating concrete floor loaded at the center of the specimen. The Winkler model considering the effect of modulus of resilient materials was able to accurately predict the cracking strength of the floating concrete floor.

  10. Lightweight self-compacting concrete reinforced with fibres for slab rehabilitation

    Directory of Open Access Journals (Sweden)

    Klein, N. S.

    2011-06-01

    Full Text Available The slabs of some buildings in Barcelona are formed by unidirectional beams, with a ceramic arch in between, which are filled with broken pottery or construction waste. These structures often present problems such as displacement of the tiles arranged over it due to the lack of stiffness of the filling material. This supposes a risk to the user and could also cause durability problems. In order to rehabilitate it, a lightweight self-compacting concrete reinforced with fibres (HLACF has been designed to be used as a filling material, improving the stiffness of the structure. This paper presents a structural analysis of a standard case and the results of an experimental campaign. The concrete showed a density of 1665 kg/m3, a slump flow of 605 mm and a compressive strength of 22.3 MPa, at 28 days. These results are in agreement with the requirements, overcoming common lightweight concrete segregation problems.

    Los forjados de ciertos edificios del ensanche de Barcelona, formados por viguetas unidireccionales con un revoltón de cerámica entre ellas y un relleno posterior (material cerámico y residuos de construcción, suelen presentar problemas de movimientos y despegues de las baldosas situadas en la parte superior, con el consiguiente riesgo para el usuario, aparte de los problemas de durabilidad asociados. Para rehabilitar esas estructuras se ha diseñado un hormigón ligero autocompactante con fibras (HLACF, como relleno de modo que mejore la rigidez a la estructura. El artículo presenta el análisis estructural de una solución tipo así como los resultados de una campaña experimental realizada. Como resultado se obtiene un hormigón de densidad de 1.665 kg/m3, escurrimiento de 605 mm y resistencia a compresión de 22,3 MPa, a los 28 días, que cumple con los requisitos y significa superar problemas de segregación previsibles para este tipo de hormigones.

  11. Solving decontaminable flooring problems

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    Pennsylvania Power and Light wanted to cover deteriorating concrete in unit 2 of its Susquehanna BWR with a smooth, durable, decontaminable coating. Traditionally, floors in the plant had been coated with epoxy paint, but many of these floors suffered delamination, and failed in three to five years. Painting with epoxy would also interrupt operations for as much as three days while the floor dried, yet critical instruments in some areas had to be monitored at least once per shift. In addition, conventional floor surface preparation produced dust and vibration around sensitive equipment. The solution was a dustless scabbling system for surface preparation, followed by the installation of a high-strength acrylic industrial floor known as Silakal. The work was carried out by Pentek. Silikal bonds to the underlying concrete, so that delamination of the floor will not occur even under severe traffic conditions. Another advantage of this type of flooring is that it cures in one hour, so floor resurfacing has only minimal impact on plant operations. (author)

  12. Calculation of shear strength of prestressed hollow core slabs by use of plastic theory

    DEFF Research Database (Denmark)

    Hoang, Linh Cao; Jørgensen, H.G.; Nielsen, Mogens Peter

    2014-01-01

    Th is paper deals with calculations of the shear capacity of precast, prestressed hollow core slabs. Such slabs are often used as floor systems in building structures. A common way to produce hollow core slabs is to use the extrusion technique where long strips of slabs are extruded and thereafter...

  13. Strengthening of RC bridge slabs using CFRP sheets

    Directory of Open Access Journals (Sweden)

    Fahmy A. Fathelbab

    2014-12-01

    Full Text Available Many old structures became structurally insufficient to carry the new loading conditions requirements. Moreover, they suffer from structural degradation, reinforcement steel bars corrosion, bad weather conditions…etc. Many official authorities in several countries had recognized many old bridges and buildings as structurally deficient by today’s standards. Due to these reasons, structural strengthening became an essential requirement and different strengthening techniques appeared in market. Fiber Reinforced Polymer (FRP strengthening techniques established a good position among all other techniques, giving excellent structural results, low time required and moderate cost compared with the other techniques. The main purpose of this research is to study analytically the strengthening of a reinforced concrete bridge slabs due to excessive loads, using externally bonded FRP sheets technique. A commercial finite element program ANSYS was used to perform a structural linear and non-linear analysis for strengthened slab models using several schemes of FRP sheets. A parametric study was performed to evaluate analytically the effect of changing both FRP stiffness and FRP schemes in strengthening RC slabs. Comparing the results with control slab (reinforced concrete slab without strengthening it is obvious that attaching FRP sheets to the RC slab increases its capacity and enhances the ductility/toughness.

  14. Experimental Study on the Structural Behavior of HSC Slab under out of plane load

    International Nuclear Information System (INIS)

    Ham, K. W.; Lee, K. J.; Park, D. S.

    2009-01-01

    HSC(Half Steel plate Concrete) Slab is a kind of SC(Steel plate Concrete) structure, so it has a similar advantage of SC structures (short construction period, lower cost and good quality control compared to RC). To apply HSC to the slab of containment building of NPP, several test with different test condition (shear span ratio, shear bar, loading type) were conducted to verify structural behavior of HSC slab structure under out of plane loading

  15. Flexural strength and behaviour of SFRSCC ribbed slab under four point bending

    Science.gov (United States)

    Ahmad, Hazrina; Hashim, Mohd Hisbany Mohd; Bakar, Afidah Abu; Hamzah, Siti Hawa; Rahman, Fadhillah Abdul

    2017-11-01

    An experimental investigation was carried out to study the ultimate strength and behaviour of SFRSCC ribbed slab under four point bending. Comparison was been made between ribbed slab that was fully reinforced with steel fibres (SFWS) with conventionally reinforced concrete ribbed slab (CS and CRC). The volume fraction of the 35 mm hooked end steel fibres used in the mix was 1% (80 kg/m3) with the aspect ratio of 65. Three full scale slab samples with the dimension of 2.8 x 1.2 m with 0.2 m thickness was constructed for the purpose of this study. The slab samples was loaded until failure in a four point bending test. As a whole, based on the results, it can be concluded that the performance of the steel fiber reinforced samples (SFWS) was found to be almost equivalent to the conventionally reinforced concrete ribbed slab sample (CRC).

  16. Modeling radon entry into Florida slab-on-grade houses

    International Nuclear Information System (INIS)

    Revzan, K.L.; Fisk, W.J.; Sextro, R.G.

    1993-01-01

    Radon entry into a Florida house whose concrete slab is supported by a permeable concrete-block stem wall and a concrete footer is modeled. The slab rests on backfill material; the same material is used to fill the footer trench. A region of undisturbed soil is assumed to extend 10 m beyond and below the footer. The soil is assumed homogeneous and isotropic except for certain simulations in which soil layers of high permeability or radium content are introduced. Depressurization of the house induces a pressure field in the soil and backfill. The Laplace equation, resulting from Darcy's law and the continuity equation, is solved using a steady-state finite-difference model to determine this field. The mass-transport equation is then solved to obtain the diffusive and advective radon entry rates through the slab; the permeable stem wall; gaps at the intersections of the slab, stem wall, and footer; and gaps in the slab. These rates are determined for variable soil, backfill, and stem-wall permeability and radium content, slab-opening width and position, slab and stem-wall diffusivity, and water table depth. The variations in soil permeability and radium content include cases of horizontally stratified soil. We also consider the effect of a gap between the edge of the slab and the stem wall that restricts the passage of soil gas from the stem wall into the house. Calculations indicate that the total radon entry rate is relatively low unless the soil or backfill permeability or radium content is high. Variations in most of the factors, other than the soil permeability and radium content, have only a small effect on the total radon entry rate. However, for a fixed soil permeability, the total radon entry rate may be reduced by a factor of 2 or more by decreasing the backfill permeability, by making the stem wall impermeable and gap-free, (possibly by constructing a one-piece slab/stem-wall/footer), or by increasing the pressure in the interior of the stem wall

  17. 111-B Metal Examination Facility Concrete Tanks Characterization Plan

    International Nuclear Information System (INIS)

    Encke, D.B.

    1997-08-01

    The 111-B Metal Examination Facility was a single-story, wood frame 'L'-shaped building built on a concrete floor slab. The facility served as a fuel failure inspection facility. Irradiated fuel pieces were stored and examined in two below grade concrete storage tanks filled with water. The tanks have been filled with grout to stabilize the contamination they contained, and overall dimensions are 5 ft 9 in. (1.5 m 22.8 cm ) wide, 9 ft 1 in. (2.7 m 2.54 cm ) deep, and 10 ft 8 in. (3.0 m 20.32 cm) long, and are estimated to weigh 39 tons. The tanks were used to store and examine failed fuel rods, using water as a radiation shield. The tanks were lined with stainless steel; however, drawings show the liner has been removed from at least one tank (south tank) and was partially filled with grout. The south tank was used to contain the Sample Storage Facility, a multi-level metal storage rack for failed nuclear fuel rods (shown in drawings H-1-2889 and -2890). Both tanks were completely grouted sometime before decontamination and demolition (D ampersand D) of the above ground facility in 1984. The 111-B Metal Examination Facility contained two concrete tanks located below floor level for storage and examination of failed fuel. The tanks were filled with concrete as part of decommissioning the facility prior to 1983 (see Appendix A for description of previous work). Funding for removal and disposal of the tanks ran out before they could be properly disposed

  18. Delamination detection in reinforced concrete using thermal inertia

    International Nuclear Information System (INIS)

    Del Grande, N K; Durbin, P F.

    1998-01-01

    We investigated the feasibility of thermal inertia mapping for bridge deck inspections. Using pulsed thermal imaging, we heat-stimulated surrogate delaminations in reinforced concrete and asphalt-concrete slabs. Using a dual-band infrared camera system, we measured thermal inertia responses of Styrofoam implants under 5 cm of asphalt, 5 cm of concrete, and 10 cm of asphalt and concrete. We compared thermal maps from solar-heated concrete and asphalt-concrete slabs with thermal inertia maps from flash-heated concrete and asphalt-concrete slabs. Thermal inertia mapping is a tool for visualizing and quantifying subsurface defects. Physically, thermal inertia is a measure of the resistance of the bridge deck to temperature change. Experimentally, it is determined from the inverse slope of the surface temperature versus the inverse square root of time. Mathematically, thermal inertia is the square root of the product of thermal conductivity, density, and heat capacity. Thermal inertia mapping distinguishes delaminated decks which have below-average thermal inertias from normal or shaded decks. Key Words: Pulsed Thermal Imaging, Thermal Inertia, Detection Of Concrete Bridgedeck Delaminations

  19. Post-Tensioned Concrete Long-Span Slabs in Projects of Modern Building Construction

    Science.gov (United States)

    Szydlowski, Rafal; Labuzek, Barbara

    2017-10-01

    Nowadays, design of modern an architectural building structures requires the use of slender and free from numerous supports slabs. The most suitable solution for above requirements are the post-tensioned slabs with unbounded tendons. Slabs prestressed by unbounded tendons are successfully used worldwide for several decades. During that time many recommendations dealing with the forming of geometry and prestressing, dimensioning and erection technology were issued. During the recent years prestressed slabs characterized by span and slenderness substantially exceeding recommended limitations were designed and erected with success in Poland. During the slabs erection and in two years of their using, the deflection of three oversized slabs were monitoring. In spite of designed the slabs significantly larger and slenderer than the recommended maximum value of span and span to depth ratio, the deflection of the slabs is definitely far from the limit value. The paper shows the geometry, characteristic and deflection of erected slabs and conclusion. Description of a very large span slab (21.3m), that was designed regarded to the information obtained from the previous realisation, is presented in this paper.

  20. Gait of dairy cows on floors with different slipperiness.

    Science.gov (United States)

    Telezhenko, E; Magnusson, M; Bergsten, C

    2017-08-01

    This study assessed the slip resistance of different types of solid flooring in cattle housing using a range of technical tests and gait analysis. Dynamic and static coefficient of friction, skid resistance, and abrasiveness were tested on concrete flooring with a smooth finish, a grooved pattern, or a tamped pattern, acid-resistant mastic asphalt, soft rubber mats, and a worn slatted concrete floor. Coefficients of friction and skid resistance were tested under clean and slurry-soiled conditions. Linear kinematic variables were assessed in 40 cows with trackway measurements after the cows passed over the floors in a straight walk. All gait variables were assessed as deviations from those obtained on the slatted concrete floor, which was used as a baseline. The coefficient of friction tests divided the floors into 3 categories: concrete flooring, which had a low coefficient of friction (0.29-0.41); mastic asphalt flooring, which had medium values (0.38-0.45); and rubber mats, which had high values (0.49-0.57). The highest abrasion (g/10 m) was on the asphalt flooring (4.48), and the concrete flooring with a tamped pattern had significantly higher abrasiveness (2.77) than the other concrete floors (1.26-1.60). Lowest values on the skid-resistance tests (dry/wet) were for smooth concrete (79/35) and mastic asphalt (65/47), especially with a slurry layer on the surface. Gait analysis mainly differentiated floors with higher friction and abrasion by longer strides and better tracking. Step asymmetry was lower on floors with high skid-resistance values. The most secure cow gait, in almost every aspect, was observed on soft rubber mats. Relationships between gait variables and physical floor characteristics ranged from average to weak (partial correlations 0.54-0.16). Thus, none of the physical characteristics alone was informative enough to characterize slip resistance. With reference to gait analysis, the abrasiveness of the hard surfaces was more informative than the

  1. Experimental and theoretical investigation of column - flat slab joint ductility

    International Nuclear Information System (INIS)

    Iskhakov, I.; Ribakov, Y.; Shah, A.

    2009-01-01

    Most modern seismic codes use ductility as one of the basic design parameters. Actually, ductility defines the ability of a structure or its elements to absorb energy by plastic deformations. Until the end of the previous century ductility was defined qualitatively. Most research works related to ductility are focused on structural elements' sections. This study was aimed at complex experimental and theoretical investigation of flat slab-column joints ductility. It is one of the first attempts to obtain quantitative values of joint's ductility for the case of high strength concrete columns and normal strength concrete slabs. It was shown that the flat slab-column joint is a three-dimension (3D) element and its ductility in horizontal and vertical directions are different. This is the main difference between ductility of elements and joint ductility. In case of flat slab-column joints, essential contribution to joint's ductility can be obtained due to the slab's confining effect. Based on experimental data, the authors demonstrate that flat slab-column joint's ductility depends on the joint's confining effect in two horizontal and vertical directions. Furthermore, the influence of slab load intensity and slab reinforcement ratio on the joint's ductility is performed in this study. It is also demonstrated that the effect of the ratio between the slab thickness and the column's section dimension on the ductility parameter is significant. Equations for obtaining a quantitative value of a flat slab-column joint's ductility parameter were developed.

  2. Energy penalties associated with the use of a sub-slab depressurization system

    International Nuclear Information System (INIS)

    Clarkin, M.; Brennan, T.; Osborne, M.C.

    1990-01-01

    One of the primary radon mitigation techniques used to reduce indoor radon concentrations in houses is a sub-slab depressurization system. In this type of system, a fan removes soil gases containing radon from beneath the floor slab and exhausts the gases to the outdoors by creating a pressure field beneath the slab that is negative relative to the basement air pressure. Because of this negative pressure, indoor conditioned air can be drawn through the floor penetrations and exhausted outdoors. In order to determine the amount of conditioned air that is being lost, a series of experiments utilizing tracer gases were performed in three houses. This paper presents the results of these experiments

  3. Watertightness in anti-flotation slabs: MIS-RJ case

    Directory of Open Access Journals (Sweden)

    C. Britez

    Full Text Available It is common in coastal cities as Rio de Janeiro, that buildings located close to the shoreline have their basements below water table level. In most cases, the engineering solution for these buildings is to design a massive anti-flotation slab to satisfy, principally, the issues related to structural dimensioning and calculation hypothesis. On the other hand, the execution of this solution imply in significant construction problems related to reinforced concrete watertightness and durability. This paper presents a case study about challenges and solutions devised to execute an anti-flotation, 1m thick, 1200m³ reinforced concrete slab for the new Museu de Imagem e Som (MIS - Sound and Image Museum, located at 50m from the seashore, at Copacabana in Rio de Janeiro, RJ. The results show that concrete proportions, concreting plan and pouring method adopted were decisive in obtaining a watertight structure, avoiding thus the employment of traditional waterproofing alternatives.

  4. Phase 2 microwave concrete decontamination results

    International Nuclear Information System (INIS)

    White, T.L.; Foster, D. Jr.; Wilson, C.T.; Schaich, C.R.

    1995-01-01

    The authors report on the results of the second phase of a four-phase program at Oak Ridge National Laboratory to develop a system to decontaminate concrete using microwave energy. The microwave energy is directed at the concrete surface through the use of an optimized wave guide antenna, or applicator, and this energy rapidly heats the free water present in the interstitial spaces of the concrete matrix. The resulting steam pressure causes the surface to burst in much the same way popcorn pops in a home microwave oven. Each steam explosion removes several square centimeters of concrete surface that are collected by a highly integrated wave guide and vacuum system. The authors call this process the microwave concrete decontamination, or MCD, process. In the first phase of the program the principle of microwaves concrete removal concrete surfaces was demonstrated. In these experiments, concrete slabs were placed on a translator and moved beneath a stationary microwave system. The second phase demonstrated the ability to mobilize the technology to remove the surfaces from concrete floors. Area and volume concrete removal rates of 10.4 cm 2 /s and 4.9 cm 3 /S, respectively, at 18 GHz were demonstrated. These rates are more than double those obtained in Phase 1 of the program. Deeper contamination can be removed by using a longer residence time under the applicator to create multiple explosions in the same area or by taking multiple passes over previously removed areas. Both techniques have been successfully demonstrated. Small test sections of painted and oil-soaked concrete have also been removed in a single pass. Concrete with embedded metal anchors on the surface has also been removed, although with some increased variability of removal depth. Microwave leakage should not pose any operational hazard to personnel, since the observed leakage was much less than the regulatory standard

  5. Assessment of Cost Variation in Solid and Hollow Floor Construction in Lagos State

    Directory of Open Access Journals (Sweden)

    Oluwaseun Sunday Dosumu

    2013-12-01

    Full Text Available The differences in construction methods between different forms of slabs construction tend to result into variation in the cost of the slabs for any building project. Thus, this study aims at assessing the variation in construction cost among various construction methods available for hollow and solid floors in construction projects within Lagos State. The research design for this study was a survey design approach and the population of the study are active professionals (Architects, Civil Engineers, Builders, Quantity Surveyors, Consultant and contractors because they are the major participants in the construction activities of the construction industry in Lagos State, Nigeria. The research is based on 46 returned questionnaires out of the 60 that was administered. The data from the questionnaires were analyzed using descriptive tools such as frequencies, percentage and mean values. The hypotheses were tested with paired sample t-test and it was found that the system or method of slab construction well known to the respondents is cast in situ, precast and semi-precast. The study also shows that the cost of in-situ solid slabs are higher than that of hollow slab which is an indication that solid slab construction is more expensive than hollow slab construction provided the hollow slab is a one-way hollow floor and not waffle floor. In pre cast solid slab construction the cost of transportation of units to sites, cost of expertise required in the construction process and the cost of fabrication off site are the three highest and most expensive aspects of precast solid slab while cost of erection and placement and the cost of grouting and topping if required are less expensive. Therefore there is difference in the cost of construction between the solid and hollow slabs but the difference is not appreciable. The study's major recommendation is that, adequate and careful analysis must be done in the choice of floor system being adopted for any

  6. Analysis of instability of tall buildings with prestressed and waffle slabs

    Directory of Open Access Journals (Sweden)

    V. M. Passos

    Full Text Available ABSTRACT The construction system of prestressed flat slabs has been gaining market in Brazil, since it eliminates the use of beams, allows you to perform structures under coluns by area and reduces the cycle of concrete slabs. Thus the analysis of global stability of buildings, takes into account the effects of 2nd order, and these additional effects to the structure obtained from the deformation thereof, calculated by the iterative method P-Delta. The Brazilian ABNT NBR 6118: 2014 [2] assesses the overall stability of reinforced concrete structures through practical parameters, which are the parameter a (Alpha and gz (Gamma z coefficient. In this research we seek to study the global stability of slender buildings consist of flat slabs, with slenderness (ratio of the smaller width with the height of the building approximately one to six, from the modeling of a building with prestressed slabs nonadherent and waffle slabs. To model will use the commercial software CAD / TQS.

  7. Lightweight self-compacting concrete reinforced with fibres for slab rehabilitation; Hormigon ligero autocompactante con fibras para rehabilitacion de forjados

    Energy Technology Data Exchange (ETDEWEB)

    Klein, N. S.; Fuente, A. de la; Aguado, A.; Maso, D.

    2011-07-01

    The slabs of some buildings in Barcelona are formed by unidirectional beams, with a ceramic arch in between, which are filled with broken pottery or construction waste. These structures often present problems such as displacement of the tiles arranged over it due to the lack of stiffness of the filling material. This supposes a risk to the user and could also cause durability problems. In order to rehabilitate it, a lightweight self-compacting concrete reinforced with fibres (HLACF) has been designed to be used as a filling material, improving the stiffness of the structure. This paper presents a structural analysis of a standard case and the results of an experimental campaign. The concrete showed a density of 1665 kg/m3, a slump flow of 605 mm and a compressive strength of 22.3 MPa, at 28 days. These results are in agreement with the requirements, overcoming common lightweight concrete segregation problems. (Author) 24 refs.

  8. Analysis of prestressed concrete slab-and-beam structures

    Science.gov (United States)

    Sapountzakis, E. J.; Katsikadelis, J. T.

    In this paper a solution to the problem of prestressed concrete slab-and-beam structures including creep and shrinkage effect is presented. The adopted model takes into account the resulting inplane forces and deformations of the plate as well as the axial forces and deformations of the beam, due to combined response of the system. The analysis consists in isolating the beams from the plate by sections parallel to the lower outer surface of the plate. The forces at the interface, which produce lateral deflection and inplane deformation to the plate and lateral deflection and axial deformation to the beam, are established using continuity conditions at the interface. The influence of creep and shrinkage effect relative with the time of the casting and the time of the loading of the plate and the beams is taken into account. The estimation of the prestressing axial force of the beams is accomplished iteratively. Both instant (e.g. friction, slip of anchorage) and time dependent losses are encountered. The solution of the arising plate and beam problems, which are nonlinearly coupled, is achieved using the analog equation method (AEM). The adopted model, compared with those ignoring the inplane forces and deformations, describes better the actual response of the plate-beams system and permits the evaluation of the shear forces at the interfaces, the knowledge of which is very important in the design of prefabricated ribbed plates.

  9. Review of Punching Shear Behaviour of Flat Slabs Reinforced with FRP Bars

    Science.gov (United States)

    Mohamed, Osama A.; Khattab, Rania

    2017-10-01

    Using Fibre Reinforced Polymer (FRP) bars to reinforce two-way concrete slabs can extend the service life, reduce maintenance cost and improve-life cycle cost efficiency. FRP reinforcing bars are more environmentally friendly alternatives to traditional reinforcing steel. Shear behaviour of reinforced concrete structural members is a complex phenomenon that relies on the development of internal load-carrying mechanisms, the magnitude and combination of which is still a subject of research. Many building codes and design standards provide design formulas for estimation of punching shear capacity of FRP reinforced flat slabs. Building code formulas take into account the effects of the axial stiffness of main reinforcement bars, the ratio of the perimeter of the critical section to the slab effective depth, and the slab thickness on the punching shear capacity of two-way slabs reinforced with FRP bars or grids. The goal of this paper is to compare experimental data published in the literature to the equations offered by building codes for the estimation of punching shear capacity of concrete flat slabs reinforced with FRP bars. Emphasis in this paper is on two North American codes, namely, ACI 440.1R-15 and CSA S806-12. The experimental data covered in this paper include flat slabs reinforced with GFRP, BFRP, and CFRP bars. Both ACI 440.1R-15 and CSA S806-12 are shown to be in good agreement with test results in terms of predicting the punching shear capacity.

  10. Novel Radon Sub-Slab Suctioning System

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn

    2013-01-01

    A new principle for radon protection is currently presented which makes use of a system of horizontal pressurised air ducts located within the lower part of the rigid insulation layer of the ground-floor slab. The function of this system is based on the principles of pressure reduction within...... a grid of horizontal air ducts with low pressure which are able to remove air and radon from the ground. Results showed the system to be effective in preventing radon infiltrating from the ground through the ground-floor slab, avoiding high concentrations of radon being accumulated inside houses....... For the system to be effective, the pressure within the ducts must be lower than the pressure inside the house. The new principle was shown to be effective in preventing radon from polluting the indoor air by introducing low pressure in the horizontal grid of air ducts. A lower pressure than the pressure inside...

  11. Evaluation of the Impact of Slab Foundation Heat Transfer on Heating and Cooling in Florida

    Energy Technology Data Exchange (ETDEWEB)

    Parker, D. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Kono, J. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Vieira, R. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Gu, L. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States)

    2016-09-01

    During the last three decades of energy-efficiency research, there has been limited study of heat transfer to slab-on-grade foundations in cooling-dominated climates. Most experimental research has focused on the impact of slab-on-grade foundations and insulation schemes on heat losses in heating-dominated climates. This is surprising because the floor area in single-family homes is generally equal to wall area, window area, or attic area, all of which have been extensively evaluated for heat-transfer properties. Moreover, slab foundations are the most common foundation type in cooling-dominated climates. Slab-on-grade construction is very popular in southern states, accounting for 77% of new home floors according to 2014 U.S. Census data. There is a widespread perception that tile flooring, as opposed to carpet, provides a cooler home interior in warm climates. Empirical research is needed because building energy simulation software programs running DOE-2 and EnergyPlus engines often rely on simplified models to evaluate the influence of flooring on interior temperature, even though in some cases more detailed models exist. The U.S. Department of Energy Building America Partnership for Improved Residential Construction (BA-PIRC) performed experiments in the Florida Solar Energy Center’s Flexible Residential Test Facility intended to assess for the first time (1) how slab-on-grade construction influences interior cooling in a cooling-dominated climate and (2) how the difference in a carpeted versus uncarpeted building might influence heating and cooling energy use. Two nominally identical side-by-side residential buildings were evaluated during the course of 1 year, from 2014 to 2015: the east building with a pad and carpet floor and the west building with a bare slab floor. A detailed grid shows temperature measurements taken on the slab surface at various locations as well as at depths of 1.0 ft, 2 ft, 5.0 ft, 10.0 ft, and 20.0 ft below the surface. Temperature

  12. External Hand Forces Exerted by Long-Term Care Staff to Push Floor-Based Lifts: Effects of Flooring System and Resident Weight.

    Science.gov (United States)

    Lachance, Chantelle C; Korall, Alexandra M B; Russell, Colin M; Feldman, Fabio; Robinovitch, Stephen N; Mackey, Dawn C

    2016-09-01

    The aim of this study was to investigate the effects of flooring type and resident weight on external hand forces required to push floor-based lifts in long-term care (LTC). Novel compliant flooring is designed to reduce fall-related injuries among LTC residents but may increase forces required for staff to perform pushing tasks. A motorized lift may offset the effect of flooring on push forces. Fourteen female LTC staff performed straight-line pushes with two floor-based lifts (conventional, motor driven) loaded with passengers of average and 90th-percentile resident weights over four flooring systems (concrete+vinyl, compliant+vinyl, concrete+carpet, compliant+carpet). Initial and sustained push forces were measured by a handlebar-mounted triaxial load cell and compared to participant-specific tolerance limits. Participants rated pushing difficulty. Novel compliant flooring increased initial and sustained push forces and subjective ratings compared to concrete flooring. Compared to the conventional lift, the motor-driven lift substantially reduced initial and sustained push forces and perceived difficulty of pushing for all four floors and both resident weights. Participants exerted forces above published tolerance limits only when using the conventional lift on the carpet conditions (concrete+carpet, compliant+carpet). With the motor-driven lift only, resident weight did not affect push forces. Novel compliant flooring increased linear push forces generated by LTC staff using floor-based lifts, but forces did not exceed tolerance limits when pushing over compliant+vinyl. The motor-driven lift substantially reduced push forces compared to the conventional lift. Results may help to address risk of work-related musculoskeletal injury, especially in locations with novel compliant flooring. © 2016, Human Factors and Ergonomics Society.

  13. Pentek concrete scabbling system: Baseline report; Greenbook (chapter)

    International Nuclear Information System (INIS)

    1997-01-01

    The Pentek scabbling technology was tested at Florida International University (FIU) and is being evaluated as a baseline technology. This report evaluates it for safety and health issues. It is a commercially available technology and has been used for various projects at locations throughout the country. The Pentek concrete scabbling system consisted of the MOOSE, SQUIRREL-I, and SQUIRREL-III scabblers. The scabblers are designed to scarify concrete floors and slabs using cross-section, tungsten carbide tipped bits. The bits are designed to remove concrete in 318 inch increments. The bits are either 9-tooth or demolition type. The scabblers are used with a vacuum system designed to collect and filter the concrete dust and contamination that is removed from the surface. The safety and health evaluation conducted during the testing demonstration focused on two main areas of exposure: dust and noise. Dust exposure was minimal, but noise exposure was significant. Further testing for each of these exposures is recommended. Because of the outdoor environment where the testing demonstration took place, results may be inaccurate. It is feasible that the dust and noise levels will be higher in an enclosed operating environment. Other areas of concern were arm-hand vibration, whole-body vibration, ergonomics, heat stress, tripping hazards, electrical hazards, machine guarding, and lockout/tagout

  14. Craters in concrete slabs due to detonation – drawbacks of material models with a Mohr-Coulomb yield surface

    Directory of Open Access Journals (Sweden)

    Conrad Markus

    2015-01-01

    Full Text Available Numerical simulations have been performed with a commercial distributed explicit FE-solver and the results have been compared with experiments. High explosive was placed in front of different concrete slabs with the dimension 100 × 100 × 16 cm. Some of the results of the simulations, in particular the profile of the craters, are not in agreement with the test results. Therefore the key characteristics of the constitutive equation based on Mohr-Coulomb yield surfaces and a damage evolution linked to the plastic strain has been reviewed.

  15. Three-dimensional Finite Element Modelling of Composite Slabs for High Speed Rails

    Science.gov (United States)

    Mlilo, Nhlanganiso; Kaewunruen, Sakdirat

    2017-12-01

    Currently precast steel-concrete composite slabs are being considered on railway bridges as a viable alternative replacement for timber sleepers. However, due to their nature and the loading conditions, their behaviour is often complex. Present knowledge of the behaviour of precast steel-concrete composite slabs subjected to rail loading is limited. FEA is an important tool used to simulate real life behaviour and is widely accepted in many disciples of engineering as an alternative to experimental test methods, which are often costly and time consuming. This paper seeks to detail FEM of precast steel-concrete slabs subjected to standard in-service loading in high-speed rail with focus on the importance of accurately defining material properties, element type, mesh size, contacts, interactions and boundary conditions that will give results representative of real life behaviour. Initial finite element model show very good results, confirming the accuracy of the modelling procedure

  16. Fire resistance of extruded hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    2017-01-01

    to the structural codes with data derived from a standard fire test and from a thorough examination of the comprehensive test documentation available on fire exposed hollow-core slabs. Findings – Mechanisms for loss of load-bearing capacity are clarified, and evidence of the fire resistance is found. Originality......Purpose – Prefabricated extruded hollow-core slabs are preferred building components for floor structures in several countries. It is therefore important to be able to document the fire resistance of these slabs proving fulfilment of standard fire resistance requirements of 60 and 120 min found...... in most national building regulations. The paper aims to present a detailed analysis of the mechanisms responsible for the loss of loadbearing capacity of hollow-core slabs when exposed to fire. Design/methodology/approach – Furthermore, it compares theoretica calculation and assessment according...

  17. Study on emission of decomposed chemicals of esters contained in PVC flooring and adhesive

    Energy Technology Data Exchange (ETDEWEB)

    Chino, Satoko; Ataka, Yuji [R and D Center, Yoshino Gypsum Co., Ltd., 2-1-1 Kohoku, Adachi-ku, Tokyo, 123-0872 (Japan); Kato, Shinsuke; Seo, Janghoo [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

    2009-07-15

    2-Ethyl-1-hexanol (2E1H) is sometimes detected in indoor air at relatively high concentrations. The emission mechanism for 2E1H is considered to be that moisture with a high pH in concrete slabs and self-leveling sub-flooring material reacts with di-2-ethylhexyl phthalate (DEHP) in the polyvinyl chloride (PVC) flooring and compounds containing the 2-ethyl-1-hexyl group in the adhesive. 2E1H is considered to be one of the causes of odor in indoor air and sick building syndrome, so it is important to clarify the 2E1H emission mechanism for IAQ. However, there are few reports on any experimentation into 2E1H emission by chemical reaction involving building materials. In this study, PVC floorings are attached using various adhesives to a self-leveling sub-flooring material that contains water, and their 2E1H emission rates are measured. Furthermore, the components of the adhesives are determined using chemical analysis. It is found that 2E1H emission rates from the floor are affected by the type of adhesive used. On the other hand, some components in the adhesives may suppress the hydrolysis of esters. The hydrolysis of polymers and residual monomers in the adhesive causes 2E1H emission from the adhesive. (author)

  18. Short communication: Flooring preferences of dairy cows at calving.

    Science.gov (United States)

    Campler, M; Munksgaard, L; Jensen, M B; Weary, D M; von Keyserlingk, M A G

    2014-02-01

    The present study investigated the flooring preference during the 30 h before parturition in Holstein dairy cows housed individually in a maternity pen. Seventeen multiparous cows were moved, on average, 2 d before expected calving date into an individual maternity pen with 3 different flooring surfaces: 10 cm of sand, pebble-top rubber mats, or concrete flooring, each covered with 15 cm of straw. Calving location, lying time, and total time and number of lying bouts on each of the floor types were recorded during 2 periods: precalving (24 to 29 h before calving) and at calving (0 to 5h before calving). Ten cows calved on sand, 6 on concrete, and 1 on the rubber mat. Lying bouts increased during the hours closest to calving, regardless of flooring. The number of lying bouts did not differ between flooring types precalving but cows had more lying bouts on sand and concrete compared with rubber at calving. Cows spent more time lying down on sand and concrete compared with rubber precalving, but lying times did not differ between treatments at calving. Cows that calved on sand spent more time lying on sand at calving compared with the other 2 flooring types. Cows that calved on concrete did not show a flooring preference at calving. These results indicate that rubber mats are the least preferred by dairy cows in the maternity pens, even when covered with a deep layer of straw. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  19. Analysis and design of composite slab by varying different parameters

    Science.gov (United States)

    Lambe, Kedar; Siddh, Sharda

    2018-03-01

    Composite deck slabs are in demand because of its faster, lighter and economical construction work. Composite slab consists of cold formed deck profiled sheet and concrete either lightweight or normal. Investigation of shear behaviour of the composite slab is very complex. Shear bond strength depends on the various parameter such as a shape of sheeting, a thickness of the sheet, type of embossment and its frequency of use, shear stiffener or intermediate stiffener, type of load, an arrangement of load, length of shear span, the thickness of concrete and support friction etc. In present study finite element analysis is carried out with ABAQUS 6.13, a simply supported composite slab is considered for the investigation of the shear bond behaviour of the composite slab by considering variation in three different parameters, the shape of a sheet, thickness of sheet and shear span. Different shear spans of two different shape of cold formed deck profiled sheet i.e. with intermediate stiffeners and without intermediate stiffeners are considered with two different thicknesses (0.8 mm and 1.2 mm) for simulation. In present work, simulation of models has done for static loading with 20 mm mesh size is considered.

  20. 26 CFR 1.48-10 - Single purpose agricultural or horticultural structures.

    Science.gov (United States)

    2010-04-01

    ... the rafters by thin steel girders and wires. The floor of the structure is a sloping concrete slab... commercial production of plants. The greenhouse is a rectangular structure with translucent fiberglass walls... structure has a sloping concrete floor. The other part of the structure constitutes more than two-thirds of...

  1. Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete.

    Science.gov (United States)

    López-Uceda, Antonio; Ayuso, Jesús; Jiménez, José Ramón; Agrela, Francisco; Barbudo, Auxiliadora; De Brito, Jorge

    2016-02-02

    This research aims to produce non-structural concrete with mixed recycled aggregates (MRA) in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%), using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results) from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors' knowledge, there have not been any upscaled applications of concrete with MRA and low cement content.

  2. Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete

    Directory of Open Access Journals (Sweden)

    Antonio López-Uceda

    2016-02-01

    Full Text Available This research aims to produce non-structural concrete with mixed recycled aggregates (MRA in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%, using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors’ knowledge, there have not been any upscaled applications of concrete with MRA and low cement content.

  3. Vibration characteristics of an APS lab facility in Building 401

    International Nuclear Information System (INIS)

    Royston, T.J.

    1998-01-01

    The vibratory behavior of a lab facility located in Building 401 of the Advanced Photon Source site at Argonne National Laboratory is summarized. Measurements of ambient vibration indicate that acceptable displacement levels are usually maintained (rms value below 0.1 microns) for the measured frequency range, above 0.2 Hz. An exception occurs when strong wind conditions excite a horizontal building resonance near 1.85 Hz to rms levels as high as 0.3 microns. Measurements of the laboratory floor's dynamic response to directly applied force excitation agree with theoretical predictions. The primary component of the floor construction is a reinforced concrete slab. The slab has a transverse fundamental resonant frequency of 18.5 Hz and an associated damping level of roughly 8.5% of critical. It is also shown via experimental measurements that the linoleum surface adhered to the concrete slab is far more compliant than the slab itself and can significantly influence the floor's dynamic response to local excitations

  4. Investigation of load transfer efficiency in jointed plain concrete pavements (JPCP using FEM

    Directory of Open Access Journals (Sweden)

    Vahid Sadeghi

    2018-05-01

    Full Text Available Owing to heavy traffic loads, rigid pavements encounter various types of failures at transverse joints during their lifetime. Three-dimensional finite-element method (3D-FEM was used to assess the structural response of jointed concrete pavement under moving tandem axle loads. In this study, 3D FEM was verified using an existing numerical model and field measurement of the concrete slab traversed by a moving truck. This paper also investigated the effects of multiple parameters: material properties, slab geometry, load magnitude and frictional status of the slab and base layer on load transfer efficiency (LTE of the transverse joints. Further study has been done to investigate the slab performance without the dowel bars which occurs when parts of the pavement needed to be repaired using precast slabs. The aggregate interlock between the new slab and the existing slab is simulated by frictional interface. In 3D FEM model, the load transfer efficiency has been improved by increasing the elasticity modules of the concrete slab and the base layer or increasing the slab thickness. This can decrease the joints' deflections, reduces the damages on pavement joints. Removing dowel bars adversely affected the load transfer. Keywords: Concrete pavement, Load transfer, Finite-element method, Dowel bar, Structural behavior

  5. A Method of Assembling Wall or Floor Elements

    DEFF Research Database (Denmark)

    2002-01-01

    The invention relates to a method of constructing, at the site of use, a building wall (1) or a building floor (1) using a plurality of prefabricated concrete or lightweight concrete plate-shaped wall of floor elements (10), in particular cast elements, which have a front side and a rear side...

  6. Material selection and embodied energy

    CSIR Research Space (South Africa)

    Ampofo-Anti, N

    2010-11-01

    Full Text Available mix concrete apron Non reinforced, ready mix concrete strip foundation Non reinforced, ready mix ground floor slab Concrete block Modular, hollow concrete block Solid concrete block Finishes Floor screed Insulated ceiling panel Perlite... Predicting the embodied energy contribution of a single material is however not as easy as green building practices assume. As illustrated by the example in Box 1, the choice of a material implies the choice of integral constituents such as insulation...

  7. Development of lightweight concrete subfloor with ethylene vinyl acetate (EVA) aggregates waste to reduce impact sound in flooring system

    OpenAIRE

    Pacheco, Fernanda; Krumenauer, Marcelo; Reis de Medeiros, Daniel; Oliveira, Maria Fernanda; Fonseca Tutikian, Bernardo

    2017-01-01

    Abstract Comfort and habitability are requirements for housing quality, affected by underfloor system. Thus, this study aims to design lightweight concrete slabs underfloor with the use of ethylene vinyl acetate (EVA) aggregates, with two grain sizes of conventional aggregates replaced with EVA. The experimental counted on four unit mixes, varying the ratio between EVA coarse and fine aggregates and natural aggregates. The underfloor plates were molded with thickness of 3, 5 and 7 centimeters...

  8. Fire resistance of extruded hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Giuliani, Luisa; Sørensen, Lars Schiøtt

    2016-01-01

    Prefabricated extruded hollow-core slabs are preferred building components for floor structures in several countries. It is therefore important to be able to document the fire resistance of these slabs proving fulfilment of standard fire resistance requirements of 60- and 120 minutes found in most...... a standard fire test and from a thorough examination of the comprehensive test documentation available on fire exposed hollow-core slabs. Mechanisms for loss of load-bearing capacity are clarified, and evidence of the fire resistance is found. For the first time the mechanisms responsible for loss of load......-bearing capacity are identified and test results and calculation approach are for the first time Applied in accordance with each other for assessment of fire resistance of the structure....

  9. Evaluation of the deflected mode of the monolithic span pieces and preassembled slabs combined action

    Science.gov (United States)

    Roshchina, Svetlana; Ezzi, Hisham; Shishov, Ivan; Lukin, Mikhail; Sergeev, Michael

    2017-10-01

    In single-story industrial buildings, the cost of roof covering comprises 40-55% of the total cost of the buildings. Therefore, research, development and application of new structural forms of reinforced concrete rafter structures, that allow to reduce material consumption and reduce the sub-assembly weight of structures, are the main tasks in the field of improving the existing generic solutions. The article suggests a method for estimating the relieving effect in the rafter structure as the result of combined deformation of the roof slabs with the end arrises. Calculated and experimental method for determining the stress and strain state of the rafter structure upper belt and the roof slabs with regard to their rigid connection has been proposed. A model of a highly effective roof structure providing a significant reduction in the construction height of the roofing and the cubic content of the building at the same time allowing to include the end arrises and a part of the slabs shelves with the help of the monolithic concrete has been proposed. The proposed prefabricated monolithic concrete rafter structure and its rigid connection with ribbed slabs allows to reduce the consumption of the prestressed slabs reinforcement by 50%.

  10. Failure analysis of edge flat-slab column connections with shear reinforcement

    OpenAIRE

    Bompa, Dan V.; Muttoni, Aurelio

    2013-01-01

    Flat-slab column connections are susceptible to brittle failure, which lead to the necessity of improving ductility and ultimate strength. In case of edge connections, the behaviour at ultimate state is highly influenced by nonsymmetrical distribution of stresses originated by a moment transfer between the slab and the column. The paper presents the test results of three full-scale reinforced concrete flat-slab edge connections with stud-rail shear reinforcement subjected to concentrated load...

  11. Experimental research on the use of micro-encapsulated Phase Change Materials to store solar energy in concrete floors and to save energy in Dutch houses

    NARCIS (Netherlands)

    Entrop, Alexis Gerardus; Brouwers, Jos; Reinders, Angelina H.M.E.

    2011-01-01

    In this paper an experimental research is presented on a new use of Phase Change Materials (PCMs) in concrete floors, in which thermal energy provided by the sun is stored in a mix of concrete and PCMs. When this thermal energy is being released – in moderate sea climates during the evening and

  12. Analysis of Double Skin Composite Slabs

    Directory of Open Access Journals (Sweden)

    Husain M. Husain

    2018-03-01

    Full Text Available This paper deals with finite element modeling of the ultimate load behavior of double skin composite (DSC slabs. In a DSC slab, shear connectors in the form of nut bolt technique studs are used to transfer shear between the outer skin made of steel plates and the concrete core. The current study is based on finite element analysis using ANSYS Version 11 APDL release computer program. Experimental programmes were carried out by the others, two simply supported DSC beams were tested until failure under a concentrated load applied at the center. These test specimens were analyzed by the finite element method and the analyses have shown that these slabs displayed a high degree of flexural characteristics, ultimate strength, and ductility. The close agreement has been observed between the finite element and experimental results for ultimate loads and load–deflection responses. The finite element model was thus found to be capable of predicting the behavior of DSC slabs accurately.

  13. Nuclear reactor cavity floor passive heat removal system

    Science.gov (United States)

    Edwards, Tyler A.; Neeley, Gary W.; Inman, James B.

    2018-03-06

    A nuclear reactor includes a reactor core disposed in a reactor pressure vessel. A radiological containment contains the nuclear reactor and includes a concrete floor located underneath the nuclear reactor. An ex vessel corium retention system includes flow channels embedded in the concrete floor located underneath the nuclear reactor, an inlet in fluid communication with first ends of the flow channels, and an outlet in fluid communication with second ends of the flow channels. In some embodiments the inlet is in fluid communication with the interior of the radiological containment at a first elevation and the outlet is in fluid communication with the interior of the radiological containment at a second elevation higher than the first elevation. The radiological containment may include a reactor cavity containing a lower portion of the pressure vessel, wherein the concrete floor located underneath the nuclear reactor is the reactor cavity floor.

  14. Design of punching shear for prestressed slabs with unbonded tendons on internal columns

    Directory of Open Access Journals (Sweden)

    L. A. R. Luchi

    Full Text Available ABSTRACT This paper is related to the punching shear in prestressed slabs with unbonded tendons for interior columns calculated by the codes ABNT NBR 6118:2007, ABNT NBR 6118:2014, EN 1992-1-1:2004 e ACI 318-11. To calculate the punching shear resistance the formulations of the NBR 6118:07, effective until April/2014, did not consider the compression of the concrete in the plane of the slab, due to prestressing. Just the inclined components of some tendons were considered for total load applied relief, but this fact did not generate a significant difference, compared to reinforced concrete, because the inclination angle is very close to zero. The American and European provisions consider a portion related to the compression of the concrete in the planeof the slab. Differences in the results obtained by the four design codes will be exposed, showing that the EC2:04 and the NBR6118:14 achieved the best results.

  15. Lateral force resisting mechanisms in slab-column connections: An analytical approach

    OpenAIRE

    Drakatos, Iaonnis; Beyer, Katrin; Muttoni, Aurelio

    2014-01-01

    In many countries reinforced concrete (RC) flat slabs supported on columns is one of the most commonly used structural systems for office and industrial buildings. To increase the lateral stiffness and strength of the structure, RC walls are typically added and carry the largest portion of the horizontal loads generated during earthquakes. While the slab-column system is typically not relevant with regard to the lateral stiffness and strength of the structure, each slab-column connection has ...

  16. Building America Case Study: Impact of Slab-Foundation Heat Transfer on Space-Conditioning Energy Use in Florida, Cocoa, Florida

    Energy Technology Data Exchange (ETDEWEB)

    2016-12-01

    Heat transfer to slab foundations has remained an area of building science with poor understanding over the last three decades of energy efficiency research. This is somewhat surprising since the area of floors in single family homes is generally equal to wall, or windows or attics which have been extensively evaluated. Research that has been done has focused in the impact of slab on grade foundations and insulation schemes on heat losses associated with heating in predominantly heating dominated climates. Slab on grade construction is very popular in cooling-dominated southern states where it accounts for 77 percent of new home floors according to U.S. Census data in 2014. There is a widespread conception that tile flooring, as opposed to carpet, makes for a cooler home interior in warm climates. Empirical research is needed as building energy simulations such as DOE-2 and EnergyPlus rely on simplified models to evaluate these influences. BA-PIRC performed experiments over an entire year from 2014-2015 in FSEC's Flexible Residential Test Facilities (FRTF) intended to assess for the first time 1) slab on grade influence in a cooling dominated climate, and 2) how the difference in a carpeted vs. uncarpeted building might influence heating and cooling. Two identical side by side residential buildings were evaluated, the East with pad and carpet and the west with a bare slab floor. A highly detailed grid of temperature measurements were taken on the slab surface at various locations as well as at depths of 1, 2.5, 5, 10 and 20 feet.

  17. Analysis of the assembling phase of lattice slabs

    Directory of Open Access Journals (Sweden)

    A. L. Sartorti

    Full Text Available Lattice slabs are usual in Brazil. They are formed by precast joists with latticed bars on a base of concrete, and a cover of concrete placed at the jobsite. The assembly of the joists and the filling elements is simple and do not require manpower with great skill, presenting low cost-benefit ratio. However, it is precisely in assembling phase that arise questions related to the scaffold support distance. A mistake in the proper positioning can lead to two undesirable situations. In one of them, a small space between the support lines increases the cost of scaffold, and in other an excessive space can generate exaggerated displacements, and even the collapse of the slab in the stage of concreting. The objective of this work is to analyze the bearing capacity of lattice joists in assembling phase, looking for information that is useful in defining the scaffold support distance. Several joists were tested to define the failure modes and their load bearing capacities. The results allowed to determine equations for calculating the appropriate distance between the support lines of the joists.

  18. Experimental research on the use of micro-encapsulated Phase Change Materials to store solar energy in concrete floors in order to save energy in Dutch houses

    NARCIS (Netherlands)

    Entrop, A.G.; Brouwers, H.J.H.; Reinders, A.H.M.E.

    2011-01-01

    In this paper an experimental research is presented on a new use of Phase Change Materials (PCMs) in concrete floors, in which thermal energy provided by the sun is stored in a mix of concrete and PCMs. When this thermal energy is being released – in moderate sea climates during the evening and

  19. Fire resistance of prefabricated monolithic slab

    Directory of Open Access Journals (Sweden)

    Gravit Marina

    2017-01-01

    Full Text Available A prefabricated monolithic slab (PMS has a number of valuable advantages, they allow to significantly decrease the weight of construction keeping the necessary structural-load capacity, to speed up and cheapen work conduction, to increase the heat isolating properties of an enclosure structure [1]. In order to create a design method of prefabricated monolithic slab fire-resistance, it's necessary to perform a series of PMS testing, one of which is being described in this article. Subjected to the test is a fragment of prefabricated monolithic slab with polystyrene concrete inserts along the beams with bent metal profile 250 mm thick, with a 2.7 m span loaded with evenly spread load equal to 600 kg/m2. After 3 hour testing for fire-resistance [2] no signs of construction ultimate behavior were detected.

  20. Impact design of reinforced concrete fuel storage structures

    International Nuclear Information System (INIS)

    Nickell, R.E.; Rashid, Y.R.; Williams, R.F.

    1987-01-01

    We characterize the loading experienced by reinforced concrete slabs, as the result of a drop or a tip-over of a dry storage cask, and we provide simple design charts and formulas by which the margin of safety of such slabs can be readily demonstrated. These charts are based on the calculation of crack patterns in the concrete and yielding in the reinforcement as the pad is loaded by the dropping or tip-over of a dry storage cask to a point of collapse. This ultimate-strength design approach is appropriate for unlikely loading events provided that adequate margin against slab collapse is maintained. (orig./HP)

  1. Continuity diaphragm for skewed continuous span precast prestressed concrete girder bridges : technical summary report.

    Science.gov (United States)

    2004-03-01

    Most highway bridges are built as cast-in-place : reinforced concrete slabs and prestressed concrete : girders. The shear connectors on the top of the girders : assure composite action between the slabs and : girders. The design guidelines for bridge...

  2. Vibrated and self-compacting fibre reinforced concrete: experimental investigation on the fibre orientation

    Science.gov (United States)

    Conforti, A.; Plizzari, G. A.; Zerbino, R.

    2017-09-01

    In addition to the fibre type and content, the residual properties of fibre reinforced concrete are influenced by fibre orientation. Consequently, the performance fibre reinforced concrete can be affected by its fresh properties (workability, flowing capacity) and by casting and compaction processes adopted. This paper focuses on the study of the orientation of steel or macro-synthetic fibres in two materials characterized by very different fresh properties: vibrated and self-compacting concrete. Four rectangular slabs 1800 mm long, 925 mm wide and 100 mm high were produced changing concrete and fibre type. From each slab, eighteen small prisms (550 mm long) were firstly cut either orthogonal or parallel to casting direction and, secondly, notched and tested in bending according to EN 14651. Experimental results showed that the toughness properties of a thin slab significantly varies both in vibrated and self-compacting concrete, even if in case of self-compacting concrete this variation resulted higher. Steel fibres led to greater variability of results compared to polymer one, underlining a different fibre orientation. A discussion on the relative residual capacity measured on the prisms sawn from the slabs and the parameters obtained from standard specimens is performed.

  3. Numerical Investigation of Slab-Column Connection by Finite Element Method

    International Nuclear Information System (INIS)

    Akram, T.; Shaikh, M.A.; Memon, A.A.

    2007-01-01

    The flat slab-on-column construction subjected to high transverse stresses concentrated at the slab-column connection can lead to a non-ductile, sudden and brittle punching failure and results in the accidental collapse of flat slab buildings. The major parameters affecting the slab-column connection are the concrete strength, slab thickness, slab reinforcement and aspect ratio of column. The application of numerical methods based on the finite element theory for solving practical tasks allow to perform virtual testing of structures and explore their behavior under load and other effects in different conditions taking into account the elastic and plastic behavior of materials, appearance and development of cracks and other damages (disintegrations), and finally to simulate the failure mechanism and its consequences. In this study, the models are developed to carry out the finite element analysis of slab- column connection using ADINA (Automatic Dynamic Incremental Nonlinear Analysis) by varying the slab thickness and slab confining reinforcement and to investigate their effect on the deflection and load carrying capacity. Test results indicate that by increasing the slab thickness, the deflection and the load carrying capacity of slab-column connection increases, more over, by increasing the slab confining reinforcement, the deflection decreases where as the load carrying capacity increases. (author)

  4. Determination of in-situ strength on selected bridge element concrete girder and slab of Nagtahan bridge using rebound hammer test

    International Nuclear Information System (INIS)

    Uy, Bernadette Betsy B.; Banaga, Renato T.

    2013-01-01

    This study examined the extent of the damage due to fire on the affected areas of the bridge structure. The need to assess the damage of the Nagtahan Bridge is very useful to provide appropriate measures in the repair or in the reinforcement of the bridge, hence will ensure its strength and integrity. The study included two (2) spans of the bridge deck/slab with specific locations of the bridge that were subjected for testing. The Rebound Hammer was used as a preliminary test in evaluating the bridge condition. Its capability is to assess the in-place uniformity of concrete, to delineate regions in a structure of poor quality or deteriorated concrete, and to estimate the in-place strength; and ultimately, for relative comparison between the different structures of the bridge. With the use of the NDT Rebound Hammer Test, the researchers were able to determine whether or not the in-situ strength of the bridge's concrete has been weakened due to fire. The DPW-Standard Specification is the government acceptable manual, containing the acceptance criteria, used as the basis for standard construction procedures in the department.(author)

  5. Internal slab-column connections under monotonic and cyclic imposed rotations

    OpenAIRE

    Drakatos, Ioannis-Sokratis; Muttoni, Aurelio; Beyer, Katrin

    2016-01-01

    Reinforced concrete flat slabs supported by slender columns are often used as gravity load resisting system for buildings in regions of moderate seismicity. Current codes of practice determine the displacement capacity of slab-column connections using empirical formulas which were calibrated against experimental studies. This article reviews and compares test configurations used in past experimental studies and presents the adopted configuration for an experimental investigation on 13 full-sc...

  6. Design and application of a small size SAFT imaging system for concrete structure

    Science.gov (United States)

    Shao, Zhixue; Shi, Lihua; Shao, Zhe; Cai, Jian

    2011-07-01

    A method of ultrasonic imaging detection is presented for quick non-destructive testing (NDT) of concrete structures using synthesized aperture focusing technology (SAFT). A low cost ultrasonic sensor array consisting of 12 market available low frequency ultrasonic transducers is designed and manufactured. A channel compensation method is proposed to improve the consistency of different transducers. The controlling devices for array scan as well as the virtual instrument for SAFT imaging are designed. In the coarse scan mode with the scan step of 50 mm, the system can quickly give an image display of a cross section of 600 mm (L) × 300 mm (D) by one measurement. In the refined scan model, the system can reduce the scan step and give an image display of the same cross section by moving the sensor array several times. Experiments on staircase specimen, concrete slab with embedded target, and building floor with underground pipe line all verify the efficiency of the proposed method.

  7. Comfort analysis of lightweight floor system

    NARCIS (Netherlands)

    Zegers, S.F.A.J.G.; Herwijnen, van F.; Randall, B.

    2007-01-01

    During the past 60 years, floor systems used in housing and office-buildings in the Netherlands were mostly made of concrete or other similar materials, These floor systems, which can be characterized as heavy, normally posed little problems concerning vibrations. In recent years, in light of

  8. The Combine Use of Semi-destructive and Non-destructive Methods for Tiled Floor Diagnostics

    Science.gov (United States)

    Štainbruch, Jakub; Bayer, Karol; Jiroušek, Tomáš; Červinka, Josef

    2017-04-01

    The combination of semi-destructive and non-destructive methods was used to asset the conditions of a tiled floor in the historical monument Minaret, situated in the park complex of the Chateau Lednice (South Moravia Region, Czech Republic), before its renovation. Another set of measurements is going to be performed after the conservation works are finished. (The comparison of the results collected during pre- and post-remediation measurements will be known and presented during the General Assembly meeting in Wien.) The diagnostic complex of methods consisted of photogrammetry, resistivity drilling and georadar. The survey was aimed to contour extends of air gaps beneath the tiles and the efficiency of filling gaps by means of injection, consolidation and gluing individual layers. The state chateau Lednice creates a part of the Lednice-Valtice precinct, a UNESCO landmark, and belongs among the greatest historic monuments in Southern Moravia. In the chateau park there is a romantic observation tower in the shape of a minaret built according to the plans of Josef Hardtmuth between 1798-1804. The Minaret has been extensively renovated for many decades including the restoration of mosaic floors from Venetian terazzo. During the static works of the Minaret building between 1999-2000, the mosaic floors in the rooms on the second floor were transferred and put back onto concrete slabs. Specifically, the floor was cut up to tiles and these were glued to square slabs which were then attached to the base plate. The transfer was not successful and the floor restoration was finalized between 2016-2017. The damage consisted in separating the original floor from the concrete plate which led to creating gaps. Furthermore, the layers of the floor were not compact. It was necessary to fill the gaps and consolidate and glue the layers. The existence of air gap between individual layers of the tiles and their degradation was detected using two different diagnostic methods: semi

  9. Prestressed concrete design

    CERN Document Server

    Hurst, MK

    1998-01-01

    This edition provides up-to-date guidance on the detailed design of prestressed concrete structures. All major topics are dealt with, including prestressed flat slabs, an important and growing application in the design of buildings.

  10. Study of global stability of tall buildings with prestressed slabs

    Directory of Open Access Journals (Sweden)

    L. A. Feitosa

    Full Text Available The use of prestressed concrete flat slabs in buildings has been increasing in recent years in the Brazilian market. Since the implementation of tall and slender buildings a trend in civil engineering and architecture fields, arises from the use of prestressed slabs a difficulty in ensuring the overall stability of a building without beams. In order to evaluate the efficiency of the main bracing systems used in this type of building, namely pillars in formed "U" in elevator shafts and stairs, and pillars in which the lengths are significantly larger than their widths, was elaborated a computational models of fictional buildings, which were processed and analyzed using the software CAD/TQS. From the variation of parameters such as: geometry of the pillars, thick slabs, characteristic strength of the concrete, reduceofthe coefficient of inertia for consideration of non-linearities of the physical elements, stiffness of the connections between slabs and pillars, among others, to analyze the influence of these variables on the overall stability of the building from the facing of instability parameter Gama Z, under Brazilian standard NBR 6118, in addition to performing the processing of building using the P-Delta iterative calculation method for the same purpose.

  11. Delamination Detection of Reinforced Concrete Decks Using Modal Identification

    Directory of Open Access Journals (Sweden)

    Shutao Xing

    2012-01-01

    Full Text Available This study addressed delamination detection of concrete slabs by analyzing global dynamic responses of structures. Both numerical and experimental studies are presented. In the numerical examples, delaminations with different sizes and locations were introduced into a concrete slab; the effects of presence, sizes, and locations of delaminations on the modal frequencies and mode shapes of the concrete slab under various support conditions were studied. In the experimental study, four concrete deck specimens with different delamination sizes were constructed, and experimental tests were conducted. Traditional peak-picking, frequency domain decomposition, and stochastic subspace identification methods were applied to the modal identification from dynamic response measurements. The modal parameters identified by these three methods correlated well. The changes in modal frequencies, damping ratios, and mode shapes that were extracted from the dynamic measurements were investigated and correlated to the actual delaminations and can indicate presence and severity of delamination. Finite element (FE models of reinforced concrete decks with different delamination sizes and locations were established. The modal parameters computed from the FE models were compared to those obtained from the laboratory specimens, and the FE models were validated. The delamination detection approach was proved to be effective for concrete decks on beams.

  12. Analyses of Concrete Structures Exposed to Fire

    DEFF Research Database (Denmark)

    Hertz, Kristian

    The text book contains the data and methods necessary for fire safety design of concrete constructions. The methods relate to standard fire as well as to any time of any other fire course.Material data are presented for concretes exposed to fire, and calculation methods are given for the ultimate...... bending capacity of beams and slabs, the ultimate shear capacity of beams, for the instability of columns and walls and for the deflection of prestressed and non-prestressed beams, slabs, walls and columns.All methods have been derived and compared to tests by Kristian Hertz....

  13. Super-light concrete decks for building floor slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Castberg, Niels Andreas; Christensen, Jacob

    2014-01-01

    to flexibility, sound insulation and fire resistance compared with present-day prefabricated structures. Full-scale tests and theoretical investigations show that the deck structure performs as intended. Also, that it is possible to assess by calculation the loadbearing capacity in bending and shear, and assess...... the pull-out strength of prestressing wires, the fire resistance and the acoustic insulation. Based on the results of the investigations, recommendations are given for further development of the structure before fully automated mass production is established....

  14. Concrete structures

    CERN Document Server

    Setareh, Mehdi

    2017-01-01

    This revised, fully updated second edition covers the analysis, design, and construction of reinforced concrete structures from a real-world perspective. It examines different reinforced concrete elements such as slabs, beams, columns, foundations, basement and retaining walls and pre-stressed concrete incorporating the most up-to-date edition of the American Concrete Institute Code (ACI 318-14) requirements for the design of concrete structures. It includes a chapter on metric system in reinforced concrete design and construction. A new chapter on the design of formworks has been added which is of great value to students in the construction engineering programs along with practicing engineers and architects. This second edition also includes a new appendix with color images illustrating various concrete construction practices, and well-designed buildings. The ACI 318-14 constitutes the most extensive reorganization of the code in the past 40 years. References to the various sections of the ACI 318-14 are pro...

  15. Wood slabs as a proposed solution to the design and construction of pavement

    Directory of Open Access Journals (Sweden)

    Carlos Alfonso Devia Castillo

    2016-01-01

    Full Text Available Alternatives to replace concrete slabs for prefabricated wood as structure of pavement with wearing course was evaluated, ensuring that these prefabrications work as a single element using finger joints. The mechanical behavior of two types of wood identified through simulations implementing a method of finite elements was evaluated, to subsequently determined optimal configuration for the alternative design with wood pavements and finally verified in the laboratory with the optimal configuration determined with simulation for a design of 440 000 vehicles shafts, with the use of the MTS machine and a load of 6.50 tons equivalent to a load of a single axle shaft with two wheels, found that for different traffic design the thickness of the slab of wood to resist this load varies between 0.125 and 0.24 meters. This research shows that prefabricated wood building systems are a viable alternative in the market for pavement construction in the structural sense; additionally, they are an innovation since they modify the structural system of slabs, conventionally built on concrete slabs and reduce environmental impact.

  16. Effect of heat curing methods on the temperature history and strength development of slab concrete for nuclear power plant structures in cold climates

    International Nuclear Information System (INIS)

    Lee, Gun Cheol; Han, Min Cheol; Baek, Dae Hyun; Koh, Kyung Taek

    2012-01-01

    The objective of this study was to experimentally investigate the effect of heat curing methods on the temperature history and strength development of slab concrete exposed to -10 degrees Celsius. The goal was to determine proper heat curing methods for the protection of nuclear power plant structures against early-age frost damage under adverse (cold) conditions. Two types of methods were studied: heat insulation alone and in combination with a heating cable. For heat curing with heat insulation alone, either sawdust or a double layer bubble sheet (2-BS) was applied. For curing with a combination of heat insulation and a heating cable, an embedded heating cable was used with either a sawdust cover, a 2-BS cover, or a quadruple layer bubble sheet (4-BS) cover. Seven different slab specimens with dimensions of 1200, 600, 200 mm and a design strength of 27 MPa were fabricated and cured at -10 degrees Celsius for 7 d. The application of sawdust and 2-BS allowed the concrete temperature to fall below 0 degrees Celsius within 40 h after exposure to -10 degrees Celsius, and then, the temperature dropped to -10 degrees Celsius and remained there for 7 d owing to insufficient thermal resistance. However, the combination of a heating cable plus sawdust or 2-BS maintained the concrete temperature around 5 degrees Celsius for 7 d. Moreover, the combination of the heating cable and 4-BS maintained the concrete temperature around 10 degrees Celsius for 7 d. This was due to the continuous heat supply from the heating cable and the prevention of heat loss by the 4-BS. For maturity development, which is an index of early-age frost damage, the application of heat insulation materials alone did not allow the concrete to meet the minimum maturity required to protect against early-age frost damage after 7 d, owing to poor thermal resistance. However, the combination of the heating cable and the heat insulating materials allowed the concrete to attain the minimum maturity level after

  17. optimizing conventional des concrete raft ng conventional design

    African Journals Online (AJOL)

    eobe

    concrete cross section area of raft slab foundation ... accurately modeling boundary cond never be ... the design of reinforced concrete flat ... undation and soil layer configuration adopted for the finite element analy .... After the application of.

  18. Comparative Study on Interface Elements, Thin-Layer Elements, and Contact Analysis Methods in the Analysis of High Concrete-Faced Rockfill Dams

    Directory of Open Access Journals (Sweden)

    Xiao-xiang Qian

    2013-01-01

    Full Text Available This paper presents a study on the numerical performance of three contact simulation methods, namely, the interface element, thin-layer element, and contact analysis methods, through the analysis of the contact behavior between the concrete face slab and the dam body of a high concrete-faced rockfill dam named Tianshengqiao-I in China. To investigate the accuracy and limitations of each method, the simulation results are compared in terms of the dam deformation, contact stress along the interface, stresses in the concrete face slab, and separation of the concrete face slab from the cushion layer. In particular, the predicted dam deformation and slab separation are compared with the in-situ observation data to classify these methods according to their agreement with the in-situ observations. It is revealed that the interface element and thin-layer element methods have their limitations in predicting contact stress, slab separation, and stresses in the concrete face slab if a large slip occurs. The contact analysis method seems to be the best choice whether the separation is finite or not.

  19. Flooring in front of the feed bunk affects feeding behavior and use of freestalls by dairy cows.

    Science.gov (United States)

    Tucker, C B; Weary, D M; de Passillé, A M; Campbell, B; Rushen, J

    2006-06-01

    In 2 experiments we assessed how preferences, time budgets, and feeding behavior of dairy cows change in response to flooring surfaces in front of the feed bunk. In Experiment 1, 12 nonlactating dairy cattle were individually housed with access to 2 standing platforms filled with either concrete or sawdust. In Experiment 2, 24 nonlactating dairy cattle were given access to either concrete or Animat rubber flooring in front of the feed bunk. In Experiment 1, cows preferred the sawdust to the concrete flooring. In both experiments, cows provided with a softer floor in front of the feed bunk spent more time standing near the feed bunk without eating (Experiment 1: 67 vs. 40 min/d on sawdust vs. concrete, respectively, SEM = 5.6 min/d; Experiment 2: 176 vs. 115 min/d on Animat vs. concrete, respectively, SEM = 20.5 min/d) compared with when they were kept on concrete. The increased time spent at the feed bunk was due to a combination of more frequent eating and standing bouts, indicating that cows were more willing to move on nonconcrete flooring. Total time spent eating was significantly greater on the softer floor in Experiment 2, but not in Experiment 1 (Exp. 1: 289 vs. 275 min/d on sawdust and concrete, respectively, SEM = 7.3 min/d; Exp. 2: 330 vs. 289 min/d on Animat and concrete, respectively, SEM = 15.4), although feed intake was increased on the sawdust treatment in Experiment 1. Cows spent significantly more time lying in the feed alley when the flooring was rubber (219 vs. 53 min/d on Animat and concrete, SEM = 53.6 min/d), perhaps because the lying area in Experiment 2 was inadequate. In conclusion, cows prefer to stand on softer flooring in front of the feed bunk, and are more willing to move on and spend more time standing in front of the feed bunk when provided with softer flooring. These results indicate that cows find softer flooring surfaces more comfortable to stand on than concrete, and highlight the importance of evaluating the comfort of the

  20. Concrete for γ radiation shielding

    International Nuclear Information System (INIS)

    Azevedo e Souza, A.C. de; Rogers, John Douglas

    1980-01-01

    The attenuation characteristics of γ radiation in concrete slabs, considering their mechanical resistence and densities were determined. One heavy concrete which was used, was prepared using as additives iron ore and Fe 2 O 3 pellets in various grain sizes. Fortran programs were used for analysing data and determining the absorption coefficients and attenuation factors. (Author) [pt

  1. Concrete for. gamma. radiation shielding

    Energy Technology Data Exchange (ETDEWEB)

    de Azevedo e Souza, A.C. (Rio de Janeiro Univ. (Brazil). Inst. de Quimica); Rogers, J D [Rio de Janeiro Univ. (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

    1980-06-01

    The attenuation characteristics of ..gamma.. radiation in concrete slabs, considering their mechanical resistence and densities were determined. One heavy concrete which was used, was prepared using as additives iron ore and Fe/sub 2/ O/sub 3/ pellets in various grain sizes. Fortran programs were used for analysing data and determining the absorption coefficients and attenuation factors.

  2. Global methods for reinforced concrete slabs

    International Nuclear Information System (INIS)

    Hoffmann, A.; Lepareux, M.; Combescure, A.

    1985-08-01

    This paper develops the global method strategy to compute elastoplastic thin shells or beams. It is shown how this methodology can be applied to the case of reinforced concrete structures. Two cases of applications are presented: one static, the other dynamic. The numerical results are compared to experimental data

  3. Processing and properties of large-sized ceramic slabs

    Energy Technology Data Exchange (ETDEWEB)

    Raimondo, M.; Dondi, M.; Zanelli, C.; Guarini, G.; Gozzi, A.; Marani, F.; Fossa, L.

    2010-07-01

    Large-sized ceramic slabs with dimensions up to 360x120 cm{sup 2} and thickness down to 2 mm are manufactured through an innovative ceramic process, starting from porcelain stoneware formulations and involving wet ball milling, spray drying, die-less slow-rate pressing, a single stage of fast drying-firing, and finishing (trimming, assembling of ceramic-fiberglass composites). Fired and unfired industrial slabs were selected and characterized from the technological, compositional (XRF, XRD) and microstructural (SEM) viewpoints. Semi-finished products exhibit a remarkable microstructural uniformity and stability in a rather wide window of firing schedules. The phase composition and compact microstructure of fired slabs are very similar to those of porcelain stoneware tiles. The values of water absorption, bulk density, closed porosity, functional performances as well as mechanical and tribological properties conform to the top quality range of porcelain stoneware tiles. However, the large size coupled with low thickness bestow on the slab a certain degree of flexibility, which is emphasized in ceramic-fiberglass composites. These outstanding performances make the large-sized slabs suitable to be used in novel applications: building and construction (new floorings without dismantling the previous paving, ventilated facades, tunnel coverings, insulating panelling), indoor furnitures (table tops, doors), support for photovoltaic ceramic panels. (Author) 24 refs.

  4. Processing and properties of large-sized ceramic slabs

    International Nuclear Information System (INIS)

    Raimondo, M.; Dondi, M.; Zanelli, C.; Guarini, G.; Gozzi, A.; Marani, F.; Fossa, L.

    2010-01-01

    Large-sized ceramic slabs with dimensions up to 360x120 cm 2 and thickness down to 2 mm are manufactured through an innovative ceramic process, starting from porcelain stoneware formulations and involving wet ball milling, spray drying, die-less slow-rate pressing, a single stage of fast drying-firing, and finishing (trimming, assembling of ceramic-fiberglass composites). Fired and unfired industrial slabs were selected and characterized from the technological, compositional (XRF, XRD) and microstructural (SEM) viewpoints. Semi-finished products exhibit a remarkable microstructural uniformity and stability in a rather wide window of firing schedules. The phase composition and compact microstructure of fired slabs are very similar to those of porcelain stoneware tiles. The values of water absorption, bulk density, closed porosity, functional performances as well as mechanical and tribological properties conform to the top quality range of porcelain stoneware tiles. However, the large size coupled with low thickness bestow on the slab a certain degree of flexibility, which is emphasized in ceramic-fiberglass composites. These outstanding performances make the large-sized slabs suitable to be used in novel applications: building and construction (new floorings without dismantling the previous paving, ventilated facades, tunnel coverings, insulating panelling), indoor furnitures (table tops, doors), support for photovoltaic ceramic panels. (Author) 24 refs.

  5. Vertical impedance measurements on concrete bridge decks for assessing susceptibility of reinforcing steel to corrosion

    Science.gov (United States)

    Bartholomew, Paul D.; Guthrie, W. Spencer; Mazzeo, Brian A.

    2012-08-01

    Corrosion is a pressing problem for aging concrete infrastructure, especially bridge decks. Because of its sensitivity to factors that affect corrosion of reinforcing steel in concrete, resistivity is an important structural health indicator for reinforced concrete structures. In this research, an instrument was developed to measure vertical impedance on concrete bridge decks. Measurements of vertical impedance on slabs prepared in the laboratory, on slabs removed from decommissioned bridge decks, and on an in-service bridge deck in the field demonstrate the utility of the new apparatus.

  6. Static, Fire and Fatigue Tests of Ultra High-Strength Fibre Reinforced Concrete and Ribbed Bars

    DEFF Research Database (Denmark)

    Hansen, Lars Pilegaard; Heshe, Gert

    2001-01-01

    A new building system has been developed during the last 10 years. This new system consists of a column / slab system with 6 x 6 m distance between the columns. The slabs are precast concrete elements of size 2.9 x 5.9 m connected through joints of ultra high strength fibre reinforced concrete...... - Densit Joint Cast ®. Also the connections between the columns and the slabs are made of this very strong concrete material. The paper describes some of the static tests carried out as well as some fire tests. Further, 2 chapters deal with some fatigue tests of the reinforcing bars as well as some fatigue...

  7. Energy Dissipation from Vibrating Floor Slabs due to Human-Structure Interaction

    Directory of Open Access Journals (Sweden)

    James M.W. Brownjohn

    2001-01-01

    Full Text Available Lightweight pre-cast flooring systems using post-tensioning to increase strength but not stiffness are increasingly popular, and vibration serviceability problems tend to govern design of such floors where human occupants are increasingly concerned with vibrations. At the same time as inducing response, stationary human observers can also participate in the response as mitigating influence and it is clear that a human behaves as a highly effective damper, even when seated.

  8. Connections in Precast Buildings using Ultra High-Strength Fibre Reinforced Concrete

    DEFF Research Database (Denmark)

    Hansen, Lars Pilegaard

    1995-01-01

    Ultra high-strength concrete adds new dimensions to the design of concrete structures. It is a brittle material but introducing fibres into the matrix changes the material into a highly ductile material. Furthermore, the fibre reinforcement increases the anchorage of traditional reinforcement bar...... and the fire resistance. Such a fibre reinforced ultra high-strength material has been used to develop a simple joint solution between slab elements in a column - slab building system....

  9. Slab Track at Facility for Accelerated Service Testing: Performance and Serviceability

    Science.gov (United States)

    2018-02-01

    The Transportation Technology Center, Inc., with funding by the Portland Cement Association and the Federal Railroad Administration, documented the available records associated with the performance of the concrete slab track section in the High Tonna...

  10. Methodology for assessing the probability of corrosion in concrete structures on the basis of half-cell potential and concrete resistivity measurements.

    Science.gov (United States)

    Sadowski, Lukasz

    2013-01-01

    In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. Potential E corr and concrete resistivity ρ in each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures.

  11. Methodology for Assessing the Probability of Corrosion in Concrete Structures on the Basis of Half-Cell Potential and Concrete Resistivity Measurements

    Directory of Open Access Journals (Sweden)

    Lukasz Sadowski

    2013-01-01

    Full Text Available In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. Potential Ecorr and concrete resistivity ρ in each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures.

  12. Beoordeling van de FSC 2000 als vervanger van de Leroux-meter voor het bepalen van de stroefheid van betonnen stalvloeren = Evaluation of the FSC 2000 as substitute for the Leroux apparatus for determination of skid resistance of concrete floors of animal houses

    NARCIS (Netherlands)

    Winkel, A.; Blanken, K.; Bokma, S.

    2010-01-01

    In this study the FSC 2000 is evaluated as a substitute for the Leroux apparatus for determination of skid resistance of concrete floors of animal houses. This study shows that the FSC 2000 is well suitable for measurements of skid resistance of concrete slats and solid floors of animal houses.

  13. The fracture of concrete under explosive shock loading

    International Nuclear Information System (INIS)

    Watson, A.J.; Sanderson, A.J.

    1982-01-01

    Concrete fracture close to the point of application of high explosive shock pressures has been studied experimentally by placing an explosive charge on the edge of a concrete slab. The extent of the crushing and cracking produced by a semi cylindrical diverging plane compressive stress pulse has been measured and complementary experiments gave the pressure transmitted at an explosive to concrete interface and the stress-strain relation for concrete at explosive strain rates. (orig.) [de

  14. Non destructive testing of concrete nuclear containment plants with surface waves: Lab experiment on decimeter slabs and on the VeRCoRs mock-up

    Science.gov (United States)

    Abraham, Odile; Legland, Jean-Baptiste; Durand, Olivier; Hénault, Jean-Marie; Garnier, Vincent

    2018-04-01

    The maintenance and evaluation of concrete nuclear containment walls is a major concern as they must, in case of an accident, ensure the confinement of the nuclear radiations and resist to the loads. A homemade multi-receiver multi-source dry contact linear probe to record ultrasonic surface waves on concrete in the frequency range [60 kHz - 200 kHz] has been used in this context. The measurement protocol includes the summation of up to 50 spatially distributed seismograms and the determination of the surface waves phase velocity dispersion curve. The probe has been tested against several concrete states under no loading (water saturation level, temperature damage). Then, the same measurements have been performed on sound and fire damaged slabs submitted to uniaxial loading (stress up to 30 % of the concrete compression resistance). It is shown that the robustness and precision of the surface waves measurement protocol make it possible to follow the stress level. In March 2017 a first experiment with this surface wave probe has been conducted on a reduced 1:3 scale nuclear containment plant (EDF VeRCoRs mock-up) under loading conditions that replicates that of decennial inspection. The surface wave phase velocity dispersion curves of each state are compared and cross-validated with other NDT results.

  15. INVESTIGATION ON THE RESPONSE OF SEGMENTED CONCRETE TARGETS TO PROJECTILE IMPACTS

    Energy Technology Data Exchange (ETDEWEB)

    Booker, Paul M.; Cargile, James D.; Kistler, Bruce L.; La Saponara, Valeria

    2009-07-19

    The study of penetrator performance without free-surface effects can require prohibitively large monolithic targets. One alternative to monolithic targets is to use segmented targets made by stacking multiple concrete slabs in series. This paper presents an experimental investigation on the performance of segmented concrete targets. Six experiments were carried out on available small scale segmented and monolithic targets using instrumented projectiles. In all but one experiment using stacked slabs, the gap between slabs remained open. In the final experiment design, grout was inserted between the slabs, and this modification produced a target response that more closely represents that of the monolithic target. The results from this study suggest that further research on segmented targets is justified, to explore in more detail the response of segmented targets and the results of large scale tests when using segmented targets versus monolithic targets.

  16. Investigation on the performance of bridge approach slab

    Directory of Open Access Journals (Sweden)

    Abdelrahman Amr

    2018-01-01

    Full Text Available In Egypt, where highway bridges are to be constructed on soft cohesive soils, the bridge abutments are usually founded on rigid piles, whereas the earth embankments for the bridge approaches are directly founded on the natural soft ground. Consequently, excessive differential settlement frequently occurs between the bridge deck and the bridge approaches resulting in a “bump” at both ends of the bridge deck. Such a bump not only creates a rough and uncomfortable ride but also represents a hazardous condition to traffic. One effective technique to cope with the bump problem is to use a reinforced concrete approach slab to provide a smooth grade transition between the bridge deck and the approach pavement. Investigating the geotechnical and structural performance of approach slabs and revealing the fundamental affecting factors have become mandatory. In this paper, a 2-D finite element model is employed to investigate the performance of approach slabs. Moreover, an extensive parametric study is carried out to appraise the relatively optimum geometries of approach slab, i.e. slab length, thickness, embedded depth and slope, that can yield permissible bumps. Different geo-mechanical conditions of the cohesive foundation soil and the fill material of the bridge embankment are examined.

  17. Experimental and numerical investigation of slabs on ground subjected to concentrated loads

    Science.gov (United States)

    Øverli, Jan

    2014-09-01

    An experimental program is presented where a slab on ground is subjected to concentrated loading at the centre, the edges and at the corners. Analytical solutions for the ultimate load capacity fit well with the results obtained in the tests. The non-linear behaviour of the slab is captured by performing nonlinear finite element analyses. The soil is modelled as a no-tension bedding and a smeared crack approach is employed for the concrete. Through a parametric study, the finite element model has been used to assess the influence of subgrade stiffness and shrinkage. The results indicate that drying shrinkage can cause severe cracking in slabs on grade.

  18. Experimental assessment of improvements in thermal performance from insulating the thermal bridge at the edge of a floor slab

    Directory of Open Access Journals (Sweden)

    N. Arias Jiménez

    2017-06-01

    Full Text Available The problematic of the article rises from the need of improving the thermal quality of the built envelope in the wall complex, specifically in the case of reinforced concrete (most used material in high-rise housing in Chile. Considering the use of insulation on the inside face of the wall, interrupts the continuity of the insulating material where the mezzanine slab and the perimeter walls meet, generating a thermal bridge known as mezzanine front. The purpose then, is to know the impact of the mentioned thermal bridge studying its properties through experimental tests on a thermal chamber. Later, the results will be integrated to a case of study that allows establishing the incidence of the bridge in the overall energetic behavior of through the integration of the results into the Thermal Analysis Simulation software (Tas. Finally, it is concluded a low incidence in the inner heat loses, becoming relevant the behavior of the superficial temperatures.

  19. Air-steam leakage through cracks in concrete

    International Nuclear Information System (INIS)

    Georges Nahas; Helene Simon

    2005-01-01

    Full text of publication follows: In the context of a severe accident in a Pressurised Water nuclear plant, the evaluation of the leakage rate through the containment wall remains a key point of the safety analysis, because it influences directly the consequences on the environment. During a severe accident, large amounts of steam could be released in the containment; internal pressure could rise beyond design limits causing cracks to appear in the internal concrete wall of the double-wall containment and fission products to leak towards the containment annulus. A research program led by the French Institute for Radiological Protection and Nuclear Safety aims to estimate this leakage. In the presence of cracks, most of the leak flows through them. Hence, a first phase of the program was to build a two-phase homogeneous model for the flow of an air-steam mixture through a idealized traversing crack, taking into account condensation phenomena, and considering crack openings from 25 μm to several hundred μm. A numerical model for the flow, coupled with heat transfer in the wall, was implemented in the Finite Element code CAST3M. This model was validated on a small scaled experiment which was made of two parallel glass plates. Comparison of the numerical and experimental results in this 'channel case' has shown good results for the total mass flow rate for channel openings greater than 100 μm. For the 50 μm opening the calculation gave a 50 % estimate of the experimental total mass flow rate. The second phase of the program is now to validate the model on cracks performed in a concrete specimen. In order to do so, we have simulated the experiment VK2/2 described in the article named 'Investigation of the leakage behavior of reinforced concrete walls' by N. Herrmann, C. Niklasch, M. Stegemann, L. Stempniewski. The reinforced concrete slab, 2.7 m long in the reinforcement direction and 1.2 m thick in the cracking direction, is placed in a mechanical set-up and an

  20. Modelling floor heating systems using a validated two-dimensional ground coupled numerical model

    DEFF Research Database (Denmark)

    Weitzmann, Peter; Kragh, Jesper; Roots, Peter

    2005-01-01

    This paper presents a two-dimensional simulation model of the heat losses and tempera-tures in a slab on grade floor with floor heating which is able to dynamically model the floor heating system. The aim of this work is to be able to model, in detail, the influence from the floor construction...... the floor. This model can be used to design energy efficient houses with floor heating focusing on the heat loss through the floor construction and foundation. It is found that it is impor-tant to model the dynamics of the floor heating system to find the correct heat loss to the ground, and further......, that the foundation has a large impact on the energy consumption of buildings heated by floor heating. Consequently, this detail should be in focus when designing houses with floor heating....

  1. Design and construction of a cable-stayed composite girder bridge with precast RC-slabs; Purekyasuto shohan gosei keta shachokoyo no sekkei to seko

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, K. [Tokyo Metropolitan Univ. (Japan). Faculty of Technology; Shimura, T.; Tachibana, Y.; Echigo, S. [Kawada Industries Inc., Tokyo (Japan)

    1995-09-20

    A report on design and execution of cable-stayed composite girder bridge with precast RC-slabs constructed first in Japan though in small scale was described. This bridge adopted steel slabs relatively low in slab height for main slab and with two boxes slab section, and was designed at an aim of being more economic and shorter in its working term in comparison with steel girder slab type, on a base of the design in a region allowable with the existing design standards. This bridge is mainly in accordance with the regulation on continuous bridge in the prescription of road bridge, and is designed for normal RC-girder selecting between girder supports to direction normal to bridge axis as usual without using specially strong concrete to the girder. And, in order to fill with the regulation on allowable tensile stress on considering effects of creep and drying shrinkage, a method adding prestress to the slabs was adopted. Furthermore, a loop-like overlap joint for cable joint for the precast girders, expansion concrete for joint portion to compose the girder with the steel slab and so forth were adopted. 12 refs., 22 figs., 5 tabs.

  2. Influence of wollastonite on mechanical properties of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Renu Mathur; A.K. Misra; Pankaj Goel

    2007-12-15

    Studies were made on cement concrete and cement-fly ash concrete mixes incorporating wollastonite as partial substitute of cementitious material and sand respectively. Improvements in compressive (28-35%) and flexural strength (36-42%) at 28 and 56 days respectively were observed by incorporation of wollastonite (10%) in concrete mixes. By incorporation of wollastonite, reduction in water absorption, drying-shrinkage and abrasion loss of concrete, and enhancement in durability against alternate freezing-thawing and sulphate attack were observed. Because of high concrete strength and abrasion resistance, a better utilization of concrete cross section is possible. Alternatively, thickness of pavement slab can be reduced by incorporation of wollastonite micro-fibres in concrete mixes.

  3. Application of Engineered Cementitious Composites (ECC) in modular floor panels

    DEFF Research Database (Denmark)

    Lárusson, Lárus Helgi; Fischer, Gregor; Jönsson, Jeppe

    2008-01-01

    This paper describes the design, manufacturing, and structural behavior of a prefabricated floor panel consisting of a modular assembly of a thin-walled ECC slab and steel truss girders. The features of this composite structure include light weight, the modular manufacturing process...... concept introduced in this paper aims at improvements in the manufacturing process of the panels by casting the ECC slab separately and subsequently joining it with the steel trusses. The focus of this paper is on design and manufacturing of a prototype modular panel and on its structural behavior under...

  4. Effect of wet curing duration on durability parameters of hydraulic cement concretes.

    Science.gov (United States)

    2010-01-01

    Hydraulic cement concrete slabs were cast and stored outdoors in Charlottesville, Virginia, to study the impact of wet curing duration on durability parameters. Concrete mixtures were produced using portland cement, portland cement with slag cement, ...

  5. The effects of different flooring types on the behavior, health, and welfare of finishing beef steers.

    Science.gov (United States)

    Elmore, M R P; Elischer, M F; Claeys, M C; Pajor, E A

    2015-03-01

    Raising beef cattle on concrete floors can negatively impact their welfare by increasing joint swelling and body lesions, as well as abnormalities in resting behavior and postural changes. We hypothesized that the addition of rubber mats to concrete pens would improve beef cattle welfare by improving performance, health, hygiene, and resting behavior. Forty-eight crossbred Angus steers were housed in pens of 4 and randomly assigned to a single flooring treatment: (1) fully slatted concrete (CON), (2) fully slatted rubber mat (SLAT), or (3) solid rubber mat (SOLID; 60% of pen floor) from 36 to 48 wk of age. Weight, ADG, lesions, gait score, joint swelling, and animal and pen cleanliness were collected every 2 wk. Behavioral time budgets and frequency of postural changes (an indicator of floor traction and comfort) were collected at 0, 6, and 12 wk. No differences in weight gain or ADG were observed. Steers on SOLID flooring (0.80 ± 0.08) showed increased lesions compared to SLAT (0.38 ± 0.08) and CON (0.37 ± 0.08; both, = 0.05); however, there was no difference between SLAT and CON. SLAT steers (1.69 ± 0.04) showed a reduced gait score compared to SOLID (1.95 ± 0.04) and CON (1.98 ± 0.04; both, flooring had less joint swelling (both knees and hocks) compared to SOLID and CON (all comparisons, flooring were dirtier than those on SLAT (2.27 ± 0.05) and CON (2.19 ± 0.05; both, flooring preferred to rest on the rubber mat vs. slatted concrete ( = 0.001). Steers on SLAT flooring changed their posture more frequently than those on SOLID and CON flooring (both, < 0.05), but SOLID and CON did not differ. Compared to CON steers, SOLID steers showed an increase in lesions and a reduction in cleanliness, whereas SLAT steers showed a decrease in gait score and joint swelling and an increase in postural changes. Combined, these data suggest that the addition of slatted rubber mats to concrete pens may improve beef cattle welfare.

  6. Concrete structures vulnerability under impact: characterization, modeling, and validation - Concrete slabs vulnerability under impact: characterization, modeling, and validation

    International Nuclear Information System (INIS)

    Xuan Dung Vu

    2013-01-01

    Concrete is a material whose behavior is complex, especially in cases of extreme loads. The objective of this thesis is to carry out an experimental characterization of the behavior of concrete under impact-generated stresses (confined compression and dynamic traction) and to develop a robust numerical tool to reliably model this behavior. In the experimental part, we have studied concrete samples from the VTT center (Technical Research Center of Finland). At first, quasi-static triaxial compressions with the confinement varies from 0 MPa (unconfined compression test) to 600 MPa were realized. The stiffness of the concrete increases with confinement pressure because of the reduction of porosity. Therefore, the maximum shear strength of the concrete is increased. The presence of water plays an important role when the degree of saturation is high and the concrete is subjected to high confinement pressure. Beyond a certain level of confinement pressure, the maximum shear strength of concrete decreases with increasing water content. The effect of water also influences the volumetric behavior of concrete. When all free pores are closed as a result of compaction, the low compressibility of the water prevents the deformation of the concrete, whereby the wet concrete is less deformed than the dry concrete for the same mean stress. The second part of the experimental program concerns dynamic tensile tests at different loading velocities, and different moisture conditions of concrete. The results show that the tensile strength of concrete C50 may increase up to 5 times compared to its static strength for a strain rate of about 100 s -1 . In the numerical part, we are interested in improving an existing constitutive coupled model of concrete behavior called PRM (Pontiroli-Rouquand-Mazars) to predict the concrete behavior under impact. This model is based on a coupling between a damage model which is able to describe the degradation mechanisms and cracking of the concrete at

  7. Thermo Active Building Systems Using Building Mass To Heat and Cool

    DEFF Research Database (Denmark)

    Olesen, Bjarne W.

    2012-01-01

    Using the thermal storage capacity of the concrete slabs between each floor in multistory buildings to heat or cool is a trend that began in the early 1990s in Switzerland.1,2 Pipes carrying water for heating and cooling are embedded in the center of the concrete slab. In central Europe (Germany,......, Austria, Netherlands, etc.), this type of system has been installed in a significant number of new office buildings since the late 1990s. The trend is spreading to other parts of the world (the rest of Europe, North America and Asia)....

  8. Experimental research of slab cast over precast joists with prestressed reinforcement

    Directory of Open Access Journals (Sweden)

    Koyankin Aleksandr Aleksandrovich

    2016-03-01

    Full Text Available At the present time reinforced concrete is the main construction material in civil and industrial construction. Cast-in-place and precast construction is gradually becoming a more widespread type of house-building, but still there is a lack of data, including experimental data, which allows evaluating the stress and strain state of a construction of a slab cast over precast joists. Experimental research of stress and strain state of slab cast over precast joists with prestressed reinforcement was carried out. An experimental model of a fragment of a hybrid precast/cast-in-place building was produced and tested (reduction scale 1:6. The experimental investigations of slab cast over precast joists with prestressed reinforcement proved that the construction solution of the framework offered in the previous works of the authors possess good stiffness, crack-resistance and bearing capacity. It well fits for constructing the slabs of long spans in residential and public buildings.

  9. Study on reinforced lightweight coconut shell concrete beam behavior under flexure

    International Nuclear Information System (INIS)

    Gunasekaran, K.; Annadurai, R.; Kumar, P.S.

    2013-01-01

    Highlights: ► Use of coconut shell as aggregate in concrete. ► Behavior of coconut shell concrete under flexure. ► SEM images of cement, sand, coconut shell and coconut shell aggregate concrete. ► Coconut shell hollow blocks and precast slabs are used in practice. - Abstract: Coconut shell has been used as coarse aggregate in the production of concrete. The flexural behavior of reinforced concrete beam made with coconut shell is analyzed and compared with the normal control concrete. Twelve beams, six with coconut shell concrete and six with normal control concrete, were fabricated and tested. This study includes the moment capacity, deflection, cracking, ductility, corresponding strains in both compression and tension, and end rotation. It was found that the flexural behavior of coconut shell concrete is comparable to that of other lightweight concretes. The results of concrete compression strain and steel tension strain showed that coconut shell concrete is able to achieve its full strain capacity under flexural loadings. Under serviceability condition, deflection and cracking characteristics of coconut shell concrete are comparable with control concrete. However, the failure zones of coconut shell concrete were larger than for control concrete beams. The end rotations of the coconut shell concrete beams just prior to failure values are comparable to other lightweight concretes. Coconut shell concrete was used to produce hollow blocks and precast slab in 2007 and they are being subjected to some practical loading till today without any problems such as deflection, bending, cracks, and damages for the past five years

  10. Influencia de la acumulacion de las flechas de servicio en forjados de hormigon con cerramientos rigidos = Influence of accumulation of service concrete truss deformation effect of rigid enclosure.

    Directory of Open Access Journals (Sweden)

    Francisco Gila

    2015-12-01

    Abstract The objective of this work is to test the direct relationship between active arrows that are generated in the upper floors of a residential building, with the elements that are in contact with the floors of the structure, is say, with the partitions. The methodology is based on the study of a series of test tube, made these for models of buildings, are all having in common the floor geometry being variable and the number of floors that are at height. The conclusions that have been reached after analyzing a 6 plants concludes that the floor slab can get to increase the value of the active deflection up to 234.93 %. In a 9-storey building the floor slab could increase their active arrow up to 241.09% for the same lighting conditions and load. In the case of a 12-storey building is concluded in the floor slab can actually increase the value of the active deflection up to 290.07%.

  11. Rubber Flooring Impact on Production and Herdlife of Dairy Cows

    Science.gov (United States)

    Use of rubber flooring in dairies has become popular because of perceived cow comfort. The overall objective of this longitudinal study was to evaluate production, reproduction, and retention of first and second lactations of cows assigned to either rubber (RUB) or concrete (CON) flooring at the fe...

  12. Structure of diaphragm floor of reactor container, construction module and construction method thereof

    International Nuclear Information System (INIS)

    Hasegawa, Hiroshi; Oikawa, Tadaaki; Ushiroda, Koichi; Matsuura, Tadashi; Komaru, Toshimi; Nemoto, Yoichi; Makita, Tatsuo; Maezawa, Sumito.

    1998-01-01

    A diaphragm floor of a reactor container has a structure comprising iron beams buried in concretes and connection members connecting the iron beams and liners, in which the liners are supported by the iron beams, and the load of the iron reinforced concretes when formed on the liner is supported by the iron beams thereby enabling to construct a diaphragm floor with no or reduced amount of temporary support members. As a result, the construction operation can be promoted by reducing the amount of the temporary support members or making the removing operation of the temporary support members unnecessary. The concrete layer comprises at least two upper and lower layers of a firstly formed concrete layer and a subsequently formed concrete layer, and the iron beams have such a strength capable of enduring the load applied when the firstly formed concrete is placed. (N.H.)

  13. Design and construction of Chiburiko Bridge (stress ribbon bridge). Chiburiko bashi (tsurishoban kyo) no sekkei to seko

    Energy Technology Data Exchange (ETDEWEB)

    Kamisakoda, K; Tokuyama, S; Sano, K; Onuma, K [Kashima Corp., Tokyo (Japan)

    1992-07-30

    Chiburiko Bridge lies across Chiburiko which is a lake for agricultural water, and is used by people, carts and cars for administration. It is a stressed-ribbon bridge with the road surface made with concrete covered bands of cables stretched between abutments, and is the first highway bridge in Japan. A report is made on the plan and construction of the bridge. Integration of the precast slab with the cast-in-place concrete as well as mutual integration of the precast slabs are validated by the use of a reproduced model of a part of the bridge. Floor slabs are suspended by cables, and can be constructed with no form nor support by integrating cast-in-place concrete with the precast slabs on mutually joined precast slabs. It has been said that the stressed-ribbon bridge has a structure suitable for long span bridges because it has a simple structure. Studies, however, seems to be necessary on the impact caused by running of vehicles and on the wind resisting stability. 3 refs., 17 figs., 2 tabs.

  14. Radon penetration of concrete slab cracks, joints, pipe penetrations, and sealants

    NARCIS (Netherlands)

    Nielson, KK; Rogers, VC; Holt, RB; Pugh, TD; Grondzik, WA; deMeijer, RJ

    1997-01-01

    Radon movement through 12 test slabs with different cracks, pipe penetrations, cold joints, masonry blocks, sealants, and tensile stresses characterized the importance of these anomalous structural domains, Diffusive and advective radon transport were measured with steady-state air pressure

  15. Self-compacting fibre reinforced concrete applied in thin plates

    NARCIS (Netherlands)

    Grunewald, S.; Shionaga, R.; Walraven, J.C.

    2013-01-01

    Floor panels produced with traditionally vibrated concrete are relatively thick due to the need to reinforce concrete and consequently, heavy. Without the need to place rebars in panels and by applying self-compacting fibre reinforced concrete (SCFRC) the production process becomes more efficient.

  16. Flexural behaviour and punching shear of selfcompacting concrete ribbed slab reinforced with steel fibres

    Directory of Open Access Journals (Sweden)

    Ahmad Hazrina

    2017-01-01

    Full Text Available This paper investigates the effects of steel fibres as a replacement to the conventional reinforcement under flexural behaviour and punching shear in self-compacting (SCC ribbed slab reinforced with steel fibres. Four ribbed slabs with similar dimensions of 2.8 m length × 1.2 m width and 0.2m thickness were constructed. Two of the samples were considered as control samples (conventionally reinforced with reinforcement bars and welded mesh while another two samples were fully reinforced with 1% (80 kg/m3 volume of steel fibres incorporated to the SCC mix. For the flexural behaviour study, the ribbed slab samples were subjected to two line loads under four point bending. Meanwhile, for the punching shear analysis, the ribbed slab samples were subjected to a point load to simulate loading from the column. The analysis of the experimental results displayed that steel fibres incorporation had been found to effectively delay the first crack occurrence under both flexural and punching shear. The steel fibre replacement has been proven to be able to sustain up to 80% and 73% of the ultimate load resistance for flexural and punching shear, respectively, in comparison to conventionally reinforced ribbed slab structure. The visual observation carried out during the experiment exhibited similar failure mode for both steel fibre reinforced and control samples. This was observed for both flexural and punching shear samples. Overall, it can be concluded that the steel fibres had displayed a promising potential to effectively replace the conventional reinforcements.

  17. Prevalence of claw disorders in Dutch dairy cows exposed to several floor systems

    NARCIS (Netherlands)

    Somers, J.G.C.J.; Frankena, K.; Noordhuizen-Stassen, E.N.; Metz, J.H.M.

    2003-01-01

    Claw health was examined in an observational study on Dutch dairy farms with either a slatted floor (SL), slatted floor with manure scraper (SL-SCR), solid concrete floor (SCF), a straw yard (SY), or a zero-grazing feeding system (ZG). Hooves of cows' hind legs were examined for the presence and

  18. Quantitative studies on impact resistance of reinforced concrete panels with steel liners under impact loading. Part 1: Scaled model impact tests

    International Nuclear Information System (INIS)

    Tsubota, H.; Kasai, Y.; Koshika, N.; Morikawa, H.; Uchida, T.; Ohno, T.; Kogure, K.

    1993-01-01

    In recent years, extensive analytical and experimental studies have been carried out to establish a rational structural design method for nuclear power plants against local damage caused by various external missiles. Through these studies, several techniques for improving die impact resistance of reinforced concrete slabs have been proposed. Of these techniques, attaching a thin steel liner onto the impacted and/or rear face of the slab is considered to be one of the most effective methods. Muto et. al. carried out full-scale impact tests using actual aircraft engines and reported that a thin corrugated steel liner attached to the rear face of a concrete panel has a significant effect in preventing scattering of scabbed concrete debris from the rear face of the target. Based on many experimental and analytical studies, UKAEA reported that a steel liner attached to a reinforced concrete slab improves its perforation and scabbing resistance, and Walter et. al. proposed a formula for predicting the equivalent thickness of a slab with a steel liner attached. The object of this study was to evaluate quantitatively the effect of a steel liner attached to a reinforced concrete slab in preventing local damage caused by rigid missiles. To achieve the object, extensive impact tests were carried out. This paper summarizes the results of these tests

  19. Concrete shaver. Innovative technology summary report

    International Nuclear Information System (INIS)

    1998-12-01

    The US Department of Energy (DOE) is in the process of decontamination and decommissioning (D and D) for many of its nuclear facilities throughout the United States. These facilities must be dismantled and the demolition waste sized into manageable pieces for handling and disposal. The facilities undergoing D and D are typically chemically and/or radiologically contaminated. To facilitate this work, DOE requires a tool capable of removing the surface of radiologically contaminated concrete floors. Operating requirements for the tool include simple and economical operation, the capability of operating in ambient temperatures from 3 C to 40 C (37 F to 104 F), and the ability to be easily decontaminated. The tool also must be safe for workers. The Marcrist Industries Limited concrete shaver is an electrically driven, self-propelled concrete and coating removal system. This technology consists of a 25-cm (10-in.)-wide diamond impregnated shaving drum powered by an electric motor and contains a vacuum port for dust extraction. The concrete shaver is ideal for use on open, flat, floor areas. The shaver may also be used on slightly curved surfaces. This shaver is self-propelled and produces a smooth, even surface with little vibration. The concrete shaver is an attractive alternative to traditional pneumatic scabbling tools, which were considered the baseline in this demonstration. The use of this tool reduces worker fatigue (compared to the baseline) due to lower vibration. The shaver is more than five times faster than the five-piston pneumatic scabbler at removing contamination from concrete. Because of this increased productivity, the shaver is 50% less costly to operate than baseline technologies. The DOE has successfully demonstrated the concrete shaver for decontaminating floors for free-release surveys prior to demolition work

  20. Development of Claw Traits and Claw Lesions in Dairy Cows kept on different floor systems

    NARCIS (Netherlands)

    Somers, J.G.C.J.; Schouten, W.G.P.; Frankena, K.; Noordhuizen-Stassen, E.N.; Metz, J.H.M.

    2005-01-01

    Several claw shape measurements, horn hardness, and horn growth and wear were recorded monthly at 12 dairy farms to investigate the effect of floor type and changes in these traits over time. Herds were either housed on a slatted floor (SL), solid concrete floor (SC), grooved floor (GR), or on a

  1. The Rubble Rescue Radar (RRR): A low power hand-held microwave device for the detection of trapped human personnel

    International Nuclear Information System (INIS)

    Haddad, W.S.

    1997-01-01

    Each year, innocent human lives are lost in collapsed structures as a result of both natural and man-made disasters. We have developed a prototype device, called the Rubble Rescue Radar (RRR) as a aid to workers trying to locate trapped victims in urban search and rescue operations. The RRR is a motion sensor incorporating Micropower Impulse Radar and is capable of detecting human breathing motions through reinforced concrete. It is lightweight, and designed to be handled by a single operator for local searches in areas where trapped victims are expected. Tests of the first prototype device were conducted on site at LLNL using a mock rubble pile consisting of a reinforced concrete pipe with two concrete floor slabs placed against one side, and random concrete and asphalt debris piled against the other. This arrangement provides safe and easy access for instruments and/or human subjects. Breathing signals of a human subject were recorded with the RRR through one floor slab plus the wall of the pipe, two slabs plus the wall of the pipe, and the random rubble plus the wall of the pipe. Breathing and heart beat signals were also recorded of a seated human subject at a distance of 1 meter with no obstructions. Results and photographs of the experimental work are presented, and a design concept for the next generation device is described

  2. "The Battery" designed with Super-Light (concrete) Decks

    DEFF Research Database (Denmark)

    Castberg, Niels Andreas; Hertz, Kristian Dahl

    This paper describes how Super-Light structures can be used as a structural principle for the buildings in the project ‘The Battery’ designed by Bjarke Ingels Group. The overall structural concept is described and the advantages of using super-light slabs for the project are explored. Especially...... the cantilevered internal corridors are investigated. Super-Light Structures is a newly patented structural concrete concept. Slabs based on the concept are the first structural element developed under the patent. The slabs called SL-decks have multiple advantages compared to traditional hollow core slabs....... The paper aims to describe the concept of how the deck can be used in these innovative buildings and how the special advantages of the SL-decks are applied....

  3. Summary review of Mound Facility's experience in decontamination of concrete

    International Nuclear Information System (INIS)

    Combs, A.B.; Davis, W.P.; Garner, J.M.; Geichman, J.R.

    1980-01-01

    Most of the current concrete decontamination work at Mound Facility involves surfaces that are contaminated with plutonium-238. Approximately 60,000 sq. ft. of concrete floors will have to be decontaminated in Mound's current Decontamination and Decommissioning (D and D) Project. Although most of these surfaces are partially protected by a barrier (tile or paint), contaminated water and acid have penetrated these barriers. The technique for decontaminating these floors is desribed. The initial cleaning of the floor involes standard water and detergent. Acids are not used in cleaning as they tend to drive the contamination deeper into the concrete surface. Next, the floor tile is manually removed inside a temporary enclosure under negative and filtered ventilation. Finally, layers of contaminated concrete are mechanically removed inside the ventilated enclosure. The suspected depth and surface area of contamination determines the type of mechanical tool used. In summary, several generic methods of concrete decontamination can be utilized: chemical, such as water, detergent, acids, paint remover, strippable paints, etc.; rotary using sanders, grinders, scarifiers, etc.; impact such as pressure washers (hydrolasers), particle blasters, scabblers, needlers, spallers, paving and rock breakers, ram hoes, etc. The particular method used depends on several factors: surface and area involved; depth of contamination; cost and availability of equipment; usage safety and radiological control; and waste generated

  4. Computational Modelling in Development of a Design Procedure for Concrete Road

    Directory of Open Access Journals (Sweden)

    B. Novotný

    2000-01-01

    Full Text Available The computational modelling plays a decisive part in development of a new design procedure for concrete pavement by quantifying impacts of individual design factors. In the present paper, the emphasis is placed on the modelling of a structural response of the jointed concrete pavement as a system of interacting rectangular slabs transferring wheel loads into an elastic layered subgrade. The finite element plate analysis is combined with the assumption of a linear contact stress variation over triangular elements of the contact region division. The linking forces are introduced to model the load transfer across the joints. The unknown contact stress nodal intensities as well as unknown linking forces are determined in an iterative way to fulfil slab/foundation and slab/slab contact conditions. The temperature effects are also considered and space is reserved for modelling of inelastic and additional environmental effects. It is pointed out that pavement design should be based on full data of pavement stressing, in contradiction to procedures accounting only for the axle load induced stresses.

  5. Heat transfer within a concrete slab applying the microwave decontamination process

    International Nuclear Information System (INIS)

    Li, W.; Ebadian, M.A.; White, T.L.; Grubb, R.G.

    1993-01-01

    Decontamination of a radioactive contaminated concrete surface is a new technology for the treatment of radioactive waste. In this paper, concrete decontamination using microwave technology is investigated theoretically. A plane wave assumption of microwave propagation has been employed to estimate the microwave field and power dissipation within the concrete. A one-dimensional, unsteady heat conduction model with microwave heat dissipation resulting from microwave-material interaction has been used to evaluate frequency, steel reinforcement within the concrete, and thermal boundary conditions are also considered in the present model. Four commonly used microwave frequencies of 0.896, 2.45, 10.6, and 18.0 GHz have been utilized in the analysis. The results revealed that as the microwave frequency increases to, or higher than 10.6 GHz, the microwave power dissipation shifts toward the front surface of the concrete. Furthermore, it was observed that use of a higher frequency microwave could reduce power intensity requirements needed to raise the temperature difference or thermal stress to the same value in the same period of time. It was found that the presence of reinforcing steel mesh causes part of the microwave energy to be blocked and reflected. Thus, the temperature or thermal stress of the concrete increases before the reinforcement, and decreases after the reinforcement. 16 refs., 6 figs., 3 tabs

  6. Top-down cracking of rigid pavements constructed with fast setting hydraulic cement concrete

    CSIR Research Space (South Africa)

    Heath, AC

    2009-01-29

    Full Text Available Jointed plain concrete pavement (JPCP) test sections were constructed using fast setting hydrualic cement concrete (FSHCC) as part of the California accelerated pavement testing program (CAL/APT). Many of the longer slabs cracked under environmental...

  7. Examination report: Remote video examination of air slots under the primary tank at 241-AN-107

    International Nuclear Information System (INIS)

    Pedersen, L.T.

    1998-01-01

    This report documents the results of remote video examination of air slots in the insulating concrete slab beneath the primary tank at 241-AN-107. Life Extension Equipment Engineering has selected tank 241-AN-107 for ultrasonic evaluation of tank wall, knuckle, and floor plates. Access to the primary tank floor plates is via the air slots which were formed into the insulating concrete slab during tank construction (reference drawings H-2-71105 and H-2-71160). Prior to deployment of the ultrasonic inspection equipment it is desirable to examine the air slots for obstructions and debris which could impede the ultrasonic equipment. The criteria, equipment description, deliverables, and responsibilities for examination of the air slots are described in HNF-1949, Rev. 0, ''Engineering Task Plan for Remote Video Examination of Air Slots Under the Primary Tank at 241-AN-107''

  8. Practical stress evaluation method of RC slab for bending moment in consideration of additional in-plane stress caused by boundary condition

    International Nuclear Information System (INIS)

    Kobayashi, Toshio; Adachi, Naohito; Masuda, Kiyoshi

    1998-01-01

    In a design of a thick RC slab such as a basemat of a nuclear reactor building, the design method as same as for RC column is usually used. In this method, bending moment and axial force which are obtained by linear Finite Element Method (FEM) for external force are considered. But the assumption for linear FEM in which concrete participates for tensile stress is different from that for reinforcement design in which concrete does not participate for tensile stress. This difference of the assumption results that in-plane tensile strain at the center of the slab depth in the reinforcement design is larger than that in linear FEM. Some effects will appear in stress distribution if this tensile strain is constrained by boundary condition. In this paper, a practical method to evaluate the boundary constrain effects for this in-plane tensile strain is proposed and a simulation analysis of a thick reinforced concrete slab with a large opening for out-of-plane force is also reported. (author)

  9. Hand forces exerted by long-term care staff when pushing wheelchairs on compliant and non-compliant flooring.

    Science.gov (United States)

    Lachance, Chantelle C; Korall, Alexandra M B; Russell, Colin M; Feldman, Fabio; Robinovitch, Stephen N; Mackey, Dawn C

    2018-09-01

    Purpose-designed compliant flooring and carpeting have been promoted as a means for reducing fall-related injuries in high-risk environments, such as long-term care. However, it is not known whether these surfaces influence the forces that long-term care staff exert when pushing residents in wheelchairs. We studied 14 direct-care staff who pushed a loaded wheelchair instrumented with a triaxial load cell to test the effects on hand force of flooring overlay (vinyl versus carpet) and flooring subfloor (concrete versus compliant rubber [brand: SmartCells]). During straight-line pushing, carpet overlay increased initial and sustained hand forces compared to vinyl overlay by 22-49% over a concrete subfloor and by 8-20% over a compliant subfloor. Compliant subflooring increased initial and sustained hand forces compared to concrete subflooring by 18-31% when under a vinyl overlay. In contrast, compliant flooring caused no change in initial or sustained hand forces compared to concrete subflooring when under a carpet overlay. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Modified creep and shrinkage prediction model B3 for serviceability limit state analysis of composite slabs

    Science.gov (United States)

    Gholamhoseini, Alireza

    2016-03-01

    Relatively little research has been reported on the time-dependent in-service behavior of composite concrete slabs with profiled steel decking as permanent formwork and little guidance is available for calculating long-term deflections. The drying shrinkage profile through the thickness of a composite slab is greatly affected by the impermeable steel deck at the slab soffit, and this has only recently been quantified. This paper presents the results of long-term laboratory tests on composite slabs subjected to both drying shrinkage and sustained loads. Based on laboratory measurements, a design model for the shrinkage strain profile through the thickness of a slab is proposed. The design model is based on some modifications to an existing creep and shrinkage prediction model B3. In addition, an analytical model is developed to calculate the time-dependent deflection of composite slabs taking into account the time-dependent effects of creep and shrinkage. The calculated deflections are shown to be in good agreement with the experimental measurements.

  11. Gaussian beam-to-slab waveguide coupler by graded index photonic crystal lens

    International Nuclear Information System (INIS)

    Bahari, B; Abrishamian, M S

    2013-01-01

    In this numerical study, a Gaussian beam-to-slab waveguide coupler for both modes of TM and TE has been studied. For this purpose, a concrete structure is suggested, in which the graded index photonic crystal lens and the slab waveguide are in the same structure composed of Si material, and can be fabricated with a single-step lithography process. For maximum power coupling, half-holes have been used as an input matching layer. Power coupling of 80% over a 450 nm bandwidth for the TM mode, and 60% over a 180 nm bandwidth for the TE mode is achieved. (paper)

  12. LIGHTWEIGHT CONCRETE BASED GRANSHLAK

    Directory of Open Access Journals (Sweden)

    NETESA M. I.

    2016-02-01

    Full Text Available Raising of problem. Concrete advisable to obtain a low strength with local secondary resources for recycling and reduce the environmental burden on the environment. But it is important to design such concrete compositions with a reduced flow of cement. It is known that the coefficient of efficiency of use of cement in the concrete of the heavy and B10 is less than about 0.5, which is almost two times smaller than in class B15 concrete and above. Even lower coefficient of efficiency in light concrete cement low strength. Therefore, it is important to find patterns determining the composition of lightweight concrete based on local-products industry with more efficient use of cement in them. Purpose.. Based on the analysis of earlier research results, including with the use of methods of mathematical planning of experiments to determine the concrete contents, which can provide the requirements for the underlying layers of the floor, the compressive strength of which should correspond to the class B5. It is important to provide the required strength at minimum flow of the cement, which is the most expensive and energy-intensive part of concrete. Conclusion. Analysis of the test results of control samples of concrete in 28-day-old, the following laws. The required tensile strength of concrete compressive strength of 7.0 MPa can be obtained in the test range when used in formulations as a filler as the Dnieper hydroelectric power station fly ash and tailings Krivoy Rog iron ore YuGOK. To ensure providing the required characteristic strength of the concrete in the underlying layers of the floor is advisable to use a nominal composition per cubic meter of concrete: cement 160 kg granshlaka Plant named after Petrovsky, 675 kg of fly ash Dnieper HPP 390 kg, 400 kg of sand, 230 liters of water. Thus, while ensuring rational grain composition components can obtain the desired strength lightweight concrete based granshlaka plant Petrovsky, using as fillers

  13. Digital Image Correlation of Concrete Slab at University of Tennessee, Knoxville

    Energy Technology Data Exchange (ETDEWEB)

    Mahadevan, Sankaran [Idaho National Lab. (INL), Idaho Falls, ID (United States); Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pham, Binh T. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kyle, Neal [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Some degradation mechanisms of concrete manifest themselves via swelling or by other shape deformation of the concrete. Specifically, degradation of concrete structure damaged by ASR is viewed as one of the dominant factors impacting the structural integrity of aging nuclear power plants. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. Number of nondestructive examination techniques (i.e., thermography, digital image correlation, mechanical deformation measurements, nonlinear impact resonance (DIC) acoustic spectroscopy, and vibro-acoustic modulation) is used to detect the damage caused by ASR. DIC techniques have been increasing in popularity, especially in micro- and nano-scale mechanical testing applications due to its relative ease of implementation and use. Advances in computer technology and digital cameras help this method moving forward. To ensure the best outcome of the DIC system, important factors in the experiment are identified. They include standoff distance, speckle size, speckle pattern, and durable paint. These optimal experimental options are selected basing on a thorough investigation. The resulting DIC deformation map indicates that this technique can be used to generate data related to degradation assessment of concrete structure damaged by the impact of ASR.

  14. Digital Image Correlation of Concrete Slab at University of Tennessee, Knoxville

    International Nuclear Information System (INIS)

    Mahadevan, Sankaran; Agarwal, Vivek; Pham, Binh T.; Kyle, Neal

    2016-01-01

    Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Some degradation mechanisms of concrete manifest themselves via swelling or by other shape deformation of the concrete. Specifically, degradation of concrete structure damaged by ASR is viewed as one of the dominant factors impacting the structural integrity of aging nuclear power plants. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. Number of nondestructive examination techniques (i.e., thermography, digital image correlation, mechanical deformation measurements, nonlinear impact resonance (DIC) acoustic spectroscopy, and vibro-acoustic modulation) is used to detect the damage caused by ASR. DIC techniques have been increasing in popularity, especially in micro- and nano-scale mechanical testing applications due to its relative ease of implementation and use. Advances in computer technology and digital cameras help this method moving forward. To ensure the best outcome of the DIC system, important factors in the experiment are identified. They include standoff distance, speckle size, speckle pattern, and durable paint. These optimal experimental options are selected basing on a thorough investigation. The resulting DIC deformation map indicates that this technique can be used to generate data related to degradation assessment of concrete structure damaged by the impact of ASR.

  15. A study on the behavior of beam-column connections in precast concrete structures: experimental analysis

    OpenAIRE

    Kataoka,M. N.; Ferreira,M. A.; El Debs,A. L. H. C.

    2012-01-01

    Due to the large increase in the use of precast concrete structures in multistory buildings, this work covers a study on the behavior of beam-column connection with emphasis on the continuity provided by the slab reinforcement. Two prototypes were tested, each one with a different detail of the continuity reinforcement distribution. In both connections, the steel area used on the concrete cover of the hollow core slab was the same, varying the amount of bars that passed through the column and...

  16. Losas de concreto reforzadas con acero inoxidable de desecho Reinforced concrete slabs with stainless steel waste

    Directory of Open Access Journals (Sweden)

    Jorge Alberto Pérez González

    2008-08-01

    Full Text Available Se muestran los resultados de un programa experimental que explora la reutilización de materiales de desecho industrial (específicamente láminas de acero inoxidable producto de la acuñación de moneda como refuerzo en losas de concreto. Para ello se elaboraron 23 especímenes tipo viga-losa a escala natural con dicho refuerzo a fin de determinar su comportamiento en términos de resistencia, ductilidad y formas de falla; el análisis experimental de modelos ensayados con diferentes cantidades de refuerzo muestra que en algunos casos, bajo ciertas condiciones de cuantías y colocación del mismo, es posible alcanzar capacidades de carga y formas de falla similares a las de especímenes de control con refuerzo tradicional. En base a estos resultados se concluye en la factibilidad de utilizar el material arriba descrito como refuerzo alternativo en elementos estructurales de concreto, tratando de encontrar alternativas más económicas en la construcción de vivienda popular.The results from an experimental program that explores the use of industrial waste materials (specifically sheets of stainless steel that result of the currency coinage as reinforcement for concrete slabs are presented. Twenty three full size beam-deck specimens were built in order to measure resistance, ductility and failure modes; the experimental analysis in models with reinforcement in different quantities shows that in some cases, under certain quantities and location, it is possible to reach similar load capacities and failure modes as specimens with traditional reinforcement. Based on these results, it is concluded the feasibility of using the material described above as alternative reinforcement in structural concrete elements, as an economic option in the construction of social housing.

  17. Forensic investigation of two voided slab bridges in the Virginia Department of Transportation's Richmond District.

    Science.gov (United States)

    2017-06-01

    The precast prestressed concrete voided slab structure is a popular bridge design because of its rapid construction and cost : savings in terms of eliminating formwork at the jobsite. However, the longitudinal shear transfer mechanism often fails, le...

  18. Perforation of a concrete slab by a missile: finite element approach

    International Nuclear Information System (INIS)

    Jamet, P.; Berriaud, C.; Millard, A.; Nahas, G.; Yuritzin, T.

    1983-08-01

    A specific concrete model has been developed to investigate the problem of concrete walls perforation by a missile: three types of damage are accounted for: traction damage, shear damage, hydrostatic pressure damage. In order to investigate the validity of this concrete model in simple compressive conditions, tests are performed in following configuration: microconcrete used in perforation tests is cast in a cylindrical mould 100 mm diameter, 50 mm wall thickness made of very strong steel. The concrete height is 400 mm. A silver layer is put on the inner face to decrease the friction coefficient. The load is transmitted to the contrete by means of a metal piston. A quasi static test is first performed using a hydraulic testing machine. A second one is then impacted by a 32 kg mass dropping from 19 meters. In both cases the displacement and the forces are recorded for comparison with calculation

  19. Low frequency vibration tests on a floating slab track in an underground laboratory

    Institute of Scientific and Technical Information of China (English)

    De-yun DING; Wei-ning LIU; Ke-fei LI; Xiao-jing SUN; Wei-feng LIU

    2011-01-01

    Low frequency vibrations induced by underground railways have attracted increasing attention in recent years. To obtain the characteristics of low frequency vibrations and the low frequency performance of a floating slab track (FST), low frequency vibration tests on an FST in an underground laboratory at Beijing Jiaotong University were carried out. The FST and an unbalanced shaker SBZ30 for dynamic simulation were designed for use in low frequency vibration experiments. Vibration measurements were performed on the bogie of the unbalanced shaker, the rail, the slab, the tunnel invert, the tunnel wall, the tunnel apex, and on the ground surface at distances varying from 0 to 80 m from the track. Measurements were also made on several floors of an adjacent building. Detailed results of low frequency vibration tests were reported. The attenuation of low frequency vibrations with the distance from the track was presented, as well as the responses of different floors of the building. The experimental results could be regarded as a reference for developing methods to control low frequency vibrations and for adopting countermeasures.

  20. Assessment of the Reliability of Concrete Slab Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C. R.

    This paper is based on research performed for the Highways Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: Concrete Bridges". It contains details of a methodology which can be used to generate Whole Life (WL) reliability profiles....

  1. Sustainability and durability analysis of reinforced concrete structures

    Science.gov (United States)

    Horáková, A.; Broukalová, I.; Kohoutková, A.; Vašková, J.

    2017-09-01

    The article describes an assessment of reinforced concrete structures in terms of durability and sustainable development. There is a short summary of findings from the literature on evaluation methods for environmental impacts and also about corrosive influences acting on the reinforced concrete structure, about factors influencing the durability of these structures and mathematical models describing the corrosion impacts. Variant design of reinforced concrete structure and assessment of these variants in terms of durability and sustainability was performed. The analysed structure was a concrete ceiling structure of a parking house for cars. The variants differ in strength class of concrete and thickness of concrete slab. It was found that in terms of durability and sustainable development it is significantly preferable to use higher class of concrete. There are significant differences in results of concrete structures durability for different mathematical models of corrosive influences.

  2. Analysis of hydrogen generation according to the specific concrete composition during severe accident

    International Nuclear Information System (INIS)

    Seo, M. R.; Kim, M. K.

    2001-01-01

    The chemical composition of reactor cavity floor concrete affects the kind and amout of gases generated by MCCI and ablation of concrete. And if affects the physical and chemical characteristics of molten pool formed in the cavity. So, the specific concrete compostion is inputted in the MAAP Code used in the Level 2 PSA. and since Ulchin Unit 3 and 4 PSA, the analysis of concrete composition has been performed by the concrete mold prepared for this usage at the installation of cavity floor concrete. But, the composition of domestic concrete for construction of NPP is nearly the same as that of the standard basaltic concrete, and the effect of minor variation in composition is expected to be negligible. This report analyze the effect of the concrete composition to the generation of hydrogen due to MCCI, and discuss the necessity of analysis about the specific concrete composition for Level 2 PSA

  3. Ultimate resistance of a reinforced concrete foundation under impulsive loading

    International Nuclear Information System (INIS)

    Aquaro, D.; Forasassi, G.; Marconi, M.

    2003-01-01

    The impact of a spent nuclear fuel cask against a reinforced concrete slab of a temporary repository for spent nuclear fuel is numerically analysed. The analysis considers accidental events in which a spent nuclear fuel cask would drop against the floor of a repository during lifting operations. Two types of solutions have been taken into account: a simple reinforced concrete structure and a structure provided with a 40 mm thick steel liner on the impacted surface, connected to a 1600 mm thick concrete bed. The model is assumed to be axisymmetric and positioned on an elastic ground (Winkler model). The concrete has been simulated as: elastic perfectly plastic under compressive stresses limited by a crushing strain; elastic linear under tensile stresses until a cracking stress value and a following decrease of stress characterized by a constant or variable softening modulus; limited ability to resist at shear stresses after cracking characterized by a shear retention factor. The steel of the reinforcement bars and of the cask has been simulated as an elastic perfectly plastic material. Several numerical simulations have been performed in order to determine the influence, on the ultimate resistance of the structure under examination, of the steel liner, of some characteristic parameters of concrete (as the softening module and the shear retention factor) and of the Winkler coefficient values, simulating the elastic behaviour of the ground. The obtained results demonstrate that a steel liner produces a lower stress in the concrete as well as in the reinforcement but the bed is still subjected to the cracking phenomenon throughout its entire width although the crushing is localized to only a few elements near the impact zone. The use of a more complex constitutive equation for the concrete considering the shear retention factor and the softening module has given results which do not differ greatly from those related to a more simplified model. A different degree of

  4. Irradiated Effect on Shear-Moment Interaction of Reinforced Concrete Slab

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Tae-Hyun; Kim, Jun Yeon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, HyungTae; Park, Kyoungsoo [Yonsei University, Seoul (Korea, Republic of); Kim, Sang-Ho [Hyundai Engineering, Seoul (Korea, Republic of)

    2015-10-15

    Several deleterious mechanisms include chronic high-temperature exposure, freeze-thaw, and chemical attack and have been reviewed extensively in the literature. On the other hand, the effect of irradiation on RC needs further investigations for the long-term operation of existing NPPs. In this regard, the RC biological shield structure is located in closest proximity to a reactor core and expected to see the highest levels of irradiation over the lifetime. The biological shield structure may undergo a large lateral load from earthquake and become thicker for a suitable shielding. Although the bending strength is easily predictable with the altering steel properties, the more complete behaviors should be studied to see if the promised performance is achievable. Given this, in this study, the shear-moment (VM) interaction of a typical one-way slab representing the biological shield structure is investigated with incremental neutron irradiation. The effect of radiation on the behavior of one-way slab is presented by the shear and moment capacity interaction diagram. The results suggest that the yield strength increase of the longitudinal reinforcement barely affects the shear strength but it increases the bending strength significantly. This may be misleading, however, as the structural capacity to observe the energy from environmental loadings such as earthquake would be actually reducing.

  5. The foundation mass concrete construction technology of Hongyun Building B tower raft

    Science.gov (United States)

    Liu, Yu; Yin, Suhua; Wu, Yanli; Zhao, Ying

    2017-08-01

    The foundation of Hongyun building B tower is made of raft board foundation which is 3300mm in the thickness and 2800mm beside side of the core tube. It is researched that the raft foundation mass concrete construction technology is expatiated from temperature and cracks of the raft foundation and the temperature control and monitoring of the concrete base slab construction and concrete curing.

  6. ANALISIS PRODUKTIVITAS METODE PELAKSANAAN PENGECORAN BETON READY MIX PADA BALOK DAN PELAT LANTAI GEDUNG

    Directory of Open Access Journals (Sweden)

    Ariany Frederika

    2017-01-01

    Full Text Available Abstract: Implementation method technology of multi-storey building concrete construction is experiencing significant growth, both in material processing and casting equipment.  Several casting equipment including concrete lift  and concrete pump have  different productivities  which contribute to time and cost.  This research aims to analyze the productivity of casting equipment, time and cost required, as well as the break-even point of casting method of ready mix concrete application on the beams and the floor slabs of buildings, particularly on the second- floor, third- floor and forth-floor using concrete lift and concrete pump. Data was obtained by conducting interviews and observations concerning casting implementation of building construction projects that use K-300 ready- mix concrete.  Regression and Correlation analysis are used to obtain time and cost comparison between both method of casting implementation, as well as Break Even Point analysis to obtain breakeven point of casting volume with regards to cost and time. The analysis showed that casting productivities  using lift on  first, second and third floor  are 7,166 m3/h, 5,945 m3/h, 5,125 m3/h, while the productivities using concrete pump on  first, second and third floor  are 36 m3/h, 30 m3/h , 24 m3/hour. Cost comparison of 1 m3 increment of casting using concrete lift and concrete pump is  Rp. 99 330: Rp.19.000 (5.23: 1,  while time ratio is  8.272 minutes: 2,172 minutes (3.8: 1. Breakeven point analysis towards casting cost showed that the second floor which has volume greater than 95.89 m3,  using concrete pump method is more optimal than concrete-lift.

  7. Non-traditional shape GFRP rebars for concrete reinforcement

    Science.gov (United States)

    Claure, Guillermo G.

    existing provisions and standards allowing for a consistent universal norm for all GFRP rebars were reached. This dissertation also presents an evaluation of the structural behavior of reinforced concrete (RC) beams and slabs using the new type of GFRP rebar consisting of a non-traditional hollow-core shape compared to "traditional" solid round rebars with equivalent cross-sectional areas within the framework of two studies, respectively. To validate the design assumptions following ACI 440.1R design guidelines, two conditions were investigated: under-reinforced (failure controlled by rupture of GFRP rebar); and, over-reinforced (failure controlled by crushing of concrete). For comparison, a cyclic three-point bending load test matrix was developed: for beams, 3 under-reinforced and 3 over-reinforced with hollow-core and solid GFRP rebars, respectively, making a total of 12 RC specimens; for slabs, 3 under-reinforced and 3 over-reinforced with hollow-core and 2 types of solid GFRP rebars, respectively, making a total of 18 RC slabs. The studies on GFRP RC beams and slabs concluded that the hollow-core GFRP rebars were as effective as their solid counterpart and ACI 440.1R design guidelines were applicable to predict their performance. It was shown that final design may be controlled by the permissible deflections as governing parameter for elements under service conditions. Also, a final study with a test matrix containing six extra specimens was generated for post-fire residual strength evaluation of fire-exposed GFRP RC slabs along with temperature gradient in the slabs and dynamic mechanical analysis (DMA) investigation on GFRP samples extracted from the fire-exposed slabs. In this study, the ability of GFRP RC slabs to retain structural integrity during a standards fire exposure as well as determining the residual structural capacity were investigated. The residual strength evaluation of the fire-exposed slabs showed a range of results varying between +/- 10%, of the

  8. Special repairs to the eroded joints of concrete slabs of Stilling Basin-3 and strengthening of splitter pier of Tunnel No. 3, Tarbela Dam Project

    Energy Technology Data Exchange (ETDEWEB)

    Khan, B.A. [WAPDA Tarbela DAM Project (Pakistan)

    1999-07-01

    Repair alternatives to correct erosion damage to the right side of the central longitudinal joint just downstream of the chute of Stilling Basin-3 are discussed. Three alternatives were considered: (1) provide a coffer dam around the plunge pool area and dewater the stilling basin prior to undertaking any repair work; (2) use Tremie concrete , or (3) use Hydrocrete, a regular concrete with some special additives to hold the aggregate, cement and water together in under-water repairs. Because of its erosion resistance in the plastic state, and its self-compacting and leveling properties, the Hydrocrete method was chosen. While repairing the erosion damage, Hilty anchors were also installed in the damaged slab portion, and the splitter pier was also strengthened by inserting mechanical anchors. The entire operation was monitored by a CCTV camera and surface to under-water communication. By choosing this method, the repairs have been completed without dewatering the stilling basin, thus achieving substantial savings. Subsequent under-water inspection by divers and video film proved the repairs to have been fully satisfactory.

  9. Degradation behavior of limestone concrete under limited time sodium exposure

    International Nuclear Information System (INIS)

    Das, S.K.; Sharma, A.K.; Ramesh, S.S.; Parida, F.C.; Kasinathan, N.; Chellapandi, P.

    2009-01-01

    Adequate safety measures are taken during design, fabrication, construction and operation of liquid sodium cooled fast breeder reactor (FBR). However, possibility of sodium leak from secondary heat transport circuits of FBR has not been completely ruled out. In the areas housing sodium pipelines such as Steam Generator Building (SGB), spilled liquid sodium not only reacts with air causing fire but also interacts with structural concrete resulting in its degradation. The structural concrete can be protected from sodium attack using sodium resistant sacrificial concrete layer or steel/refractory liners. Moreover, design and construction of sloping floor with sodium collection pit helps in minimizing the mass of sodium accumulated on the floor and exposure period. Sacrificial concrete layer on the structural concrete should meet key factors like economy, castability, easy removal of affected concrete in the event of a sodium fire and disposability of debris apart from its good resistance against hot burning sodium. Present study is directed towards testing of limestone concrete blocks (made out of 13% ordinary portland cement, 8% water, 48% coarse limestone and 31 % fine limestone aggregates)

  10. Effect of CFRP and TRM Strengthening of RC Slabs on Punching Shear Strength

    Directory of Open Access Journals (Sweden)

    Husain Abbas

    Full Text Available Abstract The paper presents experiments involving punching of RC slabs strengthened using externally bonded carbon fiber reinforced polymer (CFRP sheet and textile reinforced mortar (TRM. Twelve RC slab specimens of two concrete grades (39.9 and 63.2 MPa and employing two strengthening schemes (CFRP and TRM were tested. Specimens were supported on two opposite edges. Experimental load-displacement variations show two peak loads in strengthened slabs and one peak followed by a plateau in control. Second peak or the plateau corresponds to the combined action of aggregate interlock and the dowel action of back face rebars and strengthening layers. The dowel action of back face rebars and strengthening layers had no role in ultimate punching load (i.e. first peak. Strengthened slabs showed 9-18% increase in ultimate punching load (i.e. first peak whereas there was significant increase in the second peak load (190-276% for CFRP; 55-136% for TRM and energy absorption (~66% for CFRP and 22-56% for TRM. An analytical model was also developed for predicting the punching shear strength (first and second peaks of strengthened slabs showing good comparison with experiments.

  11. Emergency destruction of a panel residence building, type series 1-115

    Directory of Open Access Journals (Sweden)

    Malakhova Anna Nikolaevna

    2014-12-01

    Full Text Available The co-authors consider the design solution developed for a panel residence building, type series 1-115, and provide a description of the emergency destruction of structural elements of a 9-storey panel residence building of this type (built in 1979, following a gas explosion. The overall length of the building is 86.4 m; its width is 12 m. The structural system in this building represents a longitudinal wall. Its external longitudinal walls are wade of ceramsite concrete, while its interior walls are made of concrete. Its reinforced concrete hollow slabs rest on the longitudinal load-bearing walls. The transverse walls of staircases are made of concrete blocks. The strip foundation supports the load-bearing walls of the building. The epicenter of the explosion was located in the kitchen on the eighth floor of the building. The kitchen was immediately adjacent to the staircase of the building. Partial destruction of the building followed the gas explosion. Exterior walls of its eighth and ninth floors and the attic were destroyed. Panel buildings designed in pursuance of the longitudinal structural system are more vulnerable to explosive loads compared to buildings designed to the cross-wall structural system, where bearing slabs rest on three interior walls. Thus, all slabs rest on each of the three internal walls of the building on both sides. In the buildings designed to the longitudinal wall structural system, slabs rest on the two walls, one of which is external. The article is based on the report following the inspection of the technical condition of the building, undertaken subsequent to its emergency destruction.

  12. Dramix® Steel fibres in residential foundation slabs in Czech Republic: design approach

    Science.gov (United States)

    Pouillon, S.

    2017-09-01

    Steel fibres are used more and more in structural concrete elements, like residential foundation slabs. The development of high performant steel fibres (e.g. Dramix® 4D and 5D), the evolution in standardization and the demand coming from construction companies and investors are pushing this trend. Engineers are using the yield line method to design steel fibre concrete structures in an easy and economical way, especially if the structure has a regular load layout mainly containing wall loads and point loads. The load configuration, soil characteristics and material characteristics determine the final solution.

  13. Dose rate reduction using epoxy mixed lead shielding: experimental and theoretical determination of its shielding effectiveness

    International Nuclear Information System (INIS)

    Yadav, R.K.B.; Prasad, S.K.; Babu, K.S.; Hardiya, M.R.; Ullas, O.P.

    2010-01-01

    Full text: High background radiation field exists in Water Treatment Area (WTA) of Rod Cutting Building (RCB) in Cirus due to beta, gamma contamination on its floor. The high contamination on sides of wall and on floor is primarily due to deposition of activity generated during the regeneration of old mixed bed cartridges earlier (before year 1985) and presently due to deposition of contaminants by sump overflowing, wastes generated during maintenance/servicing of circulating pumps. RCB-WTA contribution to collective dose in present situation is up to 30% of the total collective dose of Cirus. Various options such as chipping of top layer of concrete floor of a sample area, in-situ placing of slab of cement and lead shot mixture were considered. In this case the man-rem consumption was high as radiation dose rate on concrete chip was 0.4 mGy/h and air activity generated was high, that too long lived with 137 Cs-as main constituent. The dose reduction factor was 1.7. In the second option the reduction in dose rate was insignificant and in-situ pouring of concrete consumed high collective dose. Hence above two options were not acceptable. Therefore the idea of tiling the contaminated floor with prefabricated epoxy mixed lead shots was accepted from ALARA point of view. It was concluded that pre-fabricated slabs of epoxy mixed lead slab of 25 mm thickness can be laid in RCB area to achieve a dose rate reduction factor of approximately five at a height of 30 cm above floor. This will result in a reduction of Person-mSv consumption in RCB by a factor of 5-10. These slabs of different thickness were fabricated outside RCB and were tested for shielding effectiveness experimentally by using radiation source and theoretically using MCNP code. Dose reduction factor of five for a point source, obtained experimentally for epoxy mixed lead shots was very near to value obtained by theoretical simulation. An extended calculation for an area source using this MCNP model gives a

  14. Effect of rubber flooring on dairy cattle stepping behavior and muscle activity.

    Science.gov (United States)

    Rajapaksha, Eranda; Winkler, Christoph; Tucker, Cassandra B

    2015-04-01

    Use of compressible flooring, such as rubber, has increased on dairy farms. Rubber improves locomotion and is well used by cattle in preference experiments that combine walking and standing. Previous work has found that rubber is particularly beneficial for lame animals, perhaps because a softer material is particularly useful when a single hoof is compromised. The goal of this work was to evaluate the effect of flooring while standing, because cattle in freestall housing spend 40 to 50% of their time engaged in this behavior. In a 2 × 2 design, cows (n = 16) were evaluated on 4 standing surfaces that varied in terms of both floor type (concrete or rubber) and presentation [same floor under all 4 legs (all 4 legs on either concrete or rubber) or a rough surface under only one hind leg and the other 3 legs on concrete or rubber] in a crossover design. Surface electromyograms were used to evaluate muscle fatigue, total activity, and movement of muscle activity between legs during 1 h of standing. Muscle fatigue was evaluated in 2 contexts: (1) static contractions when cows continuously transferred weight to each hind leg, before and after 1 h of standing, and (2) dynamic contractions associated with steps during 1 h on treatment surfaces. In addition, stepping rate, time between each consecutive step, and the latency to lie down after testing were measured. No interaction between floor type and presentation was found. Presentation had a significant effect; when one hind leg was on a rough surface, cattle took 1.7 times more steps with this leg and the non-rough hind leg had 1.2 times more muscle activity, compared with when all 4 legs were on the same surface. These changes are consistent with movement away from concrete with protrusions. When standing on rubber, muscle-activity movements among legs remained stable (0.6-0.7 movements per min) over 1 h but increased on concrete (0.6-0.9 movements per min), indicating that, like humans, cattle may sway to counteract

  15. Measures against concrete cracking in underground type light oil tank pit construction work

    International Nuclear Information System (INIS)

    Koike, Takeo; Kadowaki, Kazuhiko; Date, Masanao

    2017-01-01

    The underground type light oil tank pit set at Onagawa Nuclear Power Station is a tripartite underground pit structure made of reinforced concrete. This is a mass concrete made of deck slab / outer wall of 1.5 m in thickness and inner wall / top slab of 1.0 m in thickness. Since concrete placement season was July for the deck slab and October for the walls, the occurrence of thermal cracking was highly conceivable. As a result of investigating crack suppression measures based on the crack width of 0.2 mm or less as a guide, the application of fly ash cement and the addition of expansion material to the walls were judged effective and adopted. Thanks to these preliminary studies and careful construction control, it was possible to minimize the occurrence of cracks, but several through cracks of 0.2 mm or less were confirmed on part of the outer walls. As a countermeasure, repair by means of surface impregnation method was adopted, and quality and schedule could be secured. This paper outlines crack suppression measures and repair of the cracks that occurred after the implementation. (A.O.)

  16. Control of blast overpressure and vibrations at the Underground Research Laboratory

    International Nuclear Information System (INIS)

    Kuzyk, G.W.; Onagi, D.P.; Mohanty, B.

    1991-01-01

    AECL Research (AECL) has constructed an Underground Research Laboratory (URL) as a facility for research and development in the Canadian Nuclear Fuel Waste Management Program. The objectives of the program are to develop and evaluate the technology to ensure safe, permanent disposal of Canada's nuclear fuel waste. Several multidisciplinary experiments and engineering demonstrations are planned for the URL over the next ten years. In 1989, AECL excavated a test room for the Buffer/Container Experiment at the 240 Level. The blasts were designed to limit vibration and overpressure damage because the excavation was located close to existing furnishings and services that were very susceptible to blast-induced vibration and overpressure. An experimental room, which contained sensitive instrumentation, was located within 30 m of the initial blasts. A concrete floor slab, timber curtains and a bulkhead were installed to protect furnishings and services from fly-rock and overpressure. Five of the initial blasts were monitored. This paper describes the results of the monitoring program and the effectiveness of the blast design, floor slab and timber curtains and bulkhead in reducing blast overpressure and vibrations at the blast site. It is shown that greater than a 20-fold reduction in both blast vibrations and air overpressures can be achieved with specific combinations of blast design, installation of timber curtains and construction of a concrete floor slab

  17. Grooved floor system for cattle housing: ammonia emission reduction and good slip resistance

    NARCIS (Netherlands)

    Swierstra, D.; Braam, C.R.; Smits, M.C.J.

    2001-01-01

    To improve the slip resistance of solid floors in dairy cow houses and to achieve the ammonia emission reduction prescribed by the Dutch government, precast concrete floors with grooves and a dung scraper were investigated. The grooves parallel to the alley had 160 mm center-to-center spacing and

  18. Effect of rubber flooring on group-housed sows' gait and claw and skin lesions.

    Science.gov (United States)

    Bos, E-J; van Riet, M M J; Maes, D; Millet, S; Ampe, B; Janssens, G P J; Tuyttens, F A M

    2016-05-01

    This study evaluated the influence of floor type on sow welfare in terms of lameness, claw lesions, and skin lesions. In a 2 × 3 factorial design, we have investigated the effect of rubber coverings on concrete floors and the effect of 3 levels of dietary zinc supplementation on locomotion and claw and skin lesions in group-housed sows. Six groups of 21 ± 4 hybrid sows were monitored during 3 successive reproductive cycles. The sows were group housed from d 28 after insemination (d 0) until 1 wk before expected farrowing date (d 108) in pens with either exposed concrete floors or concrete floors covered with rubber in part of the lying area and the fully slatted area. During each reproductive cycle, locomotion and skin lesions were assessed 4 times (d 28, 50, 108, and 140) and claw lesions were assessed twice (d 50 and 140). Results are given as least squares means ± SE. Locomotion and claw scores were given in millimeters, on analog scales of 150 and 160 mm, respectively. Here, we report on the effect of floor type, which did not interact with dietary zinc concentration ( > 0.10 for all variables). At move to group (d 28) and mid gestation (d 50), no differences between floor treatments were seen in locomotion ( > 0.10). At the end of gestation (d 108), sows housed on rubber flooring scored 9.9 ± 4.1 mm better on gait ( flooring at mid gestation (d 50). However, sows on rubber flooring scored worse for "vertical cracks in the wall horn" (difference of 3.4 ± 1.7 mm; = 0.04). At the end of lactation (d 140), both "white line" (difference of 2.9 ± 1 mm; = 0.02) and "claw length" (difference of 4.7 ± 1.4 mm; flooring. No differences for skin lesions were observed between floor treatments. The improved scores for gait toward the end of gestation and some types of claw disorders at mid gestation suggest that rubber flooring in group housing has a beneficial effect on the overall leg health of sows. The documented increase in vertical cracks in the wall horn at d

  19. Medición de microdeformaciones en losas viales usando sensores de redes de Braggen fibras ópticas Microdeformation measurement of concrete roadway slabs using fiber Bragg gratings

    Directory of Open Access Journals (Sweden)

    Francisco Javier Vélez Hoyos

    2010-06-01

    Full Text Available En este trabajo se presenta un método no invasivo para la medición de microdeformaciones en estructuras de concreto usando sensores de redes de Bragg en fibras ópticas adheridos a su superficie. Se realizan mediciones en losas viales de concreto bajo una carga estática de 10 kN, encontrándose una relación aproximada de 2 : 1 entre la deformación registrada por los sensores y los valores arrojados por una simulación computacional con el método de elementos finitos. Se propone el uso de estos sensores para el monitoreo estructural de losas en una malla vial con sensores distribuidos y multiplexados por longitud de onda. Este es el primer reporte en Colombia de medición de deformación de losas viales usando sensores de fibra óptica.This work shows a non–invasive method for micro–deformation measurements of concrete structures using Bragg grating sensors in optical fibers adhered to the surface. Measurements on roadway slabs under a 10 kN static load are made, finding an approximated ratio of 2 : 1 between the deformation registered by the sensors and the values from a computational simulation with the finite element method. We propose the use of these sensors for slab structural monitoring in a road network employing distributed and wavelength multiplexed sensors. This is a first report in Colombia of roadway slabs microdeformation measurement using fiber optic sensors.

  20. Nuclear reactor control room construction

    International Nuclear Information System (INIS)

    Lamuro, R.C.; Orr, R.

    1993-01-01

    A control room for a nuclear plant is disclosed. In the control room, objects labelled 12, 20, 22, 26, 30 in the drawing are no less than four inches from walls labelled 10.2. A ceiling contains cooling fins that extend downwards toward the floor from metal plates. A concrete slab is poured over the plates. Studs are welded to the plates and are encased in the concrete. 6 figures

  1. Sodium-concrete reactions experiments and code development

    International Nuclear Information System (INIS)

    Casselman, C.; Malet, J.C.; Dufresne, J.; Bolvin, M.

    1988-01-01

    Hypothesis of hot sodium leak in a fast breeder reactor implies, for the safety organism to consider spillage of sodium on concrete. This safety analysis involves the understanding of sodium-concrete reactions, the knowledge of their consequences and to test the choiced preventive solutions. In association with EDF, the nuclear safety department had carried out an extensive experimental program, the different parts of which are connected with each aspect of this problem: - firstly, interaction between sodium and bare surface of usual concrete; - secondly, the case of a sodium spillage on a concrete surface covered with a defected liner; - thirdly, special concrete tests for a comparison with usual concrete behavior, in direct contact with hot sodium; - at last, a test which concerns a new design with a layer of the selected concrete protected with a defected liner. On the same time, theoretical work leads to elaborate a physical model to describe temporal evolution of thermal and chemical decomposition of a concrete slab under hot sodium action. SORBET-REBUS system will use quoted above test results to its validation

  2. Improved lumped models for transient combined convective and radiative cooling of multi-layer composite slabs

    International Nuclear Information System (INIS)

    An Chen; Su Jian

    2011-01-01

    Improved lumped parameter models were developed for the transient heat conduction in multi-layer composite slabs subjected to combined convective and radiative cooling. The improved lumped models were obtained through two-point Hermite approximations for integrals. Transient combined convective and radiative cooling of three-layer composite slabs was analyzed to illustrate the applicability of the proposed lumped models, with respect to different values of the Biot numbers, the radiation-conduction parameter, the dimensionless thermal contact resistances, the dimensionless thickness, and the dimensionless thermal conductivity. It was shown by comparison with numerical solution of the original distributed parameter model that the higher order lumped model (H 1,1 /H 0,0 approximation) yielded significant improvement of average temperature prediction over the classical lumped model. In addition, the higher order (H 1,1 /H 0,0 ) model was applied to analyze the transient heat conduction problem of steel-concrete-steel sandwich plates. - Highlights: → Improved lumped models for convective-radiative cooling of multi-layer slabs were developed. → Two-point Hermite approximations for integrals were employed. → Significant improvement over classical lumped model was achieved. → The model can be applied to high Biot number and high radiation-conduction parameter. → Transient heat conduction in steel-concrete-steel sandwich pipes was analyzed as an example.

  3. Electrokinetic decontamination of concrete

    International Nuclear Information System (INIS)

    Lomasney, H.L.; SenGupta, A.K.; Yachmenev, V.

    1996-01-01

    ELECTROSORB Electrokinetic Extraction Technology, developed by ISOTRON Corp., offers a cost-effective approach to treating contaminated concrete. Heavy metals/radionuclides trapped in concrete can be extracted using this process if they are chemically solubilized; solubilizers used are citric acid alone and a mixture of citric and nitric acids. A DC electric field is applied across the contaminated concrete to electrokinetically transport the solubilized contaminants from the concrete pores to a collector on the concrete surface. The collector is an extraction pad laid on the surface. The pad provides confinement for a planar electrode and solubilizer solution; it is operated under a vacuum to hold the pad against the concrete surface. Operation requires little attendance, reducing the workers' health hazards. The process incorporates a mechanism for recycling the solubilizer solution. A field demonstration of the process took place in Building 21 of DOE's Mound facility in Miamisburg, OH, over 12 days in June 1996. The thorium species present in this building's concrete floors included ThO 2 and thorium oxalate. The nitric acid was found to facilitate Th extraction

  4. Concrete deterioration: detection by ultrasonic pulse velocity method

    International Nuclear Information System (INIS)

    Sutan, N.M.; Jaafar, M.S.; Hamdan, S.

    2003-01-01

    Tests were performed to evaluate the feasibility of using Ultrasonic Pulse Velocity Method (UPVM) in detecting defect and determining its depth during the early age concrete. Five reinforced concrete (RC) slabs of grade 30, 40 and 50 specimens at day 3, 7,14 and 28 with a fabricated void at a known location were used. The results obtained were compared to determine the accuracy of the method hence the effectiveness of the method with different strength and as the concrete matures. This method detects defects in specimens during the early age The accuracy varies with concrete strength and as the concrete mature. The test results indicate the method can be used to assess the in-situ properties of concrete or for quality control on site. The method showed better accuracy with stronger concrete detects defects with the accuracy ranging from 55.75-99.62% from day 3-28 (full strength) respectively. (author)

  5. Probabilistic Fatigue Model for Reinforced Concrete Onshore Wind Turbine Foundations

    DEFF Research Database (Denmark)

    Marquez-Dominguez, Sergio; Sørensen, John Dalsgaard

    2013-01-01

    Reinforced Concrete Slab Foundation (RCSF) is the most common onshore wind turbine foundation type installed by the wind industry around the world. Fatigue cracks in a RCSF are an important issue to be considered by the designers. Causes and consequences of the cracks due to fatigue damage in RCSFs...... are discussed in this paper. A probabilistic fatigue model for a RCSF is established which makes a rational treatment of the uncertainties involved in the complex interaction between fatigue cyclic loads and reinforced concrete. Design and limit state equations are established considering concrete shear...

  6. Two innovative solutions based on fibre concrete blocks designed for building substructure

    Science.gov (United States)

    Pazderka, J.; Hájek, P.

    2017-09-01

    Using of fibers in a high-strength concrete allows reduction of the dimensions of small precast concrete elements, which opens up new ways of solution for traditional construction details in buildings. The paper presents two innovative technical solutions for building substructure: The special shaped plinth block from fibre concrete and the fibre concrete elements for new technical solution of ventilated floor. The main advantages of plinth block from fibre concrete blocks (compared with standard plinth solutions) is: easier and faster assembly, higher durability and thanks to the air cavity between the vertical part of the block, the building substructure reduced moisture level of structures under the waterproofing layer and a comprehensive solution to the final surface of building plinth as well as the surface of adjacent terrain. The ventilated floor based on fibre concrete precast blocks is an attractive structural alternative for tackling the problem of increased moisture in masonry in older buildings, lacking a functional waterproof layer in the substructure.

  7. Numerical investigation of the bearing capacity of transversely prestressed concrete deck slabs

    NARCIS (Netherlands)

    Amir, S.; Van der Veen, C.; Walraven, J.C.; De Boer, A.

    2014-01-01

    The research subject of this paper is the bearing capacity of transversely prestressed concrete bridge decks between concrete girders under concentrated loads. Experiments on a 1:2 scale model of this bridge were carried out in the laboratory and a 3D nonlinear finite element model was developed in

  8. Aplicación del método de la madurez para la estimación del plazo de descimbrado de forjados construidos con sistemas industrializados

    Directory of Open Access Journals (Sweden)

    Castro-Garrido, M. C.

    2016-03-01

    Full Text Available This article proposes a methodology for estimating the striking time for reinforced concrete slab floors build with industrial systems. For this, a study of maturity of concrete used in such construction is performed. To make the maturity curve in the laboratory, the methodology described in ASTM C1074 is implemented by calculating the activation energy for the three proposed methods and measuring the thermal history of the concrete at a controlled temperature. Finally, a reinforced concrete slab floor is monitored and the striking time is estimated. It has been observed that the final setting time is not recommended for striking slabs floors, as recommended by the manufacturers of concrete in Colombia. Striking time obtained is higher than the final setting time, having a difference of up to 11 hours at the most critical case.El presente artículo propone una metodología para la estimación del plazo de descimbrado de forjados construidos con sistemas industrializados. Para esto, se realiza un estudio de madurez de hormigones usados en este tipo de construcción. Con el fin de construir la curva de madurez en laboratorio se implementa la metodología descrita en la ASTM C1074, calculando la energía de activación por los tres métodos propuestos y midiendo el historial térmico de las mezclas a una temperatura controlada. Por último, se realiza la instrumentación en obra de una placa donde se estima la edad de descimbrado. Se ha observado que el tiempo de fraguado final no es un parámetro recomendable para descimbrar las placas, como lo recomiendan las productoras de hormigón en Colombia. La edad de descimbrado obtenida es mayor a la del tiempo de fraguado final, habiendo una diferencia de hasta 11 horas en el caso más crítico.

  9. Determination of chlorpropham (CIPC) residues, in the concrete flooring of potato stores, using quantitative (HPLC UV/VIS) and qualitative (GCMS) methods.

    Science.gov (United States)

    Douglas, Leisa; MacKinnon, Gillian; Cook, Gordon; Duncan, Harry; Briddon, Adrian; Seamark, Steven

    2018-03-01

    Isopropyl-N-(3-chlorophenyl) carbamate (CIPC, common name Chlorpropham) is commonly used for post-harvest sprout inhibition in stored potatoes. It is applied as a thermal fog which results in loss to the fabric of the store and the atmosphere. Recently, there have been concerns in the United Kingdom because of cross contamination of other crop commodities that were stored in buildings with a history of CIPC usage. This cross contamination may have occurred because of retained residues in the fabric of the stores. The retention of CIPC in concrete is poorly understood; therefore the requirement for a robust analytical method for the detection and quantification of CIPC in concrete is a critical first step in tackling this problem. A method using High-Performance Liquid Chromatography with ultraviolet detection (HPLC UV/VIS) was validated. CIPC recoveries at three concentration levels (0.4, 4.0 and 40.0 μg g -1 ) were in the range of 90.7-97.0% with relative standard deviations between 2.14 and 3.01%. The limits of detection and quantification were 0.03 and 0.1 μg g -1 , respectively. This study confirmed that CIPC was persistent in concrete to a depth of 4 cm, with >90% within the top 1 cm of the flooring. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Soft projectile impacts on thin reinforced concrete slabs: tests, modelling and simulations

    International Nuclear Information System (INIS)

    Pontiroli, C.; Rouquand, A.

    2011-01-01

    Numerical simulations of reinforced concrete structures subjected to high velocity impacts and explosions remain a difficult task today. Since ten years and more now, the CEA-Gramat has maintained a continuous research effort with the help of different French universities in order to overcome encountered difficulties in modelling the behaviour of concrete structures under severe loading. These difficulties are related to numerical aspects (convergence difficulties of the non linear stress strain relation in 3D configuration, efficiency of the numerical procedure and robustness), but also due to the ability of the material model to simulate the accurately behaviour of a very complex and heterogeneous material like concrete. A new concrete model, named PRM model, has been developed at CEA-Gramat (Pontiroli, Rouquand and Mazars) to predict the concrete response under a large range of dynamic loadings. Works presented in this paper have been performed in the framework of the French VULCAIN PGCU 2007 research project (founded by the French National Research Agency). This project aims at defining a theoretical and probabilistic methodology in order to assess the structural safety of industrial structures that might be submitted to transient loadings such as blasts or impacts generated by various projectiles. A complementary objective is to improve diagnosis, prevention or protection actions. This scientific program gathers well-known and complementary scientific institutes, firms and universities in France. (authors)

  11. United States Air Force Research on Airfield Pavement Repairs Using Precast Portland Cement Concrete (PCC) Slabs (BRIEFING SLIDES)

    National Research Council Canada - National Science Library

    Saeed, Athar

    2008-01-01

    ...) slab repairs using precast PCC slab panels. AFRL is leading the technology development by critically reviewing the research conducted to date in this arena by the Air Force and the highway and civil aviation agencies and adopting...

  12. Design of the First Italian Roundabout with Jointed Plain Concrete Pavement

    Directory of Open Access Journals (Sweden)

    Paola Di Mascio

    2018-02-01

    Full Text Available This work presents the results of the overall design of the first Italian roundabout with jointed plain concrete pavement. The examined case study complies with current international standards and practices for geometry of roundabouts and road pavements. The construction of a concrete pavement in an urban roundabout will better manage and slow down fast vehicular flows, and increase traffic fluidity in an important junction, trafficked by heavy vehicles, where maintenance works should be reduced to avoid queues. The design of the roundabout involved several competences for: defining the geometry of the four-arm junction, designing the thickness of the jointed plain concrete pavement both on the circular crown and the arms, studying the mix design of a high resistance concrete. As regard to the pavement, the result of the study was an un-dowelled concrete pavement composed of square slabs laid on a cement concrete subbase and a granular layer. The shape of the slabs has been designed to optimize the structural performance of their material, which is a high strength concrete mix derived from an extensive laboratory test work. In general, the results summarized approaches typical of different design conditions: urban ones for traffic flow and safety needs; high-traffic ones for the chosen pavement type; airport ones for the absence of dowel and tie bars at the joints. Indeed, the article has highlighted that the design process of a concrete roundabout requires multiple analyses to consider various features and correctly re-design an existing urban junction. Its geometrical design, the structural design of the concrete pavement and the theoretical and experimental design of the concrete mix were the main phases of this process and they needed different competences to conduct comprehensive and appropriate analyses.

  13. Studies on irradiation resisting paints for concrete structures in nuclear power plant, 4

    International Nuclear Information System (INIS)

    Kita, Daizo; Sumino, Masahiro; Goto, Tomoaki.

    1978-01-01

    It is necessary for irradiation resisting paints to adhere tightly to concrete in order to exhibit superior effects. Adhesion of paints to concrete is greatly affected by moisture content and the form of moisture in concrete. Further, adhesion will probably be affected by differences in concrete surface conditions between floors, walls and ceilings. Therefore, experiments were conducted with concrete to make clear allowable moisture conditions and the influence of these concrete surfaces. The following results were obtained. (1) Adhesion of paint becomes stronger as pF-value increases, that is, as moisture content falls. (2) The allowable pF-values and moisture contents were respectively 5.5 over and 4.5% under at floor, 4.4 over and 4.9% under at wall, and 4.3 over and 5% under at ceiling. (3) Fractures of paint films under these allowable conditions occurred in paint-concrete composites, and the fractured concrete thickness than was 0.5-0.8 mm and measured adhesion strength was 33 kg/cm 2 . (auth.)

  14. Neutron shielding properties of a new high-density concrete

    International Nuclear Information System (INIS)

    Lorente, A.; Gallego, E.; Vega Carrillo, H.R.; Mendez, R.

    2008-01-01

    The neutron shielding properties of a new high-density concrete (commercially available under the name Hormirad TM , developed in Spain by the company CT-RAD) have been characterized both experimentally and by Monte Carlo calculations. The shielding properties of this concrete against photons were previously studied and the material is being used to build bunkers, mazes and doors in medical accelerator facilities with good overall results. In this work, the objective was to characterize the material behaviour against neutrons, as well as to test alternative mixings including boron compounds in an effort to improve neutron shielding efficiency. With that purpose, Hormirad TM slabs of different thicknesses were exposed to an 241 Am-Be neutron source under controlled conditions in the neutron measurements laboratory of the Nuclear Engineering Department at UPM. The original mix, which includes a high fraction of magnetite, was then modified by adding different proportions of anhydrous borax (Na 2 B 4 O 7 ). In order to have a reference against common concrete used to shield medical accelerator facilities, the same experiment was repeated with ordinary (HA-25) concrete slabs. In parallel to the experiments, Monte Carlo calculations of the experiments were performed with MCNP5. The experimental results agree reasonably well with the Monte Carlo calculations. Therefore, the first and equilibrium tenth-value layers have been determined for the different types of concrete tested. The results show an advantageous behaviour of the Hormirad TM concrete, in terms of neutron attenuation against real thickness of the shielding. Borated concretes seem less practical since they did not show better neutron attenuation with respect to real thickness and their structural properties are worse. The neutron attenuation properties of Hormirad TM for typical neutron spectra in clinical LINAC accelerators rooms have been also characterized by Monte Carlo calculation. (author)

  15. Common floor system vertical earthquake-proof structure for reactor equipment

    International Nuclear Information System (INIS)

    Morishita, Masaki.

    1996-01-01

    In an LMFBR type reactor, a reactor container, a recycling pump and a heat exchanger are disposed on a common floor. Vertical earthquake-proof devices which can be stretched only in vertical direction formed by laminating large-sized bellevilles are disposed on a concrete wall at the circumference of each of reactor equipments. A common floor is placed on all of the vertical earthquake-proof devices to support the entire earthquake-proof structure simultaneously. If each of reactor equipments is loaded on the common floor and the common floor is entirely supported against earthquakes altogether, since the movement of each of the reactor equipments loaded on the common floor is identical, relative dislocation is not exerted on the main pipelines which connect the equipments. In addition, since the entire earthquake structure has a flat common floor and each of the reactor equipments is suspended to minimize the distance between a gravitational center and a support point, locking vibration is less caused to the horizontal earthquake. (N.H.)

  16. 20 CFR 654.409 - Heating.

    Science.gov (United States)

    2010-04-01

    ...) When a heating system has automatic controls, the controls shall be of the type which cut off the fuel... EMPLOYMENT SERVICE SYSTEM Housing for Agricultural Workers Housing Standards § 654.409 Heating. (a) All... concrete slab, insulated metal sheet, or other fireproof material on the floor under each stove, extending...

  17. Concretization of high level radioactive source in marine sediment

    International Nuclear Information System (INIS)

    Weiss, H.V.

    1987-01-01

    A method is described of forming a concretized coating which encapsulates a canister of heat producing materials and provides protection against corrosion by seawater when the canister is placed in an ocean floor-sediment environment. The method comprises: selecting a location on the ocean floor at such a depth that the proximate seawater thereat would be capable of reaching a temperature of at least 110 0 C. when in contact with the canister of heat producing materials. The seawater within the pores of the ocean floor sediment thereat contains sufficient amounts of calcium and sulfate to form, at the temperature, an anhydrite layer around the canister; placing the canister into the ocean floor sediment at the location; and storing the canister at the location for at least one month thereby allowing heat from the canister to raise the temperature of the seawater in the pores of the sediment proximate to the canister to at least 110 0 C. wherein anhydrite precipitates from the proximate seawater and forms a concretized layer on the exterior surfaces of the canister

  18. Numerical forensic model for the diagnosis of a full-scale RC floor

    Directory of Open Access Journals (Sweden)

    Ahmed B. Shuraim

    Full Text Available The paper presents the results of an investigation on the diagnosis and assessment of a full-scale reinforced concrete floor utilizing a 3-D forensic model developed in the framework of plasticity-damage approach. Despite the advancement in nonlinear finite element formulations and models, there is a need to verify models on nontrivial challenging structures. Various standards on strengthening existing structures consider numerical diagnosis as a major stage involving safety and economical aspects. Accordingly, model validity is a major issue that should preferably be examined against realistic large-scale tests. This was done in this study by investigating a one-story joist floor with wide shallow beams supported on columns. The surveyed cracking patterns on the entire top side of the floor were reproduced by the forensic model to a reasonable degree in terms of orientation and general location. Concrete principal plastic tensile strain was shown to be a good indirect indicator of cracking patterns. However, identifying the underlying reasons of major cracks in the floor required correlating with other key field parameters including deflections, and internal moments. Therefore, the ability of the forensic model to reproduce the surveyed damage state of the floor provided a positive indication on the material models, spatial representation, and parameter selection. Such models can be used as forensic tools for assessing the existing conditions as required by various standards and codes.

  19. Effect of different flooring systems on claw conformation of dairy cows.

    Science.gov (United States)

    Telezhenko, E; Bergsten, C; Magnusson, M; Nilsson, C

    2009-06-01

    The effect of different flooring surfaces in walking and standing areas on claw conformation, claw horn growth, and wear was studied in 2 experiments during 2 consecutive housing seasons in a research dairy herd of 170 cows. In experiment 1, the flooring systems tested were solid rubber mats, mastic asphalt with and without rubber-matted feed-stalls, and aged concrete slats. In experiment 2, slatted concrete flooring was compared with slatted rubber flooring. The cows were introduced to the respective flooring systems in early lactation and their claws were trimmed before the exposure period. Toe length, toe angle, sole concavity, and claw width, as well as claw growth and wear rates were recorded for lateral and medial claws of the left hind limb. Claw asymmetry calculations were based on these claw measurements and on differences in sole protrusion between lateral and medial soles. Asphalt floors caused shorter toe length and steeper toe angle. They also increased wear on rear claws (5.30 +/- 0.31 and 5.95 +/- 0.33 mm/mo for lateral and medial claw, respectively; LSM +/- SE) and horn growth rate (5.12 +/- 0.36 and 5.83 +/- 0.31 mm/mo of lateral and medial claws, respectively). Rubber mats instead of asphalt in walking areas reduced wear (1.36 +/- 0.19 and 2.02 +/- 0.20 mm/mo for lateral and medial claw, respectively) and claw growth (3.83 +/- 0.23 and 3.94 +/- 0.17 mm/mo for lateral and medial claw, respectively). Rubber-matted feed-stalls together with asphalt walkways decreased claw wear (3.29 +/- 0.31 and 4.10 +/- 0.32 mm/mo for lateral and medial claw, respectively). The concavity of claw soles was reduced on asphalt, especially in the lateral rear claws. Rubber matting in feed-stalls prevented loss of sole concavity compared with asphalt. Claw asymmetry did not differ between flooring systems. While different access to abrasive flooring affected claw conformation, there was no evidence that flooring system influenced the disproportion between lateral and

  20. Convective Concrete: additive manufacturing to facilitate activation of thermal mass

    Directory of Open Access Journals (Sweden)

    Dennis de Witte

    2017-12-01

    Full Text Available Convective Concrete is about a research-driven design process of an innovative thermal mass concept. The goal is to improve building energy efficiency and comfort levels by addressing some of the shortcomings of conventional building slabs with high thermal storage capacity. Such heavyweight constructions tend to have a slow response time and do not make use of the available thermal mass effectively. Convective Concrete explores new ways of using thermal mass in buildings more intelligently. To accomplish this ondemand charging of thermal mass, a network of ducts and fans is embedded in the concrete wall element. This is done by developing customized formwork elements in combination with advanced concrete mixtures. To achieve an efficient airflow rate, the embedded lost formwork and the concrete itself function like a lung.

  1. Influence of alkali-silica reaction on the physical, mechanical, and structural behaviour of reinforced concrete

    DEFF Research Database (Denmark)

    Barbosa, Ricardo Antonio

    Alkali-silica reaction (ASR) is one of the major concrete deterioration mechanisms in the world. Cracking in concrete structures due to ASR has been observed worldwide. In Denmark numerous concrete structures have been built with a critical amount of ASR-reactive aggregate, mostly as porous opaline...... and porous calcareous opaline flint in the fine aggregate fraction. During the last few decades, an increasing number of bridges in Denmark have been severely damaged due to ASR. In the most severe cases, the ASR-damaged bridges have been demolished and reconstructed due to uncertainty about their residual...... following features in common: (a) significant amount of ASR cracks were observed on and inside the slabs, (b) the ASR cracks were oriented parallel to the plane of the slabs, and (c) ASR occurred in the fine aggregate fraction. In this PhD study, both the compressive strength and tensile strength of drilled...

  2. Conductive concrete wins Popular Science prize

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1997-06-01

    A conductive concrete developed by a research team at IRC (Institute for Research in Construction, National Research Council of Canada) has won a prize in the home technology category because of its possible use in heating homes. Following the award, there have been a number of inquiries regarding possible applications for the concrete. Greatest interests in the concrete have been in its potential to heat buildings by using it as flooring. Other possible applications included de-icing pavements to building warming pads for parking aircraft. Essentially, carbon fibres and conductive particles are added to a concrete mix in such a quantity that they form a network within the mix, ensuring high electrical conductivity. A demonstration project is underway to build a 20 by 80 foot conductive concrete pad to test the material`s capability as a snow removal and de-icing tool.

  3. Convective Concrete : Additive Manufacturing to facilitate activation of thermal mass

    NARCIS (Netherlands)

    de Witte, D.; de Klijn-Chevalerias, M.L.; Loonen, R.C.G.M.; Hensen, JLM; Knaack, U.; Zimmermann, G

    2017-01-01

    This paper reports on the research-driven design process of an innovative thermal mass concept: Convective Concrete. The goal is to improve building energy efficiency and comfort levels by addressing some of the shortcomings of conventional building slabs with high thermal storage capacity. Such

  4. A Review of Soft Techniques for Electromagnetic Assessment of Concrete Condition

    Directory of Open Access Journals (Sweden)

    F. A. A. Queiroz

    2012-01-01

    makes the solution process computationally prohibitive for large problems. The inverse problem is solved by an alternative approach which uses model-free methods based on example data. Measurements with GPR equipment were performed to validate the algorithms using concrete slabs.

  5. Reduced labor and condensed schedules with cellular concrete solutions

    Energy Technology Data Exchange (ETDEWEB)

    Lavis, D. [CEMATRIX Inc., Calgary, AB (Canada)

    2008-07-01

    This paper discussed the use of cellular concrete materials in oil sands tank base foundation systems, shallow buried utility insulation systems, roadways, slabs, and buried modules. The concrete is formed from Portland cement, water, specialized pre-formed foaming agents, and air mixed in controlled proportions. Fly ash and polypropylene or glass fibers can also be used as additions. Cellular concrete can often be used to speed up construction and minimize labour requirements. Cellular concrete can be cast-in-place, and has soil-stabilizing and self-compacting features. The concrete can be produced and placed on-site at rates exceeding 120 cubic meters per hour. Cellular concrete can be pumped into place over long distances through flexible hoses. A case study comparing the cellular concrete to traditional plastic foam insulation was used to demonstrate the equivalency and adequacy of insulation, structural properties and installation costs. The study showed that although the cellular concrete had a high installation cost, greater compressive strength was gained. The concrete was self-levelling and did not require compaction or vibration. The use of the cellular concrete resulted in an accelerated construction schedule. 6 refs., 2 tabs., 6 figs.

  6. Claw disorders and disturbed locomotion in dairy cows: the effect of floor systems and implications for animal welfare

    NARCIS (Netherlands)

    Somers, Joan Gerardus Cornelius Johanna

    2004-01-01

    In modern dairy housing, flooring conditions lead to restricted locomotion and claw disorders. Epidemiological studies showed that housing on concrete floors was positively correlated with the incidence of lameness and claw disorders. Lameness and claw disorders constitute a significant health and

  7. Tests and analyses of 1/4-scale upgraded nine-bay reinforced concrete basement models

    International Nuclear Information System (INIS)

    Woodson, S.C.

    1983-01-01

    Two nine-bay prototype structures, a flat plate and two-way slab with beams, were designed in accordance with the 1977 ACI code. A 1/4-scale model of each prototype was constructed, upgraded with timber posts, and statically tested. The development of the timber posts placement scheme was based upon yield-line analyses, punching shear evaluation, and moment-thrust interaction diagrams of the concrete slab sections. The flat plate model and the slab with beams model withstood approximate overpressures of 80 and 40 psi, respectively, indicating that required hardness may be achieved through simple upgrading techniques

  8. Study and constructive analysis of an office building

    OpenAIRE

    CORT AZCÁRRAGA, PAULA

    2015-01-01

    [EN] The development is based on the study and analysis of an office building located in Drongsesteenweg, Gent 9000. The building has 4 levels and basement. The structure is with prefabricated concrete, a very typical way to build in Belgium, only the basement was built in situ. Typology floor is hollow core slab, it is a prefabricated unidirectional floor. Stairs are prefabricated too, executed by a company specialized in this type works. To the facade they use two types of bricks, ceramic a...

  9. Investigation of Concrete Floor Vibration Using Heel-Drop Test

    Science.gov (United States)

    Azaman, N. A. Mohd; Ghafar, N. H. Abd; Azhar, A. F.; Fauzi, A. A.; Ismail, H. A.; Syed Idrus, S. S.; Mokhjar, S. S.; Hamid, F. F. Abd

    2018-04-01

    In recent years, there is an increased in floor vibration problems of structures like residential and commercial building. Vibration is defined as a serviceability issue related to the comfort of the occupant or damage equipment. Human activities are the main source of vibration in the building and it could affect the human comfort and annoyance of residents in the building when the vibration exceed the recommend level. A new building, Madrasah Tahfiz located at Yong Peng have vibration problem when load subjected on the first floor of the building. However, the limitation of vibration occurs on building is unknown. Therefore, testing is needed to determine the vibration behaviour (frequency, damping ratio and mode shape) of the building. Heel-drop with pace 2Hz was used in field measurement to obtain the vibration response. Since, the heel-drop test results would vary in light of person performance, test are carried out three time to reduce uncertainty. Natural frequency from Frequency Response Function analysis (FRF) is 17.4Hz, 16.8, 17.4Hz respectively for each test.

  10. Studying of Compressive, Tensile and Flexural Strength of Concrete by Using Steel Fibers

    Directory of Open Access Journals (Sweden)

    Muslim Abdul-Ameer

    2016-12-01

    Full Text Available This research aims to study the effect of adding steel fibers on the mechanical properties of concrete. Steel fiber has a very significant effect on concrete because it delays the propagation of micro cracks that generate due to loading on concrete members such as beams and slabs, therefore ,it increases the strength of concrete. The steel fiber was used in this study as a percentage of the volume of concrete. Mix proportion was 1: 2:4 (cement: sand: gravel by volume for all mixes and using 0% as (control mix,0.1 %,0.2%,0.5 % and 1.0% of steel fibers, these ratios leads to increase the compressive, tensile ,and flexural strength of concrete, where the improvement in flexural strength was significant

  11. Assessing the most suitable floor system for growing-finishing piggery under tropical conditions using the analytic hierarchy process

    Directory of Open Access Journals (Sweden)

    Fabiana Ribeiro Caldara

    2014-03-01

    Full Text Available Studies were carried out worldwide for evaluating different types of floor systems for growing-finishing pigs, specifically for assessing their effectiveness on pig performance, health and behaviour, leaving the opportunity for using multi-criteria analysis in decisionmaking towards the selection of flooring type. This study aimed to select the most suitable floor system for growing-finishing pigs under tropical conditions, considering performance traits and farmers management aspects. The analytic hierarchy process was applied for seeking the best solution considering both the farmers’ goals and the pigs’ welfare. Aspects considered in the analysis were: economic feasibility, rearing thermal and aerial ambient, animal behaviour, performance, and health status. The input used in the calculation was based on the results of a field trial using three treatments: whole concrete floor, coffee and rice husk bedding, and wood shavings deepbedding. Rearing conditions and pigs’ physiological parameters, performance, behaviour, and health status were analysed. When the floor system was considered, the most significant criteria were economic feasibility (0.31 and overall pig performance (0.31 leading to a final deep-bedding selection ranking of coffee and rice husks (1st, concrete floor (2nd, and wood shavings (3rd. Conversely, when the animal welfare was considered, the most decisive criterion was health status (0.32, followed by physiological parameters (0.25, and behaviour (0.23 leading to a final bedding selection ranking of coffee and rice husks (1st, wood shavings (2nd, and concrete floor (3rd. Results indicate that the deep-bedding of coffee and rice husks provided the best choice for both the farmer and the growing-finishing pigs.

  12. Elasto-viscoplastic finite element model for prestressed concrete structures

    International Nuclear Information System (INIS)

    Prates Junior, N.P.; Silva, C.S.B.; Campos Filho, A.; Gastal, F.P.S.L.

    1995-01-01

    This paper presents a computational model, based on the finite element method, for the study of reinforced and prestressed concrete structures under plane stress states. It comprehends short and long-term loading situations, where creep and shrinkage in concrete and steel relaxation are considered. Elasto-viscoplastic constitutive models are used to describe the behavior of the materials. The model includes prestressing and no prestressing reinforcement, on situation with pre- and post-tension with and without bond. A set of prestressed concrete slab elements were tested under instantaneous and long-term loading. The experimental data for deflections, deformations and ultimate strength are used to compare and validate the results obtained through the proposed model. (author). 11 refs., 5 figs

  13. Design, analysis and construction of the prestressed concrete containment of the nuclear power station Gundremmingen

    International Nuclear Information System (INIS)

    Mueller, W.F.; Ick, U.

    1977-01-01

    Kraftwerk Union AG is presently constructing at Gundremmingen (Bavaria) on the River Danube a BWR twin-plant (KRB Units B and C) with a capacity of 2x1300 MWe. Owing to the wall thickness/diameter ratio the containment can be calculated as a thin-walled shell. Areas of discontinuity are subjected to three-dimensional investigations. For the design of the concrete structure different fracture safety margins are defined for the load conditions occurring in operation in the event of a loss-of-coolant accident and as a result of an aircraft or an earthquake. From this results that in the cross sectional areas without discontinuities of the prestressed outer cylinder no resultant tensions occur. For the steel liner different limits of strain are permitted for the various load conditions, bearing in mind that the integrity of the liner must remain ensured at any time. In order to keep the stresses resulting from the constraint of the containment outer cylinder in the foundation slab low, the cylindrical wall is placed on bearings. The suppression pool top slab is constrained at the containment outer cylinder and at the containment inner cylindrical wall. The inlets of the vent pipes are integrated in the slab in a way resulting in a double slab. The liner consists of 8 mm thick steel plate and is anchored in the concrete via steel sections. Mechanical equipment anchoring in the concrete is provided by welding anchor plates into the liner after the section concerned has been completed. The carcass work on the reactor building is scheduled to be completed within

  14. Virtual reality presentation for nondestructive evaluation of rebar corrosion in concrete based on IBEM

    International Nuclear Information System (INIS)

    Kyung, Je Woon; Leelarkiet, V.; Ohtsu, Masayasu; Yokata, Masaru

    2004-01-01

    In order to evaluate the corrosion of reinforcing steel-bars (rebar) in concrete, a nondestructive evaluation by the half-cell potential method is currently applied. In this study, potentials measured on a concrete surface are compensated into those on the concrete-rebar interface by the inverse boundary element method (IBEM). Because these potentials are obtained three-dimensionally (3-D), 3-D visualization is desirable. To this end, a visualization system has been developed by using VRML (Virtual Reality Modeling Language). As an application, results of a reinforced concrete (RC) slab with corroded rebars are visualized and discussed.

  15. Damaged Concrete Viaduct in an Italian Highway: Concrete Characterization and Possible Strengthening Techniques by FRP Applications in Comparison

    Science.gov (United States)

    Tittarelli, Francesca; Ruello, Maria Letizia; Capuani, Domenico; Aprile, Alessandra

    2017-10-01

    The “Fornello” viaduct in the Italian Orte-Ravenna highway (E45) is seriously damaged. In this paper, the concrete of the reinforced slab has been widely characterized to evaluate the level of damage and to identify the causes of degradation. No-destructive tests, as those based on ultrasonic waves, as well as chemical, physical and mechanical destructive tests have been carried out on specimens drawn from deteriorated and not deteriorated zones of the R/C bridge decks. Into the slab thickness, the concentration distribution of main anions has been quantified by ion chromatography. Porosimetry tests have been carried out to detect the resistance to freeze-thaw cycles of cement paste. Possible strengthening techniques by FRP applications have been compared.

  16. Precast concrete unit assessment through GPR survey and FDTD modelling

    Science.gov (United States)

    Campo, Davide

    2017-04-01

    Precast concrete elements are widely used within United Kingdom house building offering ease in assembly and added values as structural integrity, sound and thermal insulation; most common concrete components include walls, beams, floors, panels, lintels, stairs, etc. The lack of respect of the manufacturer instruction during assembling, however, may induce cracking and short/long term loss of bearing capacity. GPR is a well-established not destructive technique employed in the assessment of structural elements because of real-time imaging, quickness of data collecting and ability to discriminate finest structural details. In this work, GPR has been used to investigate two different precast elements: precast reinforced concrete planks constituting the roof slab of a school and precast wood-cement blocks with insulation material pre-fitted used to build a perimeter wall of a private building. Visible cracks affected both constructions. For the assessment surveys, a GSSI 2.0 GHz GPR antenna has been used because of the high resolution required and the small size of the antenna case (155 by 90 by 105mm) enabling scanning up to 45mm from any obstruction. Finite Difference Time Domain (FDTD) numerical modelling was also performed to build a scenario of the expected GPR signal response for a preliminary real-time interpretation and to help solve uncertainties due to complex reflection patterns: simulated radargrams were built using Reflex Software v. 8.2, reproducing the same GPR pulse used for the surveys in terms of wavelet, nominal frequency, sample frequency and time window. Model geometries were derived from the design projects available both for the planks and the blocks; the electromagnetic properties of the materials (concrete, reinforcing bars, air-filled void, insulation and wooden concrete) were inferred from both values reported in literature and a preliminary interpretation of radargrams where internal layer interfaces were clearly recognizable and

  17. Uncertainties Concerning the Free Vibration of Inhomogeneous Orthotropic Reinforced Concrete Plates

    Science.gov (United States)

    Shahsavar, Vahid Lal; Tofighi, Samira

    2014-09-01

    Analyzing nearly collapsed and broken structures gives good insights into possible architectural and engineering design mistakes and faults in the detailing and mismanagement of a construction by building contractors. Harmful vibration effects of construction operations occur frequently. The background reviews have demonstrated that the problem of the vibration serviceability of long-span concrete floors in buildings is complex and interdisciplinary in nature. In public buildings, floor vibration control is required in order to meet Serviceability Limit States that ensure the comfort of the users of a building. In industrial buildings, machines are often placed on floors. Machines generate vibrations of various frequencies, which are transferred to supporting constructions. Precision machines require a stable floor with defined and known dynamic characteristics. In recent years there has been increasing interest in the motion of elastic bodies whose material properties (density, elastic moduli, etc.) are not constant, but vary with their position, perhaps in a random manner. Concrete is a non-homogeneous and anisotropic material. Modeling the mechanical behavior of reinforced concrete (RC) is still one of the most difficult challenges in the field of structural engineering. One of several methods for determining the dynamic modulus of the elasticity of engineering materials is the vibration frequency procedure. In this method, the required variables except for the modulus of elasticity are accurately and certainly determined. In this research, the uncertainly analysis of the free vibration of inhomogeneous orthotropic reinforced concrete plates has been investigated. Due to the numerous outputs obtained, the software package has been written in Matlab, and an analysis of the data and drawing related charts has been done.

  18. The Raetrad model of radon generation and transport from soils into slab-on-grade houses

    International Nuclear Information System (INIS)

    Nielson, K.K.; Rogers, V.C.; Rogers, V.; Holt, R.B.

    1994-01-01

    Remediation planning and 222 Rn-related construction zoning require knowledge of how close and strong 226 Ra sources can be in different foundation soils under different groundwater conditions without excessively elevating indoor 222 Rn levels. A two-dimensional numerical-analytical model was developed to simulate (a) 222 Rn emanation, decay, and movement by diffusion and advection in soils around houses and in their understructures; and (b) 222 Rn accumulation in a single-zone house. The model represents foundation soils and a house in elliptical-cylindrical geometry. 222 Rn may diffuse through its floor slab or may enter via idealized cracks and openings. The model was validated with analytical calculations of two-dimensional air pressure fields and with one-dimensional calculations of 222 Rn generation with diffusion and diffusion combined with advection. Agreement generally was within 222 Rn measurements in two test-cell structures under passive and depressurized conditions averaged within 11% of measured values, well within measurement uncertainty. The corresponding average bias was only 3%. Larger variations were observed when applying the model to 50 houses. In this application, a negative bias of nearly 50% was observed due to data gaps and to poorly-characterized floor slabs and crack distributions. 41 refs., 11 fig., 3 tabs

  19. The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs

    OpenAIRE

    Jarkas, Abdulaziz M

    2010-01-01

     Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting i...

  20. Experimental verification of concrete resistance against effect of low pH

    Science.gov (United States)

    Dobias, D.; Rehacek, S.; Pokorny, P.; Citek, D.; Kolisko, J.

    2018-03-01

    In the introductory part of this article, the principles of a concrete degradation by organic acids are mentioned, these acids occur, particularly in silage and haylage troughs, biogas stations, on concrete floors and grates in the vicinity of drinking basins with an addition of formic acid and also in fermenters and slurry reservoirs. In the experimental part, the first results of monitoring resistance of a concrete with a sealing admixture on the basis of styrene-acrylate against an effect of a low pH are presented. Additional accompanying tests are stated in the tested concretes.

  1. Rigid missiles impact on reinforced concrete structures: analysis by discrete element method

    International Nuclear Information System (INIS)

    Shiu, W.J.

    2008-10-01

    The constructions likely to be subjected to some extreme loadings like reactor containment buildings have to be dimensioned accordingly. As a part of study of concrete structures, this thesis focuses on numerical modelling of rigid missile impacts against a rigid reinforced concrete slab. Based on some experiment tests data, an elasto-plastic-damaged constitutive law has been implanted into a discrete element numerical code. To calibrate certain parameters of the numerical model, some quasi static tests have been first simulated. Once the model calibration was done, some missile impact simulation tests have then been carried out. The numerical results are well agree with these provided by French Atomic Energy Agency (Cea) and the French Electrical power Company (EDF) in terms of the trajectory of the missile. We were able to show the need of a constitutive law taking into account the compaction behaviour of the concrete when the predictions of penetration and perforation of a thick slab was demanded. Finally, a parametric study confirmed that the numerical model can be used the way predictive as well as the empirical prediction law, while the first can provide additional significant mechanical description. (author)

  2. Shear capacity of ASR damaged structures – in-depth analysis of some in-situ shear tests on bridge slabs

    DEFF Research Database (Denmark)

    Hansen, Søren Gustenhoff; Barbosa, Ricardo Antonio; Hoang, Linh Cao

    2016-01-01

    This paper deals with the influence of alkali-silica reaction (ASR) on the shear capacity for concrete slabs without shear reinforcement. An experimental full-scale in-situ program consisting of four slabs from a bridge (Vosnæsvej) has been carried out and the results have been published in ref. [1......] with the principal author of this paper as co-author. After the experiments, a detailed measurement of the test specimens was conducted. Based on these measurements a thorough analysis of the experimental results was carried out and evaluated by a plastic model for shear capacity, Crack Sliding Model (CSM...

  3. Influence of Soft or Hard Floors before and after First Calving on Dairy Heifer Locomotion, Claw and Leg Health

    Directory of Open Access Journals (Sweden)

    Christer Bergsten

    2015-08-01

    Full Text Available Claw health, an important dairy cow welfare parameter, may be affected by early-life foot/leg stresses. To investigate this, groups of pregnant heifers were allocated to deep straw bedding (Soft or cubicles (Hard, both with scraped concrete feeding alleys. After the grazing season, they were re-housed in cubicle systems, half on slatted concrete (Hard and half on slatted rubber (Soft alleys. Claw measurements, contact area and pressure distribution claw/flooring, claw disorders and leg lesions were recorded at the start and end of each housing season. Locomotion and leg lesions were also scored monthly after calving. Prevalence of sole haemorrhages was higher among pregnant heifers in cubicles than in deep straw. After calving, first-calvers on Hard floors had higher odds for lameness (OR = 3.6; P < 0.01, sole haemorrhages/ulcers (OR = 2.2; P < 0.05, white-line haemorrhages (OR = 2.8; P < 0.01 and leg lesions (OR = 2.6; P < 0.02 than those on Soft floors. Lowest prevalence and severity of sole and white-line haemorrhages (non-significant in first-calvers was found in those on Soft floors and reared on Hard floors and the highest prevalence and severity on those on Hard floors reared on Soft floors. Soft flooring after calving is of most importance for healthy feet and legs.

  4. Borated concrete for ZPPR fuel storage

    International Nuclear Information System (INIS)

    Gasidlo, J.M.

    1985-01-01

    Fuel handling at the Zero Power Plutonium Reactor (ZPPR) led to two requirements for storage of ZPPR fuel: a low neutron multiplication and shielded storage to minimize personnel doses. Boron-poisoned concrete was chosen as the storge medium with boron frit as the poisoning agent. The calculated effects of water content and boron concentration led to specifying a concrete with a water content that was higher than ordinary concrete. The finite size of the boron frit particles caused concern about reduced effectiveness due to self-shielding. The self-shielding was evaluated using optical path lengths for spheres and tabulated self-shielding for slabs. The results showed that the finite-sized particles were at least 80% as effective as infinitely dilute absorption. Neutron and gamma dose rates measured in the vault verified that personnel could work in the vault on a regular basis without exceeding personnel dose limits. 4 refs., 3 figs., 7 tabs

  5. Interfacial shear behavior of composite flanged concrete beams

    Directory of Open Access Journals (Sweden)

    Moataz Awry Mahmoud

    2014-08-01

    Full Text Available Composite concrete decks are commonly used in the construction of highway bridges due to their rapid constructability. The interfacial shear transfer between the top slab and the supporting beams is of great significance to the overall deck load carrying capacity and performance. Interfacial shear capacity is directly influenced by the distribution and the percentage of shear connectors. Research and design guidelines suggest the use of two different approaches to quantify the required interfacial shear strength, namely based on the maximum compressive forces in the flange at mid span or the maximum shear flow at the supports. This paper investigates the performance of flanged reinforced concrete composite beams with different shear connector’s distribution and reinforcing ratios. The study incorporated both experimental and analytical programs for beams. Key experimental findings suggest that concentrating the connectors at the vicinity of the supports enhances the ductility of the beam. The paper proposes a simple and straight forward approach to estimate the interfacial shear capacity that was proven to give good correlation with the experimental results and selected code provisions. The paper presents a method to predict the horizontal shear force between precast beams and cast in-situ slabs.

  6. A study on the behavior of beam-column connections in precast concrete structures: experimental analysis

    Directory of Open Access Journals (Sweden)

    M. N. Kataoka

    Full Text Available Due to the large increase in the use of precast concrete structures in multistory buildings, this work covers a study on the behavior of beam-column connection with emphasis on the continuity provided by the slab reinforcement. Two prototypes were tested, each one with a different detail of the continuity reinforcement distribution. In both connections, the steel area used on the concrete cover of the hollow core slab was the same, varying the amount of bars that passed through the column and the ones that were placed adjacent to the column. The experimental results showed that the connection with bars adjacent to the column presented stiffness increase and a better cracking control. According to the classification the two tested connections can be considered semi-rigid.

  7. Statistical analysis of ultrasonic measurements in concrete

    Science.gov (United States)

    Chiang, Chih-Hung; Chen, Po-Chih

    2002-05-01

    Stress wave techniques such as measurements of ultrasonic pulse velocity are often used to evaluate concrete quality in structures. For proper interpretation of measurement results, the dependence of pulse transit time on the average acoustic impedance and the material homogeneity along the sound path need to be examined. Semi-direct measurement of pulse velocity could be more convenient than through transmission measurement. It is not necessary to assess both sides of concrete floors or walls. A novel measurement scheme is proposed and verified based on statistical analysis. It is shown that Semi-direct measurements are very effective for gathering large amount of pulse velocity data from concrete reference specimens. The variability of measurements is comparable with that reported by American Concrete Institute using either break-off or pullout tests.

  8. Nonlocal Peridynamic Modeling and Simulation on Crack Propagation in Concrete Structures

    Directory of Open Access Journals (Sweden)

    Dan Huang

    2015-01-01

    Full Text Available An extended peridynamic approach for crack propagation analysis in concrete structures was proposed. In the peridynamic constitutive model, concrete material was described as a series of interacting particles, and the short-range repulsive force and anisotropic behavior of concrete were taken into account in the expression of the interactive bonding force, which was given in terms of classical elastic constants and peridynamic horizon. The damage of material was defined locally at the level of pairwise bond, and the critical stretch of material bond was described as a function of fracture strength in the classical concrete failure theory. The efficiency and accuracy of the proposed model and algorithms were validated by simulating the propagation of mode I and I-II mixed mode cracks in concrete slabs. Furthermore, crack propagation in a double-edge notched concrete beam subjected to four-point load was simulated, in which the experimental observations are captured naturally as a consequence of the solution.

  9. Thermal Removal of Tritium from Concrete and Soil to Reduce Groundwater Impacts - 13197

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Dennis G. [Savannah River National Laboratory, Building 773-42A, Aiken, South Carolina 29808 (United States); Blount, Gerald C. [Savannah River Nuclear Solutions (United States); Wells, Leslie H.; Cardoso, Joao E.; Kmetz, Thomas F.; Reed, Misty L. [U.S Department of Energy-Savannah River Site (United States)

    2013-07-01

    Legacy heavy-water moderator operations at the Savannah River Site (SRS) have resulted in the contamination of equipment pads, building slabs, and surrounding soil with tritium. At the time of discovery the tritium had impacted the shallow (< 3-m) groundwater at the facility. While tritium was present in the groundwater, characterization efforts determined that a significant source remained in a concrete slab at the surface and within the associated vadose zone soils. To prevent continued long-term impacts to the shallow groundwater a CERCLA non-time critical removal action for these source materials was conducted to reduce the leaching of tritium from the vadose zone soils and concrete slabs. In order to minimize transportation and disposal costs, an on-site thermal treatment process was designed, tested, and implemented. The on-site treatment consisted of thermal detritiation of the concrete rubble and soil. During this process concrete rubble was heated to a temperature of 815 deg. C (1,500 deg. F) resulting in the dehydration and removal of water bound tritium. During heating, tritium contaminated soil was used to provide thermal insulation during which it's temperature exceeded 100 deg. C (212 deg. F), causing drying and removal of tritium. The thermal treatment process volatiles the water bound tritium and releases it to the atmosphere. The released tritium was considered insignificant based upon Clean Air Act Compliance Package (CAP88) analysis and did not exceed exposure thresholds. A treatability study evaluated the effectiveness of this thermal configuration and viability as a decontamination method for tritium in concrete and soil materials. Post treatment sampling confirmed the effectiveness at reducing tritium to acceptable waste site specific levels. With American Recovery and Reinvestment Act (ARRA) funding three additional treatment cells were assembled utilizing commercial heating equipment and common construction materials. This provided a

  10. Reinforced concrete structures loaded by snow avalanches : numerical and experimental approaches.

    Science.gov (United States)

    Ousset, I.; Bertrand, D.; Brun, M.; Limam, A.; Naaim, M.

    2012-04-01

    Today, due to the extension of occupied areas in mountainous regions, new strategies for risk mitigation have to be developed. In the framework of risk analysis, these latter have to take into account not only the natural hazard description but also the physical vulnerability of the exposed structures. From a civil engineering point of view, the dynamic behavior of column or portico was widely investigated especially in the case of reinforced concrete and steel. However, it is not the case of reinforced concrete walls for which only the in-plan dynamic behavior (shear behavior) has been studied in detail in the field of earthquake engineering. Therefore, the aim of this project is to study the behavior of reinforced concrete civil engineering structures submitted to out-of-plan dynamic loadings coming from snow avalanche interaction. Numerical simulations in 2D or 3D by the finite element method (FEM) are presented. The approach allows solving mechanical problems in dynamic condition involving none linearities (especially none linear materials). Thus, the structure mechanical response can be explored in controlled conditions. First, a reinforced concrete wall with a L-like shape is considered. The structure is supposed to represent a French defense structure dedicated to protect people against snow avalanches. Experimental pushover tests have been performed on a physical model. The experimental tests consisted to apply a uniform distribution of pressure until the total collapse of the wall. A 2D numerical model has been developed to simulate the mechanical response of the structure under quasi-static loading. Numerical simulations have been compared to experimental datas and results gave a better understanding of the failure mode of the wall. Moreover, the influence of several parameters (geometry and the mechanical properties) is also presented. Secondly, punching shear experimental tests have also been carried out. Reinforced concrete slabs simply supported have

  11. The dynamics of double slab subduction

    Science.gov (United States)

    Holt, A. F.; Royden, L. H.; Becker, T. W.

    2017-04-01

    We use numerical models to investigate the dynamics of two interacting slabs with parallel trenches. Cases considered are: a single slab reference, outward dipping slabs (out-dip), inward dipping slabs (in-dip) and slabs dipping in the same direction (same-dip). Where trenches converge over time (same-dip and out-dip systems), large positive dynamic pressures in the asthenosphere are generated beneath the middle plate and large trench-normal extensional forces are transmitted through the middle plate. This results in slabs that dip away from the middle plate at depth, independent of trench geometry. The single slab, the front slab in the same-dip case and both out-dip slabs undergo trench retreat and exhibit stable subduction. However, slabs within the other double subduction systems tend to completely overturn at the base of the upper mantle, and exhibit either trench advance (rear slab in same-dip), or near-stationary trenches (in-dip). For all slabs, the net slab-normal dynamic pressure at 330 km depth is nearly equal to the slab-normal force induced by slab buoyancy. For double subduction, the net outward force on the slabs due to dynamic pressure from the asthenosphere is effectively counterbalanced by the net extensional force transmitted through the middle plate. Thus, dynamic pressure at depth, interplate coupling and lithospheric stresses are closely linked and their effects cannot be isolated. Our results provide insights into both the temporal evolution of double slab systems on Earth and, more generally, how the various components of subduction systems, from mantle flow/pressure to interplate coupling, are dynamically linked.

  12. Numerical analysis of impact-penetration problems for nuclear reactor safety

    International Nuclear Information System (INIS)

    Dubois, J.J.; Chedmail, J.F.; Bianchini, J.C.

    1977-01-01

    This paper discusses the finite element and finite difference analysis of two impact penetration problems, namely a fuel cask drop on a foundation slab and a missile penetration into a reinforced concrete structure. For a realistic detailed analysis, advanced techniques were required in the following areas: reinforced concrete simulation; remeshing algorithms for penetration induced distortions; boundary condition. The fuel cask drop on a concrete slab generates complex elasto plastic waves which propagate towards the pool where tensile cracks might appear. The problem is analysed in two steps: calculation of the energy absorbed locally around the impacted area; calculation of the three dimensional wave propagation towards the pool. For the analysis of missile penetration problems, two examples are shown: a 3000 kg missile with a velocity of 132 m/s penetrates a 1.2 m thick concrete wall (PAM-GDYNS) and a 3600 kg missile with a velocity of 90 m/s (F.D. Program HEMP-ESI) penetrates a wall at a floor level. For the second case, the computed impact-penetration mechanism is

  13. Prediction of the spatial occurrence of fire induced spalling in concrete slabs using random fields

    Directory of Open Access Journals (Sweden)

    Van Coile R.

    2013-09-01

    Full Text Available As the loss of concrete cover can significantly influence the reliability of concrete elements during fire, spalling should be taken into account when performing reliability calculations. However, the occurrence and spatial variation of spalling are highly uncertain. A first step towards a probabilistic analysis of spalling is made by combining existing deterministic models with a stochastic representation of the concrete tensile strength and by using random fields to model the tensile strength spatial variation.

  14. Foundation Design for a High Bay Warehouse with a Steel Fibre Reinforced Concrete Slab

    DEFF Research Database (Denmark)

    Kasper, T.; Sørensen, Carsten Steen; Nielsen, J. B.

    2008-01-01

    . The SFRC slab is cast in 6 panels divided by free-movement joints with shear dowels. It has to be designed for closely spaced 250 kN characteristic long-term loads for complete filling of the racks. The design has been based on a German SFRC design guideline and makes use of 3D finite element soil...

  15. Fine-grain concrete from mining waste for monolithic construction

    Science.gov (United States)

    Lesovik, R. V.; Ageeva, M. S.; Lesovik, G. A.; Sopin, D. M.; Kazlitina, O. V.; Mitrokhin, A. A.

    2018-03-01

    The technology of a monolithic construction is a well-established practice among most Russian real estate developers. The strong points of the technology are low cost of materials and lower demand for qualified workers. The monolithic construction uses various types of reinforced slabs and foamed concrete, since they are easy to use and highly durable; they also need practically no additional treatment.

  16. Seismic analysis of a PWR 900 reactor: study of reactor building with soil-structure interaction and evaluation of floor spectra

    International Nuclear Information System (INIS)

    Gantenbein, F.; Aguilar, J.

    1983-08-01

    The purpose of this paper is the evaluation of seismic response and floor spectra for a typical PWR 900 reactor building with respect to soil-structure interaction for soil stiffness). The typical PWR 900 reactor building consists of a concrete cylindrical external building and roof dome, a concrete internal structure (internals) on a common foundation mat as illustrated. The seismic response is obtained by SRSS method and floor spectra directly from ground spectrum and modal properties of the structure. Seismic responses and floor spectra computation is performed in the case of two different ground spectra: EDF spectrum (mean of oscillator spectra obtained from 8 californian records) normalized to 0.2 g, and DSN spectrum (typical of shallow seism) normalized to 0.3 g. The first section is devoted to internals' modelisation, the second one to the axisymmetric model of the reactor, the third one to the seismic response, the fourth one to floor spectra

  17. Earthquake Response of Reinforced Concrete Building Retrofitted with Geopolymer Concrete and X-shaped Metallic Damper

    Science.gov (United States)

    Madheswaran, C. K.; Prakash vel, J.; Sathishkumar, K.; Rao, G. V. Rama

    2017-06-01

    A three-storey half scale reinforced concrete (RC) building is fixed with X-shaped metallic damper at the ground floor level, is designed and fabricated to study its seismic response characteristics. Experimental studies are carried out using the (4 m × 4 m) tri-axial shake-table facility to evaluate the seismic response of a retrofitted RC building with open ground storey (OGS) structure using yielding type X-shaped metallic dampers (also called as Added Damping and Stiffness-ADAS elements) and repairing the damaged ground storey columns using geopolymer concrete composites. This elasto-plastic device is normally incorporated within the frame structure between adjacent floors through chevron bracing, so that they efficiently enhance the overall energy dissipation ability of the seismically deficient frame structure under earthquake loading. Free vibration tests on RC building without and with yielding type X-shaped metallic damper is carried out. The natural frequencies and mode shapes of RC building without and with yielding type X-shaped metallic damper are determined. The retrofitted reinforced concrete building is subjected to earthquake excitations and the response from the structure is recorded. This work discusses the preparation of test specimen, experimental set-up, instrumentation, method of testing of RC building and the response of the structure. The metallic damper reduces the time period of the structure and displacement demands on the OGS columns of the structure. Nonlinear time history analysis is performed using structural analysis package, SAP2000.

  18. Thermophysical aspects of reconstruction of cold roof spaces

    Directory of Open Access Journals (Sweden)

    Semko Oleksandr

    2017-01-01

    Full Text Available The results of theoretical studies of thermal modernization of cold roof floor. The designs of overlap of long-life roofs of public buildings were considered. Overlap of these buildings are made by wooden or concrete beams and made of concrete slabs with upward edges. The problems of thermal modernization of these designs are consideration of the impact of heat-conducting inclusions on the resistance to heat. The heat-conducting inclusions of constructions are beams and vertical edges of the slabs. The results of calculations of the temperature fields were used for the analysis. The research was carried for the two temperature zones which Ukraine’s territory is divided into. The analysis of thermal protection level of structures overlap was made. The magnitude of the impact of heat-conducting inclusions on resistance to heat after thermal modernization of cold roof floor was observed. The analysis showed that the thermal protection properties of structures less than standard, therefore the insulation of areas with heat-conducting inclusions is required. The options of insulation of these areas were considered. The optimal insulation options with the least amount of additional insulation over the heat conductive areas were selected.

  19. Effect of steel fibers on plastic shrinkage cracking of normal and high strength concretes

    Directory of Open Access Journals (Sweden)

    Özgür Eren

    2010-06-01

    Full Text Available Naturally concrete shrinks when it is subjected to a drying environment. If this shrinkage is restrained, tensile stresses develop and concrete may crack. Plastic shrinkage cracks are especially harmful on slabs. One of the methods to reduce the adverse effects of shrinkage cracking of concrete is by reinforcing concrete with short randomly distributed fibers. The main objective of this study was to investigate the effect of fiber volume and aspect ratio of hooked steel fibers on plastic shrinkage cracking behavior together with some other properties of concrete. In this research two different compressive strength levels namely 56 and 73 MPa were studied. Concretes were produced by adding steel fibers of 3 different volumes of 3 different aspect ratios. From this research study, it is observed that steel fibers can significantly reduce plastic shrinkage cracking behavior of concretes. On the other hand, it was observed that these steel fibers can adversely affect some other properties of concrete during fresh and hardened states.

  20. Heat and mass transfer in a contaminated porous concrete slab with variable dielectric properties

    International Nuclear Information System (INIS)

    Li, W.; Ebadian, M.A.

    1994-01-01

    The effect of temperature dependent dielectric properties on concrete decontamination and decommissioning using microwave technology is investigated theoretically in this paper. The concrete is treated as a porous material, which has residual water and air within the pores. A one-dimensional model of unsteady heat and mass transport in the porous concrete with temperature dependent dielectric properties is developed. Based on this model, temperature and pressure with different microwave frequencies are predicted, the effects of the temperature dependent dielectric properties on microwave power dissipation, the temperature and pressure distributions for different microwave frequencies, and the different microwave power intensities are analyzed in detail. Four available industrial microwave frequencies of 0.896, 2.45, 10.6 and 18.0 GHz are used in the analysis. As a result of the dielectric properties varying with temperature, the power dissipation also varies with the heating times. Comparing the results for both temperature dependent and constant dielectric properties reveals that the variation of dielectric permittivity with temperature must be considered in a theoretical model of the concrete decontamination and decommissioning process for a low microwave frequency (f <2.45 GHz). (Author)

  1. Flexural Behavior of RC Slabs Strengthened in Flexure with Basalt Fabric-Reinforced Cementitious Matrix

    Directory of Open Access Journals (Sweden)

    Sugyu Lee

    2018-01-01

    Full Text Available This paper presents both experimental and analytical research results for predicting the flexural capacity of reinforced concrete (RC slabs strengthened in flexure with basalt fabric-reinforced cementitious matrix (FRCM. A total of 13 specimens were fabricated to evaluate the flexural behavior of RC slabs strengthened with basalt FRCM composite and were tested under four-point loading. The fiber type, tensile reinforcement ratio, and the number of fabric layers were chosen as experimental variables. The maximum load of FRCM-strengthened specimens increased from 11.2% to 98.2% relative to the reference specimens. The energy ratio and ductility of the FRCM-strengthened specimens decreased with the higher amount of fabric and tensile reinforcement. The effective stress level of FRCM fabric can be accurately predicted by a bond strength of ACI 549 and Jung’s model.

  2. Ultimate analysis of PWR prestressed concrete containment subjected to internal pressure

    International Nuclear Information System (INIS)

    Hu, H.-T.; Lin, Y.-H.

    2006-01-01

    Numerical analyses are carried out by using the ABAQUS finite element program to predict the ultimate pressure capacity and the failure mode of the PWR prestressed concrete containment at Maanshan nuclear power plant. Material nonlinearity such as concrete cracking, tension stiffening, shear retention, concrete plasticity, yielding of prestressing tendon, yielding of steel reinforcing bar and degradation of material properties due to high temperature are all simulated with proper constitutive models. Geometric nonlinearity due to finite deformation has also been considered. The results of the analysis show that when the prestressed concrete containment fails, extensive cracks take place at the apex of the dome, the junction of the dome and cylinder, and the bottom of the cylinder connecting to the base slab. In addition, the ultimate pressure capacity of the containment is higher than the design pressure by 86%

  3. Precast concrete pavement - systems and performance review

    Science.gov (United States)

    Novak, Josef; Kohoutková, Alena; Křístek, Vladimír; Vodička, Jan

    2017-09-01

    Long-term traffic restrictions belong to the key disadvantages of conventional cast-in-plane concrete pavements which have been used for technical structures such as roads, parking place and airfield pavements. As a consequence, the pressure is put on the development of such systems which have short construction time, low production costs, long-term durability, low maintenance requirements etc.. The paper presents the first step in the development of an entirely new precast concrete pavement (PCP) system applicable to airfield and highway pavements. The main objective of the review of PCP systems is to acquire a better understanding of the current systems and design methods used for transport infrastructure. There is lack of information on using PCP systems for the construction of entirely new pavements. To most extensive experience is dated back to the 20th century when hexagonal slab panels and system PAG were used in the Soviet Union for the military airfields. Since cast-in-situ pavements became more common, the systems based on precast concrete panels have been mainly utilized for the removal of damaged sections of existing structures including roads, highways etc.. Namely, it concerns Fort Miller Super Slab system, Michigan system, Uretek Stitch system and Kwik system. The presented review indicates several issues associated with the listed PCP systems and their applications to the repair and rehabilitation of existing structures. Among others, the type of manufacturing technology, particularly the position of slots for dowel bars, affects the durability and performance of the systems. Gathered information serve for the development of a new system for airfield and highway pavement construction.

  4. Time varying stress in ligaments of perforated plates with reference to prestressed concrete reactor vessels

    International Nuclear Information System (INIS)

    Stefanou, G.D.

    1978-01-01

    The work described herein relates to the prediction of stresses in materials which exhibit time varying strains with particular reference to the ligaments of perforated circular concrete slabs, subjected to long-term radial prestress and uniform elevated temperature. The perforations are reinforced with steel liners and arranged in a square central lattice symmetrical about two orthogonal axes. Special reference is made to the distribution of stress in the standpipe region of prestressed concrete cylindrical pressure or containment vessels for gas cooled reactors. In order to assess the stress distribution around the perforated zone of a circular slab, a method of analysis was developed by the author, based on the ''Equivalent Elastic Modulus'' of the perforated zone and the ''Effective Modulus Method'', utilizing experimental data obtained from tests performed on model specimens. The object of this paper is to extend the above method of analysis into the perforated region, and assess the long-term stresses in the ligaments. The proposed method is accomplished by an application of the Finite Element Method for the elastic plane stress case. Comparisons of experimental results and theoretical predictions by the proposed method, and other analytical methods are made for a series of perforated concrete slabs subjected to radial in-plane loading: 10,342 kN/m 2 (1,5000 psi), and uniform elevated temperature of 80 0 C. The investigation, though in general terms, could be applied to the perforated region of cylindrical pressure vessels for nuclear reactors. Finally the paper describes briefly in Appendix 3 a direct solution procedure for calculating time dependent stresses in concrete structures based on the principles of variational calculus. Analytical predictions obtained by the proposed method which is a step-by-step analysis, are compared with the variational principle method. (author)

  5. Technological aspects of lift-slab method in high-rise-building construction.

    Science.gov (United States)

    Gaidukov, Pavel V.; Pugach, Evgeny M.

    2018-03-01

    The utilization efficiency of slab lifting technology for high-rise-building construction is regarded in the present article. The main problem of the article is organizing technology abilities indication, which proves the method application possibility. There is the comparing of lifting technologies and sequential concrete-frame extension, as follows: the first one: the parameters are defined, and the second one: the organizational model is executed. This model defines borders of the usage methods, as well. There is the mathematic model creating, which describes boundary conditions of the present technologies usage. This model allows to predict construction efficiency for different stored-number buildings.

  6. Application of the fluid dynamics model to the field of fibre reinforced self-compacting concrete

    DEFF Research Database (Denmark)

    Svec, Oldrich; Skocek, Jan; Stang, Henrik

    Ability to properly simulate a form filling process with steel fibre reinforced self-compacting concrete is a challenging task. Such simulations may clarify the evolution of fibre orientation and distribution which in turn significantly influences final mechanical properties of the cast body. We...... have developed such a computational model and briefly introduce it in this paper. The main focus of the paper is towards validation of the ability of the model to properly mimic the flow of the fibre reinforced self-compacting concrete. An experiment was conducted where a square slab was filled...... behaviour of the self-compacting fibre reinforced concrete....

  7. Seismic Performance and Modeling of Reinforced Concrete and Post-Tensioned Precast Concrete Shear Walls

    OpenAIRE

    Tanyeri, Ahmet Can

    2014-01-01

    Past earthquakes have shown examples of unsatisfactory performance of buildings using reinforced concrete structural walls as the primary lateral-force-resisting system. In the 1994 Northridge earthquake, examples can be found where walls possessed too much overstrength, leading to unintended failure of collectors and floor systems, including precast and post-tensioned construction. In the 2010 Maule Chile earthquake, many structural wall buildings sustained severe damage. Although Chilean de...

  8. Investigation on impact resistance of steel plate reinforced concrete barriers against aircraft impact. Pt.3: Analyses of full-scale aircraft impact

    International Nuclear Information System (INIS)

    Jun Mizuno; Norihide Koshika; Eiichi Tanaka; Atsushi Suzuki; Yoshinori Mihara; Isao Nishimura

    2005-01-01

    Steel plate reinforced concrete (SC) walls and slabs are structural members in which the rebars of reinforced concrete are replaced by steel plates. Steel plate reinforced concrete structures are more attractive structural design alternatives to reinforced concrete structures, especially with thick, heavily reinforced walls and slabs such as nuclear structures, because they enable a much shorter construction period, greater earthquake resistant and more cost effectiveness. Experimental and analytical studies performed by the authors have also shown that SC structures are much more effective in mitigating damage against scaled aircraft models , as described in Parts 1 and 2 of this study. The objective of Part 3 was to determine the protective capability of SC walls and roofs against a full-scale aircraft impact by conducting numerical experiments to investigate the fracture behaviors and limit thicknesses of SC panels and to examine the effectiveness of SC panels in detail under design conditions. Furthermore, a simplified method is proposed for evaluating the localized damage induced by a full-scale engine impact. (authors)

  9. Influence of slab length on dynamic characteristics of subway train-steel spring floating slab track-tunnel coupled system

    Directory of Open Access Journals (Sweden)

    Qing-yuan Xu

    Full Text Available A subway train-steel spring floating slab track-tunnel coupling dynamic model, considering short and middle-long wavelength random track irregularities, and longitudinal connection between adjacent slabs of steel spring floating slab track, was developed. And the influence of slab length on dynamic characteristics of the system under different track conditions and train speeds are theoretically studied. The calculated results show: (1 In general, the acceleration of each component of the coupled system decreases with the increase of slab length under the perfectly smooth track condition; (2 Slab length has different influence laws on acceleration of each component of subway train-steel spring floating slab track-tunnel coupled system under random irregularity of track condition. The lower the dominant frequency distribution of vibration acceleration is, the higher influence slab length has; (3 With the increase of slab length, the force of rail, fastener and steel spring also decreases significantly, which helps to lengthen the service life of these components; (4 With the increase of slab length, the longitudinal bending moment of slab increases sharply at first, then it begins to drop slightly. When slab length exceeds the distance between two bogies of a vehicle, the longitudinal bending moment of slab changes little; (5 Slab length has significant influence on the dynamic force and displacement of the coupled system when train speed is higher.

  10. A three-dimensional rupture analysis of steel liners anchored to concrete pressure and containment vessels

    International Nuclear Information System (INIS)

    Bangash, Y.

    1987-01-01

    Steel liners or plates are anchored to concrete pressure and containment vessels for nuclear and offshore facilities. Due to extreme loading conditions a liner may buckle due to the pull-out or shearing of anchors from the base metal and concrete. Under certain conditions attributed to loadings, liner metal deterioration and cracking of concrete behind the liner, the liner may fail by rupture. This paper presents a three-dimensional analysis of steel-concrete elements, using finite elements analysis in which a provision is made for liner instability, anchor strength and stiffness, concrete cracking and finally liner rupture. The analysis is tested first on an octagonal slab with and without an anchored steel liner. It is then extended to concrete pressure and containment vessels. The analytical results obtained are compared well with those available from the experimental tests and other sources. (author)

  11. Lightweight self-compacting concrete with light expanded clay aggregate (LECA

    Directory of Open Access Journals (Sweden)

    Heiza Khaled

    2018-01-01

    Full Text Available Lightweight concretes have been successfully applied in building constructions for many years due to their favorable material properties, particularly their low specific weight in connection with a high strength, a high capability of thermal insulation and a high durability. The development leading to lightweight self-compacting concrete (LWSCC represents an important advanced step within the recent years. This concrete combines the favorable properties of a lightweight concrete with those of a self-compacting concrete. Research work is aimed on development of (LWSCC with the use of light aggregates “Light expanded clay aggregate (LECA”. In this research, first by specific gravity factor method, twenty different mix designs of (LWSCC were cast and tested to find out the values of slump flow, J-ring , V-funnel and 28 day compressive strength. Based on the results obtained, the best mix design was selected for further investigation. This paper also focuses on studying the effect of changing the reinforcement ratio on reinforced two way slabs when the dimensions were kept constant.

  12. ANALYSIS OF SUFFICIENCY OF THE BEARING CAPACITY OF BUILDING STRUCTURES OF OPERATING SITES OF MAIN BUILDINGS OF THERMAL POWER PLANTS

    Directory of Open Access Journals (Sweden)

    Alekseeva Ekaterina Leonidovna

    2012-10-01

    Full Text Available Upon examination of eleven main buildings of power plants, analysis of defects and damages of building structures was performed. Thereafter, the damageability of principal bearing structures of main buildings of thermal plants was analyzed. It was identified that the fastest growing defects and damages were concentrated in the structures of operating sites. The research of the rate of development of the most frequent damages and defects made it possible to conclude that internal corrosion of the reinforcing steel was the most dangerous defect, as far as the reinforced concrete elements of operating sites were concerned. Methods of mathematical statistics were applied to identify the reinforcing steel development pattern inside reinforced concrete elements of floors of operating sites. It was identified that the probability of corrosion of reinforced concrete elements of operating sites was distributed in accordance with the demonstrative law. Based on these data, calculation of strength of reinforced concrete slabs and metal beams was performed in terms of their regular sections, given the natural loads and the realistic condition of structures. As a result, dependence between the bearing capacity reserve ratio and the corrosion development pattern was identified for reinforced concrete slabs and metal beams of operating sites. In order to analyze the sufficiency of the bearing capacity of building structures of operating sites in relation to their time in commission, equations were derived to identify the nature of dependence between the sufficiency of the bearing capacity of reinforced concrete slabs and metal beams of the operating sites and their time in commission.

  13. Concrete decontamination by Electro-Hydraulic Scabbling (EHS). Topical report

    International Nuclear Information System (INIS)

    1996-01-01

    Electro-Hydraulic Scabbling (EHS) technology and equipment for decontaminating concrete structures from radionuclides, organic substances, and hazardous metals is being developed by Textron Systems Division (TSD). This wet scabbling technique involves the generation of powerful shock waves and intense cavitation by a strong pulsed electric discharge in a water layer at the concrete surface. The high pressure impulse results in stresses which crack and peel off a concrete layer of a controllable thickness. Scabbling produces contaminated debris of relatively small volume which can be easily removed, leaving clean bulk concrete. This new technology is being developed under Contract No. DE-AC21-93MC30164. The project objective is to develop and demonstrate a cost-efficient, rapid, controllable process to remove the surface layer of contaminated concrete while generating minimal secondary waste. The primary target of this program is uranium-contaminated concrete floors which constitute a substantial part of the contaminated area at DOE weapon facilities

  14. Ultimate load analysis of prestressed concrete reactor pressure vessels considering a general material law

    International Nuclear Information System (INIS)

    Schimmelpfennig, K.

    1975-01-01

    A method of analysis is presented, by which progressive fracture processes in axisymmetric prestressed concrete pressure vessels during increasing internal pressure can be evaulated by means of a continuum calculation considering a general material law. Formulations used in the analysis concerning material behaviour are derived on one hand from appropriate results of testing small concrete specimens, and are on the other hand gained by parametric studies in order to solve questions still existing by recalulating fracture tests on concrete bodies with more complex states of stress. Due attention is focussed on investigating the behaviour of construction members subjected to high shear forces (end slabs.). (Auth.)

  15. Observations on out-of-plane behaviour of URM walls in buildings with RC slabs

    OpenAIRE

    Tondelli, Marco; Beyer, Katrin

    2014-01-01

    In Switzerland many new residential buildings are constructed as unreinforced masonry (URM) structures or as mixed structures where URM walls are coupled with reinforced concrete (RC) walls by RC slabs. At present the boundary conditions of URM walls subjected to out-of-plane accelerations are still not well quantified. In the framework of a large research activity on RC-URM wall structures a shake-table test on a four-storey mixed structure was performed. The test specimen, which was built a...

  16. Evaluation of calculational and material models for concrete containment structures

    International Nuclear Information System (INIS)

    Dunham, R.S.; Rashid, Y.R.; Yuan, K.A.

    1984-01-01

    A computer code utilizing an appropriate finite element, material and constitutive model has been under development as a part of a comprehensive effort by the Electric Power Research Institute (EPRI) to develop and validate a realistic methodology for the ultimate load analysis of concrete containment structures. A preliminary evaluation of the reinforced and prestressed concrete modeling capabilities recently implemented in the ABAQUS-EPGEN code has been completed. This effort focuses on using a state-of-the-art calculational model to predict the behavior of large-scale reinforced concrete slabs tested under uniaxial and biaxial tension to simulate the wall of a typical concrete containment structure under internal pressure. This paper gives comparisons between calculations and experimental measurements for a uniaxially-loaded specimen. The calculated strains compare well with the measured strains in the reinforcing steel; however, the calculations gave diffused cracking patterns that do not agree with the discrete cracking observed in the experiments. Recommendations for improvement of the calculational models are given. (orig.)

  17. Effects of coffee husk as floor covering on the behavior of boars

    Directory of Open Access Journals (Sweden)

    Mariele Cristina Teles

    Full Text Available ABSTRACT The objective was to evaluate the influence of coffee husks as floor covering on the aspects of animal welfare such as behavioral characteristics, body surface temperature, and salivary cortisol levels of stabled boars. Sixteen boars were housed in individual stalls; eight were maintained in a conventional system with a concrete floor and eight were maintained on a concrete floor lined with coffee husks. The experimental period was 60 days. All animals were filmed two days prior to the start of the experiment, on both the 7th and 60th days after exposure to coffee husks, and finally two days after the removal of the material. During this period, the number of times that the animals ate, drank, stood, sat, lay down, and dug was recorded. Furthermore, both body surface temperature and salivary cortisol levels were measured at the beginning and end of the experiment. The use of coffee husks did not influence body surface temperature. Salivary cortisol levels increased during the experimental period only in the animals maintained on coffee husks. In the morning, the coffee husks decreased the number of times that the animals sat and increased the number of times that they lay down. In the afternoon, the use of coffee husks decreased the number of times that the animals stood, sat, or dug and increased the number of times that the animals lay down. Although coffee husks do not change the behavior of the animals in an expressive way, they should not be used as floor covering for boars.

  18. Vibration Analysis of Steel-Concrete Composite Box Beams considering Shear Lag and Slip

    Directory of Open Access Journals (Sweden)

    Zhou Wangbao

    2015-01-01

    Full Text Available In order to investigate dynamic characteristics of steel-concrete composite box beams, a longitudinal warping function of beam section considering self-balancing of axial forces is established. On the basis of Hamilton principle, governing differential equations of vibration and displacement boundary conditions are deduced by taking into account coupled influencing of shear lag, interface slip, and shear deformation. The proposed method shows an improvement over previous calculations. The central difference method is applied to solve the differential equations to obtain dynamic responses of composite beams subjected to arbitrarily distributed loads. The results from the proposed method are found to be in good agreement with those from ANSYS through numerical studies. Its validity is thus verified and meaningful conclusions for engineering design can be drawn as follows. There are obvious shear lag effects in the top concrete slab and bottom plate of steel beams under dynamic excitation. This shear lag increases with the increasing degree of shear connections. However, it has little impact on the period and deflection amplitude of vibration of composite box beams. The amplitude of deflection and strains in concrete slab reduce as the degree of shear connections increases. Nevertheless, the influence of shear connections on the period of vibration is not distinct.

  19. Effect of space allowance and floor type on performance, welfare and physiological measurements of finishing beef heifers.

    Science.gov (United States)

    Keane, M P; McGee, M; O'Riordan, E G; Kelly, A K; Earley, B

    2017-12-01

    Accommodating cattle indoors during the winter is widely practiced throughout Europe. There is currently no legislation surrounding the space allowance and floor type that should be provided to cattle during this time, however, concerns have been raised regarding the type of housing systems currently in use. The objective of the study was to investigate the effect of space allowance and floor type on performance and welfare of finishing beef heifers. Continental crossbred heifers (n=240: mean initial live; weight, 504 (SD 35.8) kg) were blocked by breed, weight and age and randomly assigned to one of four treatments; (i) 3.0 m2, (ii) 4.5 m2 and (iii) 6.0 m2 space allowance per animal on a fully slatted concrete floor and (iv) 6.0 m2 space allowance per animal on a straw-bedded floor, for 105 days. Heifers were offered a total mixed ration ad libitum. Dry matter intake was recorded on a pen basis and refusals were weighed back twice weekly. Heifers were weighed, dirt scored and blood sampled every 3 weeks. Whole blood was analysed for complete cell counts and serum samples were assayed for metabolite concentrations. Behaviour was recorded continuously using IR cameras from days 70 to 87. Heifers' hooves were inspected for lesions at the start of the study and again after slaughter. Post-slaughter, carcass weight, conformation and fat scores and hide weight were recorded. Heifers housed at 4.5 m2 had a greater average daily live weight gain (ADG) than those on both of the other concrete slat treatments; however, space allowance had no effect on carcass weight. Heifers accommodated on straw had a greater ADG (0.15 kg) (PSpace allowance and floor type had no effect on the number of hoof lesions gained or on any of the haematological or metabolic variables measured. It was concluded that increasing space allowance above 3.0 m2/animal on concrete slats was of no benefit to animal performance but it did improve animal cleanliness. Housing heifers on straw instead of

  20. Blast Resistance of Slurry Infiltrated Fibre Concrete with Waste Steel Fibres from Tires

    Directory of Open Access Journals (Sweden)

    Drdlová Martina

    2018-01-01

    Full Text Available The utilization of waste steel fibres (coming from the recycling process of the old tires in production of blast resistant cement based panels was assessed. Waste fibres were incorporated in slurry infiltrated fibre concrete (SIFCON, which is a special type of ultra-highperformance fibre reinforced concrete with high fibre content. The technological feasibility (i.e. suitability of the waste fibres for SIFCON technology was assessed using homogeneity test. Test specimens were prepared with three volume fractions (5; 7.5 and 10 % by vol. of waste unclassified fibres. SIFCON with industrial steel fibres (10% by vol. and ultra-highperformance fibre concrete with industrial fibres were also cast and tested for comparison purposes. Quasi-static mechanical properties were determined. Real blast tests were performed on the slab specimens (500x500x40 mm according to the modified methodology M-T0-VTU0 10/09. Damage of the slab, the change of the ultrasound wave velocity propagation in the slab specimen before and after the blast load in certain measurement points, the weight of fragments and their damage potential were evaluated and compared. Realized tests confirmed the possibility of using the waste fibres for SIFCON technology. The obtained results indicate, that the usage of waste fibres does not significantly reduce the values of SIFCON flexural and compressive strength at quasi-static load - the values were comparable to the specimens with industrially produced fibres. With increasing fibre content, the mechanical parameters are increasing as well. Using of the waste fibres reduces fragmentation of SIFCON at blast load due to the fibre size parameters. Using of low diameter fibres means more fibres in the matrix and thus better homogeneity of the whole composite with less unreinforced areas. Regarding the blast tests, the specimen with waste steel fibres showed the best resistance and outperformed also the specimen with commercial fibres. Using of

  1. Transport of accelerator produced high energy neutrons though concrete

    International Nuclear Information System (INIS)

    Prabhakar Rao, G.; Sarkar, P.K.

    1996-01-01

    Development of a computational system for estimating the production and transport of high energy neutrons in particle accelerators is reported. The energy-angle distribution of neutrons from accelerated ions bombarding thick targets is calculated by a hybrid nuclear reaction model code, ALICE-91, modified to suit the purpose. Subsequent transmission of these neutrons through concrete slabs is treated using the anisotropic source-flux iteration technique (ASFIT) in the framework of a coupled neutron-gamma transport. Several parameters of both the codes have been optimized to obtain the transmitted dose through concrete. The calculations are found to be accurate and at the same time faster compared to the detailed Monte Carlo calculations. (author). 8 refs., 2 figs

  2. Data derived from constitutive laws for description of shock wave propagation in concrete. Final report

    International Nuclear Information System (INIS)

    Eibl, J.; Ockert, J.

    1994-01-01

    Especially the need to design safe reactor containments, but also the necessity to protect facilities and human beings against impacts induced secondarily by explosions and detonations, demand simulations and design calculations of concrete under shock wave loading. The necessary computer codes are available, but the relevant constitutive laws for concrete with volumetric pressures up to more than 10000 MPa are lacking. Therefore shock wave tests have been carried out to develop such constitutive laws by loading concrete slabs with contact explosions. By the use of hot-molded carbon composition resistors shock waves propagating through the slab were measured. Pressures up to 13900 MPa were registered. Additionally shock wave velocities were determined from the different arrival times of the wave at the gages. By these two measured values and the conservation equations of mass and momentum the needed p-V relationship, the so called Hugoniot-Curve, was established up to 13900 MPa. Using the theory of Mie-Grueneisen and the so called P-α model the Hugoniot-Curve was extended to the equation of state for concrete. In a first step the deviatoric part of the constitutive law was attached from own static experiments considering the existing knowledge of strain rate effects since relevant dynamic tests under extreme loads are not available. With this constitutive law the analysis of the experiments then was backward verified in detail. (orig.) [de

  3. Influence of alkali-silica reaction and crack orientation on the uniaxial compressive strength of concrete cores from slab bridges

    DEFF Research Database (Denmark)

    Antonio Barbosa, Ricardo; Gustenhoff Hansen, Søren; Hansen, Kurt Kielsgaard

    2018-01-01

    ASR-damaged flat slab bridges in service. Furthermore, the influence of the ASR-induced crack orientation on the compressive strength and the Young’s modulus is investigated. Uniaxial compression tests, visual observations, and thin section examinations were performed on more than 100 cores drilled...... from the three severely ASR-damaged flat slab bridges. It was found that the orientation of ASR-induced cracks has a significant influence on the uniaxial compressive strength and the stress-strain relationship of the tested cores. The compressive strength in a direction parallel to ASR cracks can...

  4. Soil and gas and radon entry potentials for substructure surfaces

    International Nuclear Information System (INIS)

    Harrison, J.; Sextro, R.G.

    1990-01-01

    This paper reports on measurement techniques and parameters that describe the potential for areas of a building substructure to have high soil gas and radon entry rates which have been developed. Flows and pressures measured at test holes in substructure surfaces while the substructure was intentionally depressurized were used in a highly simplified electrical circuit to model the substructure/soil network. Data from four New Jersey houses indicate that the soil was a factor of two to six times more resistant to soil gas flow than substructure surfaces, concrete slab floors, including perimeter gaps, cracks, and other penetrations, were approximately five times more resistant to soil gas movement than hollow block walls, and radon entry potentials were highest for slab floors. These indices of entry potential may be useful for characterizing the relative leakiness of below-grade substructure surfaces and for determining the selection and placement of radon control systems

  5. High performance repairing of reinforced concrete structures

    International Nuclear Information System (INIS)

    Iskhakov, I.; Ribakov, Y.; Holschemacher, K.; Mueller, T.

    2013-01-01

    Highlights: ► Steel fibered high strength concrete is effective for repairing concrete elements. ► Changing fibers’ content, required ductility of the repaired element is achieved. ► Experiments prove previously developed design concepts for two layer beams. -- Abstract: Steel fibered high strength concrete (SFHSC) is an effective material that can be used for repairing concrete elements. Design of normal strength concrete (NSC) elements that should be repaired using SFHSC can be based on general concepts for design of two-layer beams, consisting of SFHSC in the compressed zone and NSC without fibers in the tensile zone. It was previously reported that such elements are effective when their section carries rather large bending moments. Steel fibers, added to high strength concrete, increase its ultimate deformations due to the additional energy dissipation potential contributed by fibers. When changing the fibers’ content, a required ductility level of the repaired element can be achieved. Providing proper ductility is important for design of structures to dynamic loadings. The current study discusses experimental results that form a basis for finding optimal fiber content, yielding the highest Poisson coefficient and ductility of the repaired elements’ sections. Some technological issues as well as distribution of fibers in the cross section of two-layer bending elements are investigated. The experimental results, obtained in the frame of this study, form a basis for general technological provisions, related to repairing of NSC beams and slabs, using SFHSC.

  6. Concrete model for finite element analysis of structures subjected to severe damages

    International Nuclear Information System (INIS)

    Jamet, Ph.; Millard, A.; Hoffmann, A.; Nahas, G.; Barbe, B.

    1984-01-01

    A specific concrete model has been developed, in order to perform mechanical analysis of civil engineering structures, when subjected to accidental loadings, leading to severe damages. Its formulation is based on the physical mechanisms, which have been observed on laboratory specimens. The model has been implemented into the CASTEM finite element system, and the case of a concrete slab perforation by a rigid missile has been considered. The qualitative behaviour of the structure is well predicted by the model. Comparison between numerical and experimental results is also performed, using two main curves: missile velocity versus penetration depth; reaction forces versus time. (Author) [pt

  7. Distribution of residual long-lived radioactivity in the inner concrete walls of a compact medical cyclotron vault room.

    Science.gov (United States)

    Fujibuchi, Toshioh; Nohtomi, Akihiro; Baba, Shingo; Sasaki, Masayuki; Komiya, Isao; Umedzu, Yoshiyuki; Honda, Hiroshi

    2015-01-01

    Compact medical cyclotrons have been set up to generate the nuclides necessary for positron emission tomography. In accelerator facilities, neutrons activate the concrete used to construct the vault room; this activation increases with the use of an accelerator. The activation causes a substantial radioactive waste management problem when facilities are decommissioned. In the present study, several concrete cores from the walls, ceiling and floor of a compact medical cyclotron vault room were samples 2 years after the termination of operations, and the radioactivity concentrations of radionuclides were estimated. Cylindrical concrete cores 5 cm in diameter and 10 cm in length were bored from the concrete wall, ceiling and floor. Core boring was performed at 18 points. The gamma-ray spectrum of each sample was measured using a high-purity germanium detector. The degree of activation of the concrete in the cyclotron vault room was analyzed, and the range and tendency toward activation in the vault room were examined. (60)Co and (152)Eu were identified by gamma-ray spectrometry of the concrete samples. (152)Eu and (60)Co are produced principally from the stable isotopes of europium and cobalt by neutron capture reactions. The radioactivity concentration did not vary much between the surface of the concrete and at a depth of 10 cm. Although the radioactivity concentration near the target was higher than the clearance level for radioactive waste indicated in IAEA RS-G-1.7, the mean radioactivity concentration in the walls and floor was lower than the clearance level. The radioactivity concentration of the inner concrete wall of the medical cyclotron vault room was not uniform. The areas exceeding the clearance level were in the vicinity of the target, but most of the building did not exceed the clearance levels.

  8. MODOS GUIADOS EM SLABS METAMATERIAIS GUIDED MODES IN METAMATERIAL SLABS

    Directory of Open Access Journals (Sweden)

    Leonardo André Ambrosio

    2006-12-01

    Full Text Available Este trabalho apresenta um estudo de revisão de modos propagantes em um guia-de-onda slab constituído de materiais com índices de refração negativo, os chamados metamateriais, Mostra-se que os modos guiados em um slab metamaterial possuem algumas propriedades particulares, tais como a propagação de ondas lentas simétricas ou anti-simétricas, a ausência de modos fundamentais para ondas rápidas e a possibilidade de propagação de ondas guiadas em um meio menos denso. A análise é baseada em expansões de campo no guia e nos espaços superior e inferior ao mesmo.This paper presents a review of the propagation modes in a slab waveguide consisting of negative refraction index materials, known as metamaterials. Some particular properties of guided modes in a metamaterial slab, such as slow symmetric or antisymmetric slow wave propagation, the absence of fundamental modes for fast waves and the possibility of guided waves in a less dense medium. The analysis is based on field expansions in the guide and the upper and lower spaces of it.

  9. Preface: Deep Slab and Mantle Dynamics

    Science.gov (United States)

    Suetsugu, Daisuke; Bina, Craig R.; Inoue, Toru; Wiens, Douglas A.

    2010-11-01

    We are pleased to publish this special issue of the journal Physics of the Earth and Planetary Interiors entitled "Deep Slab and Mantle Dynamics". This issue is an outgrowth of the international symposium "Deep Slab and Mantle Dynamics", which was held on February 25-27, 2009, in Kyoto, Japan. This symposium was organized by the "Stagnant Slab Project" (SSP) research group to present the results of the 5-year project and to facilitate intensive discussion with well-known international researchers in related fields. The SSP and the symposium were supported by a Grant-in-Aid for Scientific Research (16075101) from the Ministry of Education, Culture, Sports, Science and Technology of the Japanese Government. In the symposium, key issues discussed by participants included: transportation of water into the deep mantle and its role in slab-related dynamics; observational and experimental constraints on deep slab properties and the slab environment; modeling of slab stagnation to constrain its mechanisms in comparison with observational and experimental data; observational, experimental and modeling constraints on the fate of stagnant slabs; eventual accumulation of stagnant slabs on the core-mantle boundary and its geodynamic implications. This special issue is a collection of papers presented in the symposium and other papers related to the subject of the symposium. The collected papers provide an overview of the wide range of multidisciplinary studies of mantle dynamics, particularly in the context of subduction, stagnation, and the fate of deep slabs.

  10. Strain monitoring of a newly developed precast concrete track for high speed railway traffic using embedded fiber optic sensors

    Science.gov (United States)

    Crail, Stephanie; Reichel, D.; Schreiner, U.; Lindner, E.; Habel, Wolfgang R.; Hofmann, Detlef; Basedau, Frank; Brandes, K.; Barner, A.; Ecke, Wolfgang; Schroeder, Kerstin

    2002-07-01

    In a German slab track system (Feste Fahrbahn FF, system Boegl) for speeds up to 300 km/h and more different fiber optic sensors have been embedded in several levels and locations of the track system. The track system consists of prestressed precast panels of steel fiber concrete which are supported by a cat-in-situ concrete or asphalt base course. The sensors are to measure the bond behavior or the stress transfer in the track system. For that, tiny fiber-optic sensors - fiber Fabry-Perot and Bragg grating sensors - have been embedded very near to the interface of the layers. Measurements were taken on a full scale test sample (slab track panel of 6.45 m length) as well as on a real high speed track. The paper describes the measurement task and discusses aspects with regard to sensor design and prefabrication of the sensor frames as well as the embedding procedure into the concrete track. Results from static and dynamic full scale tests carried out in the testing laboratory of BAM and from measurements on a track are given.

  11. Bridge approach slabs for Missouri DOT field evaluation of alternative and cost efficient bridge approach slabs.

    Science.gov (United States)

    2013-05-01

    Based on a recent study on cost efficient alternative bridge approach slab (BAS) designs (Thiagarajan et : al. 2010) has recommended three new BAS designs for possible implementation by MoDOT namely a) 20 feet cast-inplace : slab with sleeper slab (C...

  12. Modelling of the Molten Core Concrete Interaction (MCCI)

    International Nuclear Information System (INIS)

    Guillaume, M.

    2008-01-01

    Severe accidents of nuclear power plants are very unlikely to occur, yet it is necessary to be able to predict the evolution of the accident. In some situations, heat generation due to the disintegration of fission products could lead to the melting of the core. If the molten core falls on the floor of the building, it would provoke the melting of the concrete floor. The objective of the studies is to calculate the melting rate of the concrete floor. The work presented in this report is in the continuity of the segregation phase model of Seiler and Froment. It is based on the results of the ARTEMIS experiments. Firstly, we have developed a new model to simulate the transfers within the interfacial area. The new model explains how heat is transmitted to concrete: by conduction, convection and latent heat generation. Secondly, we have modified the coupled modelling of the pool and the interfacial area. We have developed two new models: the first one is the 'liquidus model', whose main hypothesis is that there is no resistance to solute transfer between the pool and the interfacial area. The second one is 'the thermal resistance model', whose main hypothesis is that there is no solute transfer and no dissolution of the interfacial area. The second model is able to predict the evolution of the pool temperature and the melting rate in the tests 3 and 4, with the condition that the obstruction time of the interfacial area is about 10 5 s. The model is not able to explain precisely the origin of this value. The liquidus model is able to predict correctly the evolution of the pool temperature and the melting rate in the tests 2 and 6. (author) [fr

  13. The mechanical ventilation of suspended timber floors for radon remediation - a simple analysis

    International Nuclear Information System (INIS)

    Woolliscroft, M.

    1994-01-01

    Mechanical ventilation of the underfloor space is one of the most effective ways of reducing radon levels in buildings with suspended timber floors. There is a question, however, whether this ventilation should be supply or extract, sometimes extract is more effective, sometimes supply is more effective. This report presents a simple analysis of the problem and suggests the hypothesis that the relative effectiveness of supply or extract ventilation to the underfloor space depends on the relative airtightness of the floor and the soil or oversite surface. The analysis suggests that if the floor is relatively tight then supply ventilation may be more effective whereas if the floor is relatively leaky or there is oversite concrete then extract may be better. It is suggested that in either case it is better to keep the underfloor pressure low and that when mechanical ventilation is provided to the underfloor space it may be necessary to increase the number of airbricks. (author)

  14. Development of contaminated concrete removing system 'Clean cut method'

    International Nuclear Information System (INIS)

    Kinoshita, Takehiko; Tanaka, Tsutomu; Funakawa, Naoyoshi; Idemura, Hajime; Sakashita, Fumio; Tajitsu, Yoshiteru

    1989-01-01

    In the case of decommissioning nuclear facilities such as nuclear power stations, nuclear fuel facilities and RI handling facilities and carrying out reconstruction works, if there is radioactive contamination on the surfaces of concrete structures such as the floors and walls of the buildings for nuclear facilities, it must be removed. Since concrete is porous, contamination infiltrates into the inside of concrete, and the wiping of surfaces only or chemical decontamination cannot remove it, therefore in most cases, contaminated concrete must be removed. The removal of concrete surfaces has been carried out with chipping hammers, grinders and so on, but many problems arise due to it. In order to solve these problems, the mechanical cutting method was newly devised, and clean cut method (CCRS) was completed. The depth of cutting from concrete surface is set beforehand, and the part to be removed is accurately cut, at the same time, the concrete powder generated is collected nearly perfectly, and recovered into a drum. The outline of the method and the constitution of the system, the features of the clean cut method, the development of the technology for cutting concrete and the technology for recovering concrete powder, and the test of verifying decontamination are reported. (K.I.)

  15. Research and application of active hollow core slabs in building systems for utilizing low energy sources

    International Nuclear Information System (INIS)

    Xu, Xinhua; Yu, Jinghua; Wang, Shengwei; Wang, Jinbo

    2014-01-01

    Highlights: • A review on the development and modeling of active hollow core slab is presented. • The applications and performance evaluation of the slab in building are reviewed. • Finite element or finite difference method is often used in multidimensional model. • Performance evaluations of building using active slabs for ventilation are limited. • More works on the active hollow core slab are worthwhile. - Abstract: The society and the building professionals have paid much concern in recent years on building energy efficiency and the development and applications of low energy technologies for buildings/green buildings allowing the elimination, or at least reduction of dependence on electricity or fossil fuel while maintaining acceptable indoor environment. Utilizations of favorable diurnal temperature difference and ground thermal source for air conditioning are among these low energy technologies. Utilization of the hollow cores in the prefabricated slab for ventilation and the mass of the slab for thermal storage is widely used in building systems in Europe by exploiting the low energy source of the ambient air. These hollow core slabs aim at enlarging the heat transfer surface between the slab mass and the air in the core, which permits substantial heat flows even for relatively small temperature differences. This, in turn, allows the use of low energy cooling or heating sources, such as the ground, outside air or recovered process heat. In this paper, we present a comprehensive review of the research and application of active hollow core slabs in building systems for utilizing low energy sources. The principle and development of active hollow core slabs in building systems for leveling the indoor temperature fluctuation by ventilation air passing the cores are described. Calculation models of the active hollow core concrete slab as well as the practical applications and performance evaluation of the slab applied in building systems for air

  16. Comparison of impact force attenuation by various combinations of hip protector and flooring material using a simplified fall-impact simulation device.

    Science.gov (United States)

    Li, Ning; Tsushima, Eiki; Tsushima, Hitoshi

    2013-04-05

    Use of hip protectors and compliant flooring has been recommended for preventing hip fracture due to falls. We aimed to identify the factors attenuating forces in falls by comparing and analyzing the impact forces occurring with various combinations of hip protectors and flooring materials. We designed a simplified pendulum device to simulate the impact force at the hip during falling. The impact force was measured on pressure-sensitive recording film under combined conditions of two kinds of hip protector (hard or soft shell) and three kinds of floor material (concrete, wooden, or tatami matting). We then calculated the percentage force attenuation under each test condition compared with the use of a concrete floor and no hip protector. All the tests using tatami matting reduced the impact to below the average fracture threshold of elderly people (3472N). A combination of tatami and soft hip protector provided the best attenuation (72.5%). Multiple regression analyses showed that use of tatami matting and a soft hip protector had the biggest force-attenuation effect. The soft hip protector gave better percentage force attenuation than did the hard one. Use of tatami matting as a flooring material could be an effective strategy for helping prevent hip fractures. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Bearing capacity evaluation of rubblized concrete pavements

    Directory of Open Access Journals (Sweden)

    González, M.

    2009-03-01

    Full Text Available The paper presents the findings of a research work performed on a real scale concrete pavement project where Rubblizing technology was used for its structural rehabilitation. Rubblizing may be defined as a fracture technique in which a concrete pavement slab is transformed in a granular base with a very high Modulus. This technique, fractures the concrete slab in angular pieces by using a concentrated dynamic load of low amplitude and high frequency. The research work was based on field study on the rehabilitation of 5 km motorway. The structural evaluations where made, before, during and after one year construction. Measurements and site evaluation where made by using DCP, Light Weight Deflectometer and FWD (on top of asphalt layer and excavating inside pits. The structural capacity of the Rubblized layer was evaluated through theoretical analysis. Because of the anisotropic properties of the Rubblized layer the results are presented using AASHTO structural layer coefficient. The structural layer coefficients recommended are between the range of 0.25 and 0.30 for concrete slabs with thickness grater than 220 mm.El trabajo presenta los resultados de un estudio a escala real de la capacidad estructural de un firme de hormigón rehabilitado utilizando la técnica de Rubblizing. La técnica de Rubblizing ha sido traducida como el pulverizado del firme de hormigón pero, es más bien un efecto combinado de trituración y fracturación de la losa de hormigón en todo su espesor para convertir esta en una base granular de alto módulo. Esta tecnica fractura la losa de hormigón en trozos angulares y entrelazados empleando una carga dinámica concentrada, de baja amplitud y alta frecuencia. La investigación se basó en el estudio de la rehabilitación de 5 km de autopista. Los estudios de la capacidad estructural fueron realizados durante, al término y un año después de la construcción. Para las mediciones y evaluaciones de terreno se utilizó, el

  18. Thermochemical degradation of limestone aggregate concrete on exposure to sodium fire

    International Nuclear Information System (INIS)

    Premila, M.; Sivasubramanian, K.; Amarendra, G.; Sundar, C.S.

    2008-01-01

    Limestone aggregate concrete blocks were subjected to sodium fire conforming to a realistic scenario in order to qualify them as protective sacrificial layers over structural concrete flooring in liquid metal-cooled fast breeder reactors. Mid infrared absorption measurements were carried out on these sodium fire-exposed samples as a function of depth from the affected surface. Definite signatures of thermochemical degradation indicating dehydration and structural modification of the limestone concrete have been obtained. Control runs were carried out to delineate the thermal effects of sodium fires from that of the chemical interaction effects. Measurements on limestone aggregate samples treated with fused NaOH provided direct evidence of the exact mechanism of the sodium attack on concrete. The observed degradation effects were correlated to the mechanical strength of the concrete blocks and to the intensity of the sodium fire experienced

  19. Radon reduction using sub floor fans

    International Nuclear Information System (INIS)

    Harley, N.H.; Chittaporn, P.

    1996-01-01

    The basement and second floor 222 Rn concentrations in an energy efficient home were measured hourly for 6 y using continuous monitors of our design. The home had a subslab pipe network installed during construction, and for the past 2 y a 150 cfm fan was operative venting air via ductwork inside the chimney exiting on the roof. During this measurement interval, experiments were conducted with the fan in 3 modes: (1) with the subslab fan off, (2) in the conventional direction auctioning air from beneath the slab to outside, and (3) reversed, blowing outdoor air into the network under the slab. We have a large data base to show that the indoor 222 R n concentration varies inversely with the indoor/outdoor temperature difference. In order to compare the 3 fan modes directly, we selected 50 to 90 d periods when the outdoor temperature was essentially the same. For the 3 modes, the fan off, blowing upward, and blowing downward, the basement concentration averaged 80, 38, and 34 Bq m -3 , respectively. Radon peaks or surges occur over a period of about 1 d during falling barometric pressure. With the fan blowing downward, these 222 Rn peaks tend to be smaller but only marginally so. We conclude that in this home the reduction in 222 Rn with the fan and subslab pipe network operating was essentially the same regardless of the direction of flow from the fan

  20. On moisture migration in a heated concrete

    International Nuclear Information System (INIS)

    Shiina, Yasuaki

    1985-10-01

    Transient moisture migration in a slab of porous concrete being heated at one surface was analyzed with consideration of evaporation and condensation effects. Analysis was made in the existence of non-condensable fluid (air). Since partial differential equations which describe the total system are very complicated, the existence of similar solution is assumed under the condition of low dry-wet interface temperature. Then, partial differential equations were transformed into ordinary differential equations. Solutions were obtained for two boundary conditions of a permeable outer surface and a impermeable outer surface. (author)

  1. Generating Atomistic Slab Surfaces with Adsorbates

    Science.gov (United States)

    2017-12-01

    slabs of various thickness and with various vacuum spacing need be calculated. This can occur in serial or simultaneously . If performed in serial, the...the user. Although the optimization of the slab thickness and vacuum padding can be done simultaneously , it is more computationally conservative to...monolayer is a slab (True if slab), the type of mesh desired (adsorbates.py was written for “Gamma”), how detailed the mesh should be (in units of inverse

  2. Calculations of concrete plates and shells under impact load

    International Nuclear Information System (INIS)

    Kappler, H.; Krings, W.

    1982-01-01

    The dynamic behaviour of concrete slabs and shells is determined for a given load time function using axisymmetric computational models with an exact formulation for the midpoint. On the basis of a finite difference method, rotational inertia, shear deformation, elasticity and cracking are taken into account. For shells the coupling of bending moment and normal force is considered. Comparisons with two-dimensional models show good agreement connected with a considerable reduction of computational time. (orig.) [de

  3. Influence of sports flooring and shoes on impact forces and performance during jump tasks.

    Science.gov (United States)

    Malisoux, Laurent; Gette, Paul; Urhausen, Axel; Bomfim, Joao; Theisen, Daniel

    2017-01-01

    We aim to determine the influence of sports floorings and sports shoes on impact mechanics and performance during standardised jump tasks. Twenty-one male volunteers performed ankle jumps (four consecutive maximal bounds with very dynamic ankle movements) and multi-jumps (two consecutive maximal counter-movement jumps) on force plates using minimalist and cushioned shoes under 5 sports flooring (SF) conditions. The shock absorption properties of the SF, defined as the proportion of peak impact force absorbed by the tested flooring when compared with a concrete hard surface, were: SF0 = 0% (no flooring), SF1 = 19%, SF2 = 26%, SF3 = 37% and SF4 = 45%. Shoe and flooring effects were compared using 2x5 repeated-measures ANOVA with post-hoc Bonferroni-corrected comparisons. A significant interaction between SF and shoe conditions was found for VILR only (p = 0.003). In minimalist shoes, SF influenced Vertical Instantaneous Loading Rate (VILR) during ankle jumps (p = 0.006) and multi-jumps (pflooring. VILR is the variable that was the most affected.

  4. The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs

    Directory of Open Access Journals (Sweden)

    Abdulaziz M Jarkas

    2010-07-01

    Full Text Available  Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting its rebar fixing efficiency. To achieve this objective, a large volume of fixing productivity data was collected and analysed using the categorical interaction - regression method. As a result, the main and interaction effects of rebar diameter; reinforcement quantity; slab geometry; and reinforcement layer location are determined. The findings show a significant influence of these factors on the fixing operation, which can be used to provide designers and construction managers with feedback on how well the design of this activity considers the requirements of buildability, and the tangible consequences of designers‟ decisions on labour productivity

  5. The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs

    Directory of Open Access Journals (Sweden)

    Abdulaziz M Jarkas

    2010-06-01

    Full Text Available Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting its rebar fixing efficiency. To achieve this objective, a large volume of fixing productivity data was collected and analysed using the categorical interaction - regression method. As a result, the main and interaction effects of rebar diameter; reinforcement quantity; slab geometry; and reinforcement layer location are determined. The findings show a significant influence of these factors on the fixing operation, which can be used to provide designers and construction managers with feedback on how well the design of this activity considers the requirements of buildability, and the tangible consequences of designers‟ decisions on labour productivity

  6. The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs

    Directory of Open Access Journals (Sweden)

    Abdulaziz M Jarkas

    2010-06-01

    Full Text Available  Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting its rebar fixing efficiency. To achieve this objective, a large volume of fixing productivity data was collected and analysed using the categorical interaction - regression method. As a result, the main and interaction effects of rebar diameter; reinforcement quantity; slab geometry; and reinforcement layer location are determined. The findings show a significant influence of these factors on the fixing operation, which can be used to provide designers and construction managers with feedback on how well the design of this activity considers the requirements of buildability, and the tangible consequences of designers‟ decisions on labour productivity

  7. Concrete decontamination by electro-hydraulic scabbling (EHS). Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-01

    Contamination of concrete structures by radionuclides, hazardous metals and organic substances (including PCB`s) occurs at many DOE sites. The contamination of concrete structures (walls, floors, ceilings, etc.) varies in type, concentration, and especially depth of penetration into the concrete. In many instances, only the surface layer of concrete is contaminated, up to a depth of one inch, according to estimates provided in the R and D ID document. Then, removal of the concrete surface layer (scabbling) is considered to be the most effective decontamination method. Textron Systems Corp. (TSC) has developed a scabbling concept based on electro-mechanical phenomena accompanying strong electric pulses generated by applying high voltage at the concrete/water interface. Depending on the conditions, the electric discharge may occur either through a waste layer or through the concrete body itself. This report describes the development, testing, and results of this electro-mechanical process. Phase 1 demonstrated the feasibility of the process for the controlled removal of a thin layer of contaminated concrete. Phase 2 designed, fabricated, and tested an integrated subscale unit. This was tested at Fernald. In Phase 3, the scabbling unit was reconfigured to increase its power and processing rate. Technology transfer to an engineering contracting company is continuing.

  8. Concrete decontamination by electro-hydraulic scabbling (EHS). Final report

    International Nuclear Information System (INIS)

    1997-10-01

    Contamination of concrete structures by radionuclides, hazardous metals and organic substances (including PCB's) occurs at many DOE sites. The contamination of concrete structures (walls, floors, ceilings, etc.) varies in type, concentration, and especially depth of penetration into the concrete. In many instances, only the surface layer of concrete is contaminated, up to a depth of one inch, according to estimates provided in the R and D ID document. Then, removal of the concrete surface layer (scabbling) is considered to be the most effective decontamination method. Textron Systems Corp. (TSC) has developed a scabbling concept based on electro-mechanical phenomena accompanying strong electric pulses generated by applying high voltage at the concrete/water interface. Depending on the conditions, the electric discharge may occur either through a waste layer or through the concrete body itself. This report describes the development, testing, and results of this electro-mechanical process. Phase 1 demonstrated the feasibility of the process for the controlled removal of a thin layer of contaminated concrete. Phase 2 designed, fabricated, and tested an integrated subscale unit. This was tested at Fernald. In Phase 3, the scabbling unit was reconfigured to increase its power and processing rate. Technology transfer to an engineering contracting company is continuing

  9. The role of dirt floors and of firewood in rural dwellings in the epidemiology of Chagas' disease in Costa Rica.

    Science.gov (United States)

    Zeledón, R; Vargas, L G

    1984-03-01

    In an endemic area of Chagas' disease in Costa Rica, 50 houses infested with Triatoma dimidiata were re-examined after a period of 14-17 years. Criteria used were two socioeconomic parameters which are closely associated with the presence of the bugs: colonies of triatomines inside houses are favored by the presence of a dirt floor, and stored firewood is an excellent refuge for insects outdoors. Indoor infestation was completely eliminated from nine of 13 houses in which the floors had been changed from dirt to concrete during this period, and nearly eliminated from the other four, supporting the hypothesis that the disappearance of dirt floors makes it difficult for the bugs to thrive inside houses. Of the 21 houses that lost the infestation (inside, outside, or both), firewood had been eliminated in 13, and of 29 houses that remained infested firewood had been eliminated in only two. An inverse relationship was found between distance of firewood piles from the house and presence of bugs. It is supposed that a colony of insects frequently starts in stored firewood and then moves into the household if a dirt floor is present. Removal of firewood and replacement of dirt floors by concrete would provide good prophylactic measures against the transmission of Chagas' disease in areas where T. dimidiata is the vector.

  10. Preplaced aggregate concrete application on Fort St. Vrain PCRV construction

    International Nuclear Information System (INIS)

    Ople, F.S. Jr.

    1976-01-01

    Two distinct concreting methods were employed in the construction of the prestressed concrete reactor vessel (PCRV) of the Fort St. Vrain (FSV) Nuclear Generating Station, a 330 MW(e) High Temperature Gas-Cooled Reactor installation near Denver, Colorado. Preplaced aggregate concrete (PAC) techniques were employed in the PCRV bottom head and the core support floor; conventional job-mixed concrete was used in the PCRV sidewall and top head regions. This paper describes the successful application of PAC techniques utilized primarily in solving construction difficulties associated with confined and heavily congested regions of the PCRV. The PAC technique consists of placing coarse aggregate inside the forms, followed by injection of grout under pressure through embedded pipes to fill the interstices in the aggregate mass. Details of the PAC construction method including grout mix development, grouting equipment, grout pipe layout, grouting sequence, grout level monitoring, concrete temperature control, and pre-construction mockups are described. (author)

  11. Floor interaction

    DEFF Research Database (Denmark)

    Petersen, Marianne Graves; Krogh, Peter; Ludvigsen, Martin

    2005-01-01

    Within architecture, there is a long tradition of careful design of floors. The design has been concerned with both decorating floors and designing floors to carry information. Ubiquitous computing technology offers new opportunities for designing interactive floors. This paper presents three...... different interactive floor concepts. Through an urban perspective it draws upon the experiences of floors in architecture, and provides a set of design issues for designing interactive floors....

  12. Buffer mass test - Rock drilling and civil engineering

    International Nuclear Information System (INIS)

    Pusch, R.

    1982-09-01

    The buffer mass test (BMT) is being run in the former 'ventilation drift' in which a number of rock investigations were previously conducted. A number of vertical pilot holes were drilled from the tunnel floor to get information of the water inflow in possible heater hole position. The final decision of the location of the heater holes was then made, the main principle being that much water should be available in each hole with the possible exception of one of the holes. Thereafter, the diameter 0.76 m heater holes were drilled to a depth of 3-3.3 m. Additional holes were then drilled for rock anchoring of the lids of the four outer heater holes, for the rock mechanical investigation, as well as for a number of water pressure gauges. The inner, about 12 m long part of the tunnel, was separated from the outer by bulwark. The purpose of this construction was to confine a backfill, the requirements of the bulwark being to withstand the swelling pressure as well as the water pressure. Outside the bulwark an approximately 1.5-1.7 m thick concrete slab was cast on the tunnel floor, extending about 24.7 m from the bulwark. Boxing-outs with the same height as the slab and with the horizontal dimensions 1.8 x 1.8 m, were made and rock-anchored concrete lids were cast on top of them after backfilling. The slab which thus represents 'rock', also forms a basal support of the bulwark. The lids permits access to the backfill as well as to the underlying, highly compacted bentonite for rapid direct determination of the water distributin at the intended successive test stops. The construction of the slab and lids will be described in this report. (Author)

  13. Dynamic response of the high flux isotope reactor structure caused by nearby heavy load drop

    International Nuclear Information System (INIS)

    Chang, Shih-Jung.

    1995-01-01

    A heavy load of 50,000 lb is assumed to drop from 10 ft above the bottom of the High Flux Isotope Reactor (HFIR) pool at the loading station. The consequences of the dynamic impact to the bottom slab of the pool and to the nearby HFIR reactor vessel are analyzed by applying the ABAQUS computer code The results show that both the BM vessel structure and its supporting legs are subjected to elastic disturbances only and, therefore, will not be damaged. The bottom slab of the pool, however, will be damaged to about half of the slab thickness. The velocity response spectrum at the concrete floor next to the HFIR vessel as a result of the vibration caused by the impact is obtained. It is concluded, that the damage caused by heavy load drop at the loading station is controlled by the slab damage and the nearby HFIR vessel and the supporting legs will not be damaged

  14. Restless behavior increases over time, but not with compressibility of the flooring surface, during forced standing at the feed bunk.

    Science.gov (United States)

    Krebs, N; Berry, S L; Tucker, C B

    2011-01-01

    Interest in the use of rubber flooring in freestall barns has increased, but little is known about which design features of these surfaces are important for cattle. In 2 experiments, we evaluated how the type and compressibility of the flooring surface in front of the feed bunk influenced the behavioral response to 4 h of forced standing after morning milking. Two flooring types were compared: rubber and concrete. Rubber was tested at 3 levels of compressibility: 2, 4, and 35 times as compressible as concrete. Four hours of forced standing was evaluated because it mimicked conditions that can occur on dairies, particularly when waiting for artificial insemination or veterinary treatment. The effects of cow weight and hoof surface area, gait score, and hoof health on the response to treatment were evaluated. Restless behavior, as measured by number of steps, almost doubled over the 4h of forced standing, regardless of flooring material. Cows lay down, on average, within 5 min after access to the lying area was provided. These results indicate that the 4 h of forced standing was uncomfortable. No differences in restless behavior were observed in association with the type or compressibility of the flooring surface in front of the feed bunk. Cow size, hoof health, or gait score did not consistently explain the response to the flooring treatments or stepping rate, although these populations of animals were generally healthy. It is unclear if comfort did not differ between the flooring options tested during 4 h of forced standing or if alterative methodology, such as measuring more subtle shifts in weight, is required to assess design features of rubber flooring. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  15. Efficiency of fiber reinforced concrete application in structures subjected to dynamic effects

    Directory of Open Access Journals (Sweden)

    Morozov Valeriy Ivanovich

    2014-03-01

    Full Text Available Fiber reinforced concretes possess high strength under dynamic loadings, which include impact loads, thanks to their high structural viscosity. This is the reason for using them in difficult operating conditions, where increasing the performance characteristics and the structure durability is of prime importance, and the issues of the cost become less significant. Applying methods of disperse reinforcement is most challenging in case of subtle high-porous materials on mineral binders, for example foamed concrete. At the same time, the experiments conducted in Russia and abroad show, that also in other cases the concrete strength resistance several times increases as a result of disperse reinforcement. This doesn't depend on average density of the concrete and type of fiber used. In the article the fibre reinforced concrete impact resistance is analysed. Recommendations are given in regard to fibre concrete application in manufacture of monolithic floor units for industrial buildings and precast piles.

  16. Perceived floor slipperiness and floor roughness in a gait experiment.

    Science.gov (United States)

    Yu, Ruifeng; Li, Kai Way

    2015-01-01

    Slips and falls contribute to occupational injuries and fatalities globally. Both floor slipperiness and floor roughness affect the occurrence of slipping and falling. Investigations on fall-related phenomena are important for the safety and health of workers. The purposes of this study were to: compare the perceived floor slipperiness before and after walking on the floor; compare the perceived floor slipperiness with and without shoes for males and females; discuss the perceived floor roughness based on barefoot walking; and establish regression models to describe the relationship between perceived floor slipperiness and actual friction of the floors. Male and female subjects walked on 3 m walkways with or without shoes. The perceived floor slipperiness ratings both before and after their walk were collected. The perceived floor slipperiness both before and after walking were significantly affected by both floor and surface conditions. Gender, floor, surface, and footwear conditions were all significant factors affecting the adjustment of perceived floor slipperiness. The subjects made more adjustment on perceived floor slipperiness rating when they had shoes on than when they were barefooted. Regression models were established to describe the relationship between perceived floor slipperiness and floor coefficient of friction. These models may be used to estimate perceived floor slipperiness, or in reverse, the coefficient of friction of the floor, so as to prevent slipping and falling in workplaces.

  17. Dose calculations for the concrete water tunnels at 190-C Area, Hanford Site

    International Nuclear Information System (INIS)

    Kamboj, S.; Yu, C.

    1997-01-01

    The RESRAD-BUILD code was used to calculate the radiological dose from the contaminated concrete water tunnels at the 190-C Area at the Hanford Site. Two exposure scenarios, recreationist and maintenance worker, were considered. A residential scenario was not considered because the material was assumed to be left intact (i.e., the concrete would not be rubbleized because the location would not be suitable for construction of a house). The recreationist was assumed to use the tunnel for 8 hours per day for 1 week as an overnight shelter. The maintenance worker was assumed to spend 20 hours per year working in the tunnel. Six exposure pathways were considered in calculating the dose. Three external exposure pathways involved penetrating radiation emitted directly from the contaminated tunnel floor, emitted from radioactive particulates deposited on the tunnel floor, and resulting from submersion in airborne radioactive particulates. Three internal exposure pathways involved inhalation of airborne radioactive particulates; inadvertent direct ingestion of removable, contaminated material on the tunnel floor; and inadvertent indirect ingestion of airborne particulates deposited on the tunnel floor. The gradual removal of surface contamination over time and the ingrowth of decay products were considered in calculating the dose at different times. The maximum doses were estimated to be 1.5 mrem/yr for the recreationist and 0.34 mrem/yr for the maintenance worker

  18. Postural behaviour in gilts housed on concrete and rubber slats during four seasons

    Directory of Open Access Journals (Sweden)

    Željko Pavičić

    2014-10-01

    Full Text Available In the present study, postural behaviour was compared between gilts kept in service unit with different types of flooring during all seasons. The study included four 28-day production cycles and 10 gilts per cycle, equally divided into a control and an experimental group. Control gilts were housed in gestation stalls with slatted concrete floor, whereas in the experimental group the floor was covered with an adjusted rubber mat. Postural behaviour of gilts was observed 4 times per cycle for 4 hours. Study results showed that during cooler seasons, gilts in concrete stalls spent more time standing and lying sternally, whereas gilts in matted stalls were mostly lying, predominantly laterally (P<0.001 all. There were no significant between group differences according to the time the gilts spent sitting or the frequency of changing posture in any season observed. Nevertheless, experimental animals spent significantly less time changing standing to both lying positions during all seasons (P<0.01 all. In conclusion, rubber mats may improve lying comfort in gilts; however, when using rubber mats, the house thermal conditions should be taken in consideration.

  19. Does Flooring Substrate Impact Kennel and Dog Cleanliness in Commercial Breeding Facilities?

    Directory of Open Access Journals (Sweden)

    Judith Stella

    2018-04-01

    Full Text Available Evaluation of kennel flooring surfaces is needed to understand their impacts on dog health and well-being. This pilot study aimed to characterize aspects of physical health, kennel cleanliness, and dog body cleanliness on flooring types common in US breeding kennels. Subjects were 118 adult dogs housed on diamond-coated expanded metal (DCEM, polypropylene (POLY, or concrete (CON flooring at five commercial breeding facilities in Indiana, U.S. Body condition, paw, elbow, and hock health scores were recorded. Each indoor kennel and dog was visually assessed for cleanliness. Kennels were swabbed immediately after cleaning with electrostatic dry cloths and cultured for Escherichia coli. Descriptive statistics were used for analysis. Mean body condition score (BCS, kennel and dog cleanliness scores were all near ideal (3, 1.15, and 1.04, respectively. Thirty-one percent or fewer kennels at each facility were culture-positive for E. coli after cleaning. No serious paw, elbow, or hock problems were identified. Overall, the findings indicate that with appropriate management and regular access to additional surfaces, dog foot health, cleanliness, and kennel cleanliness can be maintained on the flooring types investigated.

  20. Antibacterial efficacy of commercial disinfectants on dirt floor used in poultry breeder houses

    Directory of Open Access Journals (Sweden)

    F Pilotto

    2007-06-01

    Full Text Available Dirt floors are used on most Brazilian poultry farms since the construction of concrete floors is very expensive. In vitro tests carried out to verify the effectiveness of disinfectants do not consider the adverse conditions found in poultry farms. Therefore, the present study aimed at evaluating the effect of six commercial disinfectants on the reduction of total and fecal coliforms on the dirt floor of breeder houses. The amount of disinfectant solution to be used per square meter was defined by counting total and fecal coliforms at different soil depths and by analyzing soil physical properties. Coliforms were detected at 0.5 cm, and one liter of disinfectant solution was sufficient for soil saturation at this depth. After that, the efficacy of six commercial products (caustic soda, hydrated lime, phenols 1 and 2, iodine, glutaraldehyde, and quaternary ammonium in reducing the number of coliforms, after six hours of contact with the dirt floor, was assessed using the most probable number (MPN method. Escherichia coli specimens isolated from the dirt floor were used to evaluate in vitro effectiveness of disinfectants. Products that yielded the best results in the MPN method were also effective in the in vitro tests. Among the tested disinfectants, hydrated lime was the most efficient, reducing the initial contamination by 2.9 log after six hours of contact with the dirt floor.

  1. Resistance to Internal Damage and Scaling of Concrete Air Entrained By Microspheres

    Science.gov (United States)

    Molendowska, Agnieszka; Wawrzenczyk, Jerzy

    2017-10-01

    This paper report the test results of high strength concrete produced with slag cement and air entrained with polymer microspheres in three diameters. The study focused on determining the effects of the microsphere size and quantity on the air void structure and resistance to internal cracking and scaling of the concrete. The resistance to internal cracking was determined in compliance with the requirements of the modified ASTM C666 A method on beam specimens. The scaling resistance in a 3% NaCl solution was determined using the slab test in accordance with PKN-CEN/TS 12390-9:2007. The air void structure parameters were determined to PN-EN 480-11:1998. The study results indicate that the use of microspheres is an effective air entrainment method providing very good air void structure parameters. The results show high freeze-thaw durability of polymer microsphere-based concrete in exposure class XF3. The scaling resistance test confirms that it is substantially more difficult to protect concrete against scaling in the presence of the 3% NaCl solution (exposure class XF4). Concrete scaling is a complex phenomenon controlled by a number of independent factors.

  2. A Numerical Analysis of the Resistance and Stiffness of the Timber and Concrete Composite Beam

    Science.gov (United States)

    Szumigała, Ewa; Szumigała, Maciej; Polus, Łukasz

    2015-03-01

    The article presents the results of a numerical analysis of the load capacity and stiffness of the composite timber and concrete beam. Timber and concrete structures are relatively new, they have not been thoroughly tested and they are rarely used because of technological constraints. One of the obstacles to using them is difficulty with finding a method which would allow successful cooperation between concrete and timber, which has been proposed by the authors of the present article. The modern idea of sustainable construction design requires the use of new more environmentally-friendly solutions. Wood as an ecological material is easily accessible, less energy-consuming, and under certain conditions more corrosion-resistant than steel. The analysis presented in the article showed that cooperation between a wooden beam and a concrete slab on profiled steel sheeting is possible. The analysed composite beam has a greater load capacity and stiffness than the wooden beam.

  3. PRINCIPAL STRESSES IN NON-LINEAR ANALYSIS OF BAKUN CONCRETE FACED ROCKFILL DAM

    Directory of Open Access Journals (Sweden)

    Mohd Hilton Ahmad

    2017-11-01

    Full Text Available With rapid population growth and accelerating economic development, much of the world’s WATER which requires urgent attention to ensure sustainable use. Nowadays, Concrete Faced Rockfill Dam (CFRD is preferred among dam consultant due to its advantages. They are designed to withstand all applied loads; namely gravity load due to its massive weight and hydrostatic load due to water thrust from the reservoir. Bakun CFRD, which ranks as the second highest CFRD in the world when completed, is analyzed to its safety due to both loads mentioned earlier by using Finite Element Method. 2-D plane strain finite element analysis of non-linear Duncan-Chang hyperbolic Model which formulated by Duncan and Chang is used to study the structural response of the dam in respect to the deformation and stresses of Main dam of Bakun’s CFRD project. Dead-Birth-Ghost element technique was used to simulate sequences of construction of the dam as well as during reservoir fillings. The comparison of rigid and flexible foundation on the behaviour of the dam was discussed. The maximum and minimum principal stresses are the maximum and minimum possible values of the normal stresses. The maximum principal stress controls brittle fracture. In the finite element modeling the concrete slab on the upstream was represented through six-noded element, while the interface characteristic between dam body and concrete slab was modeled using interface element. The maximum settlement and stresses of the cross section was founded and the distribution of them were discussed and tabulated in form of contours.

  4. A research on the mechanical property, work efficiency and structural characteristics of heavyweight concrete

    International Nuclear Information System (INIS)

    Ishimura, Kikuo; Ooue, Minoru; Noda, Shizuo; Suzuki, Keiichi; Ishii, Takakazu; Nakazawa, Kouichi; Mitsugi, Shiro.

    1991-01-01

    Generally thickness is increased in walls and slabs to improve the shielding ability of normal concrete in the buildings in nuclear power plants. On the other hand, the decrease of thickness of members and the decrease of building size can be expected by the adoption of heavy weight concrete. But there are little principal members such as shear walls using heavy weight concrete. Therefore, the data related to the mechanical properties and the construction method are not sufficient. This study was carried out to examine the properties and the structural characteristics of heavy weight concrete, and to establish the construction method. The selection of aggregate, the properties of aggregate and the properties of heavy weight concrete are reported. Pumping test was carried out with two kinds of the mixing proportion, and its procedure and the results are shown. The heavy weight concrete was placed as wall specimens, and its procedure and the results are described. The static loading test on shear wall specimens was carried out, and its procedure and the results are reported. Magnetite and hematite ores adopted as the aggregate caused no problem. (K.I.)

  5. Crumb Rubber Recycling in Enhancing Damping Properties of Concrete

    Science.gov (United States)

    Sugapriya, P.; Ramkrishnan, R.

    2018-02-01

    Damping plays a major role in the design of roadside structures that gets affected due to vibrations transmitted from moving traffic. In this study, fine aggregates were partially replaced with crumb rubber in concrete, at varying percentages of 5, 10, 15 and 20% by weight. Three different sets of concrete, mixed with crumb rubber were prepared using raw rubber, treated rubber and treated rubber with partial replacement of cement. Cement was partially replaced with Ultra-Fine Ground Granulated Blast furnace Slag (UFGGBS) for this study. Samples were cast, cured and tested for various properties on the 7th and 28th day. The damping ratio and frequency of the peak value from a number of waves in rubber incorporated beams were found out using a FFT Analyser along with its Strength, Damping and Sorptivity characteristics. SEM analysis was conducted to analyse the micro structural bonding between rubber and concrete. The mode shapes of pavement slabs were modelled and analysed using a FEM tool, ANSYS. From the results, the behaviour of the three sets of rubberized concrete were compared and analysed, and an optimum percentage for crumb rubber and UFGGBS was proposed to achieve best possible damping without compromising the strength properties.

  6. A comparative study of floor construction on sloping sites: an analysis of cumulative energy demand and greenhouse gas emissions

    Directory of Open Access Journals (Sweden)

    Grace Ding

    2016-03-01

    Full Text Available In order to make environmentally aware decisions, there is growing interest in the comparative energy and greenhouse gas (GHG performance of competing construction methods. Little research has been done concerning competing ground floor construction methods, especially given different site variables, such as slope and soil type. A life cycle assessment approach was adopted to analyse environmental impacts, including cumulative energy demand and GHG emissions for detached housing construction in Australia. Data was drawn from 24 case study housing projects, including 12 reinforced concrete and 12 suspended timber floor projects. The data presented in the paper compares cumulative energy demand, GHG and the constituent parts of competing construction methods. The findings indicate that the timber floors use/create significantly less cumulative energy demand and GHG emissions than concrete floors—approximately 2.1 to 2.7 times less energy and 2.3 to 2.9 times less GHG. These findings are limited to the site slope and foundation soil types identified in the paper. The main application of the work is in guidance concerning the lowest environmental impact options for detached housing construction.

  7. Improvement of molten core-concrete interaction model of the debris spreading analysis model in the SAMPSON code - 15193

    International Nuclear Information System (INIS)

    Hidaka, M.; Fujii, T.; Sakai, T.

    2015-01-01

    A debris spreading analysis (DSA) module has been developed and improved. The module is used in the severe accident analysis code SAMPSON and it has models for 3-dimensional natural convection with simultaneous spreading, melting and solidification. The existing analysis method of the quasi-3D boundary transportation to simulate downward concrete erosion for evaluation of molten-core concrete interaction (MCCI) was improved to full-3D to solve, for instance, debris lateral erosion under concrete floors at the bottom of the sump pit. In the advanced MCCI model, buffer cells were defined in order to solve numerical problems in case of trammel formation. Mass, momentum, and the advection term of energy between the debris melt cells and the buffer cells are solved. On the other hand, only the heat transfer and thermal conduction are solved between the debris melt cells and the structure cells, and the crust cells and the structure cells. As a preliminary analysis, a validation calculation was performed for erosion that occurred in the core-concrete interaction (CCI-2) test in the OECD/MCCI program. Comparison between the calculation and the CCI-2 test results showed the analysis has the ability to simulate debris lateral erosion under concrete floors. (authors)

  8. Surface Waves Propagating on Grounded Anisotropic Dielectric Slab

    Directory of Open Access Journals (Sweden)

    Zhuozhu Chen

    2018-01-01

    Full Text Available This paper investigates the characteristics of surface waves propagating on a grounded anisotropic dielectric slab. Distinct from the existing analyses that generally assume that the fields of surface wave uniformly distribute along the transverse direction of the infinitely large grounded slab, our method takes into account the field variations along the transverse direction of a finite-width slab. By solving Maxwell’s equations in closed-form, it is revealed that no pure transverse magnetic (TM or transverse electric (TE mode exists if the fields are non-uniformly distributed along the transverse direction of the grounded slab. Instead, two hybrid modes, namely quasi-TM and quasi-TE modes, are supported. In addition, the propagation characteristics of two hybrid modes supported by the grounded anisotropic slab are analyzed in terms of the slab thickness, slab width, as well as the relative permittivity tensor of the anisotropic slab. Furthermore, different methods are employed to compare the analyses, as well as to validate our derivations. The proposed method is very suitable for practical engineering applications.

  9. Radon inside rooms. Results of a series of investigations in the Fichtelgebirge mountains

    International Nuclear Information System (INIS)

    Neroth, G.

    1993-01-01

    Radon measurements and structural surveys were carried out in 16 residential buildings of a village in the Upper Franconian Fichtelgebirge. It is shown by the results that the radon exposure inside the buildings is considerably influenced by the impermeability of the components in contact with the ground: old buildings with timber floors layed directly above the ground showed relatively high radon values of up to 3300 Bq/m 3 , whereas the concentrations measured in younger buildings with a continuous concrete floor slab were less than 100 Bq/m 3 . Based on the results of the investigations proposals were elaborated showing the structural measures suited for reducing the contents of radon in the most exposed buildings. (orig.) [de

  10. Nonimaging concentrators for diode-pumped slab lasers

    Science.gov (United States)

    Lacovara, Philip; Gleckman, Philip L.; Holman, Robert L.; Winston, Roland

    1991-10-01

    Diode-pumped slab lasers require concentrators for high-average power operation. We detail the properties of diode lasers and slab lasers which set the concentration requirements and the concentrator design methodologies that are used, and describe some concentrator designs used in high-average power slab lasers at Lincoln Laboratory.

  11. Effect of Using Porcelanite as Partial Replacement of Fine Aggregate on Roller Compacted Concrete with Different Curing Methods

    Directory of Open Access Journals (Sweden)

    Abeer Abdulqader Salih

    2016-09-01

    Full Text Available Roller-Compacted Concrete is a no-slump concrete, with no reinforcing steel, no forms, no finishing and wet enough to support compaction by vibratory rollers. Due to the effect of curing on properties and durability of concrete, the main purpose of this research is to study the effect of various curing methods (air curing, 7 days water curing, and permanent water curing and porcelanite (local material used as an Internal Curing agent with different replacement percentages of fine aggregate (volumetric replacement on some properties of Roller-Compacted Concrete and to explore the possibility of introducing practical Roller-Compacted Concrete for road pavement with minimum requirement of curing. Specimens were sawed from slabs of (380*380*100 mm for determination of Ultrasonic Pulse Velocity (UPV and Voids volume. Results show that using (5 % porcelanite improved the results of UPV and Voids volume of Roller-Compacted Concrete (with air curing as compared with reference Roller-Compacted Concrete (with permanent water curing by percentages ranging from(3.6 to 28.9% and (-8 to -15.5% respectively.

  12. Evidence of fire resistance of hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    is therefore going on in the Netherlands about the fire resistance of hollow-core slabs. In 2014 the producers of hollow-core slabs have published a report of a project called Holcofire containing a collection of 162 fire tests on hollow-core slabs giving for the first time an overview of the fire tests made....... The present paper analyses the evidence now available for assessment of the fire resistance of extruded hollow-core slabs. The 162 fire tests from the Holcofire report are compared against the requirements for testing from the product standard for hollow-core slabs EN1168 and knowledge about the possible......Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes...

  13. Feasibility of Steel Fiber-Reinforced Rubberized Concrete in Cold Regions for High Volume Intersections

    Science.gov (United States)

    Abou Eid, Mahear A.

    There are many challenges faced with the use of Portland Cement Concrete (PCC) in cold regions, but with the inclusion of new technologies such as steel fibers and recycled tire crumb rubber efficient construction may be possible. Research was conducted on a modified concrete material that included both steel fibers and crumb rubber. The composite material was called Steel Fiber-Reinforced Rubberized Concrete (SFRRC). The objective of this investigation was to provide evidence showing that SFRRC can reduce tire rutting compared to asphaltic pavement. In addition, the research showed that the SFRRC could withstand freeze-thaw cycles and increase service life of roadways. Several tests were performed to determine the characteristics of the material. Freeze-thaw testing was performed to determine compressive strength loss and visual deterioration of the material. Wheel tracker rut testing was performed both with the standard steel wheel and with a modified studded rubber tire to determine plastic deformation and rut resistance. An experimental test slab was cast in place on a public approach to observe the construction procedures, the effects of studded tire wear and the frost actions in cold region conditions. Based on freeze-thaw and wheel tracker test results and observations of the experimental test slab, the SFRRC material shows viability in cold regions for resisting freeze-thaw actions. The freeze-thaw testing resulted in increased compressive strength after 300 freeze-thaw cycles and very low deterioration of material compared to standard PCC. The wheel tracker testing resulted in very low plastic deformation and minor material rutting with use of the studded rubber tire. The test slab showed very minor surface wear, no freeze-thaw cracking and no rutting after one winter of use. It is recommended that further testing of the material be conducted by means of a large-scale trial section. This would provide information with respect to cost analysis and

  14. The Vibration Based Fatigue Damage Assessment of Steel and Steel Fiber Reinforced Concrete (SFRC Composite Girder

    Directory of Open Access Journals (Sweden)

    Xu Chen

    2015-01-01

    Full Text Available The steel-concrete composite girder has been usually applied in the bridge and building structures, mostly consisting of concrete slab, steel girder, and shear connector. The current fatigue damage assessment for the composite girder is largely based on the strain values and concrete crack features, which is time consuming and not stable. Hence the vibration-based fatigue damage assessment has been considered in this study. In detail, a steel-steel fiber reinforced concrete (SFRC composite girder was tested. The steel fiber reinforced concrete is usually considered for dealing with the concrete cracks in engineering practice. The composite girder was 3.3m long and 0.45m high. The fatigue load and impact excitation were applied on the specimen sequentially. According to the test results, the concrete crack development and global stiffness degradation during the fatigue test were relatively slow due to the favourable performance of SFRC in tension. But on the other hand, the vibration features varied significantly during the fatigue damage development. Generally, it confirmed the feasibility of executing fatigue damage assessment of composite bridge based on vibration method.

  15. Flowing Air-Water Cooled Slab Nd: Glass Laser

    Science.gov (United States)

    Lu, Baida; Cai, Bangwei; Liao, Y.; Xu, Shifa; Xin, Z.

    1989-03-01

    A zig-zag optical path slab geometry Nd: glass laser cooled through flowing air-water is developed by us. Theoretical studies on temperature distribution of slab and rod configurations in the unsteady state clarify the advantages of the slab geometry laser. The slab design and processing are also reported. In our experiments main laser output characteristics, e. g. laser efficiency, polarization, far-field divergence angle as well as resonator misalignment are investigated. The slab phosphate glass laser in combination with a crossed Porro-prism resonator demonstrates a good laser performance.

  16. Long term bending behavior of ultra-high performance concrete (UHPC beams

    Directory of Open Access Journals (Sweden)

    Gheorghe-Alexandru BARBOS

    2015-12-01

    Full Text Available Unlike normal concrete (NC the behavior of ultra-high performance concrete (UHPC is different under long-term efforts, if we refer to creep, shrinkage or long-term deflections. It is well known that UHPC has special properties, like compressive strength higher than 150 MPa and tensile strength higher than 20 MPa - in case of UHPC reinforced with steel-fibers. Nevertheless, UHPC behavior is not completely elucidated in what concerns creep straining or serviceability behavior in case of structural elements. Some studies made on UHPC samples shown that creep is significantly reduced if the concrete is subjected to heat treatment and if it contains steel-fiber reinforcement. Relating thereto, it is important to know how does structural elements made of this type of concrete works in service life under long-term loadings. The results obtained on UHPC samples, regarding creep straining from tension or compression efforts may not be generalized in case of structural elements (e.g. beams, slabs, columns subjected to bending. By performing this study, it was aimed to understand the influence of heat treatment and steel-fiber addition on the rheological phenomena of UHPC bended beams.

  17. Cracked reinforced concrete walls of chimneys, silos and cooling towers as result of using formworks

    Directory of Open Access Journals (Sweden)

    Maj Marek

    2018-01-01

    Full Text Available There are presented in this paper some problems connected with reinforced concrete shell objects operation in the aggressive environment and built in method of formworks. Reinforced concrete chimneys, cooling towers, silos and other shells were built for decades. Durability of cracked shells are one of the most important parameters during process of designing, construction and exploitation of shells. Some reasons of appearance of horizontal and vertical cracks as temperature, pressure of stored material, live loads e.g. dynamic character of wind, moisture, influence of construction joints, thermal insulation, chemistry active environmental etc. reduce the carrying capacity of the walls. Formworks, as is occurred recently, are the reason for technological joints with leaking connection, imperfections of flexible formworks slabs and as result can initiate cracks. Cracked surface of this constructions causes decreasing capacity and lower the state of reliability. Horizontal, vertical cracks can caused corrosion of concrete and steel bars, decreasing stiffness of contraction, increasing of deflection and carbonation of concrete cover. Local and global imperfactions of concrete shells are increasing according to greater number of cracks...

  18. Fire resistance of a steel plate reinforced concrete bearing wall

    International Nuclear Information System (INIS)

    Kodaira, Akio; Kanchi, Masaki; Fujinaka, Hideo; Akita, Shodo; Ozaki, Masahiko

    2003-01-01

    Samples from a steel plate reinforced concrete bearing wall composed of concrete slab sandwiched between studded steel plates, were subjected to loaded fire resistance tests. There were two types of specimens: some were 1800 mm high while the rest were 3000 mm high ; thickness and width were the same for all specimens, at 200 mm and 800 mm, respectively. Under constant load conditions, one side of each specimen was heated along the standard fire-temperature curve. The results enabled us to approximate the relationship between the ratio of working load to concrete strength N/(Ac x c σ b) and the fire resistance time (t: minutes), as equation (1) for the 1800 mm - high specimen, and equation (2) for the 3000 mm - high specimen. N/(Ac x c σ b) = 2.21 x (1/t) 0.323 (1), .N/(Ac x c σ b) 2.30 x (1/t) 0.378 (2) In addition, the temperature of the unheated side of the specimens was 100degC at 240 minutes of continuous heating, clearly indicating that there was sufficient heat insulation. (author)

  19. A Numerical Analysis of the Resistance and Stiffness of the Timber and Concrete Composite Beam

    Directory of Open Access Journals (Sweden)

    Szumigała Ewa

    2015-03-01

    Full Text Available The article presents the results of a numerical analysis of the load capacity and stiffness of the composite timber and concrete beam. Timber and concrete structures are relatively new, they have not been thoroughly tested and they are rarely used because of technological constraints. One of the obstacles to using them is difficulty with finding a method which would allow successful cooperation between concrete and timber, which has been proposed by the authors of the present article. The modern idea of sustainable construction design requires the use of new more environmentally-friendly solutions. Wood as an ecological material is easily accessible, less energy-consuming, and under certain conditions more corrosion-resistant than steel. The analysis presented in the article showed that cooperation between a wooden beam and a concrete slab on profiled steel sheeting is possible. The analysed composite beam has a greater load capacity and stiffness than the wooden beam.

  20. Empirical Validation of Heat Transfer Performance Simulation of Graphite/PCM Concrete Materials for Thermally Activated Building System

    Directory of Open Access Journals (Sweden)

    Jin-Hee Song

    2017-01-01

    Full Text Available To increase the heat capacity in lightweight construction materials, a phase change material (PCM can be introduced to building elements. A thermally activated building system (TABS with graphite/PCM concrete hollow core slab is suggested as an energy-efficient technology to shift and reduce the peak thermal load in buildings. An evaluation of heat storage and dissipation characteristics of TABS in graphite/PCM concrete has been conducted using dynamic simulations, but empirical validation is necessary to acceptably predict the thermal behavior of graphite/PCM concrete. This study aimed to validate the thermal behavior of graphite/PCM concrete through a three-dimensional transient heat transfer simulation. The simulation results were compared to experimental results from previous studies of concrete and graphite/PCM concrete. The overall thermal behavior for both materials was found to be similar to experiment results. Limitations in the simulation modeling, which included determination of the indoor heat transfer coefficient, assumption of constant thermal conductivity with temperature, and assumption of specimen homogeneity, led to slight differences between the measured and simulated results.

  1. Finite element analysis of composite concrete-timber beams

    Directory of Open Access Journals (Sweden)

    N. C. S. FORTI

    Full Text Available AbstractIn the search for sustainable construction, timber construction is gaining in popularity around the world. Sustainably harvested wood stores carbon dioxide, while reforestation absorbs yet more CO2. One technique involves the combination of a concrete slab and a timber beam, where the two materials are assembled by the use of flexible connectors. Composite structures provide reduced costs, environmental benefits, a better acoustic performance, when compared to timber structures, and maintain structural safety. Composite structures combine materials with different mechanical properties. Their mechanical performance depends on the efficiency of the connection, which is designed to transmit shear longitudinal forces between the two materials and to prevent vertical detachment. This study contributes with the implementation of a finite element formulation for stress and displacement determination of composite concrete-timber beams. The deduced stiffness matrix and load vector are presented along to numerical examples. Numerical examples are compared to the analytical equations available in Eurocode 5 and to experimental data found in the literature.

  2. Early age damage quantification of actively restrained concrete using inverse analysis

    Science.gov (United States)

    Albanna, Ali

    Early-age cracking can be a significant problem in concrete pavements, floors, and bridge decks. Cracking occurs when the volumetric changes associated with drying, hydration, and temperature reduction are prevented. Good knowledge about the characteristics of early age concrete is necessary to achieve reliable crack control. Volumetric changes due to shrinkage depend on the type of concrete and its components. It has been found that light weight aggregates can work as internal reservoir to supply the concrete matrix with water that is needed during the early age; this process is called internal curing. Also fibers can give more ductility to the concrete and produce less shrinkage. There is a need to better understand the effects of early age uniaxial restraint on long term concrete mechanical performance. In this study, two types of concrete were studied (high performance fiber reinforced concrete and ordinary concrete) under actively restrained loading conditions to assess the effect on the long term fracture toughness and energy. Single edge notched specimens having dimensions of 250 mm x 150 mm x 75 mm and a notch to depth ratio of 0.33 were caste and used in both direct tension and three point bending. The direct tension tests were carried out on a direct tension loading frame constructed in house that was supplied with two mechanical jacks and load cell.

  3. Mantle wedge serpentinization effects on slab dips

    Directory of Open Access Journals (Sweden)

    Eh Tan

    2017-01-01

    Full Text Available The mechanical coupling between a subducting slab and the overlying mantle wedge is an important factor in controlling the subduction dip angle and the flow in mantel wedge. This paper investigates the role of the amount of mantle serpentinization on the subduction zone evolution. With numerical thermos-mechanical models with elasto-visco-plastic rheology, we vary the thickness and depth extent of mantle serpentinization in the mantle wedge to control the degree of coupling between the slab and mantle wedge. A thin serpentinized mantle layer is required for stable subduction. For models with stable subduction, we find that the slab dip is affected by the down-dip extent and the mantle serpentinization thickness. A critical down-dip extent exists in mantle serpentinization, determined by the thickness of the overriding lithosphere. If the down-dip extent does not exceed the critical depth, the slab is partially coupled to the overriding lithosphere and has a constant dip angle regardless of the mantle serpentinization thickness. However, if the down-dip extent exceeds the critical depth, the slab and the base of the overriding lithosphere would be separated and decoupled by a thick layer of serpentinized peridotite. This allows further slab bending and results in steeper slab dip. Increasing mantle serpentinization thickness will also result in larger slab dip. We also find that with weak mantle wedge, there is no material flowing from the asthenosphere into the serpentinized mantle wedge. All of these results indicate that serpentinization is an important ingredient when studying the subduction dynamics in the mantle wedge.

  4. Processing and properties of large-sized ceramic slabs

    Directory of Open Access Journals (Sweden)

    Fossa, L.

    2010-10-01

    Full Text Available Large-sized ceramic slabs – with dimensions up to 360x120 cm2 and thickness down to 2 mm – are manufactured through an innovative ceramic process, starting from porcelain stoneware formulations and involving wet ball milling, spray drying, die-less slow-rate pressing, a single stage of fast drying-firing, and finishing (trimming, assembling of ceramic-fiberglass composites. Fired and unfired industrial slabs were selected and characterized from the technological, compositional (XRF, XRD and microstructural (SEM viewpoints. Semi-finished products exhibit a remarkable microstructural uniformity and stability in a rather wide window of firing schedules. The phase composition and compact microstructure of fired slabs are very similar to those of porcelain stoneware tiles. The values of water absorption, bulk density, closed porosity, functional performances as well as mechanical and tribological properties conform to the top quality range of porcelain stoneware tiles. However, the large size coupled with low thickness bestow on the slab a certain degree of flexibility, which is emphasized in ceramic-fiberglass composites. These outstanding performances make the large-sized slabs suitable to be used in novel applications: building and construction (new floorings without dismantling the previous paving, ventilated façades, tunnel coverings, insulating panelling, indoor furnitures (table tops, doors, support for photovoltaic ceramic panels.

    Se han fabricado piezas de gran formato, con dimensiones de hasta 360x120 cm, y menos de 2 mm, de espesor, empleando métodos innovadores de fabricación, partiendo de composiciones de gres porcelánico y utilizando, molienda con bolas por vía húmeda, atomización, prensado a baja velocidad sin boquilla de extrusión, secado y cocción rápido en una sola etapa, y un acabado que incluye la adhesión de fibra de vidrio al soporte cerámico y el rectificado de la pieza final. Se han

  5. Experimental and Numerical Studies of Controlling Thermal Cracks in Mass Concrete Foundation by Circulating Water

    Directory of Open Access Journals (Sweden)

    Wenchao Liu

    2016-04-01

    Full Text Available This paper summarizes an engineering experience of solving the problem of thermal cracking in mass concrete by using a large project, Zhongguancun No.1 (Beijing, China, as an example. A new method is presented for controlling temperature cracks in the mass concrete of a foundation. The method involves controlled cycles of water circulating between the surface of mass concrete foundation and the atmospheric environment. The temperature gradient between the surface and the core of the mass concrete is controlled at a relatively stable state. Water collected from the well-points used for dewatering and from rainfall is used as the source for circulating water. Mass concrete of a foundation slab is experimentally investigated through field temperature monitoring. Numerical analyses are performed by developing a finite element model of the foundation with and without water circulation. The calculation parameters are proposed based on the experiment, and finite element analysis software MIDAS/CIVIL is used to calculate the 3D temperature field of the mass concrete during the entire process of heat of hydration. The numerical results are in good agreement with the measured results. The proposed method provides an alternative practical basis for preventing thermal cracks in mass concrete.

  6. Damage Model of Reinforced Concrete Members under Cyclic Loading

    Science.gov (United States)

    Wei, Bo Chen; Zhang, Jing Shu; Zhang, Yin Hua; Zhou, Jia Lai

    2018-06-01

    Based on the Kumar damage model, a new damage model for reinforced concrete members is established in this paper. According to the damage characteristics of reinforced concrete members subjected to cyclic loading, four judgment conditions for determining the rationality of damage models are put forward. An ideal damage index (D) is supposed to vary within a scale of zero (no damage) to one (collapse). D should be a monotone increasing function which tends to increase in the case of the same displacement amplitude. As for members under large displacement amplitude loading, the growth rate of D should be greater than that of D under small amplitude displacement loading. Subsequently, the Park-Ang damage model, the Niu-Ren damage model, the Lu-Wang damage model and the proposed damage model are analyzed for 30 experimental reinforced concrete members, including slabs, walls, beams and columns. The results show that current damage models do not fully matches the reasonable judgment conditions, but the proposed damage model does. Therefore, a conclusion can be drawn that the proposed damage model can be used for evaluating and predicting damage performance of RC members under cyclic loading.

  7. Finite element analysis-based study of fiber Bragg grating sensor for cracks detection in reinforced concrete

    Science.gov (United States)

    Wang, Lili; Xin, Xiangjun; Song, Jun; Wang, Honggang; Sai, Yaozhang

    2018-02-01

    Fiber Bragg sensor is applied for detecting and monitoring the cracks that occur in the reinforced concrete. We use the three-dimensional finite element model to provide the three-axial stresses along the fiber Bragg sensor and then converted the stresses as a wavelength deformation of fiber Bragg grating (FBG) reflected spectrum. For the crack detection, an FBG sensor with 10-mm length is embedded in the reinforced concrete, and its reflection spectrum is measured after loading is applied to the concrete slab. As a result, the main peak wavelength and the ratio of the peak reflectivity to the maximal side-mode reflectivity of the optic-fiber grating represent the fracture severity. The fact that the sharp decreasing of the ratio of the peak reflectivity to the maximal side-mode reflectivity represents the early crack is confirmed by the theoretical calculation. The method can be used to detect the cracks in the reinforced concrete and give safety evaluation of large-scale infrastructure.

  8. Storm-time slab thickness at low latitudes

    International Nuclear Information System (INIS)

    Chauhan, N.S.; Gurm, H.S.

    1981-01-01

    The ATS-6 data for a period of 1975-76 is used for the study of slab thickness during two moderate storms (Ksub(p) - ) around the crest of the anomaly, Ahmedabad and a very great (Ksub(p) + ) outside the equatorial anomaly region, Delhi. While at Ahmedabad, on the average, the slab thickness is found to be above the frequency. Comparison of slab thickness with foF2 and the equatorial magnetic record (for Ahmedabad only) shows that the foF2 changes alone cannot be held responsible for the slab thickness variation and thus entry of the plasma flux from the plasmasphere cannot be ruled out. The pressure variation effect of storm-time heating on the slab thickness at Ahmedabad is that even for Ksub(p)=8, the thermal expansion and the contraction effects are unable to explain complete quantitative and qualitative features of the observations

  9. Bond characteristics of steel fiber and deformed reinforcing steel bar embedded in steel fiber reinforced self-compacting concrete (SFRSCC)

    Science.gov (United States)

    Aslani, Farhad; Nejadi, Shami

    2012-09-01

    Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of the self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, ductility, toughness, energy absorption capacity, fracture toughness and cracking. Although the available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates the bond characteristics between steel fiber and SCC firstly. Based on the available experimental results, the current analytical steel fiber pullout model (Dubey 1999) is modified by considering the different SCC properties and different fiber types (smooth, hooked) and inclination. In order to take into account the effect of fiber inclination in the pullout model, apparent shear strengths ( τ ( app)) and slip coefficient ( β) are incorporated to express the variation of pullout peak load and the augmentation of peak slip as the inclined angle increases. These variables are expressed as functions of the inclined angle ( ϕ). Furthurmore, steel-concrete composite floors, reinforced concrete floors supported by columns or walls and floors on an elastic foundations belong to the category of structural elements in which the conventional steel reinforcement can be partially replaced by the use of steel fibers. When discussing deformation capacity of structural elements or civil engineering structures manufactured using SFRSCC, one must be able to describe thoroughly both the behavior of the concrete matrix reinforced with steel fibers and the interaction between this composite matrix and discrete steel reinforcement of the conventional type. However, even though the knowledge on bond behavior is essential for evaluating the overall behavior of structural components containing reinforcement and steel fibers

  10. Summary of Uranium Solubility Studies in Concrete Waste Forms and Vadose Zone Environments

    Energy Technology Data Exchange (ETDEWEB)

    Golovich, Elizabeth C.; Wellman, Dawn M.; Serne, R. Jeffrey; Bovaird, Chase C.

    2011-09-30

    One of the methods being considered for safely disposing of Category 3 low-level radioactive wastes is to encase the waste in concrete. Concrete encasement would contain and isolate the waste packages from the hydrologic environment and act as an intrusion barrier. The current plan for waste isolation consists of stacking low-level waste packages on a trench floor, surrounding the stacks with reinforced steel, and encasing these packages in concrete. These concrete-encased waste stacks are expected to vary in size with maximum dimensions of 6.4 m long, 2.7 m wide, and 4 m high. The waste stacks are expected to have a surrounding minimum thickness of 15 cm of concrete encasement. These concrete-encased waste packages are expected to withstand environmental exposure (solar radiation, temperature variations, and precipitation) until an interim soil cover or permanent closure cover is installed and to remain largely intact thereafter. Any failure of concrete encasement may result in water intrusion and consequent mobilization of radionuclides from the waste packages. This report presents the results of investigations elucidating the uranium mineral phases controlling the long-term fate of uranium within concrete waste forms and the solubility of these phases in concrete pore waters and alkaline, circum-neutral vadose zone environments.

  11. Experimental Investigation on Damping Property of Coarse Aggregate Replaced Rubber Concrete

    Science.gov (United States)

    Sugapriya, P.; Ramkrishnan, R.; Keerthana, G.; Saravanamurugan, S.

    2018-02-01

    Rubber has good damping and vibrational characteristics and can reduce cracking significantly due to its elastic nature. This property of rubber can be incorporated in concrete to control vibrations and create better pavements. Crumb Rubber on being dumped in landfills has serious repercussions and causes soil and land pollution. An innovative use of waste tires is shredding them into small pieces and using them as a replacement for coarse aggregate. Crumb rubber is obtained by chopping scrap tires, and in this study it was added in two different sets named SET 1 - Treated Crumb Rubber and concrete, and SET 2 - Treated Crumb rubber with Ultra Fine GGBS as admixture in concrete. Coarse aggregate replaces Rubber in each of the 2 SET’s in proportions of 5, 10, 15 and 20%. Properties like Compressive Strength, Young’s Modulus, Direct and Semi direct Ultrasonic Pulse Velocity, Sorptivity, Damping ratio and Frequency were found out. Deformation and mode shape were studied with modal analysis and static analysis by applying a uniform pressure corresponding to the highest compressive strength of the slab, using ANSYS.

  12. Prevention of concrete structures from collapsing

    Directory of Open Access Journals (Sweden)

    Cechmanek R.

    2018-01-01

    Full Text Available At the end of the 20th century requirements on using electrical properties of building materials emerged for application in heating of trafficable surfaces, grounding of electrostatic charges in floors, shielding of electro-magnetic fields and diagnosis of concrete structure state in the course of time. For this reason, it was necessary to design special fibre-cement elements able to transfer any mechanical impulse to an electricallymeasured signal detected as a change in electrical resistance with computer outputs. Regarding previous research studies, it was concluded that special fibre-cement composites are able to conduct electric current under specific conditions. This property is ensured by using of various kinds of carbon materials. Though carbon fibres are less conductive than metal fibres, composites with carbon fibres were evaluated as better current conductors than the composites with metal fibres. By means of various kinds of carbon particles and fibres it is possible to design cement composites with an ability to monitor changes in electrical conductivity of concretes. The designed composites are assembled with conductive wires and connected with a special electronic equipment for monitoring of changes in alternate voltage passing through the tensometer within mechanical loading of a concrete element in which the composite is integrated. The tensometers are placed preferably into parts of the concrete elements subjected to compression, such as simple reinforced columns or upper parts of longitudinal beams. Several tests of repeated loading and simultaneous monitoring of vertical as well as horizontal prefabricated concrete elements were carried out and evaluated.

  13. RESTORING A DAMAGED 16-YEAR -OLD INSULATING POLYMER CONCRETE DIKE OVERLAY: REPAIR MATERIALS AND TECHNOLOGIES.

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA,T.

    2007-01-01

    The objective of this program was to design and formulate organic polymer-based material systems suitable for repairing and restoring the overlay panels of insulating lightweight polymer concrete (ILPC) from the concrete floor and slope wall of a dike at KeySpan liquefied natural gas (LNG) facility in Greenpoint, Brooklyn, NY, just over sixteen years ago. It also included undertaking a small-scale field demonstration to ensure that the commercial repairing technologies were applicable to the designed and formulated materials.

  14. Rewetting of composite slab

    International Nuclear Information System (INIS)

    Satapathy, A.K.; Singh, K.C.

    1996-01-01

    The process of re-establishment of wetting of hot surface is of practical importance in chemical, metallurgical and nuclear industries. Rewetting is considered in emergency core cooling in nuclear reactors in the event of postulated loss of coolant accident (LOCA). This paper deals with numerical solution of the two-dimensional quasi-static conduction controlled rewetting of an infinite parallel sided composite slab assuming perfect contact is maintained at the interface. On the wetted side upstream of the quench front, a constant heat transfer coefficient is assumed. The downstream of quench front and unwetted side of slab are supposed to be adiabatic. The solution gives the quench front temperature as a function of various model parameters such as Peclet number, wet side Blot number, dimensionless thickness of slab and cladding to fuel ratio of thermal conductivities. The results show that for large values of rewetting velocities, the dimensionless rewetting temperature is unaffected by fuel properties for all values of Blot numbers. (author). 7 refs., 2 tabs., 1 fig

  15. Proportioning of Lightweight Concrete by the Inclusions of Expanded Polystyrene Beads (EPS and Foam Agent

    Directory of Open Access Journals (Sweden)

    Eethar Thanon Dawood

    2016-10-01

    Full Text Available This paper illustrates the performance of lightweight concrete using various amounts of expanded polystyrene beads (EPS and different amounts of foam agent to produce lightweight concrete. The objective of this paper is to produce lightweight concrete with good workability and strength, by different mix proportion of foam agent (0.4, 0.6, 0.8, 1, 1.2 kg/m3 and varying water cement ratio (w/c depending on the flow. Besides, various proportions using different percentages of EPS in order of volume fractions are used. The flow range used in the study is 110-130%. Each mix proportion is tested for compressive strength, modulus of rupture, density and voids ratio. The results gives acceptable ranges of strength for lightweight concrete produced by the inclusions of EPS beads and foam concrete. Therefore, the lightweight concrete produced in this work can be used for structural applications like multistory building frames, floors, bridges and prestressed or precast elements. 

  16. Analysis of an Attached Sunspace with a Thermal Inertia Floor

    Directory of Open Access Journals (Sweden)

    María José Suárez López

    2018-05-01

    Full Text Available An attached sunspace is a partially or fully glazed enclosure, usually located on the first floor, facing south (in the Northern Hemisphere and adjacent to a conditioned room. Because of the length and orientation of the glazed area, the temperature in the sunspace is usually higher than outside the building. As a Trombe–Mitchel wall, the sunspace has a considerable mass that accumulates thermal energy, but in this case the thermal mass is located in the floor. This capacity to accumulate thermal energy confers the attached sunspace features beyond passive insulation. The sunspace studied in this paper is part of an experimental building located in the North of Spain that was built in the frame of the so-called ARFRISOL project. It consists of a south-facing glazed exterior wall with both clear glass and semi-transparent photovoltaic panels, an intermediate space with a thick layer of sand over a concrete floor, and a partially glazed interior wall. In this paper, a three-dimensional computational model has been implemented to analyse the thermal behaviour inside the sunspace. This analysis takes into account, among other factors, the effects of sun position, incident solar irradiation and temperature both inside and outside.

  17. Effect of elevated temperatures on heavy concrete structural strength in Qinshan phase 3 CANDU 6 reactor buildings

    International Nuclear Information System (INIS)

    Alikhan, S.; Khan, A.F.; Chen, S.

    2005-01-01

    Heavy concrete is commonly used inside the Qinshan Phase 3 CANDU 6 reactor buildings for radiation shielding functions in order to provide access to key areas during reactor operation. In some cases, the heavy concrete elements are also structural elements. Concerns have been raised about the functional performance of the heavy concrete structural elements, specifically the primary heat transport pump (PHTS) supporting slabs, surrounding the feeder cabinets when subjected to elevated temperatures between 42 degree C and 121 degree C and their corresponding temperature gradients on a long-term basis during the normal operation of the plant. This paper presents the results of a test investigation on the strength of heavy concrete under elevated temperature conditions being experienced by the heavy concrete structural elements around the feeder cabinet to confirm that these structural elements meet their functional requirements. The loading conditions consist subjecting the specimens to the elevated temperatures and temperature gradient noted during commissioning, including the effect of epoxy coating. The heavy concrete mix proportion and materials of the test samples (ilmenite aggregate and Portland cement) are identical to those used for heavy concrete structural elements surrounding the feeder cabinet. Subsequent to the confirmation of the functional requirements of the heavy concrete structural elements, alarm limits are recommended for these structural elements. (authors)

  18. Simulation of heat and mass transfer processes in molten core debris-concrete systems. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Felde, D K

    1979-01-01

    The heat and mass transport phenomena taking place in volumetrically-heated fluids have become of interest in recent years due to their significance in assessments of fast reactor safety and post-accident heat removal (PAHR). Following a hypothetical core disruptive accident (HCDA), the core and reactor internals may melt down. The core debis melting through the reactor vessel and guard vessel may eventually contact the concrete of the reactor cell floor. The interaction of the core debris with the concrete as well as the melting of the debris pool into the concrete will significantly affect efforts to prevent breaching of the containment and the resultant release of radioactive effluents to the environment.

  19. Nonlinear soil-structure interaction due to base slab uplift on the seismic response of an HTGR plant

    International Nuclear Information System (INIS)

    Kennedy, R.P.; Short, S.A.; Wesley, D.A.; Lee, T.H.

    1975-01-01

    The importance of the nonlinear soil-structure interaction effects resulting from substantial base slab uplift occurring during a seismic excitation are evaluated. The structure considered consisted of the containment building and prestressed concrete reactor vessel for a typical HTGR plant. A simplified dynamic mathematical model was utilized consisting of a conventional lumped mass structure with soil-structure interaction accounted for by translational and rotational springs whose properties are determined by elastic half space theory. Three different site soil conditions (a rock site, a moderately stiff soil and a soft soil site) and two levels of horizontal ground motion (0.3g and 0.5g earthquakes) were considered. It may be concluded that linear analysis can be used to conservatively estimate the important behavior of the base slab, even under conditions of substantial base slab uplift. For all cases investigated, linear analysis resulted in higher base overturning moments, greater toe pressures, and greater heel uplift distances than nonlinear analyses. It may also be concluded that the nonlinear effect of uplift does not result in any significant lengthening of the fundamental period of the structure. Also, except in the short period region only negligible differences exist between instructure response spectra based on linear analysis and those based on nonlinear analysis. Finally, for sites in which soil-structure interaction is not significant, as for the rock site, the peak structural response at all locations above the base mat are not significantly influenced by the nonlinear effects of base slab uplift. However, for the two soil sites, the peak shears and moments are, in a few instances, significantly different between linear and nonlinear analyses

  20. Effects of rubber flooring during the first 2 lactations on production, locomotion, hoof health, immune functions, and stress.

    Science.gov (United States)

    Eicher, S D; Lay, D C; Arthington, J D; Schutz, M M

    2013-06-01

    Some housing systems on dairy farms can result in long-term chronic pain. The effects of acute pain on immunity have been explored, but chronic pain's influence on immune responses is still poorly understood. Therefore, the objective of this research was to determine chronic effects of flooring on immune responses and production in freestall housing for dairy cows. Thirty heifers were studied from before calving as first-calf heifers until d 180 of their second lactation. Treatments were rubber (Kraiburg; Agromatic Inc., Fond du Lac, WI) flooring or concrete with diamond grooves in a freestall barn, each in 2 quadrants of the barn. Heifers entered the treatments after calving, so the system was dynamic and each cow was considered an experimental unit. At the end of the first lactation, cows were housed in a bedded pack barn with pasture access until calving was imminent. At that time, they returned to their assigned treatment, but not necessarily into the same quadrant. Production, reproduction, cortisol, acute-phase proteins, and health data were recorded throughout lactation 1, locomotion was scored weekly, and hoof scoring and care was conducted on d 60 and 180 of lactations 1 and 2, and quantitative real-time-PCR of blood leukocytes was analyzed in mid lactation of lactation 1. Mature-equivalent milk fat, milk protein, and protein percentages during the first lactation were greater for cows on the rubber flooring. Hoof and leg therapy treatments per cow were fewer for rubber floor-housed cows. Locomotion scores were less for cows housed on rubber during the second lactation. White blood cell counts were less for cows housed on rubber, and caused by greater lymphocyte counts for cows housed on concrete. The possibility of chronic inflammation was substantiated by less IL-1β and more IL-1 receptor antagonists for cows housed on rubber at d 150 in the second lactation. Cortisol and acute-phase proteins did not differ between the treatments. Interferon-γ, IL-12

  1. 预制缝隙式线性排水沟透水水泥混凝土地面施工技术研究%Floor Construction Technology for Prefabricated Slits Linear Drainage System of Permeable Cement Concrete

    Institute of Scientific and Technical Information of China (English)

    陈海阳; 何飞

    2017-01-01

    透水水泥混凝土是一种新型多孔轻质混凝土,孔隙率大,透气、透水效果好.预制缝隙式线性排水沟透水水泥混凝土地面渗排水速度快,可避免洪涝灾害发生,符合国家"海绵城市"建设政策,能够改善城市水循环,调节空间温度和湿度,在促进节能减排、建设人与自然和谐发展过程中具有重要作用.%Cement Pervious Concrete is a kind of lightweight concrete with large porosity, which is breathable and permeable. Prefabricated slits linear drainage system with Cement Pervious Concrete floor will induce the water quickly into the ground to maintain the ecological balance of groundwater resources, improve urban heat circulation, regulate urban space temperature and humidity, which plays an important role with the promotion of energy conservation, and the process construction of the harmonious development between human and nature.

  2. Effects of flooring and restricted freestall access on behavior and claw health of dairy heifers.

    Science.gov (United States)

    Ouweltjes, W; van der Werf, J T N; Frankena, K; van Leeuwen, J L

    2011-02-01

    Claw health, locomotion, feed intake, milk yield, body weight, activity, and lying and standing behavior of dairy heifers were monitored in a single dairy herd during the first 3 mo after calving. During the first 8 wk after calving, 2 treatments were applied: restricted freestall access by closing the stalls between 2300 h and 0500 h (yes or no) and alley flooring (concrete or rubber topped slatted floors). Apart from treatments, housing was identical. The animals were kept in small groups (n=4 to 6) in adjacent barn pens. Thereafter, the animals were kept in 1 group in a freestall section with concrete slatted floor and unrestricted access to the stalls for 5 wk. All animals were fed the same partial mixed ration. We hypothesized that (1) hard flooring causes high mechanical load of the claws and (2) restricted freestall access causes prolonged standing bouts and reinforced effects of hard flooring on claws. The heifers had only minor claw lesions before first calving, and the prevalence and severity of sole hemorrhages increased during the first 3 mo after calving (from 0.24 ± 0.08 to 1.18 ± 0.14 and from 0.04 ± 0.01 to 0.24 ± 0.02, respectively), particularly in the outer hind claws. Animals kept on rubber alley flooring had lower average hemorrhage scores in wk 9 (0.13 ± 0.03 vs. 0.21 ± 0.03) and wk 14 (0.20 ± 0.03 vs. 0.27 ± 0.03) after calving, had a slower feed intake (3.05 ± 0.14 vs. 3.46 ± 0.14 g/s) and spent more time feeding (7.3 ± 0.3 vs. 6.6 ± 0.3 min/h) than animals kept on hard concrete alley floors. Restricted freestall access resulted in fewer standing bouts per day (14.4 ± 1.0 vs. 17.9 ± 1.0) and more strides per hour (99.8 ± 5.4 vs. 87.2 ± 5.4) without changing overall standing time (15.0 ± 0.3 vs. 14.7 ± 0.3 h/d) and did not affect the occurrence of sole hemorrhages. The animals with no overnight freestall access spent more time standing (55.9 ± 0.9 vs. 35.8 ± 0.9 min/h) and feeding (7.8 ± 0.3 vs. 4.3 ± 0.3 min/h) between

  3. Innovative technology summary report: Concrete grinder

    International Nuclear Information System (INIS)

    1998-09-01

    The Flex concrete grinder is a lightweight, hand-held concrete and coating removal system used for decontaminating or stripping concrete surfaces. The US Department of Energy has successfully demonstrated it for decontaminating walls and floors for free release surveys prior to demolition work. The grinder is an electric-powered tool with a vacuum port for dust extraction and a diamond grinding wheel. The grinder is suitable for flat or slightly curved surfaces and results in a smooth surface, which makes release surveys more reliable. The grinder is lightweight and produces very little vibration, thus reducing worker fatigue. The grinder is more efficient than traditional baseline, tools at removing contamination from concrete surfaces (more than four times faster than hand-held pneumatic scabbling and scaling tools). Grinder consumables (i.e., replacement diamond grinding wheel) are more expensive than the replacement carbide parts for the scaler and scabbler. However, operating costs are outweighed by the lower purchase price of the grinder (50% of the price of the baseline scaler and 8% of the price of the baseline scabbler). Overall, the concrete grinder is an attractive alternative to traditional scabbling and scaling pneumatic tools. To this end, in July 1998, the outer rod room exposed walls of the Safe Storage Enclosure (SSE), an area measuring approximately 150 m 2 , may be decontaminated with the hand-held grinder. This concrete grinder technology was demonstrated for the first time at the DOE's Hanford Site. Decontamination of a sample room walls was performed at the C Reactor to free release the walls prior to demolition. The demonstration was conducted by onsite D and D workers, who were instructed by the vendor prior to and during the demonstration

  4. Does Flooring Substrate Impact Kennel and Dog Cleanliness in Commercial Breeding Facilities?

    Science.gov (United States)

    Stella, Judith; Hurt, Moriah; Bauer, Amy; Croney, Candace

    2018-01-01

    Simple Summary It is important to understand how the flooring substrate used in dog housing impacts dog health and well-being. Aspects to consider include paw, elbow, and hock health, the cleanliness of the dog, and the ability of the floors to be cleaned easily and thoroughly. This pilot study assessed the health and cleanliness of 118 dogs housed on three different types of flooring commonly found in commercial breeding kennels. No serious paw, elbow, or hock problems were identified. Thirty-one percent or fewer kennels at each facility were found to have fecal contamination after routine cleaning and the majority of dogs were clean. These findings indicate that a well-managed kennel can maintain clean, healthy dogs on different types of flooring substrates. Abstract Evaluation of kennel flooring surfaces is needed to understand their impacts on dog health and well-being. This pilot study aimed to characterize aspects of physical health, kennel cleanliness, and dog body cleanliness on flooring types common in US breeding kennels. Subjects were 118 adult dogs housed on diamond-coated expanded metal (DCEM), polypropylene (POLY), or concrete (CON) flooring at five commercial breeding facilities in Indiana, U.S. Body condition, paw, elbow, and hock health scores were recorded. Each indoor kennel and dog was visually assessed for cleanliness. Kennels were swabbed immediately after cleaning with electrostatic dry cloths and cultured for Escherichia coli. Descriptive statistics were used for analysis. Mean body condition score (BCS), kennel and dog cleanliness scores were all near ideal (3, 1.15, and 1.04, respectively). Thirty-one percent or fewer kennels at each facility were culture-positive for E. coli after cleaning. No serious paw, elbow, or hock problems were identified. Overall, the findings indicate that with appropriate management and regular access to additional surfaces, dog foot health, cleanliness, and kennel cleanliness can be maintained on the flooring

  5. Thermal analysis of mass concrete embedded with double-layer staggered heterogeneous cooling water pipes

    International Nuclear Information System (INIS)

    Yang Jian; Hu Yu; Zuo Zheng; Jin Feng; Li Qingbin

    2012-01-01

    Removal of hydration heat from mass concrete during construction is important for the quality and safety of concrete structures. In this study, a three-dimensional finite element program for thermal analysis of mass concrete embedded with double-layer staggered heterogeneous cooling water pipes was developed based on the equivalent equation of heat conduction including the effect of cooling water pipes and hydration heat of concrete. The cooling function of the double-layer staggered heterogeneous cooling pipes in a concrete slab was derived from the principle of equivalent cooling. To improve the applicability and precision of the equivalent heat conduction equation under small flow, the cooling function was revised according to its monotonicity and empirical formulas of single-phase forced-convection heat transfer in tube flow. Considering heat hydration of concrete at later age, a double exponential function was proposed to fit the adiabatic temperature rise curve of concrete. Subsequently, the temperature variation of concrete was obtained, and the outlet temperature of cooling water was estimated through the energy conservation principle. Comparing calculated results with actual measured data from a monolith of an arch dam in China, the numerical model was proven to be effective in sufficiently simulating accurate temperature variations of mass concrete. - Highlights: ► Three-dimensional program is developed to model temperature history of mass concrete. ► Massive concrete is embedded with double-layer heterogeneous cooling pipes. ► Double exponential function is proposed to fit the adiabatic temperature rise curve. ► Outlet temperature of cooling water is estimated. ► A comparison is made between the calculated and measured data.

  6. Incidence of lameness and abrasions in piglets in identical farrowing pens with four different types of floor

    Directory of Open Access Journals (Sweden)

    Nilsson Ebba

    2009-05-01

    Full Text Available Abstract Background Lameness in piglets is a major animal welfare issue. Floor abrasiveness is a common cause of superficial injury in piglets in farrowing pens. The abrasion achieved may act as a gate for infections, which in turn may induce development of infectious arthritis. In this study, the influence of improvements of the floor quality and of increased ratios of straw in identical farrowing pens was measured. Methods The study was carried out at a herd with four identical farrowing units with solid concrete floor bedded with 1 kg chopped straw per sow and 1 hg per piglet and day. Nothing was changed in the management of the four identical farrowing units, but four experimental groups were created: Group I – control, Group II – the amount of bedding was doubled. The surface of the floor was repaired in two units, Group III – Piglet Floor®, Flowcrete Sweden AB, Perstorp, Sweden and Group IV – Thorocrete SL®, Växa Halland, Sweden. Three farrowing batches were studies in each unit. In total, 93 litters (1,073 piglets were examined for foot and skin lesions until the age of 3 weeks. The occurrence of lameness was registered until weaning at an average age of 4.5 weeks. Twenty seven lame piglets were culled instead of medicinally treated and subjected to necropsy including histopathological and microbiological examinations. Isolates of streptococci, staphylococci and E. coli were tested with respect to antimicrobial resistance. Results Piglet born on the repaired floors had the lowest prevalences of abrasions at carpus. Also the doubled straw ration decreased the abrasions. Skin lesions at carpus decreased significantly in magnitude in all four systems from day 10. At day 3, the sole bruising scores of the control unit were greater than the other three units (p Streptococcus dysgalactiae subsp. equisimilis (60%, Staphylococcus hyicus subsp. hyicus (35% and Escherichia coli (5%. These isolates were sensitive to all antibiotics

  7. Centro de cálculo IBM - Francfort (Alemania Federal

    Directory of Open Access Journals (Sweden)

    Apel, Beckert, Becker, Arquitectos

    1972-03-01

    Full Text Available This centre comprises a tall building, of approximately square cross section, and a 10 m high rectangular block. The first one houses the offices, and the second contains an IBM computer and accessories. The structure is of reinforced concrete for the vertical members, and ribbed flooring slabs for the horizontal ones. The external enclosing medium consists of precast concrete elements, and large glazed surfaces. The are features of ornamental significance, such as the indoor helicoidal stairs of unfaced concrete, and the slab covered square, with its garden and artificial lake areas. Parking space is provided in the basements.El complejo se compone de: — un rascacielos con planta sensiblemente cuadrada y 38 m de altura, y — un bloque rectangular, más bajo, de 9,90 m de alto. El primero alberga las oficinas, y el segundo se destina a cubrir todas las exigencias que se derivan del funcionamiento de un ordenador IBM. Su estructura, a base de núcleos verticales de hormigón armado, forjados nervados y cerramientos compuestos de piezas de hormigón, prefabricadas, con grandes zonas acristaladas. Hay motivos ornamentales, como la escalera helicoidal interior, de hormigón visto, y la plaza enlosada, con estanques y jardineras. Aparcamiento en el sótano.

  8. Control of exceptional points in photonic crystal slabs

    DEFF Research Database (Denmark)

    Kaminski, Piotr Marek; Taghizadeh, Alireza; Breinbjerg, Olav

    2017-01-01

    Various ways of controlling the extent of the ring of exceptional points in photonic crystal slabs are investigated. The extent of the ring in photonic crystal slabs is found to vary with the thickness of the slab. This enables recovery of Dirac cones in open, non-Hermitian systems, such as a pho...

  9. Numerical simulations and experimental measurements of steel and ice impacts on concrete for acoustic interrogation of delaminations in bridge decks

    Energy Technology Data Exchange (ETDEWEB)

    Mazzeo, Brian A.; Patil, Anjali N.; Klis, Jeffrey M. [Brigham Young University, Department of Electrical and Computer Engineering, Provo, Utah, 84602 (United States); Hurd, Randy C.; Truscott, Tadd T. [Brigham Young University, Department of Mechanical Engineering, Provo, Utah, 84602 (United States); Guthrie, W. Spencer [Brigham Young University, Department of Civil and Environmental Engineering, Provo, Utah, 84602 (United States)

    2014-02-18

    Delaminations in bridge decks typically result from corrosion of the top mat of reinforcing steel, which leads to a localized separation of the concrete cover from the underlying concrete. Because delaminations cannot be detected using visual inspection, rapid, large-area interrogation methods are desired to characterize bridge decks without disruption to traffic, without the subjectivity inherent in existing methods, and with increased inspector safety. To this end, disposable impactors such as water droplets or ice chips can be dropped using automatic dispensers onto concrete surfaces to excite mechanical vibrations while acoustic responses can be recorded using air-coupled microphones. In this work, numerical simulations are used to characterize the flexural response of a model concrete bridge deck subject to both steel and ice impactors, and the results are compared with similar experiments performed in the laboratory on a partially delaminated concrete bridge deck slab. The simulations offer greater understanding of the kinetics of impacts and the responses of materials.

  10. SUSTAINABLE TRAILER FLOORING

    Directory of Open Access Journals (Sweden)

    John Lu

    2009-05-01

    Full Text Available Different trailer flooring materials, including wood-based, aluminum, steel, and synthetic plastic floors, were evaluated in accordance with their durability and sustainability to our natural environment. Wood-based trailer flooring is an eco-friendly product. It is the most sustainable trailer flooring material compared with fossil fuel-intensive steel, aluminum, and plastics. It is renewable and recyclable. Oak, hard maple, and apitong are strong and durable hardwood species that are currently extensively used for trailer flooring. For manufacture, wood-based flooring is higher in energy efficiency and lower in carbon emission than steel, aluminum and plastics. Moreover, wood per se is a natural product that sequesters carbon. Accordingly, using more wood-based trailer flooring is effective to reduce global warming.

  11. Concrete decontamination and demolition methods

    International Nuclear Information System (INIS)

    LaGuardia, T.S.

    1980-01-01

    The US Department of Energy (DOE), Division of Environmental Control Technology, requested Nuclear Energy Services to prepare a handbook for the decontamination and decommissioning (D and D) of DOE-owned and commercially-owned radioactive facilities. the objective of the handbook is to provide the nuclear industry with guidance on the state-of-the-art methods and equipment available for decommissioning and to provide the means to estimate decommissioning costs and environmental impact. The methods available for concrete decontamination and demolition are summarized to provide an overview of some of the state-of-the-art techniques to be discussed at this workshop. The pertinent information on each method will include the selection factors such as the rate of performance in terms of concrete removal per unit time (cubic yards per day), manpower required by craft, unit cost (dollars per cubic yard) and the advantages and disadvantages. The methods included in this overview are those that have been routinely used in nuclear and nonnuclear applications or demonstrated in field tests. These methods include controlled blasting, wrecking ball or slab, backhoe mounted ram, flame torch, thermic lance, rock splitter, demolition compound, sawing, core stitch drilling, explosive cutting, paving breaker and power chisel, drill and spall, scarifying, water cannon and grinding

  12. Calculating seismic of slabs ITA NNP Garona

    International Nuclear Information System (INIS)

    Ezeberry, J. I.; Guerrero, A.; Gamarra, J.; Beltran, F.

    2014-01-01

    This article describes the methodology that Idom has employed to perform the seismic evaluation of slabs within the ITA project of the NPP Santa Maria de Garona. Seismic calculations that have been conducted include consideration of the effects of the interaction of soil structure as well as the possible take-off containers with respect to slab during the earthquake. Therefore, the main contribution of the work is the study of the coupling of rolling containers with the flexibility of the whole ground-slab For calculations has been used ABAQUS/Explicit program, allowing to solve effectively the nonlinearities listed above using explicit integration algorithms over time. The results of the calculations reflect the importance of jointly analyse the seismic responses of slab and containers. (Author)

  13. Comparison of elastic--plastic and variable modulus-cracking constitutive models for prestressed concrete reactor vessels

    International Nuclear Information System (INIS)

    Anderson, C.A.; Smith, P.D.

    1978-01-01

    The variable modulus-cracking model is capable of predicting the behavior of reinforced concrete structures (such as the reinforced plate under transverse pressure described previously) well into the range of nonlinear behavior including the prediction of the ultimate load. For unreinforced thick-walled concrete vessels under internal pressure the use of elastic--plastic concrete models in finite element codes enhances the apparent ductility of the vessels in contrast to variable modulus-cracking models that predict nearly instantaneous rupture whenever the tensile strength at the inner wall is exceeded. For unreinforced thick-walled end slabs representative of PCRV heads, the behavior predicted by finite element codes using variable modulus-cracking models is much stiffer in the nonlinear range than that observed experimentally. Although the shear type failures and crack patterns that are observed experimentally are predicted by such concrete models, the ultimate load carrying capacity and vessel-ductility are significantly underestimated. It appears that such models do not adequately model such features as aggregate interlock that could lead to an enhanced vessel reserve strength and ductility

  14. Photon transport in thin disordered slabs

    Indian Academy of Sciences (India)

    We examine using Monte Carlo simulations, photon transport in optically `thin' slabs whose thickness is only a few times the transport mean free path *, with particles of different scattering anisotropies. The confined geometry causes an auto-selection of only photons with looping paths to remain within the slab.

  15. Mechanical characterisation of the first centimeters of concrete with surface waves

    International Nuclear Information System (INIS)

    Chekroun, M.

    2008-01-01

    Cover concrete is the part of concrete structures directly in contact with the outside. Its thickness is a few centimetres and its main role is to protect reinforcement bars. Surface waves with wavelength varying from a few millimetres to a few centimetres are used to characterise this cover concrete. An estimation of the properties of the propagation of waves (phase and group velocities, damping factor) may allow us to evaluate mechanical properties and to detect possible damages. However, these waves will interact strongly with the numerous heterogeneities of the concrete (sand, aggregates,.) which dimensions are close to the wavelength. Waves will propagate in a multiple scattering regime. These effects have to be quantified in order to separate them from other effects linked to mechanical properties. An analytical and numerical study present theories of effective mediums to describe coherent wave propagation in an elastic matrix with random elastic inclusions. These models are then extended to take into account the viscoelasticity of the materials and the granulometry. We quantify with such model the importance of multiple scattering on surface wave propagation in concrete. Experimental measurements are carried on, using a specific protocol and efficient signal processing methods, allowing precise evaluation of phase and group velocity and of the damping factor of coherent surface waves on concrete or mortar slabs. The results show that these three parameters can provide complementary information on concrete properties (water to cement ratio, aggregate distribution,...), but also on other phenomenon like varying effective properties with depth. Effects of multiple scattering predicted by the model are experimentally observed, which opens interesting perspectives for the inverse problem. (author)

  16. Floors: Selection and Maintenance.

    Science.gov (United States)

    Berkeley, Bernard

    Flooring for institutional, commercial, and industrial use is described with regard to its selection, care, and maintenance. The following flooring and subflooring material categories are discussed--(1) resilient floor coverings, (2) carpeting, (3) masonry floors, (4) wood floors, and (5) "formed-in-place floors". The properties, problems,…

  17. New Trends for Reinforced Concrete Structures: Some Results of Exploratory Studies

    Directory of Open Access Journals (Sweden)

    Ricardo N. F. Carmo

    2017-10-01

    Full Text Available Today, the concrete sector is being pushed to innovate in order to better address current challenges with higher competitiveness and more sustainable solutions. Different research studies have been conducted all over the world in which novel approaches and paths were proposed. It is important to spread information to define new strategies for the future of this industry. The enhancement of concrete properties and the impact of these changes in structural design are some of the topics analysed in those studies. This paper presents four experimental studies conducted by the authors where different types of concrete and structural members were tested. The common goal of these studies was to develop innovative solutions with high performance and low environmental impact. The scope of the first study was the structural behaviour of members produced with lightweight aggregate concrete (LWAC. Results of several beams, ties, and slabs are herein presented and analysed. The advantage of using glass fibre–reinforced polymer (GFRP rebars was addressed in a second study, and main results obtained with this type of rebar are also herein presented. Recent advances in nanotechnology led to the development of concretes incorporating nanoparticles into the binder matrix. Typically, these nanoparticles have a diameter of 10–300 nanometers and are added to the mixture to reduce the porosity and increase the density of the binder matrix, improving the mechanical properties and durability. To analyse their influence on steel-to-concrete bonding and on the shear and flexural behaviour of the beams was the main goal of the third study herein described. Finally, a new concept to produce reinforced concrete members with high durability using a special concrete cover, which was the goal of the fourth study, is also herein presented.

  18. Electric radiant heating : a hot profitable idea

    Energy Technology Data Exchange (ETDEWEB)

    Lemieux, G. [Britech Corp., Toronto, ON (Canada)

    2006-09-15

    Due to the high cost of heating oil, natural gas and propane, floor mounted radiant heating systems are now proving to be a cost effective method of heating homes. The systems provide evenly distributed heat across the entire floor area. Unlike hydronic floor systems, radiant floor systems require no maintenance, and are easy to control because no mechanical rooms or boilers are required. The system is comprised of a series of resistant heating cables, a thermostat, and a solid state relay. The cables are installed in a poured concrete pad. Separate temperature control devices are used to heat individual areas of floorspace. Building automation systems can also control the heating system by using simple ambient air- and floor-mounted sensors in conjunction with relays to energize the heating cables. The cost of thermostats and heating cables to heat a standard 2000 square foot home are estimated at $9000.00, with an additional 64 hours of installation costs. It was noted that the systems may prove to be less costly in the long-term than hydronic systems, which require additional boilers, pumps and water treatments. Electric radiant heating can be an even more cost-effective application when used with thermal storage heating applications that use lower-cost off-peak electricity to generate and store heat in concrete floor slabs or ceramic bricks contained in insulated cabinets. It was concluded that radiant heating systems are a viable and cost-effective alternative to expensive hydronic systems, which are costly to install and maintain. 4 figs.

  19. Activation of the concrete in the bio shield of ITER

    International Nuclear Information System (INIS)

    Kalcheva, S.

    2005-02-01

    Calculations of neutron spectra in different parts of the tokamak building of ITER are performed. A computational geometry model of the tokamak building is prepared using MCNP-4C. The model includes adequate material composition and geometry description of the main parts of the tokamak for PPCS plant model A: toroidal field coils, vacuum vessel, shield, blanket structure, first wall, divertor, 14.1 MeV neutron source. The design and the dimensions of the bio shield are taken from the current ITER design. MCNP calculations of the neutron spectra in the bio shield (concrete) of ITER are performed, using the neutron spectra in TF coils calculated at UKAEA as external neutron source. The neutron spectra in the concrete calculated by MCNP are used as input data in the code EASY99 for estimations of the activation of the concrete in the bio shield around the tokamak. The time evolutions of the maximum (in the bio shield floor) and minimum (in the bio shield side walls) specific activity (Bq/kg) and dose rate (Sv/h.) of the main dominant nuclides in the concrete are evaluated and compared for 3 different concrete types, used as biological shield in the PWR and BR3 reactors. (author)

  20. Airborne and impact sound transmission in super-light structures

    DEFF Research Database (Denmark)

    Christensen, Jacob Ellehauge; Hertz, Kristian Dahl; Brunskog, Jonas

    2011-01-01

    -aggregate concrete. A super-light deck element is developed. It is intended to be lighter than traditional deck structures without compromising the acoustic performance. It is primarily the airborne sound insulation, which is of interest as the requirements for the impact sound insulation to a higher degree can...... be fulfilled by external means such as floorings. The acoustical performance of the slab element is enhanced by several factors. Load carrying internal arches stiffens the element. This causes a decrease in the modal density, which is further improved by the element being lighter. These parameters also...