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Sample records for concrete structures subjected

  1. Modeling of crack in concrete structures subjected to severe loadings

    International Nuclear Information System (INIS)

    Nguyen, T.G.

    2012-01-01

    Concrete is a construction materials are prevalent in the world. However, in many industries, it is becoming more common to study the safety margins of a structure with respect to solicitations. It becomes important to predict the failure mode of the structure. Much work has already been made in the world on this subject, leading to operational models in computer codes using finite elements. Nevertheless, difficulties remain, mainly related to concrete cracking. These difficulties lead to open problems concerning the location, initiation and crack propagation. The thesis explores two ways of improving methods of numerical simulation of crack propagation. The first possibility of improvement is the use of the extended finite element method, XFEM. A modeling of mechanical behavior of crack is introduced and leads to a description of crack propagation from one element to another. The second possibility is based on damage mechanics. As part of the modeling of damage generalized standard type, the localization phenomenon has been studied numerically for various behaviors: viscous or damage fragile. These behaviors are described in the same spirit that the laws of the visco-elastic or visco-plasticity or plasticity classics, from a general thermodynamic interpretation. In particular, the laws gradient of damage are also considered in conjunction with recent results from the literature. It is well known that a gradient model for interpreting the effects of scale structures under mechanical loading. It also plays an interesting role in the effects of strain localization. (author)

  2. CONCRETE MIX DESIGN FOR STRUCTURES SUBJECTED TO EXPOSURE CLASS XC1 DEPENDING ON CONCRETE COVER

    Directory of Open Access Journals (Sweden)

    O. Yu. Cherniakevich

    2016-01-01

    Full Text Available The reinforced steel corrosion which is the most important problem of reinforced concrete structures durability is generally stipulated for carbonization of concrete surrounding it. Concrete cover calculation at the design stage is predicated one because of the differences in manufacturing conditions and use of constructions. The applying of the probabilistic approaches to the carbonation process modeling allows to get predicated grade of the depth of carbonization of concrete and, thus, to settle minimum concrete cover thickness for a given projected service life of a construction. The procedures for concrete mix design for different strength classes of concrete are described in the article. Current recommendations on assignment of concrete strength class as well as concrete cover are presented. The European Standard EN 206:2013 defines the content requirements for the concrete structures operated in the exposure class XC1, including the minimum values of water-cement ratio, minimum cement content, and minimum strength class of concrete. Since the standard does not include any basis or explanations of the requirements, we made an effort to develop a scientific justification for the mentioned requirements. We developed the probabilistic models for the process of carbonation of concrete based on the concrete mix which was designed using the software VTK-Korroziya. The reinforced concrete structures with concrete cover 20–35 mm operated in the most unfavorable conditions within the exposure class XC1 were analyzed. The corresponding probabilistic calculations of the depth of carbonated concrete are described in the article. 

  3. Scale modeling of reinforced concrete structures subjected to seismic loading

    International Nuclear Information System (INIS)

    Dove, R.C.

    1983-01-01

    Reinforced concrete, Category I structures are so large that the possibility of seismicly testing the prototype structures under controlled conditions is essentially nonexistent. However, experimental data, from which important structural properties can be determined and existing and new methods of seismic analysis benchmarked, are badly needed. As a result, seismic experiments on scaled models are of considerable interest. In this paper, the scaling laws are developed in some detail so that assumptions and choices based on judgement can be clearly recognized and their effects discussed. The scaling laws developed are then used to design a reinforced concrete model of a Category I structure. Finally, how scaling is effected by various types of damping (viscous, structural, and Coulomb) is discussed

  4. Analysis of reinforced concrete structures subjected to aircraft impact loading

    International Nuclear Information System (INIS)

    Bauer, J.; Scharpf, F.; Schwarz, R.

    1983-01-01

    Concerning the evaluation of the effects of aircraft impact loading on the reactor building and the contained equipment special interest belongs to both the characteristic of loading conditions and the consideration of the nonlinear behaviour of the local impacted area as well as the overall behaviour of the structure. To cover this extensive scope of problems the fully 3-dimensional code DYSMAS/L was prepared for the analysis of highly dynamic continuum mechanics problems. For this totally Lagrangian description, derived and tested in the field of the simulation of impact phenomena and penetration of armoured structures, an extension was made for the reasonable modelling of the material behaviour of reinforced concrete. Conforming the available experimental data a nonlinear stress-strain curve is given and a continuous triaxial failure-surface is composed which allows cracking of concrete in the tensile region and its crushing in the compressive mode. For the separately modeled reinforcement an elastic-plastic stress-strain relationship with kinematic hardening is used. (orig./RW)

  5. Nonlinear analysis of reinforced concrete structures subjected to high temperature and external load

    International Nuclear Information System (INIS)

    Sugawara, Y.; Goto, M.; Saito, K.; Suzuki, N.; Muto, A.; Ueda, M.

    1993-01-01

    A quarter of a century has passed since the finite element method was first applied to nonlinear problems concerning reinforced concrete structures, and the reliability of the analysis at ordinary temperature has been enhanced accordingly. By contrast, few studies have tried to deal with the nonlinear behavior of reinforced concrete structures subjected to high temperature and external loads simultaneously. It is generally known that the mechanical properties of concrete and steel are affected greatly by temperature. Therefore, in order to analyze the nonlinear behavior of reinforced concrete subjected to external loads at high temperature, it is necessary to construct constitutive models of the materials reflecting the influence of temperature. In this study, constitutive models of concrete and reinforcement that can express decreases in strength and stiffness at high temperature have been developed. A two-dimensional nonlinear finite element analysis program has been developed by use of these material models. The behavior of reinforced concrete beams subjected simultaneously to high temperature and shear forces were simulated using the developed analytical method. The results of the simulation agreed well with the experimental results, evidencing the validity of the developed material models and the finite element analysis program

  6. Shaking of reinforced concrete structures subjected to transient dynamic analysis

    International Nuclear Information System (INIS)

    Rouzaud, Christophe

    2015-01-01

    In the design of nuclear engineering structures security and safety present a crucial aspect. Civil engineering design and the qualification of materials to dynamic loads must consider the accelerations which they undergo. These accelerations could integrate seismic activity and shaking movements consecutive to aircraft impact with higher cut-off frequency. Current methodologies for assessing this shock are based on transient analyses using classical finite element method associated with explicit numerical schemes or projection on modal basis, often linear. In both cases, to represent in meaningful way a medium-frequency content, it should implement a mesh refinement which is hardly compatible with the size of models of the civil engineering structures. In order to extend industrial methodologies used and to allow a better representation of the behavior of the structure in medium-frequency, an approach coupling a temporal and non-linear analysis for shock area with a frequency approach to treatment of shaking with VTCR (Variational Theory of Complex Rays) has been used. The aim is to use the computational efficiency of the implemented strategy, including medium frequency to describe the nuclear structures to aircraft impact. (author)

  7. 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...

  8. 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

  9. Structural Precast Concrete Handbook

    DEFF Research Database (Denmark)

    Kjærbye, Per Oluf H

    Structural concept for precast concrete systems. Design og precast reinforced concrete components. Design of precast concrete connections. Illustrations on design of precast concrete buildings. Precast concrete assembly.......Structural concept for precast concrete systems. Design og precast reinforced concrete components. Design of precast concrete connections. Illustrations on design of precast concrete buildings. Precast concrete assembly....

  10. Performance Evaluation of Waterproofing Membrane Systems Subject to the Concrete Joint Load Behavior of Below-Grade Concrete Structures

    Directory of Open Access Journals (Sweden)

    Jaeyoung Song

    2017-11-01

    Full Text Available Below-grade structures such as parking lots, underground subway tunnels, and basements are growing in scale and reaching deeper below-ground levels. In this type of environment, they become subject to higher water pressure. The concrete material of the structures is exposed to wet conditions for longer periods of time, which makes the proper adhesion of waterproofing membranes difficult. Joint movements from increased structural settlement, thermal expansion/shrinkage, and physical loads from external sources (e.g., vehicles make securing durable waterproofing challenging. While ASTM Guides, Korean Codes, and BS Practice Codes on below-grade waterproofing stress the importance of manufacturer specification for quality control, ensuring high quality waterproofing for the ever-changing scale of construction remains a challenge. This study proposes a new evaluation method and criteria which allow for the selection of waterproofing membranes based on specific performance attributes and workmanship. It subjects six different waterproofing membrane systems (installed on dry and wet surface conditioned mortar slab specimens with an artificial joint to different cyclic movement widths to 300 cycles in water to demonstrate that inadequate material properties and workmanship are key causes for leakages.

  11. 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.

  12. Ultrasonic assessment of service life of concrete structures subject to reinforcing steel corrosion

    Science.gov (United States)

    Udegbunam, Ogechukwu Christian

    Over half of the bridges in the United States were built before 1970. Such bridges and the network of roads that they carry include the Inter State system, which was built as part of the great public works program, following the end of the Second World War. During that era, the emphasis was on strength design and economical construction of new structures, and not much premium was placed on durability and maintainability concerns. Since the end of this construction boom in the early 1970s, the concern for the durability of transportation infrastructure has steadily gained prominence among those agencies that must secure, program and administer funds for maintaining highway networks. The objective of this research was to develop a nondestructive method of assessing the durability of concrete bridge decks susceptible to damage from corrosion of embedded reinforcing steel. This was accomplished by formulating a holistic approach that accounts for the major factors that influence corrosion based deterioration of reinforced concrete. In this approach, the assessment of the durability of concrete bridge decks is based on a model that estimates the time it takes for the cover concrete to fail a result of stresses caused by expansion of reinforcing steel bars, due to corrosion activities. This time to failure is comprised of two distinct periods that must be evaluated before the problem can be solved. The research consisted of an experimental program and an analytical study. In the experimental program concrete specimens were cast and tested to determine their diffusivity and mechanical properties. The diffusivity was used to evaluate the period it takes for corrosion of the reinforcing bars to commence. In the analytical study, the resistance of the concrete structure against the internal forces caused by corrosion was evaluated with the finite element techniques. This resistance was used to evaluate the period defining the failure of the cover concrete. These two periods

  13. Structural Materials: 95. Concrete

    International Nuclear Information System (INIS)

    Naus, Dan J.

    2012-01-01

    Nuclear power plant concrete structures and their materials of construction are described, and their operating experience noted. Aging and environmental factors that can affect the durability of the concrete structures are identified. Basic components of a program to manage aging of these structures are identified and described. Application of structural reliability theory to devise uniform risk-based criteria by which existing facilities can be evaluated to achieve a desired performance level when subjected to uncertain demands and to quantify the effects of degradation is outlined. Finally, several areas are identified where additional research is desired.

  14. Behavior and ultimate strength of an inner concrete structure of a nuclear reactor building subjected to thermal and seismic loads

    International Nuclear Information System (INIS)

    Omatsuzawa, K.; Suzuki, Y.; Sato, M.; Takeda, T.; Yamaguchi, T.; Yoshioka, K.; Nakayama, T.; Furuya, N.; Kawaguchi, T.; Koike, K.; Naganuma, K.

    1987-01-01

    Heating tests and heating-plus-seismic-loading tests at high temperature (T max = 175 0 C) were conducted using various concrete structural members such as beams, cylindrical walls, H-section walls, and 1/10-scale models of the inner concrete (I/C) structure in a fast breeder reactor (FBR) building. Concrete subjected to high temperature exceeding 100 0 C has a tendency to have lower Young's modulus and to shrink. As these material constants are temperature-dependent, the thermal stress occurring within the concrete structure is smaller than the values usually obtained by normal crack analysis methods. Although thermal stresses and cracks exert marked influences on the behaviors of the structures during the earlier stages of loading, they hardly affect the ultimate bending and shear strengths. Specifically, as a result of I/C model tests, it was made clear that the ultimate strength of the structure is considerably greater than the design loads under combined thermal and seismic loading conditions. (orig./HP)

  15. Calculation of a Tunnel Cross Section Subjected to Fire – with a New Advanced Transient Concrete Model for Reinforced Structures

    Directory of Open Access Journals (Sweden)

    U. Schneider

    2009-01-01

    Full Text Available The paper presents the structural application of a new thermal induced strain model for concrete – the TIS-Model. An advanced transient concrete model (ATCM is applied with the material model of the TIS-Model. The non-linear model comprises thermal strain, elastic strain, plastic strain and transient temperature strains, and load history modelling of restraint concrete structures subjected to fire.The calculations by finite element analysis (FEA were done using the SAFIR structural code. The FEA software was basically new with respect to the material modelling derived to use the new TIS-Model (as a transient model considers thermal induced strain. The equations of the ATCM consider a lot of capabilities, especially for considering irreversible effects of temperature on some material properties. By considering the load history during heating up, increasing load bearing capacity may be obtained due to higher stiffness of the concrete. With this model, it is possible to apply the thermal-physical behaviour of material laws for calculation of structures under extreme temperature conditions.A tunnel cross section designed and built by the cut and cover method is calculated with a tunnel fire curve. The results are compared with the results of a calculation with the model of the Eurocode 2 (EC2-Model. The effect of load history in highly loaded structures under fire load will be investigated.A comparison of this model with the ordinary calculation system of Eurocode 2 (EC2 shows that a better evaluation of the safety level was achieved with the new model. This opens a space for optimizing concrete structure design with transient temperature conditions up to 1000 °C. 

  16. Multi-functional smart aggregate-based structural health monitoring of circular reinforced concrete columns subjected to seismic excitations

    International Nuclear Information System (INIS)

    Gu, Haichang; Song, Gangbing; Moslehy, Yashar; Mo, Y L; Sanders, David

    2010-01-01

    In this paper, a recently developed multi-functional piezoceramic-based device, named the smart aggregate, is used for the health monitoring of concrete columns subjected to shake table excitations. Two circular reinforced concrete columns instrumented with smart aggregates were fabricated and tested with a recorded seismic excitation at the structural laboratory at the University of Nevada—Reno. In the tests, the smart aggregates were used to perform multiple monitoring functions that included dynamic seismic response detection, structural health monitoring and white noise response detection. In the proposed health monitoring approach, a damage index was developed on the basis of the comparison of the transfer function with the baseline function obtained in the healthy state. A sensor-history damage index matrix is developed to monitor the damage evolution process. Experimental results showed that the acceleration level can be evaluated from the amplitude of the dynamic seismic response; the damage statuses at different locations were evaluated using a damage index matrix; the first modal frequency obtained from the white noise response decreased with increase of the damage severity. The proposed multi-functional smart aggregates have great potential for use in the structural health monitoring of large-scale concrete structures

  17. Acoustic emission energy b-value for local damage evaluation in reinforced concrete structures subjected to seismic loadings

    Science.gov (United States)

    Sagasta, Francisco; Zitto, Miguel E.; Piotrkowski, Rosa; Benavent-Climent, Amadeo; Suarez, Elisabet; Gallego, Antolino

    2018-03-01

    A modification of the original b-value (Gutenberg-Richter parameter) is proposed to evaluate local damage of reinforced concrete structures subjected to dynamical loads via the acoustic emission (AE) method. The modification, shortly called energy b-value, is based on the use of the true energy of the AE signals instead of its peak amplitude, traditionally used for the calculation of b-value. The proposal is physically supported by the strong correlation between the plastic strain energy dissipated by the specimen and the true energy of the AE signals released during its deformation and cracking process, previously demonstrated by the authors in several publications. AE data analysis consisted in the use of guard sensors and the Continuous Wavelet Transform in order to separate primary and secondary emissions as much as possible according to particular frequency bands. The approach has been experimentally applied to the AE signals coming from a scaled reinforced concrete frame structure, which was subjected to sequential seismic loads of incremental acceleration peak by means of a 3 × 3 m2 shaking table. For this specimen two beam-column connections-one exterior and one interior-were instrumented with wide band low frequency sensors properly attached on the structure. Evolution of the energy b-value along the loading process accompanies the evolution of the severe damage at the critical regions of the structure (beam-column connections), thus making promising its use for structural health monitoring purposes.

  18. Prediction of concrete strength in massive structures

    International Nuclear Information System (INIS)

    Sakamoto, T.; Makino, H.; Nakane, S.; Kawaguchi, T.; Ohike, T.

    1989-01-01

    Reinforced concrete structures of a nuclear power plant are mostly of mass concrete with cross-sectional dimensions larger than 1.0 m. The temperature of concrete inside after placement rises due to heat of hydration of cement. It is well known that concrete strengths of mass concrete structure subjected to such temperature hysteresis are generally not equal to strengths of cylinders subjected to standard curing. In order to construct a mass concrete structure of high reliability in which the specified concrete strength is satisfied by the specified age, it is necessary to have a thorough understanding of the strength gain property of concrete in the structure and its relationships with the water-cement ratio of the mix, strength of standard-cured cylinders and the internal temperature hysteresis. This report describes the result of studies on methods of controlling concrete strength in actual construction projects

  19. Structural response of full-scale concrete bridges subjected to high load magnitudes

    DEFF Research Database (Denmark)

    Halding, Philip Skov; Schmidt, Jacob Wittrup; Jensen, Thomas Westergaard

    -shaped concrete elements. The test method is outlined in the paper, which includes a description of a novel test-rig used to apply a high magnitude loading. It was shown that the test rig could perform controlled testing in only one day, which is an important aspect, since available time (due to traffic...... disturbance) often is an issue when testing on site. Also, different types of measuring equipment such as lasers, LVDT’s and DIC-cameras was investigated, in order to evaluate the deformations during loading of one of the OT-beam bridges. The monitoring equipment was studied to verify if such equipment...... efficiently could be used for in-situ measurements. The load was applied semi-deformation controlled by a combination of dead load and hydraulic jacks. The novel high magnitude loading-rig worked well. It was also possible to achieve good readings from the monitoring equipment in combination with the applied...

  20. Concrete structures under projectile impact

    CERN Document Server

    Fang, Qin

    2017-01-01

    In this book, the authors present their theoretical, experimental and numerical investigations into concrete structures subjected to projectile and aircraft impacts in recent years. Innovative approaches to analyze the rigid, mass abrasive and eroding projectile penetration and perforation are proposed. Damage and failure analyses of nuclear power plant containments impacted by large commercial aircrafts are numerically and experimentally analyzed. Ultra-high performance concrete materials and structures against the projectile impact are developed and their capacities of resisting projectile impact are evaluated. This book is written for the researchers, engineers and graduate students in the fields of protective structures and terminal ballistics.

  1. Offshore concrete structures

    International Nuclear Information System (INIS)

    Lamas Pardo, M.; Carral Couce, L. M.

    2011-01-01

    In the offshore industry there are two possible materials for the construction of the hull of a structure; the steel and concrete, with the first one widely used until now, as in the rest of the shiphuidling industry of merchant ships, warships, etc. Materials such as aluminum, GRP or timber areused in small units with lengths lower than 100 m, and in less adverse conditions than in the offshore industry. Nevertheless, some ships/barges have been built of concrete in the past, but have been rather isolated cases which have not changed the practice in the industry. In the First and Second World War were built by the scarcity of materials, while the series of barges by Alfred A. Yee was a rare exception. Other units were also made in concrete, but almost anecdotal. Still, the behaviour of these concrete structures, especially in terms of maintenance, has been excellent. Therefore, the fact that the concrete has not had an adequate reception so far in shipbuilding, does not mean that in will not be the material best suited for the offshore industry in the future. The extra displacement and associated fuel costs in concrete ships have been found prohibitive in the past. But the loss of mobility of a concrete hull in relation to a steel hull can be perfectly offset by the advantages offered by the concrete, as the shipping and offshore industry have very different priorities. One of the main differences in these priorities is in terms of maintenance and resistance to fatigue, precisely where the concrete performs better. ships can easily be dry docked for maintenance and repair, while in the offshore platforms these works have to be done in situ so maintenance and fatigue are crucial to them. Besides these, the concrete has other advantages according to findings of several studies. And although they are interested in the conclusions that the makes as they came from people in the concrete industry, the fact that in recent years concrete offshore unit shave been built

  2. Frost damage of concrete subject to confinement

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange

    2016-01-01

    When internal frost damage is observed in real concrete structures, the usual pattern is cracks with a preferred orientation parallel to the exposed surface. When exposing concrete with poor frost resistance to a standardised freeze/thaw test in the laboratory, the orientations of the resulting...

  3. Teaching concrete structures

    DEFF Research Database (Denmark)

    Goltermann, Per

    2014-01-01

    The teaching of concrete structures has been revised and a number of new approaches have been developed, implemented and evaluated. Inductive teaching, E-learning and “patches” have been found to be improvements and may be an inspiration and help for others development of the teaching and learning...

  4. Structural behavior of reinforced concrete structures at high temperatures

    International Nuclear Information System (INIS)

    Yamazaki, N.; Yamazaki, M.; Mochida, T.; Mutoh, A.; Miyashita, T.; Ueda, M.; Hasegawa, T.; Sugiyama, K.; Hirakawa, K.; Kikuchi, R.; Hiramoto, M.; Saito, K.

    1995-01-01

    To establish a method to predict the behavior of reinforced concrete structures subjected simultaneously to high temperatures and external loads, this paper presents the results obtained in several series of tests carried out recently in Japan. This paper reports on the material properties of concrete and steel bars under high temperatures. It also considers the heat transfer properties of thick concrete walls under transient high temperatures, and the structural behavior of reinforced concrete beams subjected to high temperatures. In the tests, data up to 800 C were obtained for use in developing a computational method to estimate the non-linear behavior of reinforced concrete structures exposed to high temperatures. (orig.)

  5. Structural Concrete, Science into Practice

    NARCIS (Netherlands)

    Bruggeling, A.S.G.

    1987-01-01

    There is a need for a more rational and unified approach to all types of concrete structure, reinforced of prestressed. The first chapter explains in a historical review why the approach of reinforced concrete and that of prestressed concrete have hitherto been very different. In outlining the

  6. Spalling of concrete subjected to blast loading

    Directory of Open Access Journals (Sweden)

    Foglar M.

    2013-09-01

    Full Text Available This paper presents outcomes of the blast field tests of FRC and reinforced concrete specimens, which were performed in cooperation with the Czech Army corps and Police of the Czech Republic in the military training area Boletice. The numerical evaluation of the experiments focused on the spalling of concrete subjected to blast loading started after the first set of the tests, took almost 3 years and required further small-scale experiments performed in the labs of the Czech Technical University.

  7. Deterioration of Concrete Structures

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Chloride ingress is a common cause of deterioration of reinforced concrete bridges. Concrete may be exposed to chloride by seawater or de-icing salts. The chloride initiates corrosion of the reinforcement, which through expansion disrupts the concrete. In addition, the corrosion reduces the cross...

  8. Basic principles of concrete structures

    CERN Document Server

    Gu, Xianglin; Zhou, Yong

    2016-01-01

    Based on the latest version of designing codes both for buildings and bridges (GB50010-2010 and JTG D62-2004), this book starts from steel and concrete materials, whose properties are very important to the mechanical behavior of concrete structural members. Step by step, analysis of reinforced and prestressed concrete members under basic loading types (tension, compression, flexure, shearing and torsion) and environmental actions are introduced. The characteristic of the book that distinguishes it from other textbooks on concrete structures is that more emphasis has been laid on the basic theories of reinforced concrete and the application of the basic theories in design of new structures and analysis of existing structures. Examples and problems in each chapter are carefully designed to cover every important knowledge point. As a basic course for undergraduates majoring in civil engineering, this course is different from either the previously learnt mechanics courses or the design courses to be learnt. Compa...

  9. Nuclear Power Plant Concrete Structures

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Prabir [International Atomic Energy Agency (IAEA); Labbe, Pierre [Electricity of France (EDF); Naus, Dan [Oak Ridge National Laboratory (ORNL)

    2013-01-01

    A nuclear power plant (NPP) involves complex engineering structures that are significant items of the structures, systems and components (SSC) important to the safe and reliable operation of the NPP. Concrete is the commonly used civil engineering construction material in the nuclear industry because of a number of advantageous properties. The NPP concrete structures underwent a great degree of evolution, since the commissioning of first NPP in early 1960. The increasing concern with time related to safety of the public and environment, and degradation of concrete structures due to ageing related phenomena are the driving forces for such evolution. The concrete technology underwent rapid development with the advent of chemical admixtures of plasticizer/super plasticizer category as well as viscosity modifiers and mineral admixtures like fly ash and silica fume. Application of high performance concrete (HPC) developed with chemical and mineral admixtures has been witnessed in the construction of NPP structures. Along with the beneficial effect, the use of admixtures in concrete has posed a number of challenges as well in design and construction. This along with the prospect of continuing operation beyond design life, especially after 60 years, the impact of extreme natural events ( as in the case of Fukushima NPP accident) and human induced events (e.g. commercial aircraft crash like the event of September 11th 2001) has led to further development in the area of NPP concrete structures. The present paper aims at providing an account of evolution of NPP concrete structures in last two decades by summarizing the development in the areas of concrete technology, design methodology and construction techniques, maintenance and ageing management of concrete structures.

  10. Porous Structure of Road Concrete

    OpenAIRE

    Пшембаев, М. К.; Гиринский, В. В.; Ковалев, Я. Н.; Яглов, В. Н.; Будниченко, С. С.

    2016-01-01

    Having a great number of concrete structure classifications it is recommended to specify the following three principal types: microstructure – cement stone structure; mesostructure – structure of cement-sand mortar in concrete; macrostucture – two-component system that consists of mortar and coarse aggregate. Every mentioned-above structure has its own specific features which are related to the conditions of their formation. Thus, microstructure of cement stone can be characterized by such st...

  11. POROUS STRUCTURE OF ROAD CONCRETE

    Directory of Open Access Journals (Sweden)

    M. K. Pshembaev

    2016-01-01

    Full Text Available Having a great number of concrete structure classifications it is recommended to specify the following three principal types: microstructure – cement stone structure; mesostructure – structure of cement-sand mortar in concrete; macrostucture – two-component system that consists of mortar and coarse aggregate. Every mentioned-above structure has its own specific features which are related to the conditions of their formation. Thus, microstructure of cement stone can be characterized by such structural components as crystal intergrowth, tobermorite gel, incompletely hydrated cement grains and porous space. The most important technological factors that influence on formation of cement stone microstructure are chemical and mineralogical cement composition, its grinding fineness, water-cement ratio and curing condition. Specific cement stone microstructure is formed due to interrelation of these factors. Cement stone is a capillary-porous body that consists of various solid phases represented predominantly by sub-microcrystals of colloidal dispersion. The sub-microcrystals are able adsorptively, osmotically and structurally to withhold (to bind some amount of moisture. Protection of road concrete as a capillary-porous body is considered as one of the topical issues. The problem is solved with the help of primary and secondary protection methods. Methods of primary protection are used at the stage of designing, preparation and placing of concrete. Methods of secondary protection are applied at the operational stage of road concrete pavement. The paper considers structures of concrete solid phase and characteristics of its porous space. Causes of pore initiation, their shapes, dimensions and arrangement in the concrete are presented in the paper. The highest hazard for road concrete lies in penetration of aggressive liquid in it and moisture transfer in the cured concrete. Water permeability of concrete characterizes its filtration factor which

  12. Sodium concrete reaction - Structural considerations

    International Nuclear Information System (INIS)

    Ferskakis, G.N.

    1984-01-01

    An overview of the sodium concrete reaction phenomenon, with emphasis on structural considerations, is presented. Available test results for limestone, basalt, and magnetite concrete with various test article configurations are reviewed. Generally, tests indicate reaction is self limiting before all sodium is used. Uncertainties, however, concerning the mechanism for penetration of sodium into concrete have resulted in different theories about a reaction model. Structural behavior may be significant in the progression of the reaction due to thermal-structuralchemical interactions involving tensile cracking, compressive crushing, or general deterioration of concrete and the exposure of fresh concrete surfaces to react with sodium. Structural behavior of test articles and potential factors that could enhance the progression of the reaction are discussed

  13. Radiographic testing in concrete structures

    International Nuclear Information System (INIS)

    Oliveira, D. de

    1987-01-01

    The radiographic testing done in concrete structures is used to analyse the homogeneity, position and corrosion of armatures and to detect discontinuity in the concrete such as: gaps, cracks and segregations. This work develops a Image quality Indicator (IQI) with an adequated sensibility to detect discontinuites based on BS4408 norm. (E.G.) [pt

  14. Reliability analysis of prestressed concrete containment structures

    International Nuclear Information System (INIS)

    Jiang, J.; Zhao, Y.; Sun, J.

    1993-01-01

    The reliability analysis of prestressed concrete containment structures subjected to combinations of static and dynamic loads with consideration of uncertainties of structural and load parameters is presented. Limit state probabilities for given parameters are calculated using the procedure developed at BNL, while that with consideration of parameter uncertainties are calculated by a fast integration for time variant structural reliability. The limit state surface of the prestressed concrete containment is constructed directly incorporating the prestress. The sensitivities of the Choleskey decomposition matrix and the natural vibration character are calculated by simplified procedures. (author)

  15. Concrete with onyx waste aggregate as aesthetically valued structural concrete

    Science.gov (United States)

    Setyowati E., W.; Soehardjono, A.; Wisnumurti

    2017-09-01

    The utillization of Tulungagung onyx stone waste as an aggregate of concrete mixture will improve the economic value of the concrete due to the brighter color and high aesthetic level of the products. We conducted the research of 75 samples as a test objects to measure the compression stress, splits tensile stress, flexural tensile stress, elasticity modulus, porosity modulus and also studied 15 test objects to identify the concrete micro structures using XRD test, EDAX test and SEM test. The test objects were made from mix designed concrete, having ratio cement : fine aggregate : coarse aggregate ratio = 1 : 1.5 : 2.1, and W/C ratio = 0.4. The 28 days examination results showed that the micro structure of Tulungagung onyx waste concrete is similar with normal concrete. Moreover, the mechanical test results proved that Tulungagung onyx waste concretes also have a qualified level of strength to be used as a structural concrete with higher aesthetic level.

  16. Nondestructive testing of concrete structures

    International Nuclear Information System (INIS)

    Rufino, Randy R.; Relunia, Estrella

    1999-01-01

    Nondestructive testing of concrete is highly inhomogeneous which makes it cumbersome to setup experimental procedures and analyze experimental data. However, recent research and development activities have discovered the different methods of NDT, like the electromagnetic method, ultrasonic pulse velocity test, pulse echo/impact echo test, infrared thermography, radar or short pulse radar techniques, neutron and gamma radiometry, radiography, carbonation test and half-cell potential method available for NDT of concrete structures. NDT of concrete is emerging as a useful tool for quality control and assurance. This papers also describes the more common NDT methods discussed during the two-week course on 'Nondestructive Testing of Concrete Structures', held at the Malaysian Institute for Nuclear Technology Research (MINT) in Malaysia, which was jointly organized by MINT and the International Atomic Energy Agency (IAEA)

  17. Normal Strength Steel Fiber Reinforced Concrete Subjected to Explosive Loading

    OpenAIRE

    Mohammed Alias Yusof; Norazman Norazman; Ariffin Ariffin; Fauzi Mohd Zain; Risby Risby; CP Ng

    2011-01-01

    This paper presents the results of an experimental investigation on the behavior of plain reinforced concrete and Normal strength steel fiber reinforced concrete panels (SFRC) subjected to explosive loading. The experiment were performed by the Blast Research Unit Faculty of Engineering, University Pertahanan Nasional Malaysia A total of 8 reinforced concrete panels of 600mm x 600mm x 100mm were tested. The steel fiber reinforced concrete panels incorporated three different volume fraction, 0...

  18. Durability of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard

    1996-01-01

    The planned research will indicate, whether fibre reinforced concrete has better or worse durability than normal concrete. Durability specimens will be measured on cracked as well as uncracked specimens. Also the pore structure in the concrete will be characterized.Keywords: Fibre reinforced...... concrete, durability, pore structure, mechanical load...

  19. Damping characteristics of reinforced concrete structures

    International Nuclear Information System (INIS)

    Hisano, M.; Nagashima, I.; Kawamura, S.

    1987-01-01

    Reinforced concrete structures in a nuclear power plant are not permitted to go far into the inelasticity generally, even when subjected to strong ground motion. Therefore it is important to evaluate the damping appropriately in linear and after cracking stage before yielding in the dynamic response analysis. Next three dampings are considered of reinforced concrete structures. 1) Internal damping in linear range material damping of concrete without cracks;2) Hysteretic damping in inelastic range material hysteretic damping of concrete due to cracking and yielding;3) Damping due to the energy dissipation into the ground. Among these damping material damping affects dynamic response of a nuclear power plant on hard rock site where damping due to energy dissipation into the ground is scarcely expected. However material damping in linear and slightly nonlinear range have only been assumed without enough experimental data. In this paper such damping is investigated experimentally by the shaking table tests of reinforced concrete box-walls which modeled roughly the outer wall structure of a P.W.R. type nuclear power plant

  20. Nonlinear FE analysis of reinforced concrete panels subjected to in-plane force

    International Nuclear Information System (INIS)

    Lee, H. P.; Lee, S. J.; Jun, Y. S.; Su, J. M.

    2003-01-01

    Reinforced concrete structures subjected to in-plane force exhibit strong nonlinear behaviour due to complex material properties, cracks, interactions between concrete and steel and shear transfer exists in crack surface. Especially if there is crack formations, nonlinear behaviour increases. Thus the prediction of nonlinear behaviour of reinforced concrete includes failure or crushing is very difficult task. Various constitutive equations for concrete stress-strain relationship to predict nonlinear behaviour of reinforced concrete have been proposed. But the study for reinforced concrete analysis model using plastic material model is still demanded. So the purpose of this research is to formulate standard 8-node shell element using plasticity material model for concrete and to analyze nonlinear behaviour of RC panel subjected to in-plane force

  1. Study on prestressed concrete reactor vessel structures. II-5: Crack analysis by three dimensional finite elements method of 1/20 multicavity type PCRV subjected to internal pressure

    Science.gov (United States)

    1978-01-01

    A three-dimensional finite elements analysis is reported of the nonlinear behavior of PCRV subjected to internal pressure by comparing calculated results with test results. As the first stage, an analysis considering the nonlinearity of cracking in concrete was attempted. As a result, it is found possible to make an analysis up to three times the design pressure (50 kg/sqcm), and calculated results agree well with test results.

  2. Critical Study of Corrosion Damaged Concrete Structures

    OpenAIRE

    Sallehuddin Shah Ayop; John Cairns

    2013-01-01

    Corrosion of steel reinforcement in concrete is one of the major problems with respect to the durability of reinforced concrete structures. The degradation of the structure strength due to reinforcement corrosion decreases its design life. This paper presents the literature study on the influence of the corrosion on concrete structure starting from the mechanism of the corrosion until the deterioration stage and the structural effects of corrosion on concrete structures.

  3. Fragility assessment method of Concrete Wall Subjected to Impact Loading

    International Nuclear Information System (INIS)

    Hahm, Daegi; Shin, Sang Shup; Choi, In-Kil

    2014-01-01

    These studies have been aimed to verify and ensure the safety of the targeted walls and structures especially in the viewpoint of the deterministic approach. However, recently, the regulation and the assessment of the safety of the nuclear power plants (NPPs) against to an aircraft impact are strongly encouraged to adopt a probabilistic approach, i.e., the probabilistic risk assessment of an aircraft impact. In Korea, research to develop aircraft impact risk quantification technology was initiated in 2012 by Korea Atomic Energy Research Institute (KAERI). In this paper, for the one example of the probabilistic safety assessment approach, a method to estimate the failure probability and fragility of concrete wall subjected to impact loading caused by missiles or engine parts of aircrafts will be introduced. This method and the corresponding results will be used for the total technical roadmap and the procedure to assess the aircraft impact risk (Fig.1). A method and corresponding results of the estimation of the failure probability and fragility for a concrete wall subjected to impact loadings caused by missiles or engine parts of aircrafts was introduced. The detailed information of the target concrete wall in NPP, and the example aircraft engine model is considered safeguard information (SGI), and is not contained in this paper

  4. Destructive vibration test of a concrete structure

    International Nuclear Information System (INIS)

    Chen, C.K.; Czarnecki, R.M.; Scholl, R.E.

    1977-01-01

    Two identical full-scale 4-story reinforced concrete structures were built in 1965-1966 at the Nevada Test Site to investigate their dynamic response behavior to underground nuclear explosions. For eight years following their construction, the structures were the subject of a continuing program of vibration testing, and substantial data has been collected on the elastic response of these structures. In 1974 it was decided to conduct a high-amplitude vibration test that would cause the south structure (free of partitions) to deform beyond its elastic limit and cause major structural damage. Results of the 1974 testing program are summarized

  5. Chloride Transport in OPC Concrete Subjected to the Freeze and Thaw Damage

    Directory of Open Access Journals (Sweden)

    Ki Yong Ann

    2017-01-01

    Full Text Available To predict the durability of a concrete structure under the coupling degradation consisting of the frosting and chloride attack, microstructural analysis of the concrete pore structure should be accompanied. In this study, the correlation between the pore structure and chloride migration for OPC concrete was evaluated at the different cement content in the concrete mix accounting for 300, 350, and 400 kg/m3 at 0.45 of a free water cement ratio. The influence of frosting damage on the rate of chloride transport was assessed by testing with concrete specimens subjected to a rapid freezing and thawing cyclic environment. As a result, it was found that chloride transport was accelerated by frost damage, which was more influential at the lower cement content. The microscopic examination of the pore structure showed that the freezing environment increased the volume of the large capillary pore in the concrete matrix.

  6. 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.

  7. Design of ultra-lightweight concrete: towards monolithic concrete structures

    Directory of Open Access Journals (Sweden)

    Yu Qing Liang

    2014-04-01

    Full Text Available This study addresses the development of ultra-lightweight concrete. A moderate strength and an excellent thermal conductivity of the lightweight concrete are set as the design targets. The designed lightweight aggregates concrete is targeted to be used in monolithic concrete façade structure, performing as both load bearing element and thermal insulator. The developed lightweight concrete shows excellent thermal properties, with a low thermal conductivity of about 0.12 W/(m·K; and moderate mechanical properties, with 28-day compressive strengths of about 10-12 N/mm . This combination of values exceeds, to the researchers’ knowledge, the performance of all other lightweight building materials. Furthermore, the developed lightweight concrete possesses excellent durability properties.

  8. Design bases - Concrete structures

    International Nuclear Information System (INIS)

    Diaz-Llanos Ros, M.

    1993-01-01

    The most suitable title for Section 2 is 'Design Bases', which covers not only calculation but also the following areas: - Structural design concepts. - Project criteria. - Material specifications. These concepts are developed in more detail in the following sections. The numbering in this document is neither complete nor hierarchical since, for easier cross referencing, it corresponds to the paragraphs of Eurocode 2 Part 1 (hereinafter 'EUR-2') which are commented on. (author)

  9. Concrete structures for nuclear facilities

    International Nuclear Information System (INIS)

    1996-01-01

    The detailed requirements for the design and fabrication of the concrete structures for nuclear facilities and for the documents to be submitted to the Finnish Centre for Radiation and Nuclear Safety (STUK) are given in the guide. It also sets the requirements for the inspection of concrete structures during the construction and operation of facilities. The requirements of the guide primarily apply to new construction. As regards the repair and modification of nuclear facilities built before its publication, the guide is followed to the extent appropriate. The regulatory activities of the Finnish Centre for Radiation and Nuclear Safety during a nuclear facility's licence application review and during the construction and operation of the facility are summarised in the guide YVL 1.1

  10. Probabilistic design of fibre concrete structures

    Science.gov (United States)

    Pukl, R.; Novák, D.; Sajdlová, T.; Lehký, D.; Červenka, J.; Červenka, V.

    2017-09-01

    Advanced computer simulation is recently well-established methodology for evaluation of resistance of concrete engineering structures. The nonlinear finite element analysis enables to realistically predict structural damage, peak load, failure, post-peak response, development of cracks in concrete, yielding of reinforcement, concrete crushing or shear failure. The nonlinear material models can cover various types of concrete and reinforced concrete: ordinary concrete, plain or reinforced, without or with prestressing, fibre concrete, (ultra) high performance concrete, lightweight concrete, etc. Advanced material models taking into account fibre concrete properties such as shape of tensile softening branch, high toughness and ductility are described in the paper. Since the variability of the fibre concrete material properties is rather high, the probabilistic analysis seems to be the most appropriate format for structural design and evaluation of structural performance, reliability and safety. The presented combination of the nonlinear analysis with advanced probabilistic methods allows evaluation of structural safety characterized by failure probability or by reliability index respectively. Authors offer a methodology and computer tools for realistic safety assessment of concrete structures; the utilized approach is based on randomization of the nonlinear finite element analysis of the structural model. Uncertainty of the material properties or their randomness obtained from material tests are accounted in the random distribution. Furthermore, degradation of the reinforced concrete materials such as carbonation of concrete, corrosion of reinforcement, etc. can be accounted in order to analyze life-cycle structural performance and to enable prediction of the structural reliability and safety in time development. The results can serve as a rational basis for design of fibre concrete engineering structures based on advanced nonlinear computer analysis. The presented

  11. Steel fiber reinforced concrete subjected to elevated cyclic temperatures

    International Nuclear Information System (INIS)

    Yousif, R. A.; Rasheed, H. M.; Muhammad, H. A.

    1997-01-01

    The results from a series of tests on steel fiber reinforced concrete at elevated cyclic temperature are presented. The residual compressive strength and ultimate splitting tensile strength were nadir's on specimen ts with no fibers and with 0.5% and 1% plain steel fibers over a temperature range of 300-700 C. concrete was subjected to one, two or three cycles of heating and cooling. In general the exposure to temperature decreased the strength of concrete, although the number of heating cycles seems only to have a secondary effect. The results also show that the steel fiber reinforced concrete performs better than plain concrete. Two equations were suggested to predict the strength of concrete and the results show good agreement with the experimental values. . (authors). 10 refs., 1 tabs. 3 figs

  12. Prevention of shrinkage cracking in tight concrete structures

    International Nuclear Information System (INIS)

    Alvaredo, A.M.; Wittmann, F.H.

    1995-01-01

    It is shown that crack formation and propagation in concrete members subjected to restrained shrinkage can be realistically predicted by means of a comprehensive approach including a diffusion analysis and fracture mechanics considerations. The conditions for stable crack propagation regarding dimensions of the concrete member, degree of restraint to the imposed deformation and material properties are discussed. Guidelines on the prevention of shrinkage cracking of concrete structures are given. (author). 10 refs., 5 figs

  13. Surface Chloride Levels in Colorado Structural Concrete

    Science.gov (United States)

    2018-01-01

    This project focused on the chloride-induced corrosion of reinforcing steel in structural concrete. The primary goal of this project is to analyze the surface chloride concentration level of the concrete bridge decks throughout Colorado. The study in...

  14. Contributions to reinforced concrete structures numerical simulations

    International Nuclear Information System (INIS)

    Badel, P.B.

    2001-07-01

    In order to be able to carry out simulations of reinforced concrete structures, it is necessary to know two aspects: the behaviour laws have to reflect the complex behaviour of concrete and a numerical environment has to be developed in order to avoid to the user difficulties due to the softening nature of the behaviour. This work deals with these two subjects. After an accurate estimation of two behaviour models (micro-plan and mesoscopic models), two damage models (the first one using a scalar variable, the other one a tensorial damage of the 2 order) are proposed. These two models belong to the framework of generalized standard materials, which renders their numerical integration easy and efficient. A method of load control is developed in order to make easier the convergence of the calculations. At last, simulations of industrial structures illustrate the efficiency of the method. (O.M.)

  15. Bond-Slip Behavior of Basalt Fiber Reinforced Polymer Bar in Concrete Subjected to Simulated Marine Environment: Effects of BFRP Bar Size, Corrosion Age, and Concrete Strength

    OpenAIRE

    Yongmin Yang; Zhaoheng Li; Tongsheng Zhang; Jiangxiong Wei; Qijun Yu

    2017-01-01

    Basalt Fiber Reinforced Polymer (BFRP) bars have bright potential application in concrete structures subjected to marine environment due to their superior corrosion resistance. Available literatures mainly focused on the mechanical properties of BFRP concrete structures, while the bond-slip behavior of BFRP bars, which is a key factor influencing the safety and service life of ocean concrete structures, has not been clarified yet. In this paper, effects of BFRP bars size, corrosion age, and c...

  16. Concrete structures protection, repair and rehabilitation

    CERN Document Server

    Woodson, R Dodge

    2009-01-01

    The success of a repair or rehabilitation project depends on the specific plans designed for it. Concrete Structures: Protection, Repair and Rehabilitation provides guidance on evaluating the condition of the concrete in a structure, relating the condition of the concrete to the underlying cause or causes of that condition, selecting an appropriate repair material and method for any deficiency found, and using the selected materials and methods to repair or rehabilitate the structure. Guidance is also provided for engineers focused on maintaining concrete and preparing concrete investigation r

  17. Precast concrete sandwich panels subjected to impact loading

    Science.gov (United States)

    Runge, Matthew W.

    Precast concrete sandwich panels are a relatively new product in the construction industry. The design of these panels incorporates properties that allow for great resilience against temperature fluctuation as well as the very rapid and precise construction of facilities. The concrete sandwich panels investigated in this study represent the second generation of an ongoing research and development project. This second generation of panels have been engineered to construct midsized commercial buildings up to three stories in height as well as residential dwellings. The panels consist of a double-tee structural wythe, a foam core and a fascia wythe, joined by shear connectors. Structures constructed from these panels may be subjected to extreme loading including the effects of seismic and blast loading in addition to wind. The aim of this work was to investigate the behaviour of this particular sandwich panel when subjected to structural impact events. The experimental program consisted of fourteen concrete sandwich panels, five of which were considered full-sized specimens (2700 mm X 1200mm X 270 mm) and nine half-sized specimens (2700mm X 600mm X 270 mm) The panels were subjected to impact loads from a pendulum impact hammer where the total energy applied to the panels was varied by changing the mass of the hammer. The applied loads, displacements, accelerations, and strains at the mid-span of the panel as well as the reaction point forces were monitored during the impact. The behaviour of the panels was determined primarily from the experimental results. The applied loads at low energy levels that caused little to no residual deflection as well as the applied loads at high energy levels that represent catastrophic events and thus caused immediate failure were determined from an impact on the structural and the fascia wythes. Applied loads at intermediate energy levels representing extreme events were also used to determine whether or not the panels could withstand

  18. VISCOELASTIC STRUCTURAL MODEL OF ASPHALT CONCRETE

    Directory of Open Access Journals (Sweden)

    V. Bogomolov

    2016-06-01

    Full Text Available The viscoelastic rheological model of asphalt concrete based on the generalized Kelvin model is offered. The mathematical model of asphalt concrete viscoelastic behavior that can be used for calculation of asphalt concrete upper layers of non-rigid pavements for strength and rutting has been developed. It has been proved that the structural model of Burgers does not fully meet all the requirements of the asphalt-concrete.

  19. Strain Capacity of Reinforced Concrete Members Subjected to Uniaxial Tension

    DEFF Research Database (Denmark)

    Hagsten, Lars German; Rasmussen, Annette Beedholm; Fisker, Jakob

    2017-01-01

    The aim of this paper is to set up a method to determine the strain capacity of tension bars of reinforced concrete (RC) subjected to pure tension. Due to the interaction between reinforcement and concrete and due to the presence of cracks, the stresses in both reinforcement and concrete...... are varying along the length of the tension bar. The strain capacity of the tension bar is seen as the average strain in the reinforcement at the load level corresponding to the ultimate stress capacity of the reinforcement at the cracks. The result of the approach is in overall good agreement when comparing...

  20. Damage modelling in concrete subject to sulfate attack

    Directory of Open Access Journals (Sweden)

    N. Cefis

    2014-07-01

    Full Text Available In this paper, we consider the mechanical effect of the sulfate attack on concrete. The durability analysis of concrete structures in contact to external sulfate solutions requires the definition of a proper diffusion-reaction model, for the computation of the varying sulfate concentration and of the consequent ettringite formation, coupled to a mechanical model for the prediction of swelling and material degradation. In this work, we make use of a two-ions formulation of the reactive-diffusion problem and we propose a bi-phase chemo-elastic damage model aimed to simulate the mechanical response of concrete and apt to be used in structural analyses.

  1. Model techniques for testing heated concrete structures

    International Nuclear Information System (INIS)

    Stefanou, G.D.

    1983-01-01

    Experimental techniques are described which may be used in the laboratory to measure strains of model concrete structures representing to scale actual structures of any shape or geometry, operating at elevated temperatures, for which time-dependent creep and shrinkage strains are dominant. These strains could be used to assess the distribution of stress in the scaled structure and hence to predict the actual behaviour of concrete structures used in nuclear power stations. Similar techniques have been employed in an investigation to measure elastic, thermal, creep and shrinkage strains in heated concrete models representing to scale parts of prestressed concrete pressure vessels for nuclear reactors. (author)

  2. A study on the water permeability of concrete structures

    International Nuclear Information System (INIS)

    Loadsman, R.V.C.; Acres, D.H.; Stokes, C.J.; Wadeson, L.

    1988-03-01

    This report forms part of the DoE's research programme on the disposal of nuclear waste. The information available on the permeability of concrete and the effects of various factors on this value are reviewed. The effect of defects on the overall permeability of concrete structures is examined and the recorded performance of a range of existing concrete structures is considered with identification of some of the factors that are significant in practice. Deficiencies in the information available on this subject are identified and recommendations for further work are made including a list of structures suitable for future monitoring. (author)

  3. Radiation shielding structure for concrete structure

    International Nuclear Information System (INIS)

    Oya, Hiroshi

    1998-01-01

    Crack inducing members for inducing cracks in a predetermined manner are buried in a concrete structure. Namely, a crack-inducing member comprises integrally a shielding plate and extended plates situated at the center of a wall and inducing plates vertically disposed to the boundary portion between them with the inducing plates being disposed each in a direction perforating the wall. There are disposed integrally a pair of the inducing plate spaced at a predetermined horizontal distance on both sides of the shielding plate so as to form a substantially crank-shaped cross section and extended plates formed in the extending direction of the shielding plate, and the inducing plates are disposed each in a direction perforating the wall. Then, cracks generated when stresses are exerted can be controlled, and generation of cracks passing through the concrete structure can be prevented reliably. The reliability of a radiation shielding effect can be enhanced remarkably. (N.H.)

  4. STRUCTURAL AND THERMOPHYSICAL PROPERTIES OF HARDENING CONCRETE

    Directory of Open Access Journals (Sweden)

    L. Krasulina

    2012-01-01

    Full Text Available Structural and thermophysical properties of thermally treated concrete have been studied in the paper. The paper demonstrates regularities of changes in structural and thermophysical properties of concrete during heat treatment process. It is established that stabilization of coefficient values for heat- and temperature conductivity of concrete corresponds to completion of the process pertaining to intensive formation of the material pore structure and indicates the possibility of transition from the stage of isothermal extraction to the stage of temperature decrease. The obtained results are confirmed by studies of strength growth kinetics of concrete samples.

  5. Strengthening method of concrete structure

    Science.gov (United States)

    Inge, Wewin; Audrey; Nugroho, Sofie; Njo, Helen

    2018-03-01

    Building extension in Indonesia is not favored, and not many people know the advantages of the method because architects and engineers tend to lack the knowledge and experience. The aim of this paper is to explain a method on how to strengthen a concrete building structure that people can use/learn as a better way to cut potential cost and save time. The strengthening method explained in this paper is steel jacketing, providing a case study of this method in the extension of a restaurant located in Medan, Indonesia. In this study, engineers calculated that the tensile stress of the existing RC column and beam is not strong enough to reinforce the building extension applied load. Therefore, the steel jacketing method can be applied to improve the column and beam strength and ductility. The result of the case study proves that this is one of the best methods for building extension applied in Indonesia.

  6. Dynamic behavior of reinforced concrete beam subjected to impact load

    International Nuclear Information System (INIS)

    Ito, Chihiro; Ohnuma, Hiroshi; Sato, Koichi; Takano, Hiroshi

    1984-01-01

    The purpose of this report is to find out the impact behavior of reinforced concrete beams by means of experiment. The reinforced concrete is widely used for such an important structure as the building facilities of the nuclear power plant, and so the impact behavior of the reinforced concrete structures must be examined to estimate the resistance of concrete containment against impact load and to develope the reasonable and reliable design procedure. The impact test on reinforced concrete beam which is one of the most basic elements in the structure was conducted. Main results are summarized as follows. 1) Bending failure occured on static test. On the other hand, shear failure occured in the case of high impact velocity on impact test. 2) Penetration depth and residual deflection are approximately proportional to V 2 (V: velocity at impact). 3) Flexural wave propagates about at the speed of 2000 m/s. 4) The resistance of reinforced concrete beam against the impact load is fairly good. (author)

  7. Maintenance and Repair of Concrete Structures

    NARCIS (Netherlands)

    Bijen, J.M.J.M.

    1989-01-01

    In 1987 and 1988 a series of articles was published in the Dutchjournal "Cement" about maintenance and repair of concrete structures. The series was written to promote the transfer of know-how concerning maintenance and repair of concrete structures. Use has been made of know-how developed in the

  8. Durability of cracked fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    1998-01-01

    structure are made on specimens drilled or sawed from beams after unloading (mechanical load). The pore structure of the concretes will be studied by microscopy, sorption and suction curves. The test programme involves three different concrete qualities (water-cement ratios). Both steel fibres (ZP...

  9. Non-Destructive Testing for Concrete Structure

    International Nuclear Information System (INIS)

    Tengku Sarah Tengku Amran; Noor Azreen Masenwat; Mohamad Pauzi Ismail

    2015-01-01

    Nondestructive testing (NDT) is a technique to determine the integrity of a material, component or structure. It is essential in the inspection of alteration, repair and new construction in the building industry. There are a number of non-destructive testing techniques that can be applied to determine the integrity of concrete in a completed structure. Each has its own advantages and limitations. For concrete, these problems relate to strength, cracking, dimensions, delamination, and inhomogeneities. NDT is reasonably good and reliable tool to measure the property of concrete which also gives the fair indication of the compressive strength development. This paper discussed the concrete inspection using combined methods of NDT. (author)

  10. Temperature Response in Hardened Concrete Subjected to Tropical Rainforest Environment

    Directory of Open Access Journals (Sweden)

    E. I. Egba

    2017-06-01

    Full Text Available The objective of this paper is to characterize concrete micro-environment temperature response to the natural climate of the tropical rainforest. The peculiar warmth, high humidity, and low pressure nature of the tropical rainforest necessitated the present study. Temperature probes were inserted into concrete specimens subjected to the sheltered and unsheltered environment to measure the micro-environment temperature of the concrete, and study the hysteresis characteristics in relation to the climate temperature. Some mathematical relationships for forecasting the internal temperature of concrete in the tropical rainforest environment were proposed and tested. The proposed relationships were found reliable. It was observed that the micro-environment temperature was lower at the crest, and higher at the trough than the climate environment temperature with a temperature difference of 1-3 oC. Also, temperature response in concrete for the unsheltered micro-environment was 1.85 times faster than the response in the sheltered micro-environment. The findings of the study may be used to assist the durability assessment of concrete.

  11. Ageing management of concrete structure

    International Nuclear Information System (INIS)

    Parthipan, P.; Ramaprasad, G.S.; Senthil, R.

    2006-01-01

    It is a generally accepted fact that while designing a concrete structure the durability parameters of construction materials should be evaluated as carefully as possible like other properties such as mechanical, physical and chemical properties. No material is inherently durable as result of environmental interaction with microstructure and consequently, the properties of the materials change with time due to weathering action, chemical attack, abrasion or any mode of degradation. The main cause of ageing on structure, water, which is primary for both creation and destruction on many natural materials. In porous materials, water creates different types of physical and chemical process of degradation. The water movement through porous materials are controlled by the permeability of the respective materials. The rate of deterioration is affected by type of concentration of ions present in the water and chemical deposition of materials. Controlling weathering action, chemical attack, abrasion and selecting good quality construction material and methods of construction can increase the service life of the structure. (author)

  12. Response and Damage Assessment of Reinforced Concrete Frames subject to Earthquakes

    DEFF Research Database (Denmark)

    Skjærbæk, Poul

    When civil engineering structures made of reinforced concrete (RC) such as some types of apartment buildings, hospitals, office buildings, bridges etc. are subjected to sufficiently high dynamic loads it is well known that some kind of damage will occur in the structure. The damage introduced in ...

  13. Behaviour of concrete structures in fire

    Directory of Open Access Journals (Sweden)

    Fletcher Ian A.

    2007-01-01

    Full Text Available This paper provides a "state-of-the-art" review of research into the effects of high temperature on concrete and concrete structures, extending to a range of forms of construction, including novel developments. The nature of concrete-based structures means that they generally perform very well in fire. However, concrete is fundamentally a complex material and its properties can change dramatically when exposed to high temperatures. The principal effects of fire on concrete are loss of compressive strength, and spalling - the forcible ejection of material from the surface of a member. Though a lot of information has been gathered on both phenomena, there remains a need for more systematic studies of the effects of thermal exposures. The response to realistic fires of whole concrete structures presents yet greater challenges due to the interactions of structural elements, the impact of complex small-scale phenomena at full scale, and the spatial and temporal variations in exposures, including the cooling phase of the fire. Progress has been made on modeling the thermomechanical behavior but the treatment of detailed behaviors, including hygral effects and spalling, remains a challenge. Furthermore, there is still a severe lack of data from real structures for validation, though some valuable insights may also be gained from study of the performance of concrete structures in real fires. .

  14. STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS

    International Nuclear Information System (INIS)

    Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.

    2001-01-01

    This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits

  15. Recycled Concrete as Aggregate for Structural Concrete Production

    OpenAIRE

    Mirjana Malešev; Vlastimir Radonjanin; Snežana Marinković

    2010-01-01

    A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC) as a control concrete and two types of concrete made with natural fine and recycle...

  16. Alkali aggregate reactivity in concrete structures in western Canada

    International Nuclear Information System (INIS)

    Morgan, D.R.; Empey, D.

    1989-01-01

    In several regions of Canada, particularly parts of Ontario, Quebec and the Maritime Provinces, research, testing and evaluation of aged concrete structures in the field has shown that alkali aggregate reactivity can give rise to pronounced concrete deterioration, particularly in hydraulic structures subjected to saturation or alternate wetting and drying such as locks, dams, canals, etc. Concrete deterioration is mainly caused by alkali-silica reactions and alkali-carbonate reactions, but a third type of deterioration involves slow/late expanding alkali-silicate/silica reactivity. The alkalies NaOH and KOH in the concrete pore solutions are mainly responsible for attack on expansive rocks and minerals in concrete. Methods for evaluating alkali-aggregate reaction potential in aggregates, and field and laboratory methods for detecting deterioration are discussed. Examples of alkali-aggregate reactions in structures is western Canada are detailed, including a water reservoir at Canadian Forces Base Chilliwack in British Columbia, the Oldman River diversion and flume, the Lundbreck Falls Bridge, and the St Mary's Reservoir spillway, all in southern Alberta. Mitigative measures include avoidance of use of suspect aggregates, but if this cannot be avoided it is recommended to keep the total alkalies in the concrete as low as possible and minimize opportunities for saturation of concrete by moisture. 16 refs., 19 figs., 1 tab

  17. Volume changes in unrestrained structural lightweight concrete.

    Science.gov (United States)

    1964-08-01

    In this study a comparator-type measuring system was developed to accurately determine volume change characteristics of one structural lightweight concrete. The specific properties studied were the coefficient of linear thermal expansion and unrestra...

  18. Doubling the Life of Concrete Structures

    Energy Technology Data Exchange (ETDEWEB)

    Pesic, Batric [Univ. of Idaho, Moscow, ID (United States); Raja, Krishnan [Univ. of Idaho, Moscow, ID (United States); Xi, Yumping [Univ. of Colorado, Boulder, CO (United States); Jun, Jiheon [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-07-24

    Overall objective of the project was to study the fundamental properties of concrete (with and without steel reinforcement) with respect to chemical and physical parameters that can influence its structural integrity.

  19. Doubling the Life of Concrete Structures

    International Nuclear Information System (INIS)

    Pesic, Batric; Raja, Krishnan; Xi, Yumping; Jun, Jiheon

    2017-01-01

    Overall objective of the project was to study the fundamental properties of concrete (with and without steel reinforcement) with respect to chemical and physical parameters that can influence its structural integrity.

  20. Advanced concrete structures for thermal power plants

    International Nuclear Information System (INIS)

    Zerna, W.

    1982-01-01

    The author begins with an overview on the various types of power plants depending on the fuel used in them and then in particular deals with the reinforced concrete structures. Especially for reactor buildings and prestressed concrete pressure vessels concrete is the appropriate material. The methods of construction are described as a function of load and operation. Safety requirements brought new load types for such structures as e.g. airplane crash, internal pressure caused by pipe rupture. Dimensioning is done by means of nonlinear dynamical methods of calculation accounting for plasticizing. These methods are explained. Further the constructional principles of high natural-draft cooling towers are mentioned. (orig.) [de

  1. Leakage of pressurized gases through unlined concrete containment structures

    International Nuclear Information System (INIS)

    Rizkalla, S.H.; Simmonds, S.H.

    1983-01-01

    Eight reinforced concrete specimens were fabricated and subjected to tensile membrane forces and air pressure to study the air leakage characteristics in cracked reinforced concrete members. A mathematical expression for the rate of pressurized air flowing through an idealized crack is presented. The mathematical expression is refined by using the experimental data to describe the air flow rate through any given crack pattern. Graphical charts are also presented for the calculation of the air leakage rate through concrete cracks. The concept of equivalent crack width for a given crack pattern is introduced. The mathematical expression and graphical charts are modified to include this equivalent crack width concept. The proposed technique is applicable for the prediction of the leakage from concrete containment structures or any similar structures due to high internal pressure sufficient to initiate cracking. (orig.)

  2. Ceramic ware waste as coarse aggregate for structural concrete production.

    Science.gov (United States)

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

    2015-01-01

    The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.

  3. Structure formation control of foam concrete

    Science.gov (United States)

    Steshenko, Aleksei; Kudyakov, Aleksander; Konusheva, Viktoriya; Syrkin, Oleg

    2017-01-01

    The process of predetermined foam concrete structure formation is considered to be a crucial issue from the point of process control and it is currently understudied thus defining the need for additional research. One of the effective ways of structure formation control in naturally hardening foam concrete is reinforcement with dispersed fibers or introduction of plasticizers. The paper aims at studying the patterns of influence of microreinforcing and plasticizing additives on the structure and performance properties of foam concrete. Preparation of foam concrete mix has been conducted using one-step technology. The structure of modified foam concrete has been studied by means of electron microscopy. The cellular structure of foam concrete samples with the additives is homogeneous; the pores are uniformly distributed over the total volume. It has been revealed that introduction of the Neolas 5.2 plasticizer and microreinforcing fibers in the foam concrete mixture in the amount of 0.4 - 0.1 % by weight of cement leads to reduction of the average pore diameter in the range of 45.3 to 30.2 microns and the standard deviation of the pore average diameter from 23.6 to 9.2 in comparison with the sample without additive. Introduction of modifying additives has stimulated formation of a large number of closed pores. Thus porosity of conditionally closed pores has increased from 16.06 % to 34.48 %, which has lead to increase of frost resistance brand of foam concrete from F15 to F50 and to reduction of its water absorption by weight by 20 %.

  4. Assessing the performance of reinforced concrete structures under impact loads

    International Nuclear Information System (INIS)

    Sharma, Akanshu; Reddy, G.R.; Vaze, K.K.; Ozbolt, Josko; Hofmann, J.

    2011-01-01

    Reinforced concrete (RC) structures housing nuclear facilities must qualify against much stringent requirements of operating and accidental loads than conventional structures. One such accidental load that must be considered while assessing the performance of safety related RC structures is impact load. It is known that the behavior of concrete/reinforced concrete structures is strongly influenced by the loading rate. The RC structural members subjected to impact loads behave quite differently as compared to the same subjected to quasi-static loading due to the strain-rate influence on strength, stiffness, and ductility as well as to the activation of inertia forces. Moreover, for concrete structures, which exhibit damage and fracture phenomena, the failure mode and cracking pattern depend significantly on loading rate. In general, there is a tendency that with the increase of loading rate the failure mode changes from mode-I to mixed mode. In order to assess the performance of existing structures against impact loads that may be generated mainly due to man-made accidental conditions, it is important to have models that can realistically predict the impact behavior of concrete structures. The present paper focuses on a relatively new approach for 3D finite element analysis of RC structures under impact loads. The approach uses rate sensitive micro-plane model as constitutive law for concrete, while the strain-rate influence is captured by the activation energy. Inertia forces are implicitly accounted for through dynamic finite element analysis. It is shown with the help of different examples that the approach can very well simulate the behavior of RC structural elements under high rate loading. (author)

  5. Structural optimization of reinforced concrete container for radioactive wastes

    International Nuclear Information System (INIS)

    Tamura, M.

    1984-01-01

    A structural optimization study of reinforced concrete container for transportation and disposal of the low level radioactive waste generated in Brazilian nuclear power plants. The code requires the structural integrity of these containers when subjected to fall from specified height, avoiding environmental contamination. The structural optimization allows material and transportation cost reduction by container wall thickness reduction. The structural analysis is performed by tridimensional mathematical model using finite element method. (Author) [pt

  6. Reusing recycled aggregates in structural concrete

    Science.gov (United States)

    Kou, Shicong

    The utilization of recycled aggregates in concrete can minimize environmental impact and reduce the consumption of natural resources in concrete applications. The aim of this thesis is to provide a scientific basis for the possible use of recycled aggregates in structure concrete by conducting a comprehensive programme of laboratory study to gain a better understanding of the mechanical, microstructure and durability properties of concrete produced with recycled aggregates. The study also explored possible techniques to of improve the properties of recycled aggregate concrete that is produced with high percentages (≧ 50%) of recycled aggregates. These techniques included: (a) using lower water-to-cement ratios in the concrete mix design; (b) using fly ash as a cement replacement or as an additional mineral admixture in the concrete mixes, and (c) precasting recycled aggregate concrete with steam curing regimes. The characteristics of the recycled aggregates produced both from laboratory and a commercially operated pilot construction and demolition (C&D) waste recycling plant were first studied. A mix proportioning procedure was then established to produce six series of concrete mixtures using different percentages of recycled coarse aggregates with and without the use of fly ash. The water-to-cement (binder) ratios of 0.55, 0.50, 0.45 and 0.40 were used. The fresh properties (including slump and bleeding) of recycled aggregate concrete (RAC) were then quantified. The effects of fly ash on the fresh and hardened properties of RAC were then studied and compared with those RAC prepared with no fly ash addition. Furthermore, the effects of steam curing on the hardened properties of RAC were investigated. For micro-structural properties, the interfacial transition zones of the aggregates and the mortar/cement paste were analyzed by SEM and EDX-mapping. Moreover, a detailed set of results on the fracture properties for RAC were obtained. Based on the experimental

  7. Monitoring of Concrete Structures Using Ofdr Technique

    Science.gov (United States)

    Henault, J. M.; Salin, J.; Moreau, G.; Delepine-Lesoille, S.; Bertand, J.; Taillade, F.; Quiertant, M.; Benzarti, K.

    2011-06-01

    Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as bridges, dikes, nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on Optical Frequency Domain Reflectometry (OFDR), enables to perform temperature and strain measurements with a centimeter scale spatial resolution over hundred of meters and with a level of precision equal to 1 μstrain and 0.1 °C. Several sensing cables are designed with different materials targeting to last for decades in a concrete aggressive environment and to ensure an optimal transfer of temperature and strain from the concrete matrix to the optical fiber. Tests were carried out by embedding various sensing cables into plain concrete specimens and representative-scale reinforced concrete structural elements. Measurements were performed with an OFDR instrument; meanwhile, mechanical solicitations were imposed to the concrete element. Preliminary experiments are very promising since measurements performed with distributed sensing system are comparable to values obtained with conventional sensors used in civil engineering and with the Strength of Materials Modelling. Moreover, the distributed sensing system makes it possible to detect and localize cracks appearing in concrete during the mechanical loading.

  8. Indicators for Inspection and Maintenance Planning of Concrete Structures

    DEFF Research Database (Denmark)

    Faber, Michael Havbro; Sørensen, John Dalsgaard

    2002-01-01

    utilized and consistently updated as frequentistic information is collected. The approach is illustrated on an example considering a concrete structure subject to corrosion. It is shown how half-cell potential measurements may be utilized to update the probability of excessive repair after 50 years...

  9. Concrete structures under impact and impulsive loading

    International Nuclear Information System (INIS)

    Plauk, G.

    1982-05-01

    This book contains papers contributed to the RILEM/CEB/IABSE/IASS-Interassociation Symposium on 'Concrete Structures under Impact and Impulsive Loading'. The essential aim of this symposium is to provide an international forum for the exchange of information on existing and current research relating to impact problems as well as to identify areas to which further research activities should be directed. The subject of the symposium is far ranging. Fifty five papers were proposed and arranged in six technical sessions, a task which sometimes posed difficulties for the Organization Committee and the Advisory Group, because some of the papers touched several topics and were difficult to integrate. However, we are confident that these minor difficulties were solved to the satisfaction of everyone involved. Each session of the symposium is devoted to a major subject area and introduced by a distinguished Introductory Reporter. The large international attendance, some 21 countries are represented, and the large number of excellent papers will certainly produce a lively discussion after each session and thus help to further close the gaps in our knowledge about the behaviour of structures and materials under impact and impulsive loading. (orig./RW)

  10. Durability of thin-walled concrete structures

    International Nuclear Information System (INIS)

    Salomon, M.; Gallias, J.L.

    1991-01-01

    The aim of the present document is to draw up a survey of knowledge of the problems of ageing of reinforced concrete shell structure atmospheric coolers. The exposure conditions are particularly favourable to the induction and development of degradation which, because of the thinness of the reinforced concrete can compromise the stability and the durability of coolers. The study will be axed on the link between the specific characteristics of coolers from the point of view of operation, design and environment, also the durability of reinforced concrete. The set of factors exerting their influence on the reinforced concrete of the shell structure (condensates, rain water, temperature and humidity gradients, dynamic loads, weathering, etc.) is particularly complex. The principal degradation reactions involved are classified according to the chemical and physical action on concrete and on the reinforcement. Particular emphasis is placed on the analysis of degradation processes and the influence of the characteristics of the materials and of the medium. The aim is to determine the mechanisms which present the greatest risk for coolers. The interaction between the degradation to concrete and the change in mechanical characteristics is also studied [fr

  11. THE STUDY ON THE DURABILITY OF SUBMERGED STRUCTURE DISPLACEMENT DUE TO CONCRETE FAILURE

    Directory of Open Access Journals (Sweden)

    M. Mohd

    2016-09-01

    Full Text Available Concrete structures that exposed to marine environments are subjected to multiple deterioration mechanisms. An overview of the existing technology for submerged concrete, pressure resistant, concrete structures which related such as cracks, debonds, and delamination are discussed. Basic knowledge related to drowning durability such as submerged concrete structures in the maritime environment are the durability of a concrete and the ability to resist to weathering, chemical attack, abrasion or other deterioration processes. The measuring techniques and instrumentation for geometrical monitoring of submerged structural displacements have traditionally been categorized into two groups according to the two main groups, namely as geodetic surveying and geotechnical structural measurements of local displacements. This paper aims to study the durability of submerged concrete displacement and harmful effects of submerged concrete structures.

  12. The Effect of Elevated Temperature on Concrete Materials and Structures - a Literature Review.

    Energy Technology Data Exchange (ETDEWEB)

    Naus, Dan J [ORNL

    2006-03-01

    The objective of this limited study was to provide an overview of the effects of elevated temperature on the behavior of concrete materials and structures. In meeting this objective the effects of elevated temperatures on the properties of ordinary Portland cement concrete constituent materials and concretes are summarized. The effects of elevated temperature on high-strength concrete materials are noted and their performance compared to normal strength concretes. A review of concrete materials for elevated-temperature service is presented. Nuclear power plant and general civil engineering design codes are described. Design considerations and analytical techniques for evaluating the response of reinforced concrete structures to elevated-temperature conditions are presented. Pertinent studies in which reinforced concrete structural elements were subjected to elevated temperatures are described.

  13. The Effect of Elevated Temperature on Concrete Materials and Structures - a Literature Review

    International Nuclear Information System (INIS)

    Naus, Dan J.

    2006-01-01

    The objective of this limited study was to provide an overview of the effects of elevated temperature on the behavior of concrete materials and structures. In meeting this objective the effects of elevated temperatures on the properties of ordinary Portland cement concrete constituent materials and concretes are summarized. The effects of elevated temperature on high-strength concrete materials are noted and their performance compared to normal strength concretes. A review of concrete materials for elevated-temperature service is presented. Nuclear power plant and general civil engineering design codes are described. Design considerations and analytical techniques for evaluating the response of reinforced concrete structures to elevated-temperature conditions are presented. Pertinent studies in which reinforced concrete structural elements were subjected to elevated temperatures are described.

  14. Recycled Concrete as Aggregate for Structural Concrete Production

    Directory of Open Access Journals (Sweden)

    Mirjana Malešev

    2010-04-01

    Full Text Available A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC as a control concrete and two types of concrete made with natural fine and recycled coarse aggregate (50% and 100% replacement of coarse recycled aggregate. Ninety-nine specimens were made for the testing of the basic properties of hardened concrete. Load testing of reinforced concrete beams made of the investigated concrete types is also presented in the paper. Regardless of the replacement ratio, recycled aggregate concrete (RAC had a satisfactory performance, which did not differ significantly from the performance of control concrete in this experimental research. However, for this to be fulfilled, it is necessary to use quality recycled concrete coarse aggregate and to follow the specific rules for design and production of this new concrete type.

  15. Affective Meaning, Concreteness, and Subjective Frequency Norms for Indonesian Words

    Directory of Open Access Journals (Sweden)

    Agnes Sianipar

    2016-12-01

    Full Text Available This study investigated the lexical-semantic space organized by the semantic and affective features of Indonesian words and their relationship with gender and cultural aspects. We recruited 1,402 participants who were native speakers of Indonesian to rate affective and lexico-semantic properties of 1,490 Indonesian words. Valence, Arousal, Dominance, Predictability, Subjective Frequency, and Concreteness ratings were collected for each word from at least 52 people. We explored cultural differences between American English ANEW, Spanish ANEW, and the new Indonesian inventory (called CEFI. We found functional relationships between the affective dimensions that were similar across languages, but also cultural differences dependent on gender.

  16. A Simple Demonstration of Concrete Structural Health Monitoring Framework

    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); Cai, Guowei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Nath, Paromita [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bao, Yanqing [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bru Brea, Jose Maria [Idaho National Lab. (INL), Idaho Falls, ID (United States); Koester, David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Adams, Douglas [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kosson, David [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    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. 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. This ongoing research project is seeking to develop a probabilistic framework for health diagnosis and prognosis of aging concrete structures in a nuclear power plant subjected to physical, chemical, environment, and mechanical degradation. The proposed framework consists of four elements—damage modeling, monitoring, data analytics, and uncertainty quantification. This report describes a proof-of-concept example on a small concrete slab subjected to a freeze-thaw experiment that explores techniques in each of the four elements of the framework and their integration. An experimental set-up at Vanderbilt University’s Laboratory for Systems Integrity and Reliability is used to research effective combination of full-field techniques that include infrared thermography, digital image correlation, and ultrasonic measurement. The measured data are linked to the probabilistic framework: the thermography, digital image correlation data, and ultrasonic measurement data are used for Bayesian calibration of model parameters, for diagnosis of damage, and for prognosis of future damage. The proof-of-concept demonstration presented in this report highlights the significance of each element of the framework and their integration.

  17. Creep Behavior of High-Strength Concrete Subjected to Elevated Temperatures

    OpenAIRE

    Minho Yoon; Gyuyong Kim; Youngsun Kim; Taegyu Lee; Gyeongcheol Choe; Euichul Hwang; Jeongsoo Nam

    2017-01-01

    Strain is generated in concrete subjected to elevated temperatures owing to the influence of factors such as thermal expansion and design load. Such strains resulting from elevated temperatures and load can significantly influence the stability of a structure during and after a fire. In addition, the lower the water-to-binder (W?B) ratio and the smaller the quantity of aggregates in high-strength concrete, the more likely it is for unstable strain to occur. Hence, in this study, the compressi...

  18. Concrete

    DEFF Research Database (Denmark)

    2015-01-01

    Concrete is a component of coherent transition between a concrete base and a wooden construction. The structure is based on a quantity of investigations of the design possibilities that arise when combining digital fabrication tools and material capacities. Through tangible experiments the project...... specific for this to happen. And the knowledge and intention behind the drawing becomes specialised through the understanding of the fabrication processes and their affect on the materials.The structure Concrete is a result of a multi-angled kerf series in ash wood and a concrete base. The ash wood is cut...... using a 5-axis CNC router with a thin saw blade attached. The programming of the machining results in variations of kerfs that lets the ash wood twist into unique shapes.The shapes of the revolving ash ribbons continue into the concrete creating a cohesive shape. The form for the concrete itself is made...

  19. Nonlinear analysis of reinforced concrete structures using software package abaqus

    OpenAIRE

    Marković Nemanja; Stojić Dragoslav; Cvetković Radovan

    2014-01-01

    Reinforced concrete (AB) is characterized by huge inhomogeneity resulting from the material characteristics of the concrete, then, quasi-brittle behavior during failure. These and other phenomena require the introduction of material nonlinearity in the modeling of reinforced concrete structures. This paper presents the modeling reinforced concrete in the software package ABAQUS. A brief theoretical overview is presented of methods such as: Concrete Damage Plasticity (CDP), Smeared Concrete Cr...

  20. 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.

  1. Lateral rigidity of cracked concrete structures

    International Nuclear Information System (INIS)

    Castellani, A.; Chesi, C.

    1979-01-01

    Numerical results are discussed on the lateral rigidity of reinforced concrete structures with a given crack distribution. They have been favourably checked with experimental results for cylindrical shells under the effect of a thermal gradient producing vertical cracking or vertical plus horizontal cracking. The main effects characterizing the concrete behaviour are: (1) The shear transfer across a crack; (2) The shear transfer degradation after cyclic loading; (3) The tension stiffening provided by the concrete between crack and crack, in the normal stress transfer; (4) The temperature effect on the elastic moduli of concrete, when cracks are of thermal origin. Only the 1st effect is discussed on an experimental basis. Two broad cathegories of reinforced concrete structures have been investigated in this respect: shear walls of buildings and cylindrical containment structures. The main conclusions so far reached are: (1) Vertical cracks are unlikely to decrease the lateral rigidity to less than 80% of the original one, and to less than 90% when they do not involve the entire thickness of the wall; (2) The appearence of horizontal cracks can reduce the lateral rigidity by some 30% or more; (3) A noticeable but not yet evaluated influence is shown by cyclic loading. (orig.)

  2. Nonlinear finite element analysis of concrete structures

    International Nuclear Information System (INIS)

    Ottosen, N.S.

    1980-05-01

    This report deals with nonlinear finite element analysis of concrete structures loaded in the short-term up until failure. A profound discussion of constitutive modelling on concrete is performed; a model, applicable for general stress states, is described and its predictions are compared with experimental data. This model is implemented in the AXIPLANE-program applicable for axisymmetrick and plane structures. The theoretical basis for this program is given. Using the AXIPLANE-program various concrete structures are analysed up until failure and compared with experimental evidence. These analyses include panels pressure vessel, beams failing in shear and finally a specific pull-out test, the Lok-Test, is considered. In these analyses, the influence of different failure criteria, aggregate interlock, dowel action, secondary cracking, magnitude of compressive strenght, magnitude of tensile strenght and of different post-failure behaviours of the concrete are evaluated. Moreover, it is shown that a suitable analysis of the theoretical data results in a clear insight into the physical behaviour of the considered structures. Finally, it is demonstrated that the AXISPLANE-program for widely different structures exhibiting very delicate structural aspects gives predictions that are in close agreement with experimental evidence. (author)

  3. Selected Aspects of Computer Modeling of Reinforced Concrete Structures

    Directory of Open Access Journals (Sweden)

    Szczecina M.

    2016-03-01

    Full Text Available The paper presents some important aspects concerning material constants of concrete and stages of modeling of reinforced concrete structures. The problems taken into account are: a choice of proper material model for concrete, establishing of compressive and tensile behavior of concrete and establishing the values of dilation angle, fracture energy and relaxation time for concrete. Proper values of material constants are fixed in simple compression and tension tests. The effectiveness and correctness of applied model is checked on the example of reinforced concrete frame corners under opening bending moment. Calculations are performed in Abaqus software using Concrete Damaged Plasticity model of concrete.

  4. Failure/leakage predictions of concrete structures containing cracks

    International Nuclear Information System (INIS)

    Pan, Y.C.; Marchertas, A.H.; Kennedy, J.M.

    1984-06-01

    An approach is presented for studying the cracking and radioactive release of a reactor containment during severe accidents and extreme environments. The cracking of concrete is modeled as the blunt crack. The initiation and propagation of a crack are determined by using the maximum strength and the J-integral criteria. Furthermore, the extent of cracking is related to the leakage calculation by using a model developed by Rizkalla, Lau and Simmonds. Numerical examples are given for a three-point bending problem and a hypothetical case of a concrete containment structure subjected to high internal pressure during an accident

  5. Behaviour of a pre-stressed concrete pressure-vessel subjected to a high temperature gradient

    International Nuclear Information System (INIS)

    Dubois, F.

    1965-01-01

    After a review of the problems presented by pressure-vessels for atomic reactors (shape of the vessel, pressures, openings, foundations, etc.) the advantages of pre-stressed concrete vessels with respect to steel ones are given. The use of pre-stressed concrete vessels however presents many difficulties connected with the properties of concrete. Thus, because of the absence of an exact knowledge of the material, it is necessary to place a sealed layer of steel against the concrete, to have a thermal insulator or a cooling circuit for limiting the deformations and stresses, etc. It follows that the study of the behaviour of pre-stressed concrete and of the vessel subjected- to a high temperature gradient can yield useful information. A one-tenth scale model of a pre-stressed concrete cylindrical vessel without any side openings and without a base has been built. Before giving a description of the tests the authors consider some theoretical aspects concerning 'scale model-actual structure' similitude conditions and the calculation of the thermal and mechanical effects. The pre-stressed concrete model was heated internally by a 'pyrotenax' element and cooled externally by a very strong air current. The concrete was pre-stressed using horizontal and vertical cables held at 80 kg/cm 2 ; the thermal gradient was 160 deg. C. During the various tests, measurements were made of the overall and local deformations, the changes in water content, the elasticity modulus, the stress and creep of the cables and the depths of the cracks. The overall deformations observed are in line with thermal deformation theories and the creep of the cables attained 20 to 30 per cent according to their position relative to the internal surface. The dynamic elasticity modulus decreased by half but the concrete keeps its good mechanical properties. Finally, cracks 8 to 12 cm deep and 2 to 3 mms wide appeared in that part of the concrete which was not pre-stressed. The results obtained make it

  6. Innovating a classic course in concrete structures

    DEFF Research Database (Denmark)

    Goltermann, Per

    2016-01-01

    A large number of changes, new activities and approaches have been tested at DTU in the teaching of concrete structures: Use of mandatory assignments, handing out solutions before or after exercises, detailed or summary solutions, brush-up teaching materials, strengthened consistency in solutions...

  7. Residual strength evaluation of concrete structural components ...

    Indian Academy of Sciences (India)

    This paper presents methodologies for residual strength evaluation of concrete structural components using linear elastic and nonlinear fracture mechanics principles. The effect of cohesive forces due to aggregate bridging has been represented mathematically by employing tension softening models. Various tension ...

  8. Conceptual Design Tool for Concrete Shell Structures

    DEFF Research Database (Denmark)

    Holst, Malene Kirstine; Kirkegaard, Poul Henning

    2011-01-01

    This paper focuses on conceptual tools for concrete shell structures when working within the span of performance-based design and computational morphogenesis. The designer, referred to as the Architect-Engineer, works through several iterations parallel with aesthetic, functional and technical re...

  9. New rheological model for concrete structural analysis

    International Nuclear Information System (INIS)

    Chern, J.C.

    1984-01-01

    Long time deformation is of interest in estimating stresses of the prestressed concrete reactor vessel, in predicting cracking due to shrinkage or thermal dilatation, and in the design of leak-tight structures. Many interacting influences exist among creep, shrinkage and cracking for concrete. An interaction which researchers have long observed, is that at simultaneous drying and loading, the deformation of a concrete structure under the combined effect is larger than the sum of the shrinkage deformation of the structure at no load and the deformation of the sealed structure. The excess deformation due to the difference between observed test data and conventional analysis is regarded as the Pickett Effect. A constitutive relation explaining the Pickett Effect and other similar superposition problems, which includes creep, shrinkage (or thermal dilation), cracking, aging was developed with an efficient time-step numerical algorithm. The total deformation in the analysis is the sum of strain due to elastic deformation and creep, cracking and shrinkage with thermal dilatation. Instead of a sudden stress reduction to zero after the attainment of the strength limit, the gradual strain-softening of concrete (a gradual decline of stress at increasing strain) is considered

  10. Duracrete: Service life design for concrete structures

    NARCIS (Netherlands)

    Siemes, A.J.M.; Edvardsen, C.

    1999-01-01

    In the past decades much effort has been put into the improvement of the durability of concrete structures. This has resulted in a reasonable understanding of the main degradation processes or in experience with measures to prevent degradation. The results of this effort can be found in the present

  11. Bond-Slip Behavior of Basalt Fiber Reinforced Polymer Bar in Concrete Subjected to Simulated Marine Environment: Effects of BFRP Bar Size, Corrosion Age, and Concrete Strength

    Directory of Open Access Journals (Sweden)

    Yongmin Yang

    2017-01-01

    Full Text Available Basalt Fiber Reinforced Polymer (BFRP bars have bright potential application in concrete structures subjected to marine environment due to their superior corrosion resistance. Available literatures mainly focused on the mechanical properties of BFRP concrete structures, while the bond-slip behavior of BFRP bars, which is a key factor influencing the safety and service life of ocean concrete structures, has not been clarified yet. In this paper, effects of BFRP bars size, corrosion age, and concrete strength on the bond-slip behavior of BFRP bars in concrete cured in artificial seawater were investigated, and then an improved Bertero, Popov, and Eligehausen (BPE model was employed to describe the bond-slip behavior of BFRP bars in concrete. The results indicated that the maximum bond stress and corresponding slip decreased gradually with the increase of corrosion age and size of BFRP bars, and ultimate slip also decreased sharply. The ascending segment of bond-slip curve tends to be more rigid and the descending segment tends to be softer after corrosion. A horizontal end in bond-slip curve indicates that the friction between BFRP bars and concrete decreased sharply.

  12. Acoustic Emission Analysis of Prestressed Concrete Structures

    Science.gov (United States)

    Elfergani, H. A.; Pullin, R.; Holford, K. M.

    2011-07-01

    Corrosion is a substantial problem in numerous structures and in particular corrosion is very serious in reinforced and prestressed concrete and must, in certain applications, be given special consideration because failure may result in loss of life and high financial cost. Furthermore corrosion cannot only be considered a long term problem with many studies reporting failure of bridges and concrete pipes due to corrosion within a short period after they were constructed. The concrete pipes which transport water are examples of structures that have suffered from corrosion; for example, the pipes of The Great Man-Made River Project of Libya. Five pipe failures due to corrosion have occurred since their installation. The main reason for the damage is corrosion of prestressed wires in the pipes due to the attack of chloride ions from the surrounding soil. Detection of the corrosion in initial stages has been very important to avoid other failures and the interruption of water flow. Even though most non-destructive methods which are used in the project are able to detect wire breaks, they cannot detect the presence of corrosion. Hence in areas where no excavation has been completed, areas of serious damage can go undetected. Therefore, the major problem which faces engineers is to find the best way to detect the corrosion and prevent the pipes from deteriorating. This paper reports on the use of the Acoustic Emission (AE) technique to detect the early stages of corrosion prior to deterioration of concrete structures.

  13. Acoustic Emission Analysis of Prestressed Concrete Structures

    International Nuclear Information System (INIS)

    Elfergani, H A; Pullin, R; Holford, K M

    2011-01-01

    Corrosion is a substantial problem in numerous structures and in particular corrosion is very serious in reinforced and prestressed concrete and must, in certain applications, be given special consideration because failure may result in loss of life and high financial cost. Furthermore corrosion cannot only be considered a long term problem with many studies reporting failure of bridges and concrete pipes due to corrosion within a short period after they were constructed. The concrete pipes which transport water are examples of structures that have suffered from corrosion; for example, the pipes of The Great Man-Made River Project of Libya. Five pipe failures due to corrosion have occurred since their installation. The main reason for the damage is corrosion of prestressed wires in the pipes due to the attack of chloride ions from the surrounding soil. Detection of the corrosion in initial stages has been very important to avoid other failures and the interruption of water flow. Even though most non-destructive methods which are used in the project are able to detect wire breaks, they cannot detect the presence of corrosion. Hence in areas where no excavation has been completed, areas of serious damage can go undetected. Therefore, the major problem which faces engineers is to find the best way to detect the corrosion and prevent the pipes from deteriorating. This paper reports on the use of the Acoustic Emission (AE) technique to detect the early stages of corrosion prior to deterioration of concrete structures.

  14. Creep Behavior of High-Strength Concrete Subjected to Elevated Temperatures.

    Science.gov (United States)

    Yoon, Minho; Kim, Gyuyong; Kim, Youngsun; Lee, Taegyu; Choe, Gyeongcheol; Hwang, Euichul; Nam, Jeongsoo

    2017-07-11

    Strain is generated in concrete subjected to elevated temperatures owing to the influence of factors such as thermal expansion and design load. Such strains resulting from elevated temperatures and load can significantly influence the stability of a structure during and after a fire. In addition, the lower the water-to-binder (W-B) ratio and the smaller the quantity of aggregates in high-strength concrete, the more likely it is for unstable strain to occur. Hence, in this study, the compressive strength, elastic modulus, and creep behavior were evaluated at target temperatures of 100, 200, 300, 500, and 800 °C for high-strength concretes with W-B ratios of 30%, 26%, and 23%. The loading conditions were set as non-loading and 0.33f cu . It was found that as the compressive strength of the concrete increased, the mechanical characteristics deteriorated and transient creep increased. Furthermore, when the point at which creep strain occurred at elevated temperatures after the occurrence of transient creep was considered, greater shrinkage strain occurred as the compressive strength of the concrete increased. At a heating temperature of 800 °C, the 80 and 100 MPa test specimens showed creep failure within a shrinkage strain range similar to the strain at the maximum load.

  15. Strength and deformation characteristics of reinforced concrete shell elements subjected to in-plane forces

    International Nuclear Information System (INIS)

    Aoyagi, Yukio; Yamada, Kazuie.

    1983-01-01

    Reactor containment vessels have been made of steel so far, but since it was decided to adopt a prestressed concrete vessel in the Tsuruga No. 2 plant of Japan Atomic Power Co., the construction of the containment vessels made of prestressed concrete and reinforced concrete has been studied by various electric power companies. However in Japan, there is no standard for the design and construction of concrete structures of this kind. In the standard of foreign countries used for reference, the basis of the stipulation concerning the aseismatic design of concrete containment vessels is not distinct. In this study, the clarification of the strength and deformation when RC vessels are subjected to seismic force only or to internal pressure and seismic force was aimed at, and the result of the loading test by one or two-direction in-plane forces on RC shell elements was examined. Based on this, the method of estimating the strength and deformation of RC shell elements was proposed. The orthogonal reinforcement was adopted, and the strength of shell elements was determined by the yielding of reinforcing bars. (Kako, I.)

  16. Creep Behavior of High-Strength Concrete Subjected to Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Minho Yoon

    2017-07-01

    Full Text Available Strain is generated in concrete subjected to elevated temperatures owing to the influence of factors such as thermal expansion and design load. Such strains resulting from elevated temperatures and load can significantly influence the stability of a structure during and after a fire. In addition, the lower the water-to-binder (W–B ratio and the smaller the quantity of aggregates in high-strength concrete, the more likely it is for unstable strain to occur. Hence, in this study, the compressive strength, elastic modulus, and creep behavior were evaluated at target temperatures of 100, 200, 300, 500, and 800 °C for high-strength concretes with W–B ratios of 30%, 26%, and 23%. The loading conditions were set as non-loading and 0.33fcu. It was found that as the compressive strength of the concrete increased, the mechanical characteristics deteriorated and transient creep increased. Furthermore, when the point at which creep strain occurred at elevated temperatures after the occurrence of transient creep was considered, greater shrinkage strain occurred as the compressive strength of the concrete increased. At a heating temperature of 800 °C, the 80 and 100 MPa test specimens showed creep failure within a shrinkage strain range similar to the strain at the maximum load.

  17. Behavior of Reinforced Concrete Membrane Elements Subjected to Bidirectional Shear Loads

    OpenAIRE

    Labib, M.; Moslehy, Y.; Ayoub, A.

    2013-01-01

    The shear design and behavior of a typical membrane reinforced concrete (RC) element has been extensively studied in the past several decades. Such design requires knowledge of the constitutive behavior of RC elements subjected to a shear stress acting along its plane (in-plane shear). These constitutive models were accurately derived from experimental test data on representative RC panel elements. The true behavior of many large, complex structures, however, involves interaction between the ...

  18. Concrete finishes for highway structures.

    Science.gov (United States)

    1975-01-01

    The site conditions just about always dictate the basic layout of a structure. The choices of materials and appearance are usually made by the engineer. The materials going into the structure get a great deal of attention, but unfortunately the appea...

  19. 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.

  20. Numerical Limit Analysis of Reinforced Concrete Structures

    DEFF Research Database (Denmark)

    Larsen, Kasper Paaske

    For more than half a century, limit state analysis based on the extremum principles have been used to assess the load bearing capacity of reinforced concrete structures. Extensi- ve research within the field has lead to several techniques for performing such analysis manually. While these manual...... methods provide engineers with valuable tools for limit sta- te analysis, their application becomes difficult with increased structural complexity. The main challenge is to solve the optimization problem posed by the extremum principles. This thesis is a study of how numerical methods can be used to solve...... limit state analysis problems. The work focuses on determination of the load bearing capacity of reinforced concrete structures by employing the lower bound theorem and a finite element method using equilibrium elements is developed. The recent year’s development within the field of convex optimization...

  1. Condition monitoring and maintenance of nuclear power plant concrete structures

    International Nuclear Information System (INIS)

    Orr, R.; Prasad, N.

    1988-01-01

    Nuclear power plant concrete structures are potentially subject to deterioration due to several environmental conditions, including weather exposure, ground water exposure, and sustained high temperature and radiation levels. The nuclear power plant are generally licensed for a term of 40 years. In order to maximize the return from the existing plants, feasibility studies are in progress for continued operation of many of these plants beyond the original licensed life span. This paper describes a study that was performed with an objective to define appropriate condition monitoring and maintenance procedures. A timely implementation of a condition monitoring and maintenance program would provide a valuable database and would provide justification for extension of the plant's design life. The study included concrete structures such as the containment buildings, interior structures, basemats, intake structures and cooling towers. Age-related deterioration at several operating power plants was surveyed and the potential degradation mechanisms have been identified

  2. Research on working property and early age mechanical property of self-compacting concrete used in steel-concrete structure

    International Nuclear Information System (INIS)

    Zhao Yongguang

    2013-01-01

    Background: Self-compacting concrete that has good working property is the prerequisite of steel-concrete structure. The early age mechanical property of self-compacting concrete is the important parameter when design steel-concrete structure. Purpose: This paper attempts to research the working property and early age mechanical property of self-compacting concrete. Methods: Test is used to research the working property and early age mechanical property of self-compacting concrete. Results: Self-compacting concrete that could meet the requirement of steel-concrete structure has been mixed and parameters of early age mechanical property of self-compacting concrete which is necessary for design of steel-concrete structure have been presented. Conclusions: Base on the results, this paper can guide the construction of self-compacting concrete in steel-concrete structure and the design and construction of steel-concrete structure. (author)

  3. Utilization of recycled concrete aggregates in structural concrete by applying a fraction partitioning model

    NARCIS (Netherlands)

    Wouw, van de P.M.F.; Doudart de la Grée, G.C.H.; Florea, M.V.A.; Brouwers, H.J.H.; Bilek, V.; Kersner, Z.

    2014-01-01

    The recycling of concrete waste into new structural concrete reduces the utilization of raw materials, decreases transport and production energy cost, and saves the use of limited landfill space. Currently, recycling involves the use of recycled concrete aggregates (RCA) as road base material or in

  4. Mimicking Bone Healing Process to Self Repair Concrete Structure Novel Approach Using Porous Network Concrete

    NARCIS (Netherlands)

    Sangadji, S.; Schlangen, H.E.J.G.

    2013-01-01

    To repair concrete cracks in difficult or dangerous conditions such as underground structures or hazardous liquid containers, self healing mechanism is a promising alternative method. This research aims to imitate the bone self healing process by putting porous concrete internally in the concrete

  5. Ageing in reinforced concrete and pre-tensioned concrete structures

    International Nuclear Information System (INIS)

    Zwicky, P.; Rast, B.

    1990-01-01

    In establishing a nuclear power station's life expectancy, careful attention must be paid to structural components as well as the main systems and components. The construction industry has not as yet compiled any quantitative data on the life expectancy of structures: leading research on this subject is in the USA. As well as high-quality design and construction, the main requirements for a long life expectancy in structures are careful maintenance and complete life history documentation. As far as is known today, a station's structural components do not have to limit its life expectancy. 7 figs., 5 tabs., 16 refs

  6. FINITE ELEMENT ANALYSIS OF THE BEHAVIOUR OF REINFORCED CONCRETE COLUMNS CONFINED BY OVERLAPPING HOOPS SUBJECTED TO RAPID CONCENTRIC LOADING

    Directory of Open Access Journals (Sweden)

    Xiang Zeng

    2017-12-01

    Full Text Available The strain rate sensitivity of concrete material was discovered approximately one hundred years ago, and it has a marked effect on the behaviour of concrete members subjected to dynamic loadings such as strong earthquake and impact loading. Because of the great importance of the confined reinforced concrete (RC columns in RC structures, the dynamic behaviour of the columns induced by the strain rate effect has been studied, but only few experiments and analyses have been conducted. To investigate the behaviour of overlapping hoop-confined square reinforced normal-strength concrete columns, considering the strain rate effect at a strain rate of 10-5/sec to 10-1/sec induced by earthquake excitation, an explicit dynamic finite element analysis (FEA model was developed in ABAQUS to predict the behaviour of confined RC columns subjected to the rapid concentric loading. A locally modified stress-strain relation of confined concrete with the strain rate sensitivity of the concrete material and the confining effect of overlapping hoops were proposed to complete the simulation of the dynamic behaviour of concrete with the concrete plastic-constitutive model in ABAQUS. The finite element predictions are consistent with the existing test results. Based on the FEA model, a parametric investigation was conducted to capture more information about the behaviour of confined RC columns under varying loading rates.

  7. An Experimental Study of a Midbroken 2-Bay 6-Storey Reinforced Concrete Frame subject to Earthquakes

    DEFF Research Database (Denmark)

    Skjærbæk, P. S.; Taskin, B.; Kirkegaard, Poul Henning

    1997-01-01

    A 2-bay, 6-storey model test reinforced concrete frame (scale 1:5) subjected to sequential earthquakes of increasing magnitude is considered in this paper. The frame was designed with a weak storey, in which the columns are weakened by using thinner and weaker reinforcement bars. The aim of the w......A 2-bay, 6-storey model test reinforced concrete frame (scale 1:5) subjected to sequential earthquakes of increasing magnitude is considered in this paper. The frame was designed with a weak storey, in which the columns are weakened by using thinner and weaker reinforcement bars. The aim...... of the work is to study global response to a damaging strong motion earthquake event of such buildings. Special emphasis is put on examining to what extent damage in the weak storey can be identified from global response measurements during an earthquake where the structure survives, and what level...

  8. Nondestructive Evaluation of Thick Concrete Structures

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, Dwight A [ORNL

    2015-01-01

    Materials issues are a key concern for the existing nuclear reactor fleet in the United States as material degradation can lead to increased maintenance, increased downtime, and increased risk. Extending reactor life to 60 years and beyond will likely increase susceptibility and severity of both known and new forms of degradation. A multitude of concrete-based structures are typically part of a light water reactor plant to provide foundation, support, shielding, and containment functions. The size and complexity of nuclear power plant containment structures and the heterogeneity of Portland cement concrete make characterization of the degradation extent a difficult task. This paper examines the benefits of using time-frequency analysis with Synthetic Aperture Focusing Technique (SAFT). By using wavelet packet decomposition, the original ultrasound signals are decomposed into various frequency bands that facilitates highly selective analysis of the signal’s frequency content and can be visualized using the familiar SAFT image reconstruction algorithm.

  9. CONCRETE STRUCTURES' QUALITY CONTROL IN PRACTICE

    OpenAIRE

    Dolaček-Alduk, Zlata; Blanda, Miroslav

    2011-01-01

    The Croatian civil engineering is characterized by a lack of systematic approach to planning, control and quality assurance in all phases of project realization. The results obtained in establishing the quality management system in some segments of civil engineering production represent initial trends in solving this problem. Benefits are of two types: the achievement of quality for the contractor and obtaining that quaity is being achieved for clients. Execution of concrete structures is a c...

  10. Numerical Limit Analysis of Precast Concrete Structures

    DEFF Research Database (Denmark)

    Herfelt, Morten Andersen

    Precast concrete elements are widely used in the construction industry as they provide a number of advantages over the conventional in-situ cast concrete structures. Joints cast on the construction site are needed to connect the precast elements, which poses several challenges. Moreover, the curr...... problems are solved efficiently using state-of-the-art solvers. It is concluded that the framework and developed joint models have the potential to enable efficient design of precast concrete structures in the near future......., the current practice is to design the joints as the weakest part of the structure, which makes analysis of the ultimate limit state behaviour by general purpose software difficult and inaccurate. Manual methods of analysis based on limit analysis have been used for several decades. The methods provide...... of the ultimate limit state behaviour. This thesis introduces a framework based on finite element limit analysis, a numerical method based on the same extremum principles as the manual limit analysis. The framework allows for efficient analysis and design in a rigorous manner by use of mathematical optimisation...

  11. Concrete road barriers subjected to impact loads: An overview

    Directory of Open Access Journals (Sweden)

    Muhammad Fauzi Bin Mohd. Zain

    Full Text Available Abstract Concrete barriers prevent vehicles from entering the opposite lane and going off the road. An important factor in the design of concrete barriers is impact load, which a vehicle exerts upon collision with a concrete barrier. This study suggests that a height of 813 mm, a base width of 600 mm, and a top width of 240 mm are optimum dimensions for a concrete barrier. These dimensions ensure the stability of concrete barriers during vehicle collisions. An analytical and experimental model is used to analyze the concrete barrier design. The LS-DYNA software is utilized to create the analytical models because it can effectively simulate vehicle impact on concrete barriers. Field tests are conducted with a vehicle, whereas laboratory tests are conducted with machines that simulate collisions. Full-scale tests allow the actual simulation of vehicle collisions with concrete barriers. In the vehicle tests, a collision angle of 25°, collision speeds of 100 km per hour, and a vehicle weighing more than 2 t are considered in the reviewed studies. Laboratory tests are performed to test bridge concrete barriers in static condition.

  12. A corrosion monitoring system for existing reinforced concrete structures.

    Science.gov (United States)

    2015-05-01

    This study evaluated a multi-parameter corrosion monitoring system for existing reinforced concrete structures in chloride-laden service environments. The system was fabricated based on a prototype concrete corrosion measurement system that : had bee...

  13. Concrete

    OpenAIRE

    Kruse Aagaard, Anders

    2015-01-01

    Concrete is a component of coherent transition between a concrete base and a wooden construction. The structure is based on a quantity of investigations of the design possibilities that arise when combining digital fabrication tools and material capacities.Through tangible experiments the project discusses materiality and digitally controlled fabrications tools as direct expansions of the architect’s digital drawing and workflow. The project sees this expansion as an opportunity to connect th...

  14. Recycled construction and demolition concrete waste as aggregate for structural concrete

    Directory of Open Access Journals (Sweden)

    Ashraf M. Wagih

    2013-12-01

    Full Text Available In major Egyptian cities there is a surge in construction and demolition waste (CDW quantities causing an adverse effect on the environment. The use of such waste as recycled aggregate in concrete can be useful for both environmental and economical aspects in the construction industry. This study discusses the possibility to replace natural coarse aggregate (NA with recycled concrete aggregate (RCA in structural concrete. An investigation into the properties of RCA is made using crushing and grading of concrete rubble collected from different demolition sites and landfill locations around Cairo. Aggregates used in the study were: natural sand, dolomite and crushed concretes obtained from different sources. A total of 50 concrete mixes forming eight groups were cast. Groups were designed to study the effect of recycled coarse aggregates quality/content, cement dosage, use of superplasticizer and silica fume. Tests were carried out for: compressive strength, splitting strength and elastic modulus. The results showed that the concrete rubble could be transformed into useful recycled aggregate and used in concrete production with properties suitable for most structural concrete applications in Egypt. A significant reduction in the properties of recycled aggregate concrete (RAC made of 100% RCA was seen when compared to natural aggregate concrete (NAC, while the properties of RAC made of a blend of 75% NA and 25% RCA showed no significant change in concrete properties.

  15. Aircraft impact on nuclear power plants concrete structures

    International Nuclear Information System (INIS)

    Coombs, R.F.; Barbosa, L.C.B.; Santos, S.H.C.

    1980-01-01

    A summary about the procedures for the analysis of aircraft on concrete structures, aiming to emphasize the aspects related to the nuclear power plants safety, is presented. The impact force is determined by the Riera model. The effect of this impact force on the concrete structures is presented, showing the advantages to use nonlinear behaviour in the concrete submitted to short loads. The simplifications used are shown through a verification example of the nuclear reactor concrete shielding. (E.G.) [pt

  16. Application of concrete filled steel bearing wall to inner concrete structure fro PWR nuclear power plant

    International Nuclear Information System (INIS)

    Sekimoto, Hisashi; Tanaka, Mamoru; Inoue, Kunio; Fukihara, Masaaki; Akiyama, Hiroshi.

    1992-01-01

    'Concrete filled steel bearing wall', applied to the inner concrete structure for PWR nuclear power plant, was developed for rationalization of construction procedure at site. It was concluded through preliminary studies that this new type of wall, where concrete is placed between steel plates, is best suited for the strength members of the above structure, due to the high strength and ductility of surface steel plates and the confinement effect of filled concrete. To verify the behavior from the elastic range to the inelastic range, the ultimate strength and the failure mechanism, and to clarify experimentally the structural integrity of the inner concrete structure, which was composed of a concrete filled steel bearing wall, against seismic lateral loads, horizontal loading tests using a 1/10th scale model of the inner concrete structure for PWR nuclear power plant were conducted. As a result of the tests, the inner concrete structure composed of a concrete filled steel bearing wall appeared to have a larger load carrying capacity and a higher ductility as compared with that composed of a reinforced concrete wall. (author)

  17. Durability of cracked fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Nielsen, Laila

    1997-01-01

    (capillary water uptake) is used, involving an in-situ method and a laboratory method. Three different concrete qualities as well as steel fibres (ZP) and polypropylene fibres (PP) are used. Results of the durability tests on cracked FRC-beams are compared to results for uncracked FRC-beams and beams without......Durability studies are carried out by subjecting FRC-beams to combined mechanical and environmental load. Mechanical load is obtained by exposing beams to il-point bending until a predefined crack width is reached, using a newly developed test setup. As environmental load, exposure to water...

  18. Nondestructive evaluation of dissipative behavior of reinforced concrete structure

    Energy Technology Data Exchange (ETDEWEB)

    Luong, M.P. [Ecole Polytechnique, LMS, CNRS, 91 - Palaiseau (France)

    2001-07-01

    Current technological developments tend toward increased exploitation of materials strengths and toward tackling extreme loads and environmental actions such as offshore structures subject to wind and wave loading, or buildings in seismic area. Concrete is widely used as a construction material because of its high strength-cost ratio in many applications. Experience of earthquakes and laboratory tests has shown that well designed and detailed reinforced concrete is suitable for earthquake resistant structures. The most severe likely earthquake can be survived if the members are sufficiently ductile to absorb and dissipate seismic energy by inelastic deformation. This requires a designer to assess realistically the acceptable levels of strength and to ensure adequate dissipation. This paper proposes the use of infrared thermography as a nondestructive, noncontact and real-time technique to examine diverse mechanisms of dissipation and to illustrate the onset of damage process, stress concentration and heat dissipation localization in loaded zone. In addition, this technique can be used as a nondestructive method for evaluating the fatigue limit of concrete structure subject to repeated loading.

  19. Nondestructive evaluation of dissipative behavior of reinforced concrete structure

    International Nuclear Information System (INIS)

    Luong, M.P.

    2001-01-01

    Current technological developments tend toward increased exploitation of materials strengths and toward tackling extreme loads and environmental actions such as offshore structures subject to wind and wave loading, or buildings in seismic area. Concrete is widely used as a construction material because of its high strength-cost ratio in many applications. Experience of earthquakes and laboratory tests has shown that well designed and detailed reinforced concrete is suitable for earthquake resistant structures. The most severe likely earthquake can be survived if the members are sufficiently ductile to absorb and dissipate seismic energy by inelastic deformation. This requires a designer to assess realistically the acceptable levels of strength and to ensure adequate dissipation. This paper proposes the use of infrared thermography as a nondestructive, noncontact and real-time technique to examine diverse mechanisms of dissipation and to illustrate the onset of damage process, stress concentration and heat dissipation localization in loaded zone. In addition, this technique can be used as a nondestructive method for evaluating the fatigue limit of concrete structure subject to repeated loading

  20. Plant Life Management of the EC6 Concrete Containment Structure

    Energy Technology Data Exchange (ETDEWEB)

    Abrishami, Homayoun; Ricciuti, Rick; Khan, Azhar [CANDU Energy Inc., Mississauga (Canada)

    2012-03-15

    Aging of reinforced concrete structures due to service conditions, aggressive environments, or accidents may cause their strength, serviceability and durability to decrease over time. Due to the complex nature of safety-related structures in nuclear power plants in comparison to other structures, they possess a number of characteristics that make them comparison to other structures, they possess a number of characteristics that make them unique. These characteristics are: thick concrete cross-sections, heavy reinforcement, often one-side access only, subjected to such ageing stresses as irradiation and elevated temperature, in addition to other typical ageing mechanisms (i. e., exposure to freeze/thaw cycles, aggressive chemicals, etc.) that typically affects other types of non-nuclear structures. For a new plant, the Plant Life Management Program (PLiM) should start in the design process and then continues through construction, plant operation and decommissioning. Hence PLiM must provide not only Ageing Management program (AMP) but also provide requirements on material characteristic and the design criteria as well. The purpose of this paper is to present the Plant Life Management (PLiM) strategy for the concrete containment structure of EC6 (Enhanced CANDU 6) Nuclear Power Plant designed by CANDU Energy Inc. The EC6 is designed for 100-year plant life including a 60-year operating life and an additional 40-year decommissioning period of time. The approach adopted for the PLiM strategy of the concrete containment structure is a preventive one, key areas being: 1) design methodology, 2) material performance and 3) life cycle management and ageing management program. In addition to strength and serviceability, durability is a major consideration during the design phase, service life and up to the completion of decommissioning. Factors affecting durability design include: a) concrete performance, b) structural application, and c) consideration of environmental

  1. Plant Life Management of the EC6 Concrete Containment Structure

    International Nuclear Information System (INIS)

    Abrishami, Homayoun; Ricciuti, Rick; Khan, Azhar

    2012-01-01

    Aging of reinforced concrete structures due to service conditions, aggressive environments, or accidents may cause their strength, serviceability and durability to decrease over time. Due to the complex nature of safety-related structures in nuclear power plants in comparison to other structures, they possess a number of characteristics that make them comparison to other structures, they possess a number of characteristics that make them unique. These characteristics are: thick concrete cross-sections, heavy reinforcement, often one-side access only, subjected to such ageing stresses as irradiation and elevated temperature, in addition to other typical ageing mechanisms (i. e., exposure to freeze/thaw cycles, aggressive chemicals, etc.) that typically affects other types of non-nuclear structures. For a new plant, the Plant Life Management Program (PLiM) should start in the design process and then continues through construction, plant operation and decommissioning. Hence PLiM must provide not only Ageing Management program (AMP) but also provide requirements on material characteristic and the design criteria as well. The purpose of this paper is to present the Plant Life Management (PLiM) strategy for the concrete containment structure of EC6 (Enhanced CANDU 6) Nuclear Power Plant designed by CANDU Energy Inc. The EC6 is designed for 100-year plant life including a 60-year operating life and an additional 40-year decommissioning period of time. The approach adopted for the PLiM strategy of the concrete containment structure is a preventive one, key areas being: 1) design methodology, 2) material performance and 3) life cycle management and ageing management program. In addition to strength and serviceability, durability is a major consideration during the design phase, service life and up to the completion of decommissioning. Factors affecting durability design include: a) concrete performance, b) structural application, and c) consideration of environmental

  2. Monitoring corrosion in reinforced concrete structures

    Science.gov (United States)

    Kung, Peter; Comanici, Maria I.

    2014-06-01

    Many defects can cause deterioration and cracks in concrete; these are results of poor concrete mix, poor workmanship, inadequate design, shrinkage, chemical and environmental attack, physical or mechanical damage, and corrosion of reinforcing steel (RS). We want to develop a suite of sensors and systems that can detect that corrosion is taking place in RS and inform owners how serious the problem is. By understanding the stages of the corrosion process, we can develop special a sensor that detects each transition. First, moisture ingress can be monitored by a fiber optics humidity sensor, then ingress of Chloride, which acts as a catalyst and accelerates the corrosion process by converting iron into ferrous compounds. We need a fiber optics sensor which can quantify Chloride ingress over time. Converting ferric to ferrous causes large volume expansion and cracks. Such pressure build-up can be detected by a fiber optic pressure sensor. Finally, cracks emit acoustic waves, which can be detected by a high frequency sensor made with phase-shifted gratings. This paper will discuss the progress in our development of these special sensors and also our plan for a field test by the end of 2014. We recommend that we deploy these sensors by visually inspecting the affected area and by identifying locations of corrosion; then, work with the designers to identify spots that would compromise the integrity of the structure; finally, drill a small hole in the concrete and insert these sensors. Interrogation can be done at fixed intervals with a portable unit.

  3. Self-sensing of carbon nanofiber concrete columns subjected to reversed cyclic loading

    Science.gov (United States)

    Howser, R. N.; Dhonde, H. B.; Mo, Y. L.

    2011-08-01

    Civil infrastructures are generally a country's most expensive investment, and concrete is the most widely used material in the construction of civil infrastructures. During a structure's service life, concrete ages and deteriorates, leading to substantial loss of structural integrity and potentially resulting in catastrophic disasters such as highway bridge collapses. A solution for preventing such occurrences is the use of structural health monitoring (SHM) technology for concrete structures containing carbon nanofibers (CNF). CNF concrete has many structural benefits. CNF restricts the growth of nanocracks in addition to yielding higher strength and ductility. Additionally, test results indicate a relationship between electrical resistance and concrete strain, which can be well utilized for SHM. A series of reinforced concrete (RC) columns were built and tested under a reversed cyclic loading using CNF as a SHM device. The SHM device detected and assessed the level of damage in the RC columns, providing a real-time health monitoring system for the structure's overall integrity.

  4. Self-sensing of carbon nanofiber concrete columns subjected to reversed cyclic loading

    International Nuclear Information System (INIS)

    Howser, R N; Dhonde, H B; Mo, Y L

    2011-01-01

    Civil infrastructures are generally a country's most expensive investment, and concrete is the most widely used material in the construction of civil infrastructures. During a structure's service life, concrete ages and deteriorates, leading to substantial loss of structural integrity and potentially resulting in catastrophic disasters such as highway bridge collapses. A solution for preventing such occurrences is the use of structural health monitoring (SHM) technology for concrete structures containing carbon nanofibers (CNF). CNF concrete has many structural benefits. CNF restricts the growth of nanocracks in addition to yielding higher strength and ductility. Additionally, test results indicate a relationship between electrical resistance and concrete strain, which can be well utilized for SHM. A series of reinforced concrete (RC) columns were built and tested under a reversed cyclic loading using CNF as a SHM device. The SHM device detected and assessed the level of damage in the RC columns, providing a real-time health monitoring system for the structure's overall integrity

  5. Economic effects of full corrosion surveys for aging concrete structures

    NARCIS (Netherlands)

    Polder, R.B.; Peelen, W.H.A.; Raupach, M.; Reichling, K.

    2013-01-01

    This paper investigates the economic effects of full corrosion surveys of concrete structures. The background is that the existing concrete infrastructure is aging, while being exposed to aggressive influences, which increases the occurrence of corrosion and related concrete damage over time. The

  6. A coupled thermo-hydro-mechanical-damage model for concrete subjected to moderate temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Bary, B.; Carpentier, O. [CEA Saclay, DEN/DPC/SCCME/LECBA, F-91191 Gif Sur Yvette, (France); Ranc, G. [CEA VALRHO, DEN/DTEC/L2EC/LCEC, F-30207 Bagnols Sur Ceze, (France); Durand, S. [CEA Saclay, DEN/DM2S/SEMT/LM2S, F-91191 Gif Sur Yvette, (France)

    2008-07-01

    This study focuses on the concrete behavior subjected to moderate temperatures, with a particular emphasis on the transient thermo-hydric stage. A simplified coupled thermo-hydro-mechanical model is developed with the assumption that the gaseous phase is composed uniquely of vapor. Estimations of the mechanical parameters, Biot coefficient and permeability as a function of damage and saturation degree are provided by applying effective-medium approximation schemes. The isotherm adsorption curves are supposed to depend upon both temperature and crack-induced porosity. The effects of damage and parameters linked to transfer (in particular the adsorption curves) on the concrete structure response in the transient phase of heating are then investigated and evaluated. To this aim, the model is applied to the simulation of concrete cylinders with height and diameter of 0.80 m subjected to heating rates of 0.1 and 10 degrees C/min up to 160 degrees C. The numerical results are analyzed, commented and compared with experimental ones in terms of water mass loss, temperatures and gas pressures evolutions. A numerical study indicates that some parameters have a greater influence on the results than others, and that certain coupling terms in the mass conservation equation of water may be neglected. (authors)

  7. Proof testing of CANDU concrete containment structures

    International Nuclear Information System (INIS)

    Pandey, M.D.

    1996-05-01

    Prior to commissioning of a CANDU reactor, a proof pressure test is required to demonstrate the structural integrity of the containment envelope. The test pressure specified by AECB Regulatory Document R-7 (1991) was selected without a rigorous consideration of uncertainties associated with estimates of accident pressure and conatinment resistance. This study was undertaken to develop a reliability-based philosophy for defining proof testing requirements that are consistent with the current limit states design code for concrete containments (CSA N287.3).It was shown that the upodated probability of failure after a successful test is always less than the original estimate

  8. Ultrasonic measurements of undamaged concrete layer thickness in a deteriorated concrete structure

    NARCIS (Netherlands)

    Demcenko, A.; Visser, Roy; Akkerman, Remko

    2016-01-01

    Ultrasonic wave propagation in deteriorated concrete structures was studied numerically and experimentally. Ultrasonic single-side access immersion pulse-echo and diffuse field measurements were performed in deteriorated concrete structures at 0.5 MHz center frequency. Numerically and experimentally

  9. Nonlinear analysis of reinforced concrete structures using software package abaqus

    Directory of Open Access Journals (Sweden)

    Marković Nemanja

    2014-01-01

    Full Text Available Reinforced concrete (AB is characterized by huge inhomogeneity resulting from the material characteristics of the concrete, then, quasi-brittle behavior during failure. These and other phenomena require the introduction of material nonlinearity in the modeling of reinforced concrete structures. This paper presents the modeling reinforced concrete in the software package ABAQUS. A brief theoretical overview is presented of methods such as: Concrete Damage Plasticity (CDP, Smeared Concrete Cracking (CSC, Cap Plasticity (CP and Drucker-Prager model (DPM. We performed a nonlinear analysis of two-storey reinforced concrete frame by applying CDP method for modeling material nonlinearity of concrete. We have analyzed damage zones, crack propagation and loading-deflection ratio.

  10. Sensitivity of Reliability Estimates in Partially Damaged RC Structures subject to Earthquakes, using Reduced Hysteretic Models

    DEFF Research Database (Denmark)

    Iwankiewicz, R.; Nielsen, Søren R. K.; Skjærbæk, P. S.

    The subject of the paper is the investigation of the sensitivity of structural reliability estimation by a reduced hysteretic model for a reinforced concrete frame under an earthquake excitation.......The subject of the paper is the investigation of the sensitivity of structural reliability estimation by a reduced hysteretic model for a reinforced concrete frame under an earthquake excitation....

  11. 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)

  12. Finite element analysis of degraded concrete structures - Workshop proceedings

    International Nuclear Information System (INIS)

    1999-09-01

    This workshop is related to the finite element analysis of degraded concrete structures. It is composed of three sessions. The first session (which title is: the use of finite element analysis in safety assessments) comprises six papers which titles are: Historical Development of Concrete Finite Element Modeling for Safety Evaluation of Accident-Challenged and Aging Concrete Structures; Experience with Finite Element Methods for Safety Assessments in Switzerland; Stress State Analysis of the Ignalina NPP Confinement System; Prestressed Containment: Behaviour when Concrete Cracking is Modelled; Application of FEA for Design and Support of NPP Containment in Russia; Verification Problems of Nuclear Installations Safety Software of Strength Analysis (NISS SA). The second session (title: concrete containment structures under accident loads) comprises seven papers which titles are: Two Application Examples of Concrete Containment Structures under Accident Load Conditions Using Finite Element Analysis; What Kind of Prediction for Leak rates for Nuclear Power Plant Containments in Accidental Conditions; Influence of Different Hypotheses Used in Numerical Models for Concrete At Elevated Temperatures on the Predicted Behaviour of NPP Core Catchers Under Severe Accident Conditions; Observations on the Constitutive Modeling of Concrete Under Multi-Axial States at Elevated Temperatures; Analyses of a Reinforced Concrete Containment with Liner Corrosion Damage; Program of Containment Concrete Control During Operation for the Temelin Nuclear Power Plant; Static Limit Load of a Deteriorated Hyperbolic Cooling Tower. The third session (concrete structures under extreme environmental load) comprised five papers which titles are: Shear Transfer Mechanism of RC Plates After Cracking; Seismic Back Calculation of an Auxiliary Building of the Nuclear Power Plant Muehleberg, Switzerland; Seismic Behaviour of Slightly Reinforced Shear Wall Structures; FE Analysis of Degraded Concrete

  13. A study on the effects of seawater on the durable life of concrete structures(II)

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Byung Hwan; Jang, Bong Suk; Jang, Seung Yeop; Jeon, Se Jin; Yu, Yeong; Park, Dae Gyun; Hyeong, Sang Soo [Seoul National Univ., Seoul (Korea, Republic of)

    1999-02-15

    Recently, large scale concrete structures such as nuclear power plants and offshore structures are actively being built in this country. These structures are subject to heavy attack due to seawater environment. A reasonable consideration for corrosion has not been paid to the structures in the past decades due to insufficient research data and guidelines. The durability is emerging as one of the most important factors. In the design and construction of concrete structures. The purpose of the present study is, therefore, to explore the corrosion mechanism and penetration mechanism of chloride ion, and to establish the evaluation procedure of durability life of concrete structures. In this study, the chloride ion concentration of seawater around our country have been analyzed and the deterioration mechanism of concrete structures have been also analyzed. The penetration mechanism of seawater into the concrete has been also studied. To this end, a comprehensive experimental program has been setup. The major test variables include the type of cement and the type of mineral admixture. The strength test as well as corrosion test have been conducted to explore the effects of chloride ion penetration on the properties of concrete. The corrosion mechanism and the penetration of chloride ion into concrete structures have been studied. These results will allow the estimation of durable life of concrete structures in nuclear power plants. The experimental results and the developed theory in the present study can be efficiently used to analyze the chloride ion penetration and to estimate the durability of concrete structures In nuclear power plants. The present study may also provide strong basis to evaluate the remaining service life of concrete structures in nuclear power plants.

  14. 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.

  15. Behaviour of concrete nuclear containment structures upto ultimate failure with special reference to MAPP-1 containment

    International Nuclear Information System (INIS)

    Appa Rao, T.V.S.R.

    1975-01-01

    Theoretical and experimental methods for investigating the behaviour of concrete secondary containment structures subjected to loads upto their ultimate failure have been discussed in the paper. Need for inelastic nonlinear analysis of containments has been emphasized. Different contitutive models of concrete that can be employed in the nonlinear analysis of concrete structures were briefly reviewed. Based on the experimental results obtained in a 1:12 scale model test conducted at the Structural Engineering Research (Regional) Centre, Madras, behaviour of the MAPP-1 containment to internal pressure loading upto its ultimate failure has been discussed. (author)

  16. Injection technologies for the repair of damaged concrete structures

    CERN Document Server

    Panasyuk, V V; Sylovanyuk, V P

    2014-01-01

    This book analyzes the most important achievements in science and engineering practice concerning operational factors that cause damage to concrete and reinforced concrete structures. It includes methods for assessing their strength and service life, especially those that are based on modern concepts of the fracture mechanics of materials. It also includes basic approaches to the prediction of the remaining service life for long-term operational structures. Much attention is paid to injection technologies for restoring the serviceability of damaged concrete and reinforced concrete structures. In particular, technologies for remedying holes, cracks, corrosion damages etc. The books contains sample cases in which the above technologies have been used to restore structural integrity and extend the reliable service life of concrete and reinforced concrete constructions, especially NPPs, underground railways, bridges, seaports and historical relics.

  17. Experimental on moisture migration and pore pressure formation of concrete members subjected to high temperature

    International Nuclear Information System (INIS)

    Nagao, Kakuhiro; Nakane, Sunao

    1993-01-01

    The experimental studies concerning temperature, moisture migration, and pore pressure of mass concrete mock-up specimens heated up to high temperature at 110degC to 600degC, were performed, so as to correctly estimate the moisture migration behaviour of concrete members subjected to high temperature, which is considered significantly influenced on physical properties of concrete. As a results, it is confirmed that the moisture migration behavior of concrete members can be explained by temperature and pore pressure, and indicate the characteristics both sealed condition (dissipation of moisture is prevented) and unsealed condition (dissipation of moisture occur). (author)

  18. Maintenance and preservation of concrete structures. Report 3: Abrasion-erosion resistance of concrete

    Science.gov (United States)

    Liu, T. C.

    1980-07-01

    This report describes a laboratory test program on abrasion-erosion resistance of concrete, including the development of a new underwater abrasion-erosion test method. This program was designed to evaluate the relative abrasion-erosion resistance of various materials considered for use in the repair of erosion-damaged concrete structures. The test program encompassed three concrete types (conventional concrete, fiber-reinforced concrete, and polymer concrete); seven aggregate types (limestone, chert, trap rock, quartzite, granite, siliceous gravel, and slag); three principal water-cement rations (0.72, 0.54, and 0.40); and six types of surface treatment (vacuum, polyurethane coating, acrylic mortar coating, epoxy mortar coating, furan resin mortar coating, and iron aggregate topping). A total of 114 specimens made from 41 batches of concrete was tested. Based on the test data obtained, a comprehensive evaluation of the effects of various parameters on the abrasion-erosion resistance of concrete was presented. Materials suitable for use in the repair of erosion-damaged concrete structures were recommended. Additional work to correlate the reported findings with field performance was formulated.

  19. Extracting and identifying concrete structural defects in GPR images

    Science.gov (United States)

    Ye, Qiling; Jiao, Liangbao; Liu, Chuanxin; Cao, Xuehong; Huston, Dryver; Xia, Tian

    2018-03-01

    Traditionally most GPR data interpretations are performed manually. With the advancement of computing technologies, how to automate GPR data interpretation to achieve high efficiency and accuracy has become an active research subject. In this paper, analytical characterizations of major defects in concrete structures, including delamination, air void and moisture in GPR images, are performed. In the study, the image features of different defects are compared. Algorithms are developed for defect feature extraction and identification. For validations, both simulation results and field test data are utilized.

  20. The Service Life Evaluation for Concrete Structure of NPP

    International Nuclear Information System (INIS)

    Lee, Choon Min; Kim, Seong Soo; Bae, Sung Hwan; Sik, Yoon Eui

    2014-01-01

    Prolonged exposure to the marine environment degrades the durability of concrete and shortens the service life of concrete due to degradation factors such as chloride, carbonation, freezing and thawing, sulfate. Therefore, many country's organizations like the Korea Concrete Institute (KCI), the American Concrete Institute (ACI), the International Federation for Structural Concrete (FIB), the American Society for Testing and Material (ASTM) which recognized the seriousness of this deterioration proposed equation models to evaluate the service life for the concrete structures. As a result, this paper is to especially consider the service life evaluation using these equation models for concrete structure of NPP in Korea compared with 60 years as a design service life. The concrete durability evaluation for Shin-Hanul NPP units 1 and 2 is carried out by using typically proposed assessment models in domestic and foreign standard. It is confirmed that the service life of concrete durability for each of deterioration factors is significantly higher than 60 years as a design service life. As a result, the study of combined deterioration for the concrete structures of NPP in future is positively necessary and maintenance control through regular monitoring should be conducted to secure safety margin basis

  1. Topology Optimization for Conceptual Design of Reinforced Concrete Structures

    DEFF Research Database (Denmark)

    Amir, Oded; Bogomolny, Michael

    2011-01-01

    Design of reinforced concrete structures is governed by the nonlinear behavior of concrete and by its dierent strengths in tension and compression. The purpose of this article is to present a computational procedure for optimal conceptual design of reinforced concrete structures, based on topology...... must be consid- ered. Optimized distribution of material is achieved by introducing interpolation rules for both elastic and plastic material properties. Several numerical examples illustrate the capability and potential of the proposed procedure....

  2. Porous Network Concrete : A bio-inspired building component to make concrete structures self-healing

    NARCIS (Netherlands)

    Sangadji, S.

    2015-01-01

    The high energy consumption, its corresponding emission of CO2 and financial losses due to premature failure are the pressing sustainability issues which must be tackled by the concrete infrastructure industry. Enhancement of concrete materials and durability of structures (designing new

  3. Seismic fragility of a reinforced concrete structure

    Energy Technology Data Exchange (ETDEWEB)

    Kurmann, Davide [Axpo Power AG, Baden (Switzerland); Proske, Dirk [Axpo Power AG, Doettingen (Switzerland); Cervenka, Jan [Cervenka Consulting, Prague (Czech Republic)

    2013-05-15

    Structures can be exposed to seismic loading. For structures of major importance, extreme seismic loadings have to be considered. The proof of safety for such loadings requires sophisticated analysis. This paper introduces an analysis method which of course still includes simplifications, but yields to a far more realistic estimation of the seismic load bearing capacity of reinforced concrete structures compared to common methods. It is based on the development of pushover curves and the application of time-histories for the dynamic model to a representative harmonic oscillator. Dynamic parameters of the oscillator, such as modal mass and damping are computed using a soil-structure-interaction analysis. Based on the pushover-curve nonlinear force-deformation-capacities are applied to the oscillator including hysteresis behaviour characteristics. The oscillator is then exposed to time-histories of several earthquakes. Based on this computation the ductility is computed. The ductility can be scaled based upon the scaling of the time-histories. Since both, the uncertainty of the earthquake by using different timehistories and the uncertainty of the structure by using characteristic and mean material values, are considered, the uncertainty of the structure under seismic loading can be explicitly represented by a fragility. (orig.)

  4. Damage Detection of a Concrete Column Subject to Blast Loads Using Embedded Piezoceramic Transducers.

    Science.gov (United States)

    Xu, Kai; Deng, Qingshan; Cai, Lujun; Ho, Siuchun; Song, Gangbing

    2018-04-28

    Some of the most severe structural loadings come in the form of blast loads, which may be caused by severe accidents or even terrorist activities. Most commonly after exposure to explosive forces, a structure will suffer from different degrees of damage, and even progress towards a state of collapse. Therefore, damage detection of a structure subject to explosive loads is of importance. This paper proposes a new approach to damage detection of a concrete column structure subjected to blast loads using embedded piezoceramic smart aggregates (SAs). Since the sensors are embedded in the structure, the proposed active-sensing based approach is more sensitive to internal or through cracks than surface damage. In the active sensing approach, the embedded SAs act as actuators and sensors, that can respectively generate and detect stress waves. If the stress wave propagates across a crack, the energy of the wave attenuates, and the reduction of the energy compared to the healthy baseline is indicative of a damage. With a damage index matrix constructed by signals obtained from an array of SAs, cracks caused by blast loads can be detected throughout the structure. Conventional sensing methods such as the measurement of dynamic strain and acceleration were included in the experiment. Since columns are critical elements needed to prevent structural collapse, knowledge of their integrity and damage conditions is essential for safety after exposure to blast loads. In this research, a concrete column with embedded SAs was chosen as the specimen, and a series of explosive tests were conducted on the column. Experimental results reveal that surface damages, though appear severe, cause minor changes in the damage index, and through cracks result in significant increase of the damage index, demonstrating the effectiveness of the active sensing, enabled by embedded SAs, in damage monitoring of the column under blast loads, and thus providing a reliable indication of structural

  5. Aging of nuclear safety related concrete structures

    International Nuclear Information System (INIS)

    Cerny, R.; Vydra, V.; Toman, J.; Vodak, F.

    1994-01-01

    An analysis of aging processes in nuclear-safety-related concrete structures (NSRCS) is presented. The major environmental stressor and aging factors affecting the performance of NSRCS are summarized, as are drying and plastic shrinkage, expansion of water during the freeze-thaw cycle, water passing through cracks dissolving or leaching the soluble calcium hydroxide, attack of acid rain and ground water, chemical reactions between particular aggregates and the alkaline solution within cement paste, reaction of calcium hydroxide in cement paste hydration products with atmospheric carbon dioxide, and physical radiation effects of neutrons and gamma radiation. The current methods for aging management in NSRCS are analyzed and evaluated. A new treatment is presented for the monitoring, evaluation and prediction of aging processes, consisting in a combination of theoretical methods, laboratory experiments, in-situ measurements and numerical simulations. 24 refs

  6. Aging Evaluation of Nuclear Power Plant Concrete Structures

    International Nuclear Information System (INIS)

    Kitsutaka, Y.; Takesue, N.; Tsukagoshi, M.

    2012-01-01

    In this paper, method on the aging evaluation in nuclear power plant concrete structures was investigated. Problems on the durability evaluation of reinforced concrete structures were pointed out and an evaluation framework was considered. In view of the importance of evaluating the degree of deterioration of reinforced concrete structures, relationships should be formulated among the number of years elapsed, t, the amount of action of a deteriorative factor, F, the degree of material deterioration, D, and the performance of the structure, P. Evaluation by PDFt diagrams combining these relationships may be effective. A detailed procedure of durability evaluation for a reinforced concrete structure using PDFt concept is presented for the deterioration factors of thermal effect, irradiation, neutralization and penetration of salinity by referring to the recent papers. And the evaluation framework of the deteriorated material constitutive model which can be used for the numerical analysis of the integrity evaluation for the concrete structure was proposed. (author)

  7. Required performance to the concrete structure of the accelerator facilities

    International Nuclear Information System (INIS)

    Irie, Masaaki; Yoshioka, Masakazu; Miyahara, Masanobu

    2006-01-01

    As for the accelerator facility, there is many a thing which is constructed as underground concrete structure from viewpoint such as cover of radiation and stability of the structure. Required performance to the concrete structure of the accelerator facility is the same as the general social infrastructure, but it has been possessed the feature where target performance differs largely. As for the body sentence, expressing the difference of the performance which is required from the concrete structure of the social infrastructure and the accelerator facility, construction management of the concrete structure which it plans from order of the accelerator engineering works facility, reaches to the design, supervision and operation it is something which expresses the method of thinking. In addition, in the future of material structural analysis of the concrete which uses the neutron accelerator concerning view it showed. (author)

  8. Enhancing corrosion resistance of reinforced concrete structures with hybrid fiber reinforced concrete

    International Nuclear Information System (INIS)

    Blunt, J.; Jen, G.; Ostertag, C.P.

    2015-01-01

    Highlights: • Reinforced concrete beams were subjected to cyclic flexural loading. • Hybrid fiber reinforced composites were effective in reducing corrosion rates. • Crack resistance due to fibers increased corrosion resistance of steel rebar. • Galvanic corrosion measurements underestimated corrosion rates. • Polarization resistance measurements predicted mass loss more accurately. - Abstract: Service loads well below the yield strength of steel reinforcing bars lead to cracking of reinforced concrete. This paper investigates whether the crack resistance of Hybrid Fiber Reinforced Concrete (HyFRC) reduces the corrosion rate of steel reinforcing bars in concrete after cyclic flexural loading. The reinforcing bars were extracted to examine their surface for corrosion and compare microcell and macrocell corrosion mass loss estimates against direct gravimetric measurements. A delay in corrosion initiation and lower active corrosion rates were observed in the HyFRC beam specimens when compared to reinforced specimens containing plain concrete matrices cycled at the same flexural load

  9. Increased strength of concrete subject to high loading rates

    International Nuclear Information System (INIS)

    Curbach, M.

    1987-01-01

    Within the scope of this work various problems are discussed which occur in connection with concrete under high tensile loading rates (e.g. when a plane crashes on a nuclear power plant very high loads occur which act only for a very short time). Particularly the causes for the already frequently noticed increases in strength with increasing loading rates are investigated and also the question whether this increased strength can be taken into account when dimensioning a construction. (MM) [de

  10. Analysis of crack propagation in concrete structures with structural information entropy

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The propagation of cracks in concrete structures causes energy dissipation and release, and also causes energy redistribution in the structures. Entropy can characterize the energy redistribution. To investigate the relation between the propagation of cracks and the entropy in concrete structures, cracked concrete structures are treated as dissipative structures. Structural information entropy is defined for concrete structures. A compact tension test is conducted. Meanwhile, numerical simulations are also carried out. Both the test and numerical simulation results show that the structural information entropy in the structures can characterize the propagation of cracks in concrete structures.

  11. Quality control of fireproof coatings for reinforced concrete structures

    Science.gov (United States)

    Gravit, Marina; Dmitriev, Ivan; Ishkov, Alexander

    2017-10-01

    The article analyzes methods of quality inspection of fireproof coatings (work flow, measuring, laboratory, etc.). In modern construction there is a problem of lack of distinct monitoring for the fire protection testing. There is a description of this testing for reinforced concrete structures. The article shows the results of calculation quality control of hatches as an example of fireproof coating for reinforced concrete structures.

  12. Conservation of concrete structures according to fib Model Code 2010

    NARCIS (Netherlands)

    Matthews, S.; Bigaj-Van Vliet, A.; Ueda, T.

    2013-01-01

    Conservation of concrete structures forms an essential part of the fib Model Code for Concrete Structures 2010 (fib Model Code 2010). In particular, Chapter 9 of fib Model Code 2010 addresses issues concerning conservation strategies and tactics, conservation management, condition surveys, condition

  13. Design of fire resistant concrete structures, using validated Fem models

    NARCIS (Netherlands)

    Erich, S.J.F.; Overbeek, van A.B.M.; Heijden, van der G.H.A.; Pel, L.; Huinink, H.P.; Vervuurt, A.H.J.M.; Schlangen, E.; Schlutter, de G.

    2008-01-01

    Fire safety of buildings and structures is an important issue, and has a great impact on human life and economy. One of the processes negatively affecting the strength of a concrete building or structure during fire is spalling. Many examples exists in which spalling of concrete during fire has

  14. Factor Structure of the Piagetian Stage of Concrete Operations.

    Science.gov (United States)

    Klausmeier, Herbert J.; Sipple, Thomas S.

    1982-01-01

    The Piagetian developmental stage of concrete operational thought and the theoretical groupement structures underlying children's performance of 12 concrete operations tasks are discussed. Tasks were shown to develop in five related sets. Three factor structures were found in this longitudinal study. (Author/CM)

  15. 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)

  16. On the Degradation of Concrete in Marine Structures

    DEFF Research Database (Denmark)

    Burcharth, Hans F.; Hofman Frisch, P.; Freisleben, P.

    1985-01-01

    Concrete is a cheap and extremely handy material and as such used extensively also in marine structures. Everybody dealing with this material knows examples of concrete apparently of almost infinite durability but also examples where serious degradation started shortly after completion of the str......Concrete is a cheap and extremely handy material and as such used extensively also in marine structures. Everybody dealing with this material knows examples of concrete apparently of almost infinite durability but also examples where serious degradation started shortly after completion...

  17. Probabilistic Analysis of Structural Member from Recycled Aggregate Concrete

    Science.gov (United States)

    Broukalová, I.; Šeps, K.

    2017-09-01

    The paper aims at the topic of sustainable building concerning recycling of waste rubble concrete from demolition. Considering demands of maximising recycled aggregate use and minimising of cement consumption, composite from recycled concrete aggregate was proposed. The objective of the presented investigations was to verify feasibility of the recycled aggregate cement based fibre reinforced composite in a structural member. Reliability of wall from recycled aggregate fibre reinforced composite was assessed in a probabilistic analysis of a load-bearing capacity of the wall. The applicability of recycled aggregate fibre reinforced concrete in structural applications was demonstrated. The outcomes refer to issue of high scatter of material parameters of recycled aggregate concretes.

  18. Effects of Crack and Climate Change on Service Life of Concrete Subjected to Carbonation

    Directory of Open Access Journals (Sweden)

    Xiao-Yong Wang

    2018-04-01

    Full Text Available Carbonation is among the primary reasons for the initiation of the corrosion of steel rebar in reinforced concrete (RC structures. Due to structural loading effects and environmental actions, inevitable cracks have frequently occurred in concrete structures since the early ages. Additionally, climate change, which entails increases in CO2 concentration and environmental temperature, will also accelerate the carbonation of concrete. This article presents an analytical way of predicting the service life of cracked concrete structures considering influences of carbonation and climate change. First, using a hydration model, the quantity of carbonatable materials and concrete porosity were calculated. Carbonation depth was evaluated considering properties of concrete materials and environmental conditions. Second, the influence of cracks on CO2 diffusivity was examined. Carbonation depth for cracked concrete was evaluated using equivalent CO2 diffusivity. The effects of climate change, for example, growing CO2 concentration and environmental temperature, were considered using different schemes of carbonation models. Third, different climate change scenarios (such as Representative Concentration Pathways (RCP 2.6, RCP 4.5, RCP 8.5 and upper 90% confidence interval of RCP 8.5 and time slices (such as 2000 and 2050 were used for case studies. By utilizing the Monte Carlo method, the influences of various climate change scenarios on the service life loss of concrete structures were highlighted.

  19. Capacity assessment of concrete containment vessels subjected to aircraft impact

    International Nuclear Information System (INIS)

    Andonov, Anton; Kostov, Marin; Iliev, Alexander

    2015-01-01

    Highlights: • An approach to assess the containment capacity to aircraft impact via fragility curves is proposed. • Momentum over Area was defined as most suitable reference parameter to describe the aircraft load. • The effect of the impact induced damages on the containment pressure capacity has been studied. • The studied containment shows no reduction of the pressure capacity for the investigated scenarios. • The effectiveness of innovative protective structure against aircraft impact has been evaluated. - Abstract: The paper describes the procedure and the results from the assessment of the vulnerability of a generic pre-stressed containment structure subjected to a large commercial aircraft impact. Impacts of Boeing 737, Boeing 767 and Boeing 747 have been considered. The containment vulnerability is expressed by fragility curves based on the results of a number of nonlinear dynamic analyses. Three reference parameters have been considered as impact intensity measure in the fragility curve definition: peak impact force (PIF), peak impact pressure (PIP) and Momentum over Area (MoA). Conclusions on the most suitable reference parameter as well on the vulnerability of such containment vessels are drawn. The influence of the aircraft impact induced damages on the containment ultimate pressure capacity is also assessed and some preliminary conclusions on this are drawn. The paper also addresses a conceptual design of a protective structure able to decrease the containment vulnerability and provide a preliminary assessment of the applicability of such concept.

  20. Capacity assessment of concrete containment vessels subjected to aircraft impact

    Energy Technology Data Exchange (ETDEWEB)

    Andonov, Anton, E-mail: anton.andonov@mottmac.com; Kostov, Marin; Iliev, Alexander

    2015-12-15

    Highlights: • An approach to assess the containment capacity to aircraft impact via fragility curves is proposed. • Momentum over Area was defined as most suitable reference parameter to describe the aircraft load. • The effect of the impact induced damages on the containment pressure capacity has been studied. • The studied containment shows no reduction of the pressure capacity for the investigated scenarios. • The effectiveness of innovative protective structure against aircraft impact has been evaluated. - Abstract: The paper describes the procedure and the results from the assessment of the vulnerability of a generic pre-stressed containment structure subjected to a large commercial aircraft impact. Impacts of Boeing 737, Boeing 767 and Boeing 747 have been considered. The containment vulnerability is expressed by fragility curves based on the results of a number of nonlinear dynamic analyses. Three reference parameters have been considered as impact intensity measure in the fragility curve definition: peak impact force (PIF), peak impact pressure (PIP) and Momentum over Area (MoA). Conclusions on the most suitable reference parameter as well on the vulnerability of such containment vessels are drawn. The influence of the aircraft impact induced damages on the containment ultimate pressure capacity is also assessed and some preliminary conclusions on this are drawn. The paper also addresses a conceptual design of a protective structure able to decrease the containment vulnerability and provide a preliminary assessment of the applicability of such concept.

  1. Concrete structures. Contribution to the safety assessment of existing structures

    Directory of Open Access Journals (Sweden)

    D. COUTO

    Full Text Available The safety evaluation of an existing concrete structure differs from the design of new structures. The partial safety factors for actions and resistances adopted in the design phase consider uncertainties and inaccuracies related to the building processes of structures, variability of materials strength and numerical approximations of the calculation and design processes. However, when analyzing a finished structure, a large number of unknown factors during the design stage are already defined and can be measured, which justifies a change in the increasing factors of the actions or reduction factors of resistances. Therefore, it is understood that safety assessment in existing structures is more complex than introducing security when designing a new structure, because it requires inspection, testing, analysis and careful diagnose. Strong knowledge and security concepts in structural engineering are needed, as well as knowledge about the materials of construction employed, in order to identify, control and properly consider the variability of actions and resistances in the structure. With the intention of discussing this topic considered complex and diffuse, this paper presents an introduction to the safety of concrete structures, a synthesis of the recommended procedures by Brazilian standards and another codes, associated with the topic, as well a realistic example of the safety assessment of an existing structure.

  2. Study on Detailing Design of Precast Concrete Frame Structure

    Science.gov (United States)

    Lida, Tian; Liming, Li; Kang, Liu; Jiao, Geng; Ming, Li

    2018-03-01

    Taking a certain precast concrete frame structure as an example, this paper introduces the general procedures and key points in detailing design of emulative cast-in-place prefabricated structure from the aspects of structural scheme, precast element layout, shop drawing design and BIM 3D modelling. This paper gives a practical solution for the detailing design of precast concrete frame structure under structural design codes in China.

  3. Long-term properties of concrete in nuclear containment structures

    International Nuclear Information System (INIS)

    Field, S.N.; Bamforth, P.B.

    1991-01-01

    Over the last thirty years a large volume of testing has been carried out on concretes used in prestressed concrete pressure vessels and similar structures. The main aim of the work has been to provide the designers with a prediction method for elastic moduli and creep deformation which takes into account temperature and age at loading. This paper summarises and reviews the results from the six concretes tested by Taywood Engineering Ltd (T.E.L.), comparing mixes with and without PFA. (author)

  4. Modelling of the Deterioration of Reinforced Concrete Structures

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Stochastic modelling of the deterioration of reinforced concrete structures is addressed in this paper on basis of a detailed modelling of corrosion initiation and corrosion cracking. It is proposed that modelling of the deterioration of concrete should be based on a sound understanding...... of the physical and chemical properties of the concrete. The relationship between rebar corrosion and crack width is investigated. A new service life definition based on evolution of the corrosion crack width is proposed....

  5. Long-term analysis of slender concrete structures with cracking

    International Nuclear Information System (INIS)

    Chern, J.C.; Marchertas, A.H.

    1985-01-01

    A special form of the finite element program, which is based on the equilibrium of forces in various cross sections of the beam together with the principle of virtual work, is presented for solving concrete beam problems. This analytical method uses the newly developed rheological element and exponential algorithm for computing time-dependent deformation and stress distribution in cracked concrete members subjected to sustained loads, temperature, or drying. Temperature and moisture effects on hydration (aging) and creep rate are included. The rate effects of temperature and moisture on the deformation of concrete are also taken into account in the formulation. Numerical examples are used to illustrate the validity of the analysis on concrete beams. Plain and reinforced concrete beams subjected to bending, heating or drying are analyzed and checked against experimental data

  6. 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.

  7. Standardization principles of radiographic investigation of concrete structures

    International Nuclear Information System (INIS)

    Runkiewicz, L.

    1979-01-01

    The PN-78/B-06264 Polish Standard concerning the radiographic methods of concrete structure control is discussed. It concerns the inner structure of the building elements, dimensions and position of honeycombs and reinforcement. (author)

  8. Behaviour of prestressed concrete containment structures

    International Nuclear Information System (INIS)

    MacGregor, J.G.; Murray, D.W.; Simmonds, S.H.

    1980-05-01

    The most significant finds from a study to assess the response of prestressed concrete secondary containment structures for nuclear reactors under the influence of high internal overpressures are presented. A method of analysis is described for determining the strains and deflections including effects of inelastic behaviour at various points in the structure resulting from increasing internal pressures. Experimentally derived relationships between the strains and crack spacing, crack width and leakage rate are given. These procedures were applied to the Gentilly-2 containment building to obtain the following results: (1) The first through-the-wall cracks would occur in the dome at 48 psi or 2.3 times the proof test pressure. (2) At this pressure leakage would begin and would increase exponentially as the pressure increases such that at 93% of the predicted failure load the calculated leakage rate would be approximately equal to the volume of the containment each second. (3) Assuming the pressurizing medium could be supplied sufficiently rapidly, failure would occur due to rupture of the horizontal tendons at approximately 77 psi. (author)

  9. Monitoring Ingress of Moisture in Structural Concrete Using a Novel Optical-Based Sensor Approach

    International Nuclear Information System (INIS)

    Yeo, T L; Cox, M A C; Boswell, L F; Sun, T; Grattan, K T V

    2006-01-01

    The detection of moisture ingress in concrete is important for structural monitoring and in this work is realised by monitoring the shift in the characteristic wavelength of a fibre Bragg grating-based sensor. The sensor relies upon a moisture-sensitive polymer layer deposited on the fibre Bragg grating (FBG) and the strain induced on it as a result of polymer swelling is monitored. Moisture ingress experiments were carried out using two such optical fibre sensors, placed at varying distances from the edge of the face of standard concrete cubes to the inner part of the concrete sample and subjected to water at a constant temperature. Information on the properties of different types of concrete and thus potentially on the migration of dissolved salts and their effect on reinforcement bars within concrete can be obtained

  10. Characteristics of Structural Breakdown in Plastic Concrete and ...

    African Journals Online (AJOL)

    Characteristics of Structural Breakdown in Plastic Concrete and Their Potentials for Quality Control. ... A typical trace has four such significant features which characterise the mix. The significance of these features are analysed in relation to the functional requirements of plastic concrete in practice. Finally, the potentials of ...

  11. Early stage beneficial effects of cathodic protection in concrete structures

    NARCIS (Netherlands)

    Polder, R.B.; Peelen, W.H.A.; Neeft, E.A.C.; Stoop, B.T.J.

    2010-01-01

    Over the last 25 years, cathodic protection (CP) of reinforced concrete structures suffering from chloride induced reinforcement corrosion has shown to be successful and durable. CP current causes steel polarisation, electrochemical reactions and ion transport in the concrete. CP systems are

  12. Processing disaster debris liberating aggregates for structural concrete

    NARCIS (Netherlands)

    van de Wouw, P.M.F.; Florea, M.V.A.; Brouwers, H.J.H.; Schmidt, W.; Msinjili, N.S.

    2016-01-01

    Worldwide, the removal of debris and reconstruction is requested when natural disasters and conflicts cause damaged or collapsed buildings. The on-site recycling of concrete waste into new structural concrete decreases transport and production energy costs, reduces the utilization of raw materials,

  13. Evaluation of microbially-influenced degradation of massive concrete structures

    International Nuclear Information System (INIS)

    Hamilton, M.A.; Rogers, R.D.; Zolynski, M.; Veeh, R.

    1996-01-01

    Many low level waste disposal vaults, both above and below ground, are constructed of concrete. One potential contributing agent to the destruction of concrete structures is microbially-influenced degradation (MID). Three groups of bacteria are known to create conditions that are conducive to destroying concrete integrity. They are sulfur oxidizing bacteria, nitrifying bacteria, and heterotrophic bacteria. Research is being conducted at the Idaho National Engineering Laboratory to assess the extent of naturally occurring microbially influenced degradation (MID) and its contribution to the deterioration of massive concrete structures. The preliminary steps to understanding the extent of MID, require assessing the microbial communities present on degrading concrete surfaces. Ultimately such information can be used to develop guidelines for preventive or corrective treatments for MID and aid in formulation of new materials to resist corrosion. An environmental study was conducted to determine the presence and activity of potential MID bacteria on degrading concrete surfaces of massive concrete structures. Scanning electron microscopy detected bacteria on the surfaces of concrete structures such as bridges and dams, where corrosion was evident. Enumeration of sulfur oxidizing thiobacilli and nitrogen oxidizing Nitrosomonas sp. and Nitrobacter sp. from surface samples was conducted. Bacterial community composition varied between sampling locations, and generally the presence of either sulfur oxidizers or nitrifiers dominated, although instances of both types of bacteria occurring together were encountered. No clear correlation between bacterial numbers and degree of degradation was exhibited

  14. Quality Control of Concrete Structure For APR1400 Construction

    International Nuclear Information System (INIS)

    Seo, Inseop; Song, Changhak; Kim, Duill

    2012-01-01

    Nuclear structure shall be constructed to protect internal facilities in the normal operation against external accidents such as the radiation shielding, earthquakes and to be leak-proof of radioactive substances to the external environment in case of loss of coolants. containment and auxiliary building of nuclear power plants are built in reinforced concrete structures to maintain these protection functions. Nuclear structures shall be designed to ensure soundness in operation since they are located on the waterfront where is easy do drain the cooling water and so deterioration and damage of concrete structures caused by seawater can occur. Durability is ensured for concrete structures of APR1400, a Korea standard NPP, in compliance with all safety requirements. In particular, owners perform quality control directly on the production and pouring of cast in place concrete for the concrete structure construction to make sure concrete structures established with quality homogeneity and durability. This report is to look into the quality control standard and management status of cast in place concrete for APR1400 construction

  15. Creep and creep recovery of concrete subjected to triaxial compressive stresses at elevated temperature

    International Nuclear Information System (INIS)

    Ohnuma, Hiroshi; Abe, Hirotoshi

    1979-01-01

    In order to design rationally the vessels made of prestressed concrete for nuclear power stations and to improve the accuracy of high temperature creep analysis, the Central Research Institute of Electric Power Industry had carried out the proving experiments with scale models. In order to improve the accuracy of analysis, it is important to grasp the creep behavior of the concrete subjected to triaxial compressive stresses at high temperature as the basic property of concrete, because actual prestressed concrete vessels are in such conditions. In this paper, the triaxial compression creep test at 60 deg. C using the concrete specimens with same mixing ratio as the scale models is reported. The compressive strength of the concrete at the age of 28 days was 406 kg/cm 2 , and the age of the concrete at the time of loading was 63 days. Creep and creep recovery were measured for 5 months and 2 months, respectively. The creep of concrete due to uniaxial compression increased with temperature rise, and the creep strain at 60 deg. C was 2.54 times as much as that at 20 deg. C. The effective Poisson's ratio in triaxial compression creep was 0.15 on the average, based on the creep strain due to uniaxial compression at 60 deg. C. The creep recovery rate in high temperature, triaxial compression creep was 33% on the average. (Kako, I.)

  16. Ecosecent:: Essence, Subject and Structure

    Directory of Open Access Journals (Sweden)

    Kozachenko Hanna V.

    2014-02-01

    Full Text Available The article shows that due to multi-laterality the knowledge about security is distributed by various branches, one of which is ecosestate, within which conditions of secure functioning of socio-economic systems and methods of their provision are studied. It shows the essence of ecosecent as a component of the “state – region (branch – subject of economic activity” ecosestate vertical – a set of knowledge about economic security of subjects of economic activity. It considers reasons that cause establishment of ecosecent: practical needs and a necessity to reconsider basic concepts of the essence, limits and factors of economy. It formulates the subject of ecosecent. It considers the status of the “economic security of the subject of economic activity” notion as its state, described with a set of parameters or characteristic features as characteristics of the subject of economic activity as a condition of its activity and as a set of actions that allow ensuring or preservation of the state of security, in other words, protection of the subject of economic activity. It presents general approaches to structuring of ecosecent by activity, functional and branch features.

  17. Reliability of Arch dams subject to concrete swelling

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J.M.; Silva, H.S.; Pinho, S. de [Laboratorio Nacional de Engenharia Civil (LNEC), Lisboa (Portugal)] [and others

    1995-12-31

    In this report, results of several studies are presented. The main aim of those studies was to assess the reliability of the three arch dams, in which swelling occurred due to alkali- aggregate reactions in various stages of development and having different effects on their reliability: the Cahora-Bassa dam, in Mozambique, where swelling accumulated up to the moment are very moderate and their development is apparently homogeneous; Santa-Luzia dam, in Portugal, where accumulated swelling have already considerable magnitude, nevertheless, important fissuration has not been observed up to the moment due to the homogeneous development of the swelling process; Alto-Ceira dam, also in Portugal, where accumulated swelling have also considerable magnitude but with a heterogeneous development, causing in conjunction with thermal variations important fissuration. Mention is made of mineralogical, chemical and petrographic analyses carried out for identification of the nature of reactions developed in each case and the back-analysis and other technics used in the assessment of the magnitude and distribution of swelling. Results are presented of measurement tests of the ultrasonic pulse velocity, used both in the assessment of alterations in the physical properties of concretes and in the determination of the depth of fissuration. Results are also presented of tests for characterisation of the rheology of integral concrete. Lastly, considerations are made about the reliability of the works on the basis of studies and the results of analyses of the state of stress, performed by means of the finite element method, by assuming for either visco-elastic or visco-elastic-plastic behaviour.

  18. Sustainable monitoring of concrete structures : strength and durability performance of polymer-modified self-sensing concrete

    OpenAIRE

    Torgal, Fernando Pacheco; Gonzalez, J.; Jalali, Said

    2012-01-01

    Concrete structures all over the world are reaching the end of their service life sooner than expected. This is due to the fact that ordinary Portland cement-based concrete deteriorates under environmental actions and also that structural inspections and conservation actions are expensive. Besides, as they consume energy and non-renewable resources, they have negative environmental impacts. Self-sensing concrete provides an alternative way of monitoring concrete-reinforced structures...

  19. Behavior of prestressed concrete subjected to low temperatures and cyclic loading

    International Nuclear Information System (INIS)

    Berner, D.E.

    1984-01-01

    Concrete has exhibited excellent behavior in cryogenic containment vessels for several decades under essentially static conditions. Tests were conducted to determine the response of prestressed lightweight concrete subjected to high-intensity cyclic loading and simultaneous cryogenic thermal shock, simulating the relatively dynamic conditions encountered offshore or in seismic areas. Lightweight concrete has several attractive properties for cryogenic service including: (1) very low permeability, (2) good strain capacity, (3) relatively low thermal conductivity, and (4) a low modulus of elasticity. Experimental results indicated that the mechanical properties of plain lightweight concrete significantly increase with moisture content at low temperatures, while cyclic loading fatigue effects are reduced at low temperatures. Also, tests on uniaxially and on biaxially prestressed lightweight concrete both indicate that the test specimens performed well under severe cyclic loading and cryogenic thermal shock with only moderate reduction in flexural stiffness. Supplementary tests conducted in this study indicate that conventionally reinforced concrete degrades significantly faster than prestressed concrete when subjected to cyclic loading and thermal shock

  20. Performance of Hydrophobisation Techniques in Case of Reinforced Concrete Structures

    Science.gov (United States)

    Błaszczyński, Tomasz; Osesek, Mateusz; Gwozdowski, Błażej; Ilski, Mirosław

    2017-10-01

    Concrete is, unchangeably, one of the most frequently applied building materials, also in the case of bridges, overpasses or viaducts. Along with the aging of such structures, the degradation of concrete, which may accelerate the corrosion of reinforcing steel and drastically decrease the load-bearing capacity of the structure, becomes an important issue. The paper analyzes the possibilities of using deep hydrophobisation in repairing reinforced concrete engineering structures. The benefits of properly securing reinforced concrete structures from the damaging effects of UV radiation, the influence of harmful gases, or progression of chlorine induced corrosion have been presented, especially in regards to bridge structures. The need to calculate the costs of carrying out investments along with the expected costs of maintaining such structures, as well as the high share of costs connected with logistics, has also been indicated in the total costs of repair works.

  1. Residual strength evaluation of concrete structural components ...

    Indian Academy of Sciences (India)

    fundamental material parameters that can be determined for use in design or evaluation. ... of plain and reinforced concrete beams using fracture mechanics principles. Design equations ... components accounting for tension softening effect.

  2. Frost resistance of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    1999-01-01

    Frost resistance of fibre reinforced concrete with 2.5-4.2% air and 6-9% air (% by volume in fresh concrete) casted in the laboratory and in-situ is compared. Steel fibres with hooked ends (ZP, length 30 mm) and polypropylene fibres (PP, CS, length 12 mm) are applied. It is shown that· addition...... of 0.4-1% by volume of fibres cannot replace air entrainment in order to secure a frost resistant concrete; the minimum amount of air needed to make the concrete frost resistant is not changed when adding fibres· the amount of air entrainment must be increased when fibres are added to establish...

  3. Degradation of Waterfront Reinforced Concrete Structures

    African Journals Online (AJOL)

    Key words: Degradation, reinforced concrete, Dar es Salaam port. Abstract—One of the ... especially corrosion of the reinforcement. ... Corrosion of steel reinforcement contributes .... cracks along the line of reinforcement bars and most of the ...

  4. Properties and Behavior of Geopolymer Concrete Subjected to Explosive Air Blast Loading: A Review

    Directory of Open Access Journals (Sweden)

    Mohd Mortar Nurul Aida

    2017-01-01

    Full Text Available The severe damage to civilian buildings, public area, jet aircraft impact and defense target under explosive blast loading can cause a huge property loss. Most of researcher discusses the topics on design the concrete material model to sustain againts the explosive detonation. The implementation of modern reinforcement steels and fibres in ordinary Portland cement (OPC concrete matrix can reduce the extreme loading effects. However, most researchers have proved that geopolymer concrete (GPC has better mechanical properties towards high performance concrete, compared to OPC. GPC has the high early compressive strength and high ability to resist the thermal energy from explosive detonation. In addition, OPC production is less environmental friendly than geopolymer cement. Geopolymer used can lead to environmental protection besides being improved in mechanical properties. Thus, this paper highlighted on an experimental, numerical and the analytical studies cause of the explosive detonation impact to concrete structures.

  5. Serviceability design load factors and reliability assessments for reinforced concrete containment structures

    International Nuclear Information System (INIS)

    Han Bong Koo

    1998-01-01

    A reinforced concrete nuclear power plant containment structure is subjected to various random static and stochastic loads during its lifetime. Since these loads involve inherent randomness and other uncertainties, an appropriate probabilistic model for each load must be established in order to perform reliability analysis. The current ASME code for reinforced concrete containment structures are not based on probability concepts. The stochastic nature of natural hazard or accidental loads and the variations of material properties require a probabilistic approach for a rational assessment of structural safety and performance. The paper develops probability-based load factors for the limit state design of reinforced concrete containment structures. The purpose of constructing reinforced concrete containment structure is to protect against radioactive release, and so the use of a serviceability limit state against crack failure that can cause the emission of radioactive materials is suggested as a critical limit state for reinforced concrete containment structures. Load factors for the design of reinforced concrete containment structures are proposed and carried out the reliability assessments. (orig.)

  6. Review of Repair Materials for Fire-Damaged Reinforced Concrete Structures

    Science.gov (United States)

    Zahid, MZA Mohd; Abu Bakar, BH; Nazri, FM; Ahmad, MM; Muhamad, K.

    2018-03-01

    Reinforced concrete (RC) structures perform well during fire and may be repaired after the fire incident because their low heat conductivity prevents the loss or degradation of mechanical strength of the concrete core and internal reinforcing steel. When an RC structure is heated to more than 500 °C, mechanical properties such as compressive strength, stiffness, and tensile strength start to degrade and deformations occur. Although the fire-exposed RC structure shows no visible damage, its residual strength decreases compared with that in the pre-fire state. Upon thorough assessment, the fire-damaged RC structure can be repaired or strengthened, instead of subjecting to partial or total demolition followed by reconstruction. The structure can be repaired using several materials, such as carbon fiber-reinforced polymer, glass fiber-reinforced polymer, normal strength concrete, fiber-reinforced concrete, ferrocement, epoxy resin mortar, and high-performance concrete. Selecting an appropriate repair material that must be compatible with the substrate or base material is a vital step to ensure successful repair. This paper reviews existing repair materials and factors affecting their performance. Of the materials considered, ultra-high-performance fiber-reinforced concrete (UHPFRC) exhibits huge potential for repairing fire-damaged RC structures but lack of information available. Hence, further studies must be performed to assess the potential of UHPFRC in rehabilitating fire-damaged RC structures.

  7. Effect of high temperature on integrity of concrete containment structures

    International Nuclear Information System (INIS)

    Bhat, P.D.

    1986-01-01

    The effect of high temperature on concrete material properties and structural behavior are studied in order to relate these effects to the performance of concrete containment structures. Salient data obtained from a test program undertaken to study the behavior of a restrained concrete structure under thermal gradient loads up to its ultimate limit are described. The preliminary results indicate that concrete material properties can be considered to remain unaltered up to temperatures of 100 0 C. The presence of thermal gradients did not significantly affect the structures ultimate mechanical load capacity. Relaxation of restraint forces due to creep was found to be an important factor. The test findings are compared with the observations made in available literature. The effect of test findings on the integrity analysis of a containment structure are discussed. The problem is studied from the viewpoint of a CANDU heavy water reactor containment

  8. Structural analysis of reinforced concrete structures under monotonous and cyclic loadings: numerical aspects

    International Nuclear Information System (INIS)

    Lepretre, C.; Millard, A.; Nahas, G.

    1989-01-01

    The structural analysis of reinforced concrete structures is usually performed either by means of simplified methods of strength of materials type i.e. global methods, or by means of detailed methods of continuum mechanics type, i.e. local methods. For this second type, some constitutive models are available for concrete and rebars in a certain number of finite element systems. These models are often validated on simple homogeneous tests. Therefore, it is important to appraise the validity of the results when applying them to the analysis of a reinforced concrete structure, in order to be able to make correct predictions of the actual behaviour, under normal and faulty conditions. For this purpose, some tests have been performed at I.N.S.A. de Lyon on reinforced concrete beams, subjected to monotonous and cyclic loadings, in order to generate reference solutions to be compared with the numerical predictions given by two finite element systems: - CASTEM, developed by C.E.A./.D.E.M.T. - ELEFINI, developed by I.N.S.A. de Lyon

  9. Concrete material characterization reinforced concrete tank structure Multi-Function Waste Tank Facility

    International Nuclear Information System (INIS)

    Winkel, B.V.

    1995-01-01

    The purpose of this report is to document the Multi-Function Waste Tank Facility (MWTF) Project position on the concrete mechanical properties needed to perform design/analysis calculations for the MWTF secondary concrete structure. This report provides a position on MWTF concrete properties for the Title 1 and Title 2 calculations. The scope of the report is limited to mechanical properties and does not include the thermophysical properties of concrete needed to perform heat transfer calculations. In the 1970's, a comprehensive series of tests were performed at Construction Technology Laboratories (CTL) on two different Hanford concrete mix designs. Statistical correlations of the CTL data were later generated by Pacific Northwest Laboratories (PNL). These test results and property correlations have been utilized in various design/analysis efforts of Hanford waste tanks. However, due to changes in the concrete design mix and the lower range of MWTF operating temperatures, plus uncertainties in the CTL data and PNL correlations, it was prudent to evaluate the CTL data base and PNL correlations, relative to the MWTF application, and develop a defendable position. The CTL test program for Hanford concrete involved two different mix designs: a 3 kip/in 2 mix and a 4.5 kip/in 2 mix. The proposed 28-day design strength for the MWTF tanks is 5 kip/in 2 . In addition to this design strength difference, there are also differences between the CTL and MWTF mix design details. Also of interest, are the appropriate application of the MWTF concrete properties in performing calculations demonstrating ACI Code compliance. Mix design details and ACI Code issues are addressed in Sections 3.0 and 5.0, respectively. The CTL test program and PNL data correlations focused on a temperature range of 250 to 450 F. The temperature range of interest for the MWTF tank concrete application is 70 to 200 F

  10. PS buildings : reinforced concrete structure for shielding "bridge" pillar

    CERN Multimedia

    CERN PhotoLab

    1956-01-01

    The PS ring traverses the region between the experimental halls South and North (buildings Nos 150 and 151) under massive bridge-shaped concrete beams. This pillar stands at the S-W end of the structure.

  11. Characterization and mediation of microbial deterioration of concrete bridge structures.

    Science.gov (United States)

    2013-04-01

    Samples obtained from deteriorated bridge structures in Texas were cultured in growth medium containing thiosulfate as an energy source and investigated for acid production, type of acid produced by microbes and the bio-deterioration of concrete cyli...

  12. Durability performance of submerged concrete structures - phase 2.

    Science.gov (United States)

    2015-09-01

    This project determined that severe corrosion of steel can occur in the submerged : portions of reinforced concrete structures in marine environments. Field studies of decommissioned : pilings from Florida bridges revealed multiple instances of stron...

  13. Steel-concrete bond model for the simulation of reinforced concrete structures

    International Nuclear Information System (INIS)

    Mang, Chetra

    2015-01-01

    Reinforced concrete structure behavior can be extremely complex in the case of exceeding the cracking threshold. The composite characteristics of reinforced concrete structure should be finely presented especially in the distribution stress zone between steel-concrete at their interface. In order to compute the industrial structures, a perfect relation hypothesis between steel and concrete is supposed in which the complex phenomenon of the two-material relation is not taken into account. On the other hand, this perfect relation is unable to predict the significant disorders, the repartition, and the distribution of the cracks, which is directly linked to the steel. In literature, several numerical methods are proposed in order to finely study the concrete-steel bond behavior, but these methods give many difficulties in computing complex structures in 3D. With the results obtained in the thesis framework of Torre-Casanova (2012), the new concrete-steel bond model has been developed to improve performances (iteration numbers and computational time) and the representation (cyclic behavior) of the initial one. The new model has been verified with analytical solution of steel-concrete tie and validated with the experimental results. The new model is equally tested with the structural scale to compute the shear wall behavior in the French national project (CEOS.fr) under monotonic load. Because of the numerical difficulty in post-processing the crack opening in the complex crack formation, a new crack opening method is also developed. This method consists of using the discontinuity of relative displacement to detect the crack position or using the slip sign change between concrete-steel. The simulation-experiment comparison gives validation of not only the new concrete-steel bond model but also the new crack post-processing method. Finally, the cyclic behavior of the bond law with the non-reduced envelope is adopted and integrated in the new bond model in order to take

  14. Constitutive relation of concrete containing meso-structural characteristics

    Directory of Open Access Journals (Sweden)

    Li Guo

    Full Text Available A constitutive model of concrete is proposed based on the mixture theory of porous media within thermodynamic framework. By treating concrete as a multi-phase multi-component mixture, we constructed the constitutive functions for elastic, interfacial, and plastic strain energy respectively. A constitutive law of concrete accommodating internal micro-cracks and interfacial boundaries was established. The peak stress predicted with the developed model depends primarily on the volume ratio of aggregate, and the results explain very well reported experimental phenomena. The strain-stress curve under uniaxial loading was found in a good agreement with experimental data for concrete with three different mixing proportions. Keywords: Constitutive model of concrete, Mixture theory of porous media, Meso-structure, Interfacial energy

  15. Performance of Hybrid Steel Fibers Reinforced Concrete Subjected to Air Blast Loading

    Directory of Open Access Journals (Sweden)

    Mohammed Alias Yusof

    2013-01-01

    Full Text Available This paper presents the results of the experimental data and simulation on the performance of hybrid steel fiber reinforced concrete (HSFRC and also normal reinforced concrete (NRC subjected to air blast loading. HSFRC concrete mix consists of a combination of 70% long steel hook end fibre and also 30% of short steel hook end fibre with a volume fraction of 1.5% mix. A total of six concrete panels were subjected to air blast using plastic explosive (PE4 weighing 1 kg each at standoff distance of 0.3 meter. The parameters measured are mode of failure under static and blast loading and also peak overpressure that resulted from detonation using high speed data acquisition system. In addition to this simulation work using AUTODYN was carried out and validated using experimental data. The experimental results indicate that hybrid steel fiber reinforced concrete panel (HSFRC possesses excellent resistance to air blast loading as compared to normal reinforced concrete (NRC panel. The simulation results were also found to be close with experimental data. Therefore the results have been validated using experimental data.

  16. Global models for studying the non linear behavior of structures. Application to reinforced concrete structures

    International Nuclear Information System (INIS)

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

    1982-06-01

    The application of global methods to design reinforced concrete structures was investigated. The dynamic calculation of beam structures can be carried out very economically and with suitable accuracy by these methods. Moreover, one ideal application of global methods is design to failure, in order to estimate the safety margins of a given structure subject to accidental stresses, such as explosions, earthquakes, aircraft crash etc. In all cases, the global method combined with finite element programs serves to determine the failure automatically, and offers a good estimate of the failure load [fr

  17. Flexural strength of structural concrete repaired with HBPMM cement

    International Nuclear Information System (INIS)

    Memon, G.H.; Khaskheli, G.B.; Kumar, A.

    2009-01-01

    To repair damaged concrete structures, Dadabhoy Cement Factory in Sindh has launched a product known as HBPMM (Hi-Bond Polymer Modified Mortar) cement. HBPMM is used to repair various concrete structures in Pakistan but the experimental back up regarding the real performance of the product, as far as flexural strength of concrete is concerned, is not well known yet. This study is thus aimed to investigate the flexural strength of structural concrete repaired with HBPMM compared to that repaired with OPC (Ordinary Portland Cement). In total 32 concrete beams (6x6x18) having compressive strength of 3000 and 5000 psi were manufactured. To obtain flexural strength of the beams, these were splitted by using a UTM (Universal Testing Machine). Beams were then repaired with different applications of HBPMM and OPC. After 28 days of curing, the repaired beams were re-splitted to determine the flexural strength of repaired beams. Results show that both HBPMM and OPC are not very effective. However, the performance of HBPMM remained slightly better than that of OPC. Both OPC and HBPMM remained more efficient in case of 5000 psi concrete than that of 3000 psi concrete. Flexural strength of repaired beams could be increased by increasing application of the repairing material. (author)

  18. Evaluation and rehabilitation of corrosion damaged reinforced concrete structures

    International Nuclear Information System (INIS)

    Paul, I.S.

    1999-01-01

    For the last two decades, rehabilitation of corrosion damaged concrete structures has been one of the most important challenges faced by the construction industry throughout the world. The extent of the damage is significant in cold climates and also in hot and humid climates. In both cases, the corrosion is invariably initiated by ingress of salts into the concrete either from de-icing salts used on roads, or from salt-laden air, soils or ground water. However, there is a contrast in sites of distress in the two climatic regions mentioned above. In cold climates, where de-icing salts are used, the damage is generally to superstructures and is therefore visible, but in hot, humid coastal regions damage is primarily in the substructures and may not be so clearly apparent. This paper presents the corrosion mechanism in concrete deterioration, the methods of evaluation of the damaged structures, and rehabilitation strategies. A case history of a concrete rehabilitation project is included together with some lessons learned in rehabilitation of corrosion damaged structures. Recommendations are made for maintenance of concrete structures and a warning is issued that salt run-off from roads in cold climates may cause distress in below ground concrete structures, similar to structures in hot and humid climates with saline groundwater and soils. (author)

  19. The effects of pressure dependent constitutive model to simulate concrete structures failure under impact loads

    Science.gov (United States)

    Mokhatar, S. N.; Sonoda, Y.; Kamarudin, A. F.; Noh, M. S. Md; Tokumaru, S.

    2018-04-01

    The main objective of this paper is to explore the effect of confining pressure in the compression and tension zone by simulating the behaviour of reinforced concrete/mortar structures subjected to the impact load. The analysis comprises the numerical simulation of the influences of high mass low speed impact weight dropping on concrete structures, where the analyses are incorporated with meshless method namely as Smoothed Particle Hydrodynamics (SPH) method. The derivation of the plastic stiffness matrix of Drucker-Prager (DP) that extended from Von-Mises (VM) yield criteria to simulate the concrete behaviour were presented in this paper. In which, the displacements for concrete/mortar structures are assumed to be infinitesimal. Furthermore, the influence of the different material model of DP and VM that used numerically for concrete and mortar structures are also discussed. Validation upon existing experimental test results is carried out to investigate the effect of confining pressure, it is found that VM criterion causes unreal impact failure (flexural cracking) of concrete structures.

  20. Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

    Science.gov (United States)

    Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

    2014-01-01

    Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion. PMID:24558346

  1. Monitoring corrosion of steel bars in reinforced concrete structures.

    Science.gov (United States)

    Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

    2014-01-01

    Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion.

  2. Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

    Directory of Open Access Journals (Sweden)

    Sanjeev Kumar Verma

    2014-01-01

    Full Text Available Corrosion of steel bars embedded in reinforced concrete (RC structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP method. This paper also presents few techniques to protect concrete from corrosion.

  3. Ductility of Reinforced Concrete Structures in Flexure

    DEFF Research Database (Denmark)

    Hestbech, Lars

    2013-01-01

    In this thesis, a rotational capacity model for flexural reinforced concrete elements is presented. The model is based on the general assumption, that any other failure mode than bending is prevented by proper design. This includes failure due to shear, anchorage, concentrated loads etc. Likewise...... are not necessarily so. An example shows the applicability of the model and a parametric study shows the advantages of the model compared with code provisions. Finally, improvements of the compression zone modelling is performed in order to include a better performance when concrete crushing is the failure criterion...

  4. 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....

  5. Durability reliability analysis for corroding concrete structures under uncertainty

    Science.gov (United States)

    Zhang, Hao

    2018-02-01

    This paper presents a durability reliability analysis of reinforced concrete structures subject to the action of marine chloride. The focus is to provide insight into the role of epistemic uncertainties on durability reliability. The corrosion model involves a number of variables whose probabilistic characteristics cannot be fully determined due to the limited availability of supporting data. All sources of uncertainty, both aleatory and epistemic, should be included in the reliability analysis. Two methods are available to formulate the epistemic uncertainty: the imprecise probability-based method and the purely probabilistic method in which the epistemic uncertainties are modeled as random variables. The paper illustrates how the epistemic uncertainties are modeled and propagated in the two methods, and shows how epistemic uncertainties govern the durability reliability.

  6. Structural Behaviors of Reinforced Concrete Piers Rehabilitated with FRP Wraps

    Directory of Open Access Journals (Sweden)

    Junsuk Kang

    2017-01-01

    Full Text Available The use of fiber-reinforced polymer (FRP wraps to retrofit and strengthen existing structures such as reinforced concrete piers is becoming popular due to the higher tensile strength, durability, and flexibility gained and the method’s ease of handling and low installation and maintenance costs. As yet, however, few guidelines have been developed for determining the optimum thicknesses of the FRP wraps applied to external surfaces of concrete or masonry structures. In this study, nonlinear pushover finite element analyses were utilized to analyze the complex structural behaviors of FRP-wrapped reinforced rectangular piers. Design parameters such as pier section sizes, pier heights, pier cap lengths, compressive strengths of concrete, and the thicknesses of the FRP wraps used were thoroughly tested under incremental lateral and vertical loads. The results provide useful guidelines for analyzing and designing appropriate FRP wraps for existing concrete piers.

  7. Modeling of fracture of protective concrete structures under impact loads

    Energy Technology Data Exchange (ETDEWEB)

    Radchenko, P. A., E-mail: radchenko@live.ru; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S. [Tomsk State University of Architecture and Building, Tomsk, 634003 (Russian Federation)

    2015-10-27

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

  8. Sensor Systems for Corrosion Monitoring in Concrete Structures

    Directory of Open Access Journals (Sweden)

    K.Kumar

    2006-05-01

    Full Text Available It is a need of permanently embedded corrosion monitoring devices to monitor the progress of corrosion problems on a new or existing reinforced concrete structures before embarking on repair or rehabilitation of the structures. Numerous devices are available for investigating corrosion problems, because no single technique exists which tells an engineer what he needs to know, namely how much damage there is on a structure now and how rapidly the damage will grow with time. In this investigation the studies on the sensors systems based on the measurements of half cell potential of rebars inside the concrete, resistivity of concrete, corrosion rate of rebars by eddy current measurements and sensing of chloride ions are reported. An integrated system consists of above sensors are fabricated and embedded into concrete. The response from each sensor was acquired and analyzed by NI hardware through LabVIEW software.

  9. Modeling of fracture of protective concrete structures under impact loads

    Science.gov (United States)

    Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

    2015-10-01

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

  10. 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)

  11. Reinforced concrete containment structures in high seismic zones

    International Nuclear Information System (INIS)

    Aziz, T.S.

    1977-01-01

    A new structural concept for reinforced concrete containment structures at sites where earthquake ground motions in terms of the Safe Shutdown Earthquake (SSE) exceeds 0.3 g is presented. The structural concept is based on: (1) an inner steel-lined concrete shell which houses the reactor and provides shielding and containment in the event of loss of coolant accident; (2) an outer annular concrete shell structure which houses auxiliary reactor equipment and safeguards systems. These shell structures are supported on a common foundation mat which is embedded in the subgrade. Under stipulated earthquake conditions the two shell structures interact to resist lateral inertia forces. Thus the annular structure which is not a pressure boundary acts as a lateral support for the inner containment shell. The concept is practical, economically feasible and new to practice. (Auth.)

  12. Probabilistic methods for condition assessment and life prediction of concrete structures in nuclear power plants

    International Nuclear Information System (INIS)

    Ellingwood, B.R.; Mori, Yasuhiro

    1993-01-01

    A probability-based methodology is being developed in support of the NRC Structural Aging Program to assist in evaluating the reliability of existing concrete structures in nuclear power plants under potential future operating loads and extreme evironmental and accidental events. The methodology includes models to predict structural deterioration due to environmental stressors, a database to support the use of these models, and methods for analyzing time-dependent reliability of concrete structural components subjected to stochastic loads. The methodology can be used to support a plant license extension application by providing evidence that safety-related concrete structures in their current (service) condition are able to withstand future extreme events with a level of reliability sufficient for public health and safety. (orig.)

  13. A survey of the mechanical properties of concrete for structural purposes prepared on construction sites

    Directory of Open Access Journals (Sweden)

    R. R. J. RIBEIRO

    Full Text Available Abstract This paper aims to study the concrete dosage conditions for structural purposes in construction sitesl, and the impacts of non-compliance of structural concrete for structural safety, having as study case the city of Angicos / RN. Were analyzed the dynamic elasticity modulus, static elasticity modulus and the compressive strength of concrete samples. Was conducted to collect the survey data, a field research aiming to gather information about dosage of concrete used in the works, as well as the collection of cylindrical specimens of 150 mm diameter by 300 mm of height, prepared according to practice of those professionals. The study indicated a clear necessity to reflection on the subject, since there is no concern, or even, a lack of knowledge by the interviewed professionals regarding the care and procedures necessary for the production of concrete with satisfactory quality, once at least 50% of evaluated construction sites presented compressive strength lower than 20 MPa, minimal strength to structural concrete, as recommended by ABNT-NBR 6118:2014.

  14. Constitutive Models for Design of Sustainable Concrete Structures

    Science.gov (United States)

    Brozovsky, J.; Cajka, R.; Koktan, J.

    2018-04-01

    The paper deals with numerical models of reinforced concrete which are expected to be useful to enhance design of sustainable reinforced concrete structures. That is, the models which can deliver higher precision of results than the linear elastic models but which are still feasible for engineering practice. Such models can be based on an elastic-plastic material. The paper discusses properties of such models. A material model based of the Chen criteria and the Ohtani hardening model for concrete was selected for further development. There is also given a comparison of behaviour of such model with behaviour of a more complex smeared crack model which is based on principles of fracture mechanics.

  15. Report on aging of nuclear power plant reinforced concrete structures

    International Nuclear Information System (INIS)

    Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

    1996-03-01

    The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs

  16. Report on aging of nuclear power plant reinforced concrete structures

    Energy Technology Data Exchange (ETDEWEB)

    Naus, D.J.; Oland, C.B. [Oak Ridge National Lab., TN (United States); Ellingwood, B.R. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering

    1996-03-01

    The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs.

  17. Quality control of concrete structures in nuclear power plant, (3)

    International Nuclear Information System (INIS)

    Takahashi, Hisao; Kawaguchi, Tohru; Oike, Takeshi; Morimoto, Shoichi; Takeshita, Shigetoshi.

    1979-01-01

    In general, concrete placed in the winter season has a tendency to have lower strength at the age of 4 weeks due to low curing temperature after placement. Therefore, under the Japanese code, the target mix Proportions in the winter season are modified adding an extra correction factor based on air temperature. Meanwhile, the quality control system for mass concrete to be placed in the winter system is indistinct at this stage. It is the aim of this report to present the results of investigations to clarify the following two subjects: (1) whether the correction factor due to temperature is needed or not for mass concrete in the winter season; (2) what kind of curing should be applied to control cylinders for estimating strength of mass concrete. (author)

  18. Numerical Simulation of Shock Response and Dynamic Fracture of a Concrete Dam Subjected to Impact Load

    Directory of Open Access Journals (Sweden)

    Lu Lu

    2016-01-01

    Full Text Available The shock response and dynamic fracture of concrete gravity dams under impact load are the key problems to evaluate the antiknock safety of the dam. This study aims at understanding the effects of impact shock on the elastic response and dynamic fracture of concrete gravity dams. Firstly, this paper uses acceleration records of a concrete gravity dam under impact to establish the correct way to determine the concrete gravity dam of the fundamental frequency and present cut sheets multi-degree-of-freedom dynamic modeling. Under strong impact loading, the constitutive relation of concrete gravity dam and the highest frequency of the impact are uncertain. So, the main advantage of this method is avoiding the use of elastic modulus in the calculation. The result indicates that the calculation method is a reliable computational method for concrete gravity dams subjected to impact. Subsequently, the failure process of dam models was numerically simulated based on ABAQUS commercial codes. Finally, this paper puts forward suggestions for future research based on the results of the analysis.

  19. A study on the effects of seawater on the durable life of concrete structures(I)

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Byung Hwan; Chang, Bong Seok; Chang, Seung Yeob; Cheon, Se Jin; Cheong, Sang Hwa; Yu, Yeong; Shin, Yong Seok; Shin, Myeong Su; Hyeong, Sang Su [Seoul Nationl Univ., Seoul (Korea, Republic of)

    1998-06-15

    Recently, large scale concrete structures such as Nuclear Power Plants and offshore structures are actively being built in this country. These structures are subject to heavy attack due to seawater environment. A reasonable consideration for corrosion has not been paid to the structures in the past decades due to insufficient research data and guidelines. The durability os emerging as one of the most important factors in the design and construction of concrete structures. The purpose of the present study is, therefore, to explore the corrosion mechanism and penetration mechanism of chloride ion, and to establish the evaluation procedure of durability life of concrete structures. A comprehensive experimental program has been set up and severe the types and amount of cement and mineral admixtures. The test results on the corrosion and strength characteristics of various concrete with be reported in the second-year report since the corrosion tests need long time. The results can be used in the design and construction of concrete structures in the future.

  20. Stainless steel reinforcement for durability in concrete structures

    International Nuclear Information System (INIS)

    Cochrane, D.J.

    1998-01-01

    Stainless steels and concrete are materials which the nuclear industry, more than any other, has given special attention to over the years. It is the intention of this paper to inform congress about developments outside the nuclear industry, in the use of stainless steel as reinforcement (rebar) in concrete structures. It is left to individual engineers within the industry to assess the implications of this information to applications with which they will be familiar. (author)

  1. THEORETICAL AND EXPERIMENTAL STUDY OF STRUCTURES SUBJECTED TO EARTHQUAKES

    Energy Technology Data Exchange (ETDEWEB)

    Soubirou, A.

    1967-12-31

    The object of the study was the investigation of the behaviour of structures subject to earthquakes. After .describing and analysing seismic movements, useful concepts for earthquake-proofing structures are lintroduced. Then, the dynamic behaviour of systems with n degrees of freedom was studied in order to evolve the theoretical computation of seismic behaviour, a typical application being reticulated structures. The next stage was showing the computational procedure for seismic spectra and the natural frequencies of buildings, an attempt being made to define earthquake-proofing criteria for a special type of reinforced-concrete construction. . The last matter dealt with is elastoplastic behaviour of structures, a study of increasingly growing importance.

  2. Corrosion of Carbon Steel and Corrosion-Resistant Rebars in Concrete Structures Under Chloride Ion Attack

    Science.gov (United States)

    Mohamed, Nedal; Boulfiza, Mohamed; Evitts, Richard

    2013-03-01

    Corrosion of reinforced concrete is the most challenging durability problem that threatens reinforced concrete structures, especially structures that are subject to severe environmental conditions (i.e., highway bridges, marine structures, etc.). Corrosion of reinforcing steel leads to cracking and spalling of the concrete cover and billions of dollars are spent every year on repairing such damaged structures. New types of reinforcements have been developed to avoid these high-cost repairs. Thus, it is important to study the corrosion behavior of these new types of reinforcements and compare them to the traditional carbon steel reinforcements. This study aimed at characterizing the corrosion behavior of three competing reinforcing steels; conventional carbon steel, micro-composite steel (MMFX-2) and 316LN stainless steel, through experiments in carbonated and non-carbonated concrete exposed to chloride-laden environments. Synthetic pore water solutions have been used to simulate both cases of sound and carbonated concrete under chloride ions attack. A three-electrode corrosion cell is used for determining the corrosion characteristics and rates. Multiple electrochemical techniques were applied using a Gamry PC4™ potentiostat manufactured by Gamry Instruments (Warminster, PA). DC corrosion measurements were applied on samples subjected to fixed chloride concentration in the solution.

  3. Structural and seismic analyses of waste facility reinforced concrete storage vaults

    International Nuclear Information System (INIS)

    Wang, C.Y.

    1995-01-01

    Facility 317 of Argonne National Laboratory consists of several reinforced concrete waste storage vaults designed and constructed in the late 1940's through the early 1960's. In this paper, structural analyses of these concrete vaults subjected to various natural hazards are described, emphasizing the northwest shallow vault. The natural phenomenon hazards considered include both earthquakes and tornados. Because these vaults are deeply embedded in the soil, the SASSI (System Analysis of Soil-Structure Interaction) code was utilized for the seismic calculations. The ultimate strength method was used to analyze the reinforced concrete structures. In all studies, moment and shear strengths at critical locations of the storage vaults were evaluated. Results of the structural analyses show that almost all the waste storage vaults meet the code requirements according to ACI 349--85. These vaults also satisfy the performance goal such that confinement of hazardous materials is maintained and functioning of the facility is not interrupted

  4. Peculiarities of Thermal Treatment of Monolithic Reinforced Concrete Structures

    Science.gov (United States)

    Kuchin, V. N.; Shilonosova, N. V.

    2017-11-01

    A mathematical program has been developed that allows one to determine the parameters of heat treatment of monolithic structures. One of the quality indicators of monolithic reinforced concrete structures is the level of temperature stresses arising in the process of heat treatment and further operation of structures. In winter at heat treatment the distribution of temperatures along the cross-section of the structure is uneven. A favorable thermo-stressed state in a concrete massif occurs when using the preheating method, providing the concrete temperature in the center of the structure is greater than at the periphery. In this case, after the strength is set and the temperature is later equalized along the cross-section, the central part of the structure tends to decrease its dimensions more but the extreme zones prevent it. Therefore, the center is in a state of tension, and the extreme zones on the periphery are compressed. In compressed concrete there is a lesser chance of cracks or defects. The temperature gradient over the section of the structure, the stress in the concrete and its strength are determined. When calculating the temperature and strength fields, the stress level was determined - a value equal to the ratio of the tensile stresses in the section under consideration to the tensile strength of the concrete in this section at the same time. The nature of the change in stress level is determined by the massive structure and power of the formwork heaters. It is shown that under unfavorable conditions the stress level is close to the critical value. The greatest temperature gradient occurs in the outer layers adjacent to the heating formwork. A technology for concrete conditioning is proposed which makes it possible to reduce the temperature stresses along the cross-section of the structure. The time for concrete conditioning in the formwork is reduced. In its turn, it further reduces labor costs and the cost of concrete work along with the cost of

  5. Corrosion initiation and service life of concrete structures

    International Nuclear Information System (INIS)

    Byung Hwan Oh; Bong Seok Jang

    2005-01-01

    The Corrosion of steel reinforcements in concrete is of great concern in the view of safety and durability of reinforced concrete structures. The reinforced concrete structures exposed to sea environments suffer from corrosion of steel bars due to chloride ingress. The chloride penetration into concrete is influenced by many parameters such as type of cement, mixture proportions and existence of rebars. The conventional diffusion analyses have neglected the existence of steel bar in concrete. The purpose of the present paper is, therefore, to explore the effects of reinforcement on the chloride diffusion in concrete structures by incorporating realistic diffusion models. To this end, the nonlinear binding isotherm which includes the effects of cement types and mixture proportion has been introduced in the chloride diffusion analysis. The effects of reinforcements on the chloride penetration have been analyzed through finite element analysis. The present study indicates that the chlorides are accumulated in front of a reinforcing bar and the accumulation of chlorides is much more pronounced for the case of larger-size bars. The higher accumulation of chlorides at bar location causes faster corrosion of reinforcing bars. The corrosion initiation time reduces by about 30-40 percent when the existence of rebar is considered in the chloride diffusion analysis. (authors)

  6. Mathematical Model to Predict the Permeability of Water Transport in Concrete Structure

    OpenAIRE

    Solomon Ndubuisi Eluozo

    2013-01-01

    Mathematical model to predict the permeability of water transport in concrete has been established, the model is to monitor the rate of water transport in concrete structure. The process of this water transport is based on the constituent in the mixture of concrete. Permeability established a relation on the influence of the micropores on the constituent that made of concrete, the method of concrete placement determine the rate of permeability deposition in concrete structure, permeability es...

  7. Local and Modal Damage Indicators for Reinforced Concrete Shear Frames Subject to Earthquakes

    DEFF Research Database (Denmark)

    Köylüoglu, H. U.; Nielsen, Søren R. K.; Abbott, J.

    Local, modal and overall damage indicators for reinforced concrete shear frames subject to seismic excitation are defined and studied. Each storey of the shear frame is represented by a Clough and Johnston hysteretic oscillator with degrading elastic fraction of the restoring force. The local max...

  8. Plant life management of the ACR-1000 Concrete containment structure

    International Nuclear Information System (INIS)

    Abrishami, H.H.; Ricciuti, R.; Elgohary, M.

    2009-01-01

    The Ageing of reinforced concrete structures due to service conditions, aggressive environments, or accidents may cause their strength, serviceability and durability to decrease over time. For a new plant, a Plant Life Management (PLiM) program should start in the design process and then continues through the plant operation and decommissioning. Hence, PLiM must provide not only Ageing Management program (AMP) but also provide requirements on material characteristic and design criteria as well. The purpose of this paper is to present the Plant Life Management (PLiM) strategy for the concrete containment structure of the ACR-10001 (Advanced CANDU Reactor) designed by AECL. The ACR-1000 is designed for a 100-year plant life including 60-year operating life and an additional 40-year decommissioning period. The approach adopted for the PLiM strategy of the concrete containment structure is a preventive one, key areas being: 1) design methodology, 2) material performance and 3) ageing management program. During the design phase, in addition to strength and serviceability, durability, throughout the service life and decommissioning phase of the ACR-1000 structure, is a major consideration. Factors affecting durability design include: a) concrete performance, b) structural application, and c) consideration of environmental conditions. In addition to addressing the design methodology and material performance requirements, a systematic approach for the ageing management program for the concrete containment structure is presented. (authors)

  9. Aging of concrete containment structures in nuclear power plants

    International Nuclear Information System (INIS)

    Naus, D.J.; Oland, C.B.; Ellingwood, B.; Mori, Yasuhiro; Arndt, E.G.

    1992-01-01

    Concrete structures play a vital role in the safe operation of all light-water reactor plants in the US Pertinent concrete structures are described in terms of their importance design, considerations, and materials of construction. Degradation factors which can potentially impact the ability of these structures to meet their functional and performance requirements are identified. Current inservice inspection requirements for concrete containments are summarized. A review of the performance history of the concrete components in nuclear power plants is provided. A summary is presented. A summary is presented of the Structural Aging (SAG) Program being conducted at the Oak Ridge National Laboratory for the US Nuclear Regulatory Commission. The SAG Program is addressing the aging management of safety-related concrete structures in nuclear power plants for the purpose of providing improved bases for their continued service. The program consists of a management task and three technical tasks: materials property data base, structural component assessment/repair technologies, and quantitiative methodology for continued service conditions. Objectives and a summary of accomplishments under each of these tasks are presented

  10. A method for the realization of complex concrete gridshell structures in pre-cast concrete

    DEFF Research Database (Denmark)

    Larsen, Niels Martin; Egholm Pedersen, Ole; Pigram, Dave

    2012-01-01

    concrete casting techniques, complex funicular structures can be constructed using prefabricated elements in a practical, affordable and materially efficient manner. A recent case study is examined, in which the methodology has been used to construct a pavilion. Custom written dynamic relaxation software...

  11. Study of structural reliability of existing concrete structures

    Science.gov (United States)

    Druķis, P.; Gaile, L.; Valtere, K.; Pakrastiņš, L.; Goremikins, V.

    2017-10-01

    Structural reliability of buildings has become an important issue after the collapse of a shopping center in Riga 21.11.2013, caused the death of 54 people. The reliability of a building is the practice of designing, constructing, operating, maintaining and removing buildings in ways that ensure maintained health, ward suffered injuries or death due to use of the building. Evaluation and improvement of existing buildings is becoming more and more important. For a large part of existing buildings, the design life has been reached or will be reached in the near future. The structures of these buildings need to be reassessed in order to find out whether the safety requirements are met. The safety requirements provided by the Eurocodes are a starting point for the assessment of safety. However, it would be uneconomical to require all existing buildings and structures to comply fully with these new codes and corresponding safety levels, therefore the assessment of existing buildings differs with each design situation. This case study describes the simple and practical procedure of determination of minimal reliability index β of existing concrete structures designed by different codes than Eurocodes and allows to reassess the actual reliability level of different structural elements of existing buildings under design load.

  12. Homogenised constitutive model dedicated to reinforced concrete plates subjected to seismic solicitations

    International Nuclear Information System (INIS)

    Combescure, Christelle

    2013-01-01

    Safety reassessments are periodically performed on the EDF nuclear power plants and the recent seismic reassessments leaded to the necessity of taking into account the non-linear behaviour of materials when modeling and simulating industrial structures of these power plants under seismic solicitations. A large proportion of these infrastructures is composed of reinforced concrete buildings, including reinforced concrete slabs and walls, and literature seems to be poor on plate modeling dedicated to seismic applications for this material. As for the few existing models dedicated to these specific applications, they present either a lack of dissipation energy in the material behaviour, or no micromechanical approach that justifies the parameters needed to properly describe the model. In order to provide a constitutive model which better represents the reinforced concrete plate behaviour under seismic loadings and whose parameters are easier to identify for the civil engineer, a constitutive model dedicated to reinforced concrete plates under seismic solicitations is proposed: the DHRC (Dissipative Homogenised Reinforced Concrete) model. Justified by a periodic homogenisation approach, this model includes two dissipative phenomena: damage of concrete matrix and internal sliding at the interface between steel rebar and surrounding concrete. An original coupling term between damage and sliding, resulting from the homogenisation process, induces a better representation of energy dissipation during the material degradation. The model parameters are identified from the geometric characteristics of the plate and a restricted number of material characteristics, allowing a very simple use of the model. Numerical validations of the DHRC model are presented, showing good agreement with experimental behaviour. A one dimensional simplification of the DHRC model is proposed, allowing the representation of reinforced concrete bars and simplified models of rods and wire mesh

  13. SELF-HEALING CAPACITY OF CONCRETE - COMPUTER SIMULATION STUDY OF UNHYDRATED CEMENT STRUCTURE

    Directory of Open Access Journals (Sweden)

    Huan He

    2011-05-01

    Full Text Available Aggregate occupies at least three-quarters of the volume of concrete, so its impact on concrete's properties is large. The aggregate's influence on the non-hydrated part of the matured paste is assessed by concurrent algorithm-based computer simulation system SPACE in this paper. A distinction is made between interfacial zones (ITZs and bulk paste. Containers with rigid boundaries were employed for the production of series of cement pastes. They were subjected to quantitative microstructure analysis. Relevant gradient structures in the ITZ and bulk are presented and discussed. The relevance of this structure information for possible selfhealing of cracks is briefly discussed.

  14. Modelling of stiffness and damping change in reinforced concrete structures under seismic actions

    International Nuclear Information System (INIS)

    Koenig, G.; Oetes, A.

    1985-01-01

    Restoring force and energy dissipation properties of ductile reinforced concrete structures during seismic excitation are investigated. Interpreting the results of earthquake simulation experiments with large scale reinforced concrete structural members mainly subjected to cyclic bending the various types of the force-deflection response and energy dissipation capability will be identified. Two alternative concepts are suggested for modelling: A rigorous model which considers the numerous deformation and dissipation mechanisms using a step by step algorithm for analysis and a simplified practical model which employs a modified spectrum analysis technique and a simple updating procedure for changing stiffness and damping properties of the members. (orig.)

  15. A new concept for the targeted cutting of concrete structures

    International Nuclear Information System (INIS)

    Reinhardt, Steffen; Gentes, Sascha; Weidemann, Roman; Geimer, Marcus

    2011-01-01

    The decontamination and crushing of reinforced concrete is a main part during deconstruction of nuclear facilities. The selective treatment of contaminated or activated material is of special interest, since the non-contaminated material can be transferred into the normal reprocessing cycle. In the frame of a project concerning the innovative cutting of massive reinforced concrete structures an all-purpose system for spatially restricted and defined cutting of strongly reinforced concrete including packaging suitable for final disposal was developed. Due to the remote handling of the machine the dose rate for personnel can be reduced significantly. Main part of the system is the tool that can cut highly reinforced concrete without system or component replacement. The authors describe preliminary tests of these tools, further experiments and process optimization are necessary before the tools can be integrated into the new system.

  16. Nondestructive test for estimating strength of concrete in structure

    International Nuclear Information System (INIS)

    Nozaki, Yoshitsugu; Soshiroda, Tomozo

    1997-01-01

    Evaluation of the quality of concrete in structures, especially strength estimation is said to be one of the most important problem and needed to establish test method especial tv for non-destructive method in situ. The paper describes the nondestructive test to estimate strength of concrete. From experimental study using full scale model wall, strength estimating equations are proposed by ultra-sonic pulse velocity, rebound hardness of Schmidt hammer and combined with two methods. From statistical study of the results of experiments, errors of estimated strength by the proposed equations are suggested. The validity of the equations are verified by investigation for existing reinforced concrete buildings aged 20 - 50 years. And it was found from the statistical study that the strength estimating equations need to be corrected in applying to tons aged concrete, and correction factor to those squat ions were suggested. Furthermore the corrected proposed equations were verified by applying to buildings investigated the other case.

  17. Study on polyurethane foamed concrete for use in structural applications

    Directory of Open Access Journals (Sweden)

    Iman Kattoof Harith

    2018-06-01

    Full Text Available Recently, foamed concrete is being widely used in civil construction and building, because of its high fluidity and settlement, low self-weight and low thermal conductivity. However, it has some major setbacks such as low strength and increased shrinkage at later ages. The strength gain of concrete depends upon several variables; one of these is the curing conditions. This work aims to study the potential production of foamed concrete as a sustainable structural material by varying the curing methods. For this purpose, sample cubes, cylinders and prisms were prepared to find the compressive strength, modulus of elasticity and drying shrinkage at different ages. Samples of the polyurethane foamed concrete cured under four different curing regimes (water, moisture, sealing by membrane-forming curing compound and air curing. At the end of the study, polyurethane foamed concrete used for this study has shown the potential for use in structural applications. Also, the results show that the samples cured by moisture have the highest compressive strength at all ages. Keywords: Polyurethane foamed concrete, Curing conditions, Fly ash, Compressive strength, Static modulus of elasticity drying shrinkage

  18. Ultimate load capacity assessment of reinforced concrete shell structures

    International Nuclear Information System (INIS)

    Gupta, Amita; Singh, R.K.; Kushwaha, H.S.; Mahajan, S.C.; Kakodkar, A.

    1993-01-01

    The objective of this study is to develop capability for prediction of ultimate load capacity of reinforced concrete shell structures. The present finite element code ULCA (Ultimate Load Capacity Assessment) adopts a degenerate concept of formulating general isoparametric shell element with a layered approach in the thickness direction. Different failure modes such as crushing, tensile cracking and reinforcement yielding are recognised for various problems. The structure fails by crushing of concrete when the concrete strain/stress reaches the ultimate stress or strain of concrete. Material nonlinearities as a result of tension cracking, tension stiffening between reinforcement and concrete in cracked region and yielding of reinforcement are considered along with geometric nonlinearity. Thus with this code it is possible to predict the pressure at which the first cracking, first through thickness cracking, first yielding of reinforcement occurs. After validating the code with few bench mark problems for different failure modes a reinforced concrete nuclear containment is analysed for its ultimate capacity and the results are matched with the published results. Further the ultimate load capacity of outer containment wall of Narora Atomic Power Station is predicted. It is observed that containment fails in membrane region and has a sufficient margin against design pressure. (author). 9 refs., 56 figs., 3 tabs., 1 appendix with 4 tabs

  19. Towards practical multiscale approach for analysis of reinforced concrete structures

    Science.gov (United States)

    Moyeda, Arturo; Fish, Jacob

    2017-12-01

    We present a novel multiscale approach for analysis of reinforced concrete structural elements that overcomes two major hurdles in utilization of multiscale technologies in practice: (1) coupling between material and structural scales due to consideration of large representative volume elements (RVE), and (2) computational complexity of solving complex nonlinear multiscale problems. The former is accomplished using a variant of computational continua framework that accounts for sizeable reinforced concrete RVEs by adjusting the location of quadrature points. The latter is accomplished by means of reduced order homogenization customized for structural elements. The proposed multiscale approach has been verified against direct numerical simulations and validated against experimental results.

  20. Structural Effects of Reinforced Concrete Beam Due to Corrosion

    Science.gov (United States)

    Noh, Hamidun Mohd; Idris, Nur'ain; Noor, Nurazuwa Md; Sarpin, Norliana; Zainal, Rozlin; Kasim, Narimah

    2018-03-01

    Corrosion of steel in reinforced concrete is one of the main issues among construction stakeholders. The main consequences of steel corrosion include loss of cross section of steel area, generation of expansive pressure which caused cracking of concrete, spalling and delaminating of the concrete cover. Thus, it reduces the bond strength between the steel reinforcing bar and concrete, and deteriorating the strength of the structure. The objective of this study is to investigate the structural effects of corrosion damage on the performance of reinforced concrete beam. A series of corroded reinforced concrete beam with a corrosion rate of 0%, 20% and 40% of rebar corrosion is used in parametric study to assess the influence of different level of corrosion rate to the structural performance. As a result, the used of interface element in the finite element modelling predicted the worst case of corrosion analysis since cracks is induced and generate at this surface. On the other hand, a positive linear relationship was sketched between the increase of expansive pressure and the corrosion rate. Meanwhile, the gradient of the graph is decreased with the increase of steel bar diameter. Furthermore, the analysis shows that there is a significant effect on the load bearing capacity of the structure where the higher corrosion rate generates a higher stress concentration at the mid span of the beam. This study could predict the residual strength of reinforced concrete beam under the corrosion using the finite element analysis. The experimental validation is needed on the next stage to investigate the quantitative relation between the corrosion rate and its influence on the mechanical properties.

  1. Significance of Alkali-Silica reaction in nuclear safety-related concrete structures

    International Nuclear Information System (INIS)

    Le Pape, Y.; Field, K.G.; Mattus, C.H.; Naus, D.J.; Busby, J.T.; Saouma, V.; Ma, Z.J.; Cabage, J.V.; Guimaraes, M.

    2015-01-01

    Nuclear Power Plant license renewal up to 60 years and possible life extension beyond has established a renewed focus on long-term aging of nuclear generating stations materials, and particularly, on concrete. Large irreplaceable sections of most nuclear generating stations include concrete components. The Expanded Materials Degradation Analysis, jointly performed by the Department of Energy, the U.S. Nuclear Regulatory Commission, the Academia and the Power Generation Industry, identified the need to develop a consistent knowledge base of alkali-silica reaction (ASR) within concrete as an urgent priority (Graves et al., 2014). ASR results in an expansion of Concrete produced by the reaction between alkali (generally from cement), reactive aggregate (like amorphous silica) and water absorption. ASR causes expansion, cracking and loss of mechanical properties. Considering that US commercial reactors in operation enter the age when ASR distress can be potentially observed and that numerous non-nuclear infrastructures (transportation, energy production) in a majority of the States have already experienced ASR-related concrete degradation, the susceptibility and significance of ASR for nuclear concrete structures must be addressed. This paper outlines an on-going research program including the investigation of the possibility of ASR in nuclear power plants, and the assessment of the residual shear bearing capacity of ASR-subjected nuclear structures. (authors)

  2. SEISMIC PERFORMANCE OF MOMENT-RESISTING CONCRETE FRAMES SUBJECTED TO EARTHQUAKE EXCITATION

    Directory of Open Access Journals (Sweden)

    FADZLI MOHAMED NAZRI

    2014-12-01

    Full Text Available In this study, moment-resisting concrete frames (MRCFs were designed based on Eurocodes 2 and 8, which indicate the seismic provisions and requirements for building design and construction. This study aims to investigate the damage measure of MRCFs subjected to earthquake excitation by pushover analysis (POA and incremental dynamic analysis (IDA. In POA, inverted triangular lateral load and uniform lateral load patterns were used to produce a base shear–drift curve. In IDA, seven far-field and seven near-field ground motion records were selected to establish the base shear–drift relationship. Structural response and damage measures were examined by the performance-based seismic design limit states. Vision 2000 proposed four performance states, namely, fully operational, operational, life safety (LS, and near collapse. The results showed that the designed structures have low stiffness because all MRCFs failed to meet the LS limit state. The base shear–drift relationship produced a higher demand in IDA than in POA. In POA, the lateral uniform load pattern produced higher demand than the lateral inverted triangular load pattern. In IDA, the farfield effect produced higher demand than the near-field effect. POA approximated IDA accurately at the elastic stage, but the approximation failed after the yield point.

  3. Effect of Climate Change on Service Life of High Volume Fly Ash Concrete Subjected to Carbonation—A Korean Case Study

    Directory of Open Access Journals (Sweden)

    Ki-Bong Park

    2017-01-01

    Full Text Available The increase in CO2 concentrations and global warming will increase the carbonation depth of concrete. Furthermore, temperature rise will increase the rate of corrosion of steel rebar after carbonation. On the other hand, compared with normal concrete, high volume fly ash (HVFA concrete is more vulnerable to carbonation-induced corrosion. Carbonation durability design with climate change is crucial to the rational use of HVFA concrete. This study presents a probabilistic approach that predicts the service life of HVFA concrete structures subjected to carbonation-induced corrosion resulting from increasing CO2 concentrations and temperatures. First, in the corrosion initiation stage, a hydration-carbonation integration model is used to evaluate the contents of the carbonatable material, porosity, and carbonation depth of HVFA concrete. The Monte Carlo method is adopted to determine the probability of corrosion initiation. Second, in the corrosion propagation stage, an updated model is proposed to evaluate the rate of corrosion, degree of corrosion for cover cracking of concrete, and probability of corrosion cracking. Third, the whole service life is determined considering both corrosion initiation stage and corrosion propagation stage. The analysis results show that climate change creates a significant impact on the service life of durable concrete.

  4. Simulation of reinforced concrete short shear wall subjected to cyclic loading

    International Nuclear Information System (INIS)

    Parulekar, Y.M.; Reddy, G.R.; Vaze, K.K.; Pegon, P.; Wenzel, H.

    2014-01-01

    Highlights: • Prediction of the capacity of squat shear wall using tests and analysis. • Modification of model of concrete in the softening part. • Pushover analysis using softened truss theory and FE analysis is performed. • Modified concrete model gives reasonable accurate peak load and displacement. • The ductility, ultimate load and also crack pattern can be accurately predicted. - Abstract: This paper addresses the strength and deformation capacity of stiff squat shear wall subjected to monotonic and pseudo-static cyclic loading using experiments and analysis. Reinforced concrete squat shear walls offer great potential for lateral load resistance and the failure mode of these shear walls is brittle shear mode. Shear strength of these shear walls depend strongly on softening of concrete struts in principal compression direction due to principal tension in other direction. In this work simulation of the behavior of a squat shear wall is accurately predicted by finite element modeling by incorporating the appropriate softening model in the program. Modification of model of concrete in the softening part is suggested and reduction factor given by Vecchio et al. (1994) is used in the model. The accuracy of modeling is confirmed by comparing the simulated response with experimental one. The crack pattern generated from the 3D model is compared with that obtained from experiments. The load deflection for monotonic loads is also obtained using softened truss theory and compared with experimental one

  5. Behaviour of smart reinforced concrete beam with super elastic shape memory alloy subjected to monotonic loading

    Science.gov (United States)

    Hamid, Nubailah Abd; Ibrahim, Azmi; Adnan, Azlan; Ismail, Muhammad Hussain

    2018-05-01

    This paper discusses the superelastic behavior of shape memory alloy, NiTi when used as reinforcement in concrete beams. The ability of NiTi to recover and reduce permanent deformations of concrete beams was investigated. Small-scale concrete beams, with NiTi reinforcement were experimentally investigated under monotonic loads. The behaviour of simply supported reinforced concrete (RC) beams hybrid with NiTi rebars and the control beam subject to monotonic loads were experimentally investigated. This paper is to highlight the ability of the SMA bars to recover and reduce permanent deformations of concrete flexural members. The size of the control beam is 125 mm × 270 mm × 1000 mm with 3 numbers of 12 mm diameter bars as main reinforcement for compression and 3 numbers of 12 mm bars as tension or hanger bars while 6 mm diameter at 100 mm c/c used as shear reinforcement bars for control beam respectively. While, the minimal provision of 200mm using the 12.7mm of superelastic Shape Memory Alloys were employed to replace the steel rebar at the critical region of the beam. In conclusion, the contribution of the SMA bar in combination with high-strength steel to the conventional reinforcement showed that the SMA beam has exhibited an improve performance in term of better crack recovery and deformation. Therefore the usage of hybrid NiTi with the steel can substantially diminish the risk of the earthquake and also can reduce the associated cost aftermath.

  6. Maintenance Planning for Chloride Initiated Corrosion in Concrete Structures

    DEFF Research Database (Denmark)

    Engelund, S.; Sørensen, John Dalsgaard

    1998-01-01

    Corrosion of the reinforcement in concrete structures can be initiated when the chloride concentration around the reinforcement exceeds a threshold value. In order to prevent the corrosion from reaching a stage where the load-bearing capacity of a given structure suffers a substantial decrease...

  7. Compressive behavior of pervious concretes and a quantification of the influence of random pore structure features

    International Nuclear Information System (INIS)

    Deo, Omkar; Neithalath, Narayanan

    2010-01-01

    Research highlights: → Identified the relevant pore structure features of pervious concretes, provided methodologies to extract those, and quantified the influence of these features on compressive response. → A model for stress-strain relationship of pervious concretes, and relationship between model parameters and parameters of the stress-strain relationship developed. → Statistical model for compressive strength as a function of pore structure features; and a stochastic model for the sensitivity of pore structure features in strength prediction. - Abstract: Properties of a random porous material such as pervious concrete are strongly dependent on its pore structure features, porosity being an important one among them. This study deals with developing an understanding of the material structure-compressive response relationships in pervious concretes. Several pervious concrete mixtures with different pore structure features are proportioned and subjected to static compression tests. The pore structure features such as pore area fractions, pore sizes, mean free spacing of the pores, specific surface area, and the three-dimensional pore distribution density are extracted using image analysis methods. The compressive stress-strain response of pervious concretes, a model to predict the stress-strain response, and its relationship to several of the pore structure features are outlined. Larger aggregate sizes and increase in paste volume fractions are observed to result in increased compressive strengths. The compressive response is found to be influenced by the pore sizes, their distributions and spacing. A statistical model is used to relate the compressive strength to the relevant pore structure features, which is then used as a base model in a Monte-Carlo simulation to evaluate the sensitivity of the predicted compressive strength to the model terms.

  8. Determining the in situ concrete strength of existing structures for assessing their structural safety

    NARCIS (Netherlands)

    Steenbergen, R.D.J.M.; Vervuurt, A.H.J.M.

    2012-01-01

    EN 13791 applies when assessing the in situ compressive strength of structures and precast concrete components. According to the code itself, it may be adopted when doubt arises about the compressive strength of a concrete. For assessing the structural safety of existing structures, however, the

  9. Pore Structure Characterization in Concrete Prepared with Carbonated Fly Ash

    Science.gov (United States)

    Sahoo, Sanjukta

    2018-03-01

    Carbon dioxide capture and storage (CCS) is a technique to address the global concern of continuously rising CO2 level in the atmosphere. Fly ash is considered as a suitable medium for CCS due to presence of metal oxides. The fly ash which has already sequestered carbon dioxide is referred to as carbonated fly ash. Recent research reveals better durability of concretes using carbonated fly ash as part replacement of cement. In the present research pore structure characterization of the carbonated fly ash concrete has been carried out. Mercury Intrusion porosimetry test has been conducted on control concrete and concrete specimens using fly ash and carbonated fly ash at replacement levels of 25% and 40%. The specimens have been water cured for 28 days and 90 days. It is observed that porosity reduction rate is more pronounced in carbonated fly ash concrete compared to control concrete at higher water curing age. Correlation analysis is also carried out which indicates moderately linear relationship between porosity % and pore distribution with particle size and water curing.

  10. Three dimensional finite element linear analysis of reinforced concrete structures

    International Nuclear Information System (INIS)

    Inbasakaran, M.; Pandarinathan, V.G.; Krishnamoorthy, C.S.

    1979-01-01

    A twenty noded isoparametric reinforced concrete solid element for the three dimensional linear elastic stress analysis of reinforced concrete structures is presented. The reinforcement is directly included as an integral part of the element thus facilitating discretization of the structure independent of the orientation of reinforcement. Concrete stiffness is evaluated by taking 3 x 3 x 3 Gauss integration rule and steel stiffness is evaluated numerically by considering three Gaussian points along the length of reinforcement. The numerical integration for steel stiffness necessiates the conversion of global coordiantes of the Gaussian points to nondimensional local coordinates and this is done by Newton Raphson iterative method. Subroutines for the above formulation have been developed and added to SAP and STAP routines for solving the examples. The validity of the reinforced concrete element is verified by comparison of results from finite element analysis and analytical results. It is concluded that this finite element model provides a valuable analytical tool for the three dimensional elastic stress analysis of concrete structures like beams curved in plan and nuclear containment vessels. (orig.)

  11. Applications of fiber optic sensors in concrete structural health monitoring

    Science.gov (United States)

    Dai, Jingyun; Zhang, Wentao; Sun, Baochen; Du, Yanliang

    2007-11-01

    The research of fiber optic extrinsic Fabry-Perot interferometer (EFPI) sensors and their applications in concrete structural health monitoring are presented in this paper. Different types of fiber optic EFPI sensors are designed and fabricated. Experiments are carried out to test the performance of the sensors. The results show that the sensors have good linearity and stability. The applications of the fiber optic EFPI sensors in concrete structural health monitoring are also introduced. Ten fiber optic sensors are embedded into one section of the Liaohe Bridge in Qinghuangdao-Shenyang Railway. Field test demonstrates that the results of fiber optic sensors agree well with conventional strain gauges.

  12. Structural Applications of Fibre Reinforced Concrete in the Czech Republic

    Science.gov (United States)

    Kohoutková, A.; Broukalová, I.

    2017-09-01

    The paper presents improvement of function and performance of the precast structural members by using fibre reinforced concrete (FRC) instead of ordinary reinforced concrete and attempts to transfer innovative technologies from laboratory in academic sphere into real industrial production which is cost-effective and brings about savings of labour and material. Three examples of successful technology transfer are shown - application of FRC in an element without common rebar reinforcement, in the element with steel rebar reinforcement and SFRC pre-tensioned structural element. Benefits of FRC utilization are discussed.

  13. Potential applications of steel fibre reinforced concrete to improve seismic response of frame structures

    International Nuclear Information System (INIS)

    Adhikari, S.; Patnaik, A.

    2012-01-01

    Fibre reinforced concrete has gained acceptance in several civil engineering applications. The proclivity of new generation of engineers to use steel fibre reinforced concrete can be attributed to some distinct functional and structural benefits that it can provide compared to conventional reinforced concrete. Fibre reinforced concrete has been found to increase the post-cracking tensile strength of concrete thus facilitating pseudo-plastic response, improved energy absorption, and better energy dissipation capabilities that lead to better structural response under cyclic loading. These factors suggest benefits in considering the use of steel fibre reinforced concrete to enhance the structural response of reinforced concrete structures under earthquake loading. This paper summarizes useful background on steel fibre reinforced concrete, the benefits over conventional reinforced concrete, and its response to cyclic excitation. The authors believe that steel fibre reinforced concrete is a suitable ductile high performance material that is gaining acceptance for applications in frame structures and is particularly suitable for enhancing seismic response. (author)

  14. Offshore concrete structures; Estructuras Offshore (mar adentro) de Hormigon

    Energy Technology Data Exchange (ETDEWEB)

    Lamas Pardo, M.; Carral Couce, L. M.

    2011-07-01

    In the offshore industry there are two possible materials for the construction of the hull of a structure; the steel and concrete, with the first one widely used until now, as in the rest of the shipbuilding industry of merchant ships, warships, etc. Materials such as aluminum, GRP or timber areused in small units with lengths lower than 100 m, and in less adverse conditions than in the offshore industry. Nevertheless, some ships/barges have been built of concrete in the past, but have been rather isolated cases which have not changed the practice in the industry. In the First and Second World War were built by the scarcity of materials, while the series of barges by Alfred A. Yee was a rare exception. Other units were also made in concrete, but almost anecdotal. Still, the behaviour of these concrete structures, especially in terms of maintenance, has been excellent. Therefore, the fact that the concrete has not had an adequate reception so far in shipbuilding, does not mean that in will not be the material best suited for the offshore industry in the future. The extra displacement and associated fuel costs in concrete ships have been found prohibitive in the past. But the loss of mobility of a concrete hull in relation to a steel hull can be perfectly offset by the advantages offered by the concrete, as the shipping and offshore industry have very different priorities. One of the main differences in these priorities is in terms of maintenance and resistance to fatigue, precisely where the concrete performs better. ships can easily be dry docked for maintenance and repair, while in the offshore platforms these works have to be done in situ so maintenance and fatigue are crucial to them. Besides these, the concrete has other advantages according to findings of several studies. And although they are interested in the conclusions that the makes as they came from people in the concrete industry, the fact that in recent years concrete offshore unit shave been built

  15. 77 FR 69508 - Inservice Inspection of Prestressed Concrete Containment Structures With Grouted Tendons

    Science.gov (United States)

    2012-11-19

    ... Containment Structures With Grouted Tendons AGENCY: Nuclear Regulatory Commission. ACTION: Regulatory guide... (RG) 1.90, ``Inservice Inspection of Prestressed Concrete Containment Structures with Grouted Tendons... appropriate surveillance program for prestressed concrete containment structures with grouted tendons...

  16. Experimental study of a macrocrack propagation in a concrete specimen subjected to creep loading

    Science.gov (United States)

    Rossi, P.; Boulay, C.; Tailhan, J.-L.; Martin, E.

    2013-07-01

    Structures managers need a better prediction of the delayed failure of concrete structures, especially for very important structures like nuclear power plant encasement. Sustained loadings at high level (above 75% of loading capacity of the structure), can lead to structure failure after some time. In this study, a series of 4-point bending tests were performed in order to characterize the creep behaviour of pre-cracked beams under high load level. The specimens were made of normal strength concrete. A power law relationship is observed between the secondary deflection creep rate and the failure time. It is also shown that when crack propagation occurs during the creep loading, the creep deflection rate increases with the creep loading level and with the crack propagation rate.

  17. Local response of concrete structures to explosive loading

    International Nuclear Information System (INIS)

    Freund, H.U.; Krutzik, N.J.; Muller, K.

    1989-01-01

    This paper reports on the HDR safety program experiments performed concerning demolition of concrete structures and pipes by explosive charges. The precalculability of the local structure reaction as well as that of the global plant was checked. The effect on the bore hole wall by the detonating explosive and the local concrete behavior around the bore hole were investigated. The measured pressure-time history in and around the bore hole is compared with the calculated values. The calculated values seem to be near reality (as far as measurements are available), concerning pressure rise curve within the bore hole and the peak pressure. The analysis of the blow off contours performed with two variations of the material strength of the concrete plates is presented

  18. Hybrid Bridge Structures Made of Frp Composite and Concrete

    Science.gov (United States)

    Rajchel, Mateusz; Siwowski, Tomasz

    2017-09-01

    Despite many advantages over the conventional construction materials, the contemporary development of FRP composites in bridge engineering is limited due to high initial cost, low stiffness (in case of glass fibers) and sudden composite failure mode. In order to reduce the given limitations, mixed (hybrid) solutions connecting the FRP composites and conventional construction materials, including concrete, have been tested in many countries for 20 years. Shaping the hybrid structures based on the attributes of particular materials, aims to increase stiffness and reduce cost without losing the carrying capacity, lightness and easiness of bridges that includes such hybrid girders, and to avoid the sudden dangerous failure mode. In the following article, the authors described examples of hybrid road bridges made of FRP composite and concrete within the time of 20 years and presented the first Polish hybrid FRP-concrete road bridge. Also, the directions of further research, necessary to spread these innovative, advanced and sustainable bridge structures were indicated.

  19. Analysis of FRP bars used as reinforcement in concrete structures

    Directory of Open Access Journals (Sweden)

    Kinga Brózda

    2016-09-01

    Full Text Available In the design and construction of building and engineering structures, it is of utmost importance to provide their reliability and safety. The use of FRP (Fiber Reinforced Polymers bars as reinforcement of structural concrete elements could help reducing the typical defects of reinforced concrete and increase its strength parameters. In the paper the selected FRP bar characteristic properties are presented and advantages derived therefrom are specified. Furthermore, the most commonly used in construction types of FRP bars, depending on the raw material used during the production process are listed. In addition, the possibility of recycling of elements reinforced with FRP bars is presented and compared with traditional reinforced concrete (reinforced with steel bars. The production method of FRP bars (pultrusion is shown. Moreover, the advantages and disadvantages of using this method are discussed.

  20. Strength and deformational characteristics of three-way reinforced concrete containment models subjected to lateral forces

    International Nuclear Information System (INIS)

    Aoyagi, Y.; Yamada, K.; Takahashi, T.

    1981-01-01

    With a view to investigating the earthquake resistance characteristics of reinforced concrete containments two cylindrical models with three-way system of bars were made and loaded laterally up to failure combined with or without internal pressures, simulating the conditions in which containments were subjected to earthquake forces at a simultaneous LOCA or at normal operation. The main conclusions obtained withing the limit of the experiments are as follows. (1) Stresses in reinforcements in three-way reinforced concrete plate elements can reasonably be estimated by the equations proposed by Baumann. It is, however, necessary to take into consideration the contributions of concrete between cracks to the deformation in order to accurately estimate the average strains in the plate elements, applying such a formula as CEB as reformed by the authors. (2) The strength capacity of three-way reinforced concrete containments against lateral forces combined with internal pressure is somewhat inferior to that of orthogonally reinforced one if compared on the condition that the volumetric reinforcement ratios are the same for the two cases of reinforcement arrangements. However, three-way reinforcement improves initial shear rigidity as well as ultimate horizontal deformability for lateral forces. (3) The ability for three-way reinforced concrete containment to absorb strain energy in the range of large deformations is superior to that of orthogonally reinforced one. The equivalent viscous damping coefficient for the former is markedly larger than that for the latter, especially at the increased deformational stages. These experimental evidences suggent that three-way system of reinforcement may constitute one of the prospective measures to improve the earthquake resistance of reinforced concrete containments. (orig./HP)

  1. Design optimization of embedded ultrasonic transducers for concrete structures assessment.

    Science.gov (United States)

    Dumoulin, Cédric; Deraemaeker, Arnaud

    2017-08-01

    In the last decades, the field of structural health monitoring and damage detection has been intensively explored. Active vibration techniques allow to excite structures at high frequency vibrations which are sensitive to small damage. Piezoelectric PZT transducers are perfect candidates for such testing due to their small size, low cost and large bandwidth. Current ultrasonic systems are based on external piezoelectric transducers which need to be placed on two faces of the concrete specimen. The limited accessibility of in-service structures makes such an arrangement often impractical. An alternative is to embed permanently low-cost transducers inside the structure. Such types of transducers have been applied successfully for the in-situ estimation of the P-wave velocity in fresh concrete, and for crack monitoring. Up to now, the design of such transducers was essentially based on trial and error, or in a few cases, on the limitation of the acoustic impedance mismatch between the PZT and concrete. In the present study, we explore the working principles of embedded piezoelectric transducers which are found to be significantly different from external transducers. One of the major challenges concerning embedded transducers is to produce very low cost transducers. We show that a practical way to achieve this imperative is to consider the radial mode of actuation of bulk PZT elements. This is done by developing a simple finite element model of a piezoelectric transducer embedded in an infinite medium. The model is coupled with a multi-objective genetic algorithm which is used to design specific ultrasonic embedded transducers both for hard and fresh concrete monitoring. The results show the efficiency of the approach and a few designs are proposed which are optimal for hard concrete, fresh concrete, or both, in a given frequency band of interest. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Seismic Performance Evaluation of Reinforced Concrete Frames Subjected to Seismic Loads

    Science.gov (United States)

    Zameeruddin, Mohd.; Sangle, Keshav K.

    2017-06-01

    Ten storied-3 bays reinforced concrete bare frame designed for gravity loads following the guidelines of IS 456 and IS 13920 for ductility is subjected to seismic loads. The seismic demands on this building were calculated by following IS 1893 for response spectra of 5% damping (for hard soil type). Plastic hinges were assigned to the beam and column at both ends to represent the failure mode, when member yields. Non-linear static (pushover) analysis was performed to evaluate the performance of the building in reference to first (ATC 40), second (FEMA 356) and next-generation (FEMA 440) performance based seismic design procedures. Base shear against top displacement curve of structure, known as pushover curve was obtained for two actions of plastic hinge behavior, force-controlled (brittle) and deformation-controlled (ductile) actions. Lateral deformation corresponding to performance point proves the building capability to sustain a certain level of seismic loads. The failure is represented by a sequence of formation of plastic hinges. Deformation-controlled action of hinges showed that building behaves like strong-column-weak-beam mechanism, whereas force-controlled action showed formation of hinges in the column. The study aims to understand the first, second and next generation performance based design procedure in prediction of actual building responses and their conservatism into the acceptance criteria.

  3. Cathodic protection of reinforced concrete structures in the Netherlands - Experience and developments: Cathodic protection of concrete - 10 years experience

    NARCIS (Netherlands)

    Polder, R.B.

    1998-01-01

    Cathodic protection (CP) of reinforcing steel in concrete structures has been used successfully for over 20 years. CP is able to stop corrosion in a reliable and economical way where chloride contamination has caused reinforcement corrosion and subsequent concrete damage. To new structures where

  4. Superelastic SMA–FRP composite reinforcement for concrete structures

    International Nuclear Information System (INIS)

    Wierschem, Nicholas; Andrawes, Bassem

    2010-01-01

    For many years there has been interest in using fiber-reinforced polymers (FRPs) as reinforcement in concrete structures. Unfortunately, due to their linear elastic behavior, FRP reinforcing bars are never considered for structural damping or dynamic applications. With the aim of improving the ductility and damping capability of concrete structures reinforced with FRP reinforcement, this paper studies the application of SMA–FRP, a relatively novel type of composite reinforced with superelastic shape memory alloy (SMA) wires. The cyclic tensile behavior of SMA–FRP composites are studied experimentally and analytically. Tests of SMA–FRP composite coupons are conducted to determine their constitutive behavior. The experimental results are used to develop and calibrate a uniaxial SMA–FRP analytical model. Parametric and case studies are performed to determine the efficacy of the SMA–FRP reinforcement in concrete structures and the key factors governing its behavior. The results show significant potential for SMA–FRP reinforcement to improve the ductility and damping of concrete structures while still maintaining its elastic characteristic, typical of FRP reinforcement

  5. Analysis of underground concrete pipelines subjected to seismic high-frequency loads

    OpenAIRE

    Abbasiverki, Roghayeh

    2016-01-01

    Buried pipelines are tubular structures that are used for transportation of important liquid materials and gas in order to provide safety for human life. During an earthquake, imposed loads from soil deformations on concrete pipelines may cause severe damages, possibly causing disturbance in vital systems, such as cooling of nuclear power facilities. The high level of safety has caused a demand for reliable seismic analyses, also for structures built in the regions that have not traditionally...

  6. Modeling reinforced concrete durability : [summary].

    Science.gov (United States)

    2014-06-01

    Many Florida bridges are built of steel-reinforced concrete. Floridas humid and marine : environments subject steel in these structures : to corrosion once water and salt penetrate the : concrete and contact the steel. Corroded steel : takes up mo...

  7. Bond Behavior of Wet-Bonded Carbon Fiber-Reinforced Polymer-Concrete Interface Subjected to Moisture

    OpenAIRE

    Yiyan Lu; Tao Zhu; Shan Li; Zhenzhen Liu

    2018-01-01

    The use of carbon fiber-reinforced polymer (CFRP) composite materials to strengthen concrete structures has become popular in coastal regions with high humidity levels. However, many concrete structures in these places remain wet as a result of tides and wave-splashing, so they cannot be completely dried before repair. Therefore, it is vital to investigate the effects of moisture on the initial and long-term bond behavior between CFRP and wet concrete. This research assesses the effects of mo...

  8. Applicability Problem in Optimum Reinforced Concrete Structures Design

    Directory of Open Access Journals (Sweden)

    Ashara Assedeq

    2016-01-01

    Full Text Available Optimum reinforced concrete structures design is very complex problem, not only considering exactness of calculus but also because of questionable applicability of existing methods in practice. This paper presents the main theoretical mathematical and physical features of the problem formulation as well as the review and analysis of existing methods and solutions considering their exactness and applicability.

  9. Condition Indicators for Inspection Planning of Concrete Structures

    DEFF Research Database (Denmark)

    Faber, Michael Havbro; Sørensen, John Dalsgaard

    2002-01-01

    Based on previous work by the authors a Bayesian formulation of condition indicators is developed further whereby in conjunction with a systems modelling of concrete structures the experience and expertise of the inspection personnel may be fully utilized. It is shown how the predicted evolution ...

  10. Design, Analysis And Realization Of Topology Optimized Concrete Structures

    DEFF Research Database (Denmark)

    Søndergaard, Asbjørn; Dombernowsky, Per

    2012-01-01

    This paper proposes the application of topology optimisation as a constitutive design tool for design and form-finding of architectural concrete structures, and realisation of these designs using large scale CNCmilling of polystyrene form-work for in situ casting....

  11. Seismic fragility of reinforced concrete structures in nuclear facilities

    International Nuclear Information System (INIS)

    Gergely, P.

    1985-01-01

    The failure and fragility analyses of reinforced concrete structures and elements in nuclear reactor facilities within the Seismic Safety Margins Research Program (SSMRP) at the Lawrence Livermore National Laboratory are evaluated. Uncertainties in material modeling, behavior of low shear walls, and seismic risk assessment for nonlinear response receive special attention. Problems with ductility-based spectral deamplification and prediction of the stiffness of reinforced concrete walls at low stress levels are examined. It is recommended to use relatively low damping values in connection with ductility-based response reductions. The study of static nonlinear force-deflection curves is advocated for better nonlinear dynamic response predictions

  12. Research requirements for improved design of reinforced concrete containment structures

    International Nuclear Information System (INIS)

    Banerjee, A.K.; Holley, M.J. Jr.

    1978-01-01

    Reinforced concrete is a competitive material for the construction of nuclear power plant containment structures. However, the designer is constrained by limited data on the behavior of certain construction details which require him to use what may be excessive rebar quantities and lead to difficult and costly construction. This paper discusses several design situations where research is recommended to increase the designer's options, to facilitate construction, and to extend the applicability of reinforced concrete to such changing containment requirements as may be imposed by an evolving nuclear technology. (Auth.)

  13. Scope and selection of structures subject to aging management review

    International Nuclear Information System (INIS)

    Mendoza, G.; Diaz, A.; Viais, J.; Carmona, M.; Santander, L.

    2014-10-01

    The purpose of this work is to determine the structures included within the scope of license renewal based on the performance of the functions and select those intended for aging management review; one purpose is to show the methodology used to establish the structure and structural components that are subject to a review of aging management, within the framework of license renewal rule. This is through the application of different types of structures and structural components related and unrelated to safety located in the rooms of the reactor building where there are components of the reactor core isolation cooling system (Rcic), these structures are poured concrete, concrete block, structural steel, shielding walls, attached metal, pile foundations, etc.; other non- security related , such as: 1) inherent characteristics not related to security that protect the equipment related to the safety of the missiles, that is, walls, low walls, dikes, doors, etc., which also provide flood barriers to structures, systems and components related to safety, 2 ) whipping restrictions on non- security, shields mitigation jet, vent panels , etc. that are designed and installed to protect equipment related with the safety of the effects of a broken line of high energy. Only rooms where there are components of the Rcic 68 structures within the scope were identified. (Author)

  14. Studies on various characteristics of concrete structures using crushed sand

    International Nuclear Information System (INIS)

    Mimatsu, Makoto; Sugita, Hideaki; Yonemura, Masataka.

    1985-01-01

    With the recent advances of construction industry, the demands for concrete, hence for aggregate, are rising. The sand as such is in extreme shortage due to the exhaustion of river sand. Under the situation, the recent trends are for the use of crushed sand, i.e. the artificial sand obtained by crushing rocks, which have advantages of stabilized quality and adequate supplies. In building of nuclear power plants requiring large amounts of concrete, the usage of crushed sand is now unavoidable. The following are described : the situation of aggregate in Kyushu. production method of crushed sand and the quality standards, rocks used for crushed stone and sand and the properties, quality survey on crushed sand and the basic tests, characteristic tests of crushed-stone and -sand mixed concrete, the application of crushed sand in structures of the Sendai Nuclear Power Station. (Mori, K.)

  15. 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

  16. A PVDF-Based Sensor for Internal Stress Monitoring of a Concrete-Filled Steel Tubular (CFST) Column Subject to Impact Loads.

    Science.gov (United States)

    Du, Guofeng; Li, Zhao; Song, Gangbing

    2018-05-23

    Impact loads can have major adverse effects on the safety of civil engineering structures, such as concrete-filled steel tubular (CFST) columns. The study of mechanical behavior and stress analysis of CFST columns under impact loads is very important to ensure their safety against such loads. At present, the internal stress monitoring of the concrete cores CFST columns under impact loads is still a very challenging subject. In this paper, a PVDF (Polyvinylidene Fluoride) piezoelectric smart sensor was developed and successfully applied to the monitoring of the internal stress of the concrete core of a CFST column under impact loads. The smart sensor consists of a PVDF piezoelectric film sandwiched between two thin steel plates through epoxy. The protection not only prevents the PVDF film from impact damages but also ensures insulation and waterproofing. The smart sensors were embedded into the circular concrete-filled steel tube specimen during concrete pouring. The specimen was tested against impact loads, and testing data were collected. The time history of the stress obtained from the PVDF smart sensor revealed the evolution of core concrete internal stress under impact loads when compared with the impact force⁻time curve of the hammer. Nonlinear finite element simulations of the impact process were also carried out. The results of FEM simulations had good agreement with the test results. The results showed that the proposed PVDF piezoelectric smart sensors can effectively monitor the internal stress of concrete-filled steel tubular columns under impact loads.

  17. Aging of concrete structures in nuclear power plants

    International Nuclear Information System (INIS)

    Naus, D.J.; Pland, C.B.; Arndt, E.G.

    1991-01-01

    The Structural Aging (SAG) Program, sponsored by the US Nuclear Regulatory Commission (USNRC) and conducted by the Oak Ridge National Laboratory (ORNL), had the overall objective of providing the USNRC with an improved basis for evaluating nuclear power plant structures for continued service. The program consists of three technical tasks: materials property data base, structural component assessment/repair technology, and quantitative methodology for continued service determinations. Major accomplishments under the SAG Program during the first two years of its planned five-year duration have included: development of a Structural Materials Information Center and formulation of a Structural Aging Assessment Methodology for Concrete Structures in Nuclear Power Plants. 9 refs

  18. Experimental and Empirical Time to Corrosion of Reinforced Concrete Structures under Different Curing Conditions

    Directory of Open Access Journals (Sweden)

    Ahmed A. Abouhussien

    2014-01-01

    Full Text Available Reinforced concrete structures, especially those in marine environments, are commonly subjected to high concentrations of chlorides, which eventually leads to corrosion of the embedded reinforcing steel. The total time to corrosion of such structures may be divided into three stages: corrosion initiation, cracking, and damage periods. This paper evaluates, both empirically and experimentally, the expected time to corrosion of reinforced concrete structures. The tested reinforced concrete samples were subjected to ten alternative curing techniques, including hot, cold, and normal temperatures, prior to testing. The corrosion initiation, cracking, and damage periods in this investigation were experimentally monitored by an accelerated corrosion test performed on reinforced concrete samples. Alternatively, the corrosion initiation time for counterpart samples was empirically predicted using Fick’s second law of diffusion for comparison. The results showed that the corrosion initiation periods obtained experimentally were comparable to those obtained empirically. The corrosion initiation was found to occur at the first jump of the current measurement in the accelerated corrosion test which matched the half-cell potential reading of around −350 mV.

  19. Embedded Distributed Optical Fiber Sensors in Reinforced Concrete Structures-A Case Study.

    Science.gov (United States)

    Barrias, António; Casas, Joan R; Villalba, Sergi

    2018-03-26

    When using distributed optical fiber sensors (DOFS) on reinforced concrete structures, a compromise must be achieved between the protection requirements and robustness of the sensor deployment and the accuracy of the measurements both in the uncracked and cracked stages and under loading, unloading and reloading processes. With this in mind the authors have carried out an experiment where polyimide-coated DOFS were installed on two concrete beams, both embedded in the rebar elements and also bonded to the concrete surface. The specimens were subjected to a three-point load test where after cracking, they are unloaded and reloaded again to assess the capability of the sensor when applied to a real loading scenarios in concrete structures. Rayleigh Optical Frequency Domain Reflectometry (OFDR) was used as the most suitable technique for crack detection in reinforced concrete elements. To verify the reliability and accuracy of the DOFS measurements, additional strain gauges were also installed at three locations along the rebar. The results show the feasibility of using a thin coated polyimide DOFS directly bonded on the reinforcing bar without the need of indention or mechanization. A proposal for a Spectral Shift Quality (SSQ) threshold is also obtained and proposed for future works when using polyimide-coated DOFS bonded to rebars with cyanoacrylate adhesive.

  20. Rational and Safe Design of Concrete Transportation Structures for Size Effect and Multi-Decade Sustainability

    Science.gov (United States)

    2012-10-01

    The overall goal of this project was to improve the safety and sustainability in the design of large : prestressed concrete bridges and other transportation structures. The safety of large concrete : structures, including bridges, has been insufficie...

  1. Analysis of seismic effects on reinforced concrete structures

    International Nuclear Information System (INIS)

    Tai, A.A.

    1981-12-01

    An important bibliographical research was undertaken in order to make the best possible analysis of the dynamic behaviour of materials and of structural components. This research work was completed by the study of the structures tested on a seismic table. The results obtained from this preliminary study, particularly those concerning the modification in the rigidity of reinforced concrete structures under alternate and seismic loading, enabled a calculation method (called ''equivalent static'') to be drawn up for analyzing the behaviour of reinforced concrete structures in earthquakes. This method takes into account the non-linearity of the behaviour of materials, in particular. The earthquake responses that were obtained by this method on gantries tested on a vibrating table, tally very satisfactorily with the test figures [fr

  2. Application of global elements to a reinforced concrete structure

    International Nuclear Information System (INIS)

    Morand, O.

    1994-01-01

    The dimensioning of nuclear facilities requires to take into account the possible risk of earthquakes. However such installations are generally complex structures with reinforced concrete poles, walls, beams and porches. In this study, a seismic analysis of such a structure is proposed. The use of the Castem 2000 global element code was attempted to dynamically simulate the behaviour of the reinforced concrete elements. However, no suitable modeling has been found for the storeys, the functioning of which being dominated by carrying walls. Concerning the porch-type storeys, monotonous static loads were simulated and provided information on the local and global behaviour of these structures. Thus, representative global elements could be realized for these structures. Results obtained are satisfactory for these storeys which essentially undergo a bending deformation. (J.S.)

  3. Lattice Modeling of Early-Age Behavior of Structural Concrete

    OpenAIRE

    Pan, Yaming; Prado, Armando; Porras, Roc?o; Hafez, Omar M.; Bolander, John E.

    2017-01-01

    The susceptibility of structural concrete to early-age cracking depends on material composition, methods of processing, structural boundary conditions, and a variety of environmental factors. Computational modeling offers a means for identifying primary factors and strategies for reducing cracking potential. Herein, lattice models are shown to be adept at simulating the thermal-hygral-mechanical phenomena that influence early-age cracking. In particular, this paper presents a lattice-based ap...

  4. Design and Construction of Concrete Structures in View of Early-Age Thermal Effects

    DEFF Research Database (Denmark)

    Andersen, Mette Elbæk

    1997-01-01

    The report is the result of a Ph.D. study conducted at DTU. The subject is early-age concrete with focus on the influence of heat development on the cracking risc of concrete.......The report is the result of a Ph.D. study conducted at DTU. The subject is early-age concrete with focus on the influence of heat development on the cracking risc of concrete....

  5. Residual characteristic properties of ternary blended steel fibre reinforced concrete subjected to sustained elevated temperature

    Directory of Open Access Journals (Sweden)

    Sinha Deepa A.

    2013-09-01

    Full Text Available To study the behavior of ternary blended steel fibre reinforced concrete when subjected to 800 Deg.C and 1000 Deg.C for 3 hours. It has been found that the ternary blended steel fibre reinforced concrete containing (FA+GGBFS and (FA+MK offer higher resistance to sustained elevated temperatures upto 800 Deg.C, where as the blend containing (FA+SF does not offer any resistance at this temperature. The study reveals that the blend containing (FA+GGBFS and (FA+MK gives highest resistance at replacement levels of (10+20 and (15+15 respectively at sustained exposure to 800 Deg.C.

  6. Tests and calculations of reinforced concrete beams subject to dynamic reversed loads

    International Nuclear Information System (INIS)

    Livolant, M.; Hoffmann, A.; Gauvain, J.

    1978-01-01

    This study presents the tests of a reinforced concrete beam conducted by the Department of Mechanical and Thermal Studies at the Centre d'Etudes Nucleaires, Saclay, France. The actual behavior of nuclear power plant buildings submitted to seismic loads is generally non linear even for moderate seismic levels. The non linearity is specially important for reinforced concrete beams type buildings. To estimate the safety factors when the building is designed by standard methods, accurate non linear calculations are necessary. For such calculations one of the most difficult point is to define a correct model for the behavior of a reinforced beam subject to reversed loads. For that purpose, static and dynamic experimental tests on a shaking table have been carried out and a model reasonably accurate has been established and checked on the tests results

  7. 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.)

  8. Simulation of reinforced concrete NPP structures

    International Nuclear Information System (INIS)

    Zverev, A.B.; Yaskevich, E.E.; Tarannikov, V.N.; Loginov, A.Ya.; Lagutov, V.I.

    1989-01-01

    Analysis of stress-strained state of NPP frame structures at different stages of their operation using the method of physical simulation, is conducted. Comparison of model investigations to the data of full-scale deformation measurement allows one to define the strength resource of the structures under operation. Bench test layout and results of investigations into strength, deformation, thermal-physical and acoustic emission parameters of the investigated processes during model loading, are presented

  9. Concrete structures under impact loading: general aspects

    Directory of Open Access Journals (Sweden)

    Cornelia Baeră

    2016-09-01

    Full Text Available Dynamic loading conditions distress the structural integrity of a structure differently than the static ones. Such actions transfer high rate strains and instant energy waves to the structure, inducing the possibility of imminent collapse and casualties as a direct consequence. In the latest years, considering the dramatic increase of terrorist threats and global warming, the structural safety criteria imply more than ever the need to withstand this kind of loading (e.g., missiles and blast, projectiles, strong winds, tornados and earthquakes in addition to the static ones. The aim of this paper is to provide a general overview with regard to impact loading in terms of defining the phenomenon from physical and mechanical perspective, its complex local or global effect on the targeted structure, relevant material characteristics, main research approaches, namely theoretical studies and experimental procedures developed for improving the predictability of the dynamic loads and their effects. New directions in developing superior cementitious composites, with better characteristics in terms of dynamic loading performance are also emphasized.

  10. Experimental assessment of air permeability in a concrete shear wall subjected to simulated seismic loading

    International Nuclear Information System (INIS)

    Girrens, S.P.; Farrar, C.R.

    1991-07-01

    A safety concern for the proposed Special Nuclear Materials Laboratory (SNML) facility at the Los Alamos National Laboratory was air leakage from the facility if it were to experience a design basis earthquake event. To address this concern, a study was initiated to estimate air leakage, driven by wind-generated pressure gradients, from a seismically damaged concrete structure. This report describes a prototype experiment developed and performed to measure the air permeability in a reinforced concrete shear wall, both before and after simulated seismic loading. A shear wall test structure was fabricated with standard 4000-psi concrete mix. Static load-cycle testing was used to simulate earthquake loading. Permeability measurements were made by pressurizing one side of the shear wall above atmospheric conditions and recording the transient pressure decay. As long as the structure exhibited linear load displacement response, no variation in the air permeability was detected. However, experimental results indicate that the air permeability in the shear wall increased by a factor of 40 after the wall had been damaged (cracked). 17 figs., 8 tabs

  11. Design of concrete structures important to safety of nuclear facilities

    International Nuclear Information System (INIS)

    2001-10-01

    Civil engineering structures in nuclear installations form an important feature having implications to safety performance of these installations. The objective and minimum requirements for the design of civil engineering buildings/structures to be fulfilled to provide adequate assurance for safety of nuclear installations in India (such as pressurised heavy water reactor and related systems) are specified in the Safety standard for civil engineering structures important to safety of nuclear facilities. This standard is written by AERB to specify guidelines for implementation of the above civil engineering safety standard in the design of concrete structures important to safety

  12. Analysis of aircraft impact to concrete structures

    International Nuclear Information System (INIS)

    Arros, Jorma; Doumbalski, Nikolay

    2007-01-01

    Analysis of aircraft impact to nuclear power plant structures is discussed utilizing a simplified model of a 'fictitious nuclear building' to perform analyses using LS-DYNA software, representing the loading: (i) by the Riera force history method and (ii) by modeling the crash by impacting a model of a plane similar to Boeing 747-400 to the structure (i.e., 'missile-target interaction method'). Points discussed include: (1) comparison of shock loading within the building as obtained from the Riera force history analysis versus from the missile-target interaction analysis, (2) sensitivity of the results on the assumed Riera force loading area, (3) linear versus nonlinear modeling and (4) on failure criteria

  13. Limit analysis of solid reinforced concrete structures

    DEFF Research Database (Denmark)

    Larsen, Kasper Paaske

    2009-01-01

    Recent studies have shown that Semidefinite Programming (SDP) can be used effectively for limit analysis of isotropic cohesive-frictional continuums using the classical Mohr-Coulomb yield criterion. In this paper we expand on this previous research by adding reinforcement to the model and a solid...... reinforcement and it is therefore possible to analyze structures with complex reinforcement layouts. Tests are conducted to validate the method against well-known analytical solutions....

  14. Full surface inspection methods regarding reinforcement corrosion of concrete structures

    International Nuclear Information System (INIS)

    Reichling, K.; Raupach, M.; Broomfield, J.; Gulikers, J.; L'Hostis, Valerie

    2013-01-01

    For reinforced concrete structures a localisation of all significant critical areas can only be done by a full surface inspection. The economic advantages are obvious: uncritical areas have not to be repaired expensively.The first step of the assessment should always be a visual inspection. The range of deterioration causes can be limited and the degree of deterioration may be estimated roughly. The inspection program can be adjusted to the requirements. By means of a full surface potential mapping areas with a high risk for chloride induced reinforcement corrosion can be localised, although no deteriorations are visually detectable at the concrete surface. In combination with concrete cover depth and resistivity measurements areas with corrosion promoting exposure conditions can be localised even if the reinforcement is not yet de-passivated. The following publication gives an overview about the essential full surface investigation methods to localise critical areas regarding corrosion of steel in concrete. The selection of methods is based on the inspection procedure given in reference 2. (authors)

  15. Limit load analysis of thick-walled concrete structures

    International Nuclear Information System (INIS)

    Argyris, J.H.; Faust, G.; Willam, K.J.

    1975-01-01

    The paper illustrates the interaction of constitutive modeling and finite element solution techniques for limit load prediction of concrete structures. On the constitutive side, an engineering model of concrete fracture is developed in which the Mohr-Coulomb criterion is augmented by tension cut-off to describe incipient failure. Upon intersection with the stress path the failure surface collapses for brittle behaviour according to one of three softening rules, no-tension, no-cohesion, and no-friction. The stress transfer accompanying the energy dissipation during local failure is modelled by several fracture rules which are examined with regard to ultimate load prediction. On the numerical side the effect of finite element idealization is studied first as far as ultimate load convergence is concerned. Subsequently, incremental tangential and initial load techniques are compared together with the effect of step size. Limit load analyses of a thick-walled concrete ring and a lined concrete reactor closure conclude the paper with examples from practical engineering. (orig.) [de

  16. Application of the self-diagnosis composite into concrete structure

    Science.gov (United States)

    Matsubara, Hideaki; Shin, Soon-Gi; Okuhara, Yoshiki; Nomura, Hiroshi; Yanagida, Hiroaki

    2001-04-01

    The function and performance of the self-diagnosis composites embedded in mortar/concrete blocks and concrete piles were investigated by bending tests and electrical resistance measurements. Carbon powder (CP) and carbon fiber (CF) were introduced in glass fiber reinforced plastics composites to obtain electrical conductivity. The CP composite has commonly good performances in various bending tests of block and pile specimens, comparing to the CF composite. The electrical resistance of the CP composite increases in a small strain to response remarkably micro-crack formation at about 200 (mu) strain and to detect well to smaller deformations before the crack formation. The CP composite possesses a continuous resistance change up to a large strain level near the final fracture of concrete structures reinforced by steel bars. The cyclic bending tests showed that the micro crack closed at unloading state was able to be evaluated from the measurement of residual resistance. It has been concluded that the self- diagnosis composite is fairly useful for the measurement of damage and fracture in concrete blocks and piles.

  17. Reliability algorithms applied to reinforced concrete structures durability assessment

    Directory of Open Access Journals (Sweden)

    C. G. Nogueira

    Full Text Available This paper addresses the analysis of probabilistic corrosion time initiation in reinforced concrete structures exposed to ions chloride penetration. Structural durability is an important criterion which must be evaluated in every type of structure, especially when these structures are constructed in aggressive atmospheres. Considering reinforced concrete members, chloride diffusion process is widely used to evaluate the durability. Therefore, at modelling this phenomenon, corrosion of reinforcements can be better estimated and prevented. These processes begin when a threshold level of chlorides concentration is reached at the steel bars of reinforcements. Despite the robustness of several models proposed in the literature, deterministic approaches fail to predict accurately the corrosion time initiation due to the inherently randomness observed in this process. In this regard, the durability can be more realistically represented using probabilistic approaches. A probabilistic analysis of ions chloride penetration is presented in this paper. The ions chloride penetration is simulated using the Fick's second law of diffusion. This law represents the chloride diffusion process, considering time dependent effects. The probability of failure is calculated using Monte Carlo simulation and the First Order Reliability Method (FORM with a direct coupling approach. Some examples are considered in order to study these phenomena and a simplified method is proposed to determine optimal values for concrete cover.

  18. In situ nonlinear ultrasonic technique for monitoring microcracking in concrete subjected to creep and cyclic loading.

    Science.gov (United States)

    Kim, Gun; Loreto, Giovanni; Kim, Jin-Yeon; Kurtis, Kimberly E; Wall, James J; Jacobs, Laurence J

    2018-08-01

    This research conducts in situ nonlinear ultrasonic (NLU) measurements for real time monitoring of load-induced damage in concrete. For the in situ measurements on a cylindrical specimen under sustained load, a previously developed second harmonic generation (SHG) technique with non-contact detection is adapted to a cylindrical specimen geometry. This new setup is validated by demonstrating that the measured nonlinear Rayleigh wave signals are equivalent to those in a flat half space, and thus the acoustic nonlinearity parameter, β can be defined and interpreted in the same way. Both the acoustic nonlinearity parameter and strain are measured to quantitatively assess the early-age damage in a set of concrete specimens subjected to either 25 days of creep, or 11 cycles of cyclic loading at room temperature. The experimental results show that the acoustic nonlinearity parameter is sensitive to early-stage microcrack formation under both loading conditions - the measured β can be directly linked to the accumulated microscale damage. This paper demonstrates the potential of NLU for the in situ monitoring of mechanical load-induced microscale damage in concrete components. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Thermal analysis of GFRP-reinforced continuous concrete decks subjected to top fire

    Science.gov (United States)

    Hawileh, Rami A.; Rasheed, Hayder A.

    2017-12-01

    This paper presents a numerical study that investigates the behavior of continuous concrete decks doubly reinforced with top and bottom glass fiber reinforced polymer (GFRP) bars subjected to top surface fire. A finite element (FE) model is developed and a detailed transient thermal analysis is performed on a continuous concrete bridge deck under the effect of various fire curves. A parametric study is performed to examine the top cover thickness and the critical fire exposure curve needed to fully degrade the top GFRP bars while achieving certain fire ratings for the deck considered. Accordingly, design tables are prepared for each fire curve to guide the engineer to properly size the top concrete cover and maintain the temperature in the GFRP bars below critical design values in order to control the full top GFRP degradation. It is notable to indicate that degradation of top GFRP bars do not pose a collapse hazard but rather a serviceability concern since cracks in the negative moment region widen resulting in simply supported spans.

  20. DEVELOPMENT OF NON-DESTRUCTIVE MONITORING SYSTEM FOR CHLORIDE PENETRATION INTO REINFORCED CONCRETE STRUCTURES

    Directory of Open Access Journals (Sweden)

    Antoni Antoni

    2006-01-01

    Full Text Available Reinforced concrete structures in marine environment are subjected to chloride penetration, which significantly degrades the structural performance due to the occurrence of corrosion in the steel reinforcement. The performance degradation of the structures would reduce the intended service life and caused higher maintenance and repair cost. Therefore, system to monitor chloride penetration into reinforced concrete before the starting corrosion of reinforcement is indispensable. An embedded probe system to detect chloride penetration into concrete was developed in Japan. This probe consists of a cementitious material body and some number of wires as sensors, which are set in the shallow ditches around the probe body. The system detect the chloride penetration by monitoring the initiation time of wire corrosion, it also has the advantages of continuous monitoring and early warning on the onset of corrosion in the reinforcement. However, the probe had not yet had high sensitivity for detecting critical chloride content in concrete. Therefore to increase its sensitivity, four types of improvements, namely partial coating of the wires, waterproofing on the probe body, filling the ditches with porous material and supplying small current on the wires were evaluated in this study. From the experimental result, it was observed that supplying small current and partial coating of the wires could improve the sensitivity of the probe significantly, while waterproofing treatment on the probe body and filling the ditches did not have significant contribution.

  1. Reinforced concrete containment structures in high seismic zones

    International Nuclear Information System (INIS)

    Aziz, T.S.

    1977-01-01

    A new structural concept for reinforced concrete containment structures at sites where earthquake ground motions in terms of the Safe Shutdown Earthquake (SSE) exceeds 0.3 g is presented. The structural concept is based on: (1) an inner steel-lined concrete shell which houses the reactor and provides shielding and containment in the event of loss of coolant accident; (2) an outer annular concrete shell structure which houses auxilary reactor equipment and safeguards systems. These shell structures are supported on a common foundation mat which is embeded in the subgrade. Under stipulated earthquake conditions the two shell structures interact to resist lateral inertia forces. Thus the annular structure which is not a pressure boundary acts as a lateral support for the inner containment shell. The concept is practical, economically feasible and new to practice. An integrated configuration which includes the interior shell, the annular structure and the subgrade is analyzed for several static and dynamic loading conditions. The analysis is done using a finite difference solution scheme for the static loading conditions. A semi-analytical three-dimensional finite element scheme combined with a Fast Fourier Transform (FFT) algorithm is used for the dynamic loading conditions. The effects of cracking of the containment structure due to pressurization in conjunction with earthquake loading are discussed. Analytical results for both the finite difference and the finite element schemes are presented and the sensitivity of the results to changes in the input parameters is studied. General recommendations are given for plant configurations where high seismic loading is a major design consideration

  2. Strength Prediction and Failure Modes of Concrete Specimens Subjected to the Split Test

    DEFF Research Database (Denmark)

    Hoang, Linh Cao; Andersen, M.E.; Hansen, N.T.

    2014-01-01

    This paper deals with modelling and test of concrete specimens subjected to the Brazilian split test. Based on the fictitious crack concept, a simple model for the crack propagation process in the splitting plane is developed. From the model, it is possible to determine the distribution of residual...... tensile strength as crack propagation take place. The residual tensile strength is thereafter used in a rigid plastic analysis of the splitting failure. Based on this combined approach, the ultimate load may either be governed by crack propagation or by a plastic failure, which then terminates the crack...

  3. Data on optimum recycle aggregate content in production of new structural concrete.

    Science.gov (United States)

    Paul, Suvash Chandra

    2017-12-01

    This data presented herein are the research summary of "mechanical behavior and durability performance of concrete containing recycled concrete aggregate" (Paul, 2011) [1]. The results reported in this article relate to an important parameter of optimum content of recycle concrete aggregate (RCA) in production of new concrete for both structural and non-structural applications. For the purpose of the research various types of physical, mechanical and durability tests are performed for concrete made with different percentages of RCA. Therefore, this data set can be a great help of the readers to understand the mechanism of RCA in relates to the concrete properties.

  4. Numerical modelling of crack initiation and propagation in concrete structure under hydro-mechanical loading

    International Nuclear Information System (INIS)

    Bian, H.B.; Jia, Y.; Shao, J.F.

    2012-01-01

    Document available in extended abstract form only. This subject is devoted to numerical analysis of crack initiation and propagation in concrete structures due to hydro-mechanical coupling processes. When the structures subjected to the variation in hydraulic conditions, fractures occur as a consequence of coalescence of diffuse damage. Consequently, the mechanical behaviour of concrete is described by an isotropic damage model. Once the damage reaches a critical value, a macroscopic crack is initiated. In the framework of extended Finite Element Method (XFEM), the propagation of localized crack is studied in this paper. Each crack is then considered as a discontinuity surface of displacement. According to the determination of crack propagation orientations, a tensile stress-based criterion is used. Furthermore, spatial variations of mechanical properties of concrete are also taken into account using the Weibull distribution function. Finally, the proposed model is applied to numerical analysis of a concrete liner in the context of feasibility studies for geological storage of radioactive wastes. The numerical results show that the proposed approach is capable to reproduce correctly the initiation and propagation crack process until the complete failure of concrete structures during hydro-mechanical loading. The concrete is most widely used construction material in many engineering applications. It is generally submitted to various environmental loading: such as the mechanical loading, the variation of relative humidity and the exposure to chemical risk, etc. In order to evaluate the safety and durability of concrete structures, it is necessary to get a good knowledge on the influence of loading path on the concrete behaviour. The objective of this paper is to study numerically the crack propagation in concrete structure under hydro-mechanical loading,.i.e. the mechanical behaviour of concrete subjected to drying process. The drying process leads to desiccation

  5. Prediction of Chloride Diffusion in Concrete Structure Using Meshless Methods

    Directory of Open Access Journals (Sweden)

    Ling Yao

    2016-01-01

    Full Text Available Degradation of RC structures due to chloride penetration followed by reinforcement corrosion is a serious problem in civil engineering. The numerical simulation methods at present mainly involve finite element methods (FEM, which are based on mesh generation. In this study, element-free Galerkin (EFG and meshless weighted least squares (MWLS methods are used to solve the problem of simulation of chloride diffusion in concrete. The range of a scaling parameter is presented using numerical examples based on meshless methods. One- and two-dimensional numerical examples validated the effectiveness and accuracy of the two meshless methods by comparing results obtained by MWLS with results computed by EFG and FEM and results calculated by an analytical method. A good agreement is obtained among MWLS and EFG numerical simulations and the experimental data obtained from an existing marine concrete structure. These results indicate that MWLS and EFG are reliable meshless methods that can be used for the prediction of chloride ingress in concrete structures.

  6. Strengthening of Concrete Structures with cement based bonded composites

    DEFF Research Database (Denmark)

    Täljsten, Björn; Blanksvärd, Thomas

    2008-01-01

    Polymers). The method is very efficient and has achieved world wide attention. However, there are some drawbacks with the use of epoxy, e.g. working environment, compatibility and permeability. Substituting the epoxy adherent with a cement based bonding agent will render a strengthening system...... with improved working environment and better compatibility to the base concrete structure. This study gives an overview of different cement based systems, all with very promising results for structural upgrading. Studied parameters are structural retrofit for bending, shear and confinement. It is concluded...

  7. Seismic reliability assessment methodology for CANDU concrete containment structures

    International Nuclear Information System (INIS)

    Stephens, M.J.; Nessim, M.A.; Hong, H.P.

    1995-05-01

    A study was undertaken to develop a reliability-based methodology for the assessment of existing CANDU concrete containment structures with respect to seismic loading. The focus of the study was on defining appropriate specified values and partial safety factors for earthquake loading and resistance parameters. Key issues addressed in the work were the identification of an approach to select design earthquake spectra that satisfy consistent safety levels, and the use of structure-specific data in the evaluation of structural resistance. (author). 23 refs., 9 tabs., 15 figs

  8. Seismic damage assessment of reinforced concrete containment structures

    International Nuclear Information System (INIS)

    Cho, HoHyun; Koh, Hyun-Moo; Hyun, Chang-Hun; Kim, Moon-Soo; Shin, Hyun Mock

    2003-01-01

    This paper presents a procedure for assessing seismic damage of concrete containment structures using the nonlinear time-history numerical analysis. For this purpose, two kinds of damage index are introduced at finite element and structural levels. Nonlinear finite element analysis for the containment structure applies PSC shell elements using a layered approach leading to damage indices at finite element and structural levels, which are then used to assess the seismic damage of the containment structure. As an example of such seismic damage assessment, seismic damages of the containment structure of Wolsong I nuclear power plant in Korea are evaluated against 30 artificial earthquakes generated with a wide range of PGA according to US NRC regulatory guide 1.60. Structural responses and corresponding damage index according to the level of PGA and nonlinearity are investigated. It is also shown that the containment structure behaves elastically for earthquakes corresponding to or lower than DBE. (author)

  9. A Demonstration of Concrete Structural Health Monitoring Framework for Degradation due to Alkali-Silica Reaction

    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); Neal, Kyle [Idaho National Lab. (INL), Idaho Falls, ID (United States); Nath, Paromita [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bao, Yanqing [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cai, Guowei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Peter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Adams, Douglas [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kosson, David [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-04-01

    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. 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. This ongoing research project is seeking to develop a probabilistic framework for health diagnosis and prognosis of aging concrete structures in a nuclear power plant that is subjected to physical, chemical, environment, and mechanical degradation. The proposed framework consists of four elements: monitoring, data analytics, uncertainty quantification and prognosis. This report focuses on degradation caused by ASR (alkali-silica reaction). Controlled specimens were prepared to develop accelerated ASR degradation. Different monitoring techniques – thermography, digital image correlation (DIC), mechanical deformation measurements, nonlinear impact resonance acoustic spectroscopy (NIRAS), and vibro-acoustic modulation (VAM) -- were used to detect the damage caused by ASR. Heterogeneous data from the multiple techniques was used for damage diagnosis and prognosis, and quantification of the associated uncertainty using a Bayesian network approach. Additionally, MapReduce technique has been demonstrated with synthetic data. This technique can be used in future to handle large amounts of observation data obtained from the online monitoring of realistic structures.

  10. Study of the performance of four repairing material systems for hydraulic structures of concrete dams

    Directory of Open Access Journals (Sweden)

    Kormann A. C. M.

    2003-01-01

    Full Text Available Four types of repairing materials are studied as function of either a conventional concrete or a reference-concrete (RefC, these are: polymer-modified cement mortar (PMor, steel fiber concrete (SFco, epoxy mortar (EMor and silica fume mortar (SFmo, to be applied in hydraulic structures surfaces subjected to a high velocity water flow. Besides the mechanical requests and wearing resistance of hydraulic concrete dam structures, especially the spillway surfaces, the high solar radiation, the environmental temperature and wet and dry cycles, contribute significantly to the reduction of their lifespan. RefC and the SFco were developed based on a usual concrete mixture used in slabs of spillways. The average RefC mixture used was 1: 1.61: 2.99: 0.376, with Pozzolan-modified Portland cement consumption of 425 kg/m³. EMor and PMor mixtures followed the information given by the manufacturers and lab experience. Tests on concrete samples were carried out in laboratory simulating normally found environmental situations in order to control the mechanical resistance and the aging imposed conditions, such as solar radiation and humidity. Also, physicochemical characterizing tests were made for all used materials. From the analyzed results, two of them presented a higher performance: the EMor and SFmo. SFco presented good adherence to the RefC and good mechanical performance. However, it also presented apparent metal corrosion in humidity tests, being indicated for use, with caution, as an intermediate layer in underwater repairs. In a general classification, considering all tests, including their field applications, the better performance material systems were EMor- SFmo> SFco> PMor.

  11. Structural health and dynamic behavior of residential buildings: field challenges in the rehab of damaged reinforced concrete

    Directory of Open Access Journals (Sweden)

    Chalhoub M. S.

    2014-01-01

    Full Text Available Reinforced concrete buildings require special consideration under dynamic excitations due to their anisotropic material properties. Strain compatibility equations are used in concrete analysis and design with assumptions about the stress and strain field across member section and member length. However, these assumptions fall short of describing real life behavior when concrete elements deteriorate, age or undergo cyclic loading. This paper addresses the structural health of reinforced concrete buildings and proposes an analytical model to account for concrete damage through loss of bond. The proposed model relates steel loading that causes bond distress to design parameters such as development length and bar properties, and therefore could be complemented by field measurement. The paper proposes a diagnosis method and discusses the sustainability of the structure by assisting in a simplistic decision rule as to whether to perform minor fixes, major rehabilitation, or disposal. Emphasis is placed on the difference between reversible and irreversible effects of cyclic loading on structural behaviour, and draws a distinction between damage to the girder and damage to the column in the overall structural system. The model is compared to empirical results to address field challenges faced when the structure is subjected to severe conditions in its ambient environment, or to unusual loading. Deterioration in concrete causes alteration in its composite behavior with the reinforcing steel. This affects the fundamental period of the structure, and its response to seismic loading.

  12. Performance and working life of cathodic protection systems for concrete structures

    NARCIS (Netherlands)

    Polder, R.B.; Worm, D.; Courage, W.; Leegwater, G.

    2012-01-01

    Corrosion of reinforcing steel in concrete structures causes concrete cracking and steel diameter reduction, eventually resulting in loss of safety. Conventional repair means heavy, labour intensive and costly work and the required quality level is under economic pressure. Consequently, conventional

  13. Activities at ORNL in support of continuing the service of nuclear power plant concrete structures

    International Nuclear Information System (INIS)

    Naus, D.J.

    2012-01-01

    In general, nuclear power plant concrete structure's performance has been very good; however, aging of concrete structures occurs with the passage of time that can potentially result in degradation if its effects are not controlled. Safety-related nuclear power plant concrete structures are described. In-service inspection and testing requirements in the U.S. are summarized. The interaction of the license renewal process and concrete structures is noted. A summary of operating experience related to aging of nuclear power plant concrete structures is provided. Several candidate areas are identified where additional research would be beneficial for aging management of nuclear power plant concrete structures. Finally, an update on recent activities at Oak Ridge National Laboratory related to aging management of nuclear power plant concrete structures is provided. (author)

  14. Flexural behavior of concrete beam with mechanical splices of reinforcement subjected to cyclic loading

    International Nuclear Information System (INIS)

    Nab, H. S.; Kim, W. B.

    2008-01-01

    In nuclear power plant structures, the mechanical rebar splices are designated and constructed on the basis of ACI and ASME code. Regardless of good performance on mechanical rebar splices, these splicing methods that did not be registered on ASME code have not restricted to apply to construction site. In this study, the main candidate splice is cold roll formed parallel threaded splice. This was registered newly in ASME Section III division 2 CC 4333 'Mechanical Splices' in 2004. To compare the traditional rebar splice with mechanical rebar splices, concrete beams were made to evaluate the ductility of spliced reinforcing bars. Based on Experimental results, it was identified that the mechanical rebar splices by parallel threaded coupler had better accumulated dissipation energy capacity to resist seismic behavior than the traditional lapping splices. It showed that concrete specimens with D36 reinforcing bar coupler are 1.8 times better performance and that concrete specimens with D22 reinforcing bar coupler are 2.8 times better performance. (authors)

  15. Durability of fibre reinforced concrete structures exposed to combined mechanical and environmental load

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard

    1999-01-01

    The main conclusions from a research project on durability of cracked fibre reinforced concrete structures exposed to chlorides, water or freeze-thaw are presented. The effect of fibres and cracks on the durability of concrete is studied.......The main conclusions from a research project on durability of cracked fibre reinforced concrete structures exposed to chlorides, water or freeze-thaw are presented. The effect of fibres and cracks on the durability of concrete is studied....

  16. Current state of knowledge on the behavior of steel liners in concrete containments subjected to overpressurization loads

    International Nuclear Information System (INIS)

    von Riesemann, W.A.; Parks, M.B.

    1993-01-01

    In the United States, concrete containment buildings for commercial nuclear power plants have steel liners that act as the intemal pressure boundary. The liner abuts the concrete, acting as the interior concrete form. The liner is attached to the concrete by either studs or by a continuous structural shape (such as a T-section or channel) that is either continuously or intermittently welded to the liner. Studs are commonly used in reinforced concrete containments, while prestressed containments utilize a structural element as the anchorage. The practice in some countries follows the US practice, while in other countries the containment does not have a steel liner. In this latter case, there is a true double containment, and the annular region between the two containments is vented. This paper will review the practice of design of the liner system prior to the consideration of severe accident loads (overpressurization loads beyond the design conditions)

  17. Considerations on the repassivation of corroded reinforced concrete structures

    International Nuclear Information System (INIS)

    Cobo, A.; Gonzalez, M. N.; Otero, E.; Gonzalez, J. A.

    2000-01-01

    An analysis is made of the responses of clean and precorroded steel electrodes in Ca(OH) 2 saturated solutions and in cement mortar, using gravimetric, metallographic and electrochemical techniques, essentially polarisation resistance measurements. The paper aims to answer some important questions about the corrosion of reinforced concrete structures (RCS) which, though seemingly elementary, continue to arouse controversy in scientific, technical and economical circles, such as the following: What corrosion rates are dangerous in RCS? What concrete resistivities guarantee sufficient durability of RCS?. Is it possible to detain corrosion once it has begun?. Can corroded RCS be repassivated? Are electrochemical RCS rehabilitation methods efficient, and if so, when? The results obtained indicate that electrochemical chloride removal and realkalisation cannot repassive heavily corroded steel surfaces, however they can be effective methods to prevent corrosion provided they are used before the transition from the passive state to the active one occurs. If applied to late, are useless for this purpose. (Author) 25 refs

  18. Effects of temperature, mechanical loading and of their interactions on the permeability of structural concrete

    International Nuclear Information System (INIS)

    Choinska, M.

    2006-11-01

    Concrete permeability may influence the durability of structures indirectly by controlling the penetration rate of aggressive agents, but also directly if the structure has a confinement role, like containment vessels of nuclear power plants for instance. In the industrial background on the safety of these structures, the objective of this study is to characterize the evolution of concrete permeability under the effects of temperature and mechanical loading. The permeability tests are performed on hollow concrete cylinders, subjected to temperature up to 150 C and compressive loading up to failure. Experimental results reveal that the effects of temperature and damage may be decoupled for the estimation of permeability and enable us to propose a relation between permeability, damage and temperature. However, this relation may only be applied in the pre-peak phase as concrete remains micro-cracked. In order to overcome this limit to be able to model also permeability increase in the post-peak phase, another parameter, which is crack opening, is introduced in the relation between permeability and damage. This problem, investigated by modelling, is exploited according to two approaches. The first one is based on the definition of a matching law between existing relations of permeability evolution with damage and with crack opening. With this approach the tendencies are similar to the observed ones on the experimental results. The second approach consists in linking from a mechanical point of view damage with crack opening in order to apply the Poiseuille's law for permeability determination. Experimental validation of this approach, emerging towards a continuous model capable to reproduce permeability variations of a concrete structure, constitutes a major perspective of this work. (author)

  19. Ultimate internal pressure capacity of concrete containment structures

    International Nuclear Information System (INIS)

    Krishnaswamy, C.N.; Namperumal, R.; Al-Dabbagh, A.

    1983-01-01

    Lesson learned from the accident at Three-Mile Island nuclear plant has necessitated the computation of the ultimate internal pressure capacity of containment structures as a licensing requirement in the U.S. In general, a containment structure is designed to be essentially elastic under design accident pressure. However, as the containment pressure builds up beyond the design value due to a more severe postulated accident, the containment response turns nonlinear as it sequentially passes through cracking of concrete, yielding of linear plate, yielding of rebar, and yielding of post-tensioning tendon (if the containment concrete is prestressed). This paper reports on the determination of the ultimate internal pressure capacity and nonlinear behavior of typical reinforced and prestressed concrete BWR containments. The probable modes of failure, the criteria for ultimate pressure capacity, and the most critical sections are described. Simple equations to hand-calculate the ultimate pressure capacity and the nonlinear behavior at membrane sections of the containment shell are presented. A nonlinear finite element analysis performed to determine the nonlinear behavior of the entire shell including nonmembrane sections is briefly discribed. The analysis model consisted of laminated axisymmetric shell finite elements with nonlinear stress-strain properties for each material. Results presented for typical BWR concrete containments include nonlinear response plots of internal pressure versus containment deflection and strains in the liner, rebar, and post-tensioning tendons at the most stressed section in the shell. Leak-tightness of the containment liner and the effect of thermal loads on the ultimate capacity are discussed. (orig.)

  20. Design of reinforced concrete containment structures for thermal gradients effects

    International Nuclear Information System (INIS)

    Bhat, P.D.; Vecchio, F.

    1983-01-01

    The need for more accurate prediction of structural behaviour, particularly under extreme load conditions, has made the consideration of thermal gradient effects and increasingly important part of the design of reinforced concrete structures for nuclear applications. While the thermal effects phenomenon itself has been qualitatively well understood, the analytical complications involved in theoretical analysis have made it necessary to resort to major simplifications for practical design applications. A number of methods utilizing different variations in approach have been developed and are in use today, including one by Ontario Hydro which uses an empirical relationship for determining an effective moment of inertia for cracked members. (orig./WL)

  1. Vibration tests of a 4-story concrete structure

    International Nuclear Information System (INIS)

    Chen, C.K.; Czarnecki, R.M.; Scholl, R.E.

    1976-01-01

    A series of forced vibration tests on a full-scale 4-story reinforced concrete test structure was performed to investigate its dynamic response before, after, and during the time it underwent structural damage. Nondestructive tests were conducted first, exciting four translational modes at force levels within the elastic limit, during which the structure suffered no structural damage. Next, a destructive test excited only the lowest translational mode at high-amplitude destructive levels, during which the structure exhibited inelastic response and suffered major structural damage. Post-destructive tests used force levels similar to the nondestructive tests. The work was in support of the program to develop methods for predicting building response to and damage from underground nuclear explosions

  2. Novel approach to make concrete structures self-healing using porous network concrete

    NARCIS (Netherlands)

    Sangadji, S.; Schlangen, E.

    2012-01-01

    Many researchers proposed self healing mechanism using hollow fibres and or microcapsule containing a modifying agent dispersed in the concrete to prolong its service life and make it more durable. A novel self healing concrete concept is proposed in this paper by using porous network concrete

  3. Experimental Studies on Behaviour of Reinforced Geopolymer Concrete Beams Subjected to Monotonic Static Loading

    Science.gov (United States)

    Madheswaran, C. K.; Ambily, P. S.; Dattatreya, J. K.; Ramesh, G.

    2015-06-01

    This work describes the experimental investigation on behaviour of reinforced GPC beams subjected to monotonic static loading. The overall dimensions of the GPC beams are 250 mm × 300 mm × 2200 mm. The effective span of beam is 1600 mm. The beams have been designed to be critical in shear as per IS:456 provisions. The specimens were produced from a mix incorporating fly ash and ground granulated blast furnace slag, which was designed for a compressive strength of 40 MPa at 28 days. The reinforced concrete specimens are subjected to curing at ambient temperature under wet burlap. The parameters being investigated include shear span to depth ratio (a/d = 1.5 and 2.0). Experiments are conducted on 12 GPC beams and four OPCC control beams. All the beams are tested using 2000 kN servo-controlled hydraulic actuator. This paper presents the results of experimental studies.

  4. Mechanical properties of two-way different configurations of prestressed concrete members subjected to axial loading

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chaobi; Chen, Jian Yun; Xu, Qiang; Li, Jing [School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian (China)

    2015-08-15

    In order to analyze the mechanical properties of two-way different configurations of prestressed concrete members subjected to axial loading, a finite element model based on the nuclear power plant containments is demonstrated. This model takes into account the influences of different principal stress directions, the uniaxial or biaxial loading, and biaxial loading ratio. The displacement-controlled load is applied to obtain the stress-strain response. The simulated results indicate that the differences of principal stress axes have great effects on the stress-strain response under uniaxial loading. When the specimens are subjected to biaxial loading, the change trend of stress with the increase of loading ratio is obviously different along different layout directions. In addition, correlation experiments and finite element analyses were conducted to verify the validity and reliability of the analysis in this study.

  5. Numerical Derivation of Iso-Damaged Curve for a Reinforced Concrete Beam Subjected to Blast Loading

    Directory of Open Access Journals (Sweden)

    Temsah Yehya

    2018-01-01

    Full Text Available Many engineering facilities are severely damaged by blast loading. Therefore, many manufacturers of sensitive, breakable, and deformed structures (such as facades of glass buildings carry out studies and set standards for these installations to withstand shock waves caused by explosions. Structural engineers also use these standards in their designs for various structural elements by following the ISO Damage Carve, which links pressure and Impulse. As all the points below this curve means that the structure is safe and will not exceed the degree of damage based on the various assumptions made. This research aims to derive the Iso-Damage curve of a reinforced concrete beam exposed to blast wave. An advanced volumetric finite element program (ABAQUS will be used to perform the derivation.

  6. Use of pulsating water jet technology for removal of concrete in repair of concrete structures

    Czech Academy of Sciences Publication Activity Database

    Sitek, Libor; Foldyna, Josef; Martinec, Petr; Ščučka, Jiří; Bodnárová, L.; Hela, R.

    2011-01-01

    Roč. 6, č. 4 (2011), s. 235-242 ISSN 1822-427X R&D Projects: GA ČR GA103/07/1662; GA ČR GP101/07/P512; GA AV ČR 1QS300860501; GA MŠk ED2.1.00/03.0082 Grant - others:GA MPO(CZ) FR-TI2/390 Program:FR Institutional research plan: CEZ:AV0Z30860518 Keywords : high-speed water jet technology * pulsating jet * rotating jets * removal of concrete layer Subject RIV: JQ - Machines ; Tools Impact factor: 1.610, year: 2011 http://www.bjrbe.vgtu.lt/volumes/en/volume6/number4/03.php

  7. Contribution to the numerical study of concrete behaviour and of reinforced concrete structures submitted to coupled thermal and mechanical solicitations: a damageable thermo-elasto-plastic approach

    International Nuclear Information System (INIS)

    Nechnech, W.

    2000-12-01

    The aim of this research is the development of an Finite Element model for the analysis of reinforced concrete structures under thermal, mechanical loadings or any combination of them. An available synthesis of results on the concrete behavior under thermal solicitation is exposed. The different behavior of concrete that can be founded notably in thermo-mechanical analysis (Damage, unilateral phenomenon, thermo-mechanical interaction,...) are underlined. The various families of modeling are analyzed thereafter while underlining the important aspects of the behavior that each one can re-transcribe. A new thermo-plastic damage model for plain concrete subjected to combined thermal and cyclic loading is developed using the concept of plastic-work-hardening and stiffness degradation in continuum damage mechanics. Two damage variables are used: the first one for mechanical action and the second one for thermal action. Further, thermo-mechanical interaction strains have been introduced to describe the influence of mechanical loading on the physical process of thermal expansion of concrete. The constitutive relations for elastoplastic responses are decoupled from the degradation damage responses by using the effective stress concept. This method provides advantages in the numerical implementation. A simple and thermodynamically consistent scalar degradation model is introduced to simulate the effect of damage on elastic stiffness and its recovery during crack opening and closing. Efficient computational algorithms for the proposed model are subsequently explored and performance of this model is demonstrated with numerical examples. (author)

  8. Prediction model for carbonation depth of concrete subjected to freezing-thawing cycles

    Science.gov (United States)

    Xiao, Qian Hui; Li, Qiang; Guan, Xiao; Xian Zou, Ying

    2018-03-01

    Through the indoor simulation test of the concrete durability under the coupling effect of freezing-thawing and carbonation, the variation regularity of concrete neutralization depth under freezing-thawing and carbonation was obtained. Based on concrete carbonation mechanism, the relationship between the air diffusion coefficient and porosity in concrete was analyzed and the calculation method of porosity in Portland cement concrete and fly ash cement concrete was investigated, considering the influence of the freezing-thawing damage on the concrete diffusion coefficient. Finally, a prediction model of carbonation depth of concrete under freezing-thawing circumstance was established. The results obtained using this prediction model agreed well with the experimental test results, and provided a theoretical reference and basis for the concrete durability analysis under multi-factor environments.

  9. Numerical simulation of deformation and fracture of space protective shell structures from concrete and fiber concrete under pulse loading

    International Nuclear Information System (INIS)

    Radchenko, P A; Batuev, S P; Radchenko, A V; Plevkov, V S

    2015-01-01

    This paper presents results of numerical simulation of interaction between aircraft Boeing 747-400 and protective shell of nuclear power plant. The shell is presented as complex multilayered cellular structure comprising layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was held three-dimensionally using the author's algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. The dynamics of stress-strain state and fracture of structure were studied. Destruction is described using two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of shell cellular structure—cells start to destruct in unloading wave, originating after output of compression wave to the free surfaces of cells. (paper)

  10. Reliability-based inspection of prestressed concrete containment structures

    International Nuclear Information System (INIS)

    Pandey, M.D.

    1996-03-01

    A study was undertaken to develop a reliability-based approach to the planning of inspection programs for prestressed concrete containment structures. The main function of the prestressing system is to ensure the leak integrity of the containment by maintaining a compressive state of stress under the tensile forces which arise in a hypothesized loss of coolant accident. Prestressing force losses (due to creep and shrinkage, stress relaxation or tendon corrosion) can lead to tensile stresses under accident pressure, resulting in loss of containment leak integrity due to concrete cracking and tensile yielding of the non-prestressed reinforcement. Therefore, the evaluation of prestressing inspection programs was based on their effectiveness in maintaining an acceptable reliability level with respect to a limit state representing yeilding of non-prestressed reinforcement. An annual target reliability of 10 -4 was used for this limit state. As specified in CSA-N287.7, the evaluation of prestressing systems for containment structures is based on the results of lift-off tests to determine the prestressing force. For unbonded systems the tests are carried out on a randomly selected sample from each tendon group in the structure. For bonded systems, the test is carried out on an unbonded test beam that matches the section geometry and material properties of the containment structure. It was found that flexural testing is useful in updating the probability of concrete cracking under accident pressure. For unbonded systems, the analysis indicated that the sample size recommended by the CSA Standard (4% of the tendon population) is adequate. The CSA recommendation for a five year inspection interval is conservative unless severe degradation of the prestressing system, characterized by a high prestressing loss rate (>3%) and a large coefficient of variation of the measured prestressing force (>15%), is observed

  11. 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

  12. Analytical predictions for the performance of a reinforced concrete containment model subject to overpressurization

    International Nuclear Information System (INIS)

    Weatherby, J.R.; Clauss, D.B.

    1987-01-01

    Under the sponsorship of the US Nuclear Regulatory Commission, Sandia National Laboratories is investigating methods for predicting the structural performance of nuclear reactor containment buildings under hypothesized severe accident conditions. As part of this program, a 1/6th-scale reinforced concrete containment model will be pressurized to failure in early 1987. Data generated by the test will be compared to analytical predictions of the structural response in order to assess the accuracy and reliability of the analytical techniques. As part of the pretest analysis effort, Sandia has conducted a number of analyses of the containment structure using the ABAQUS general purpose finite element code. This paper describes results from a nonlinear axisymmetric shell analysis as well as the material models and failure criteria used in conjunction with the analysis

  13. Fully probabilistic design: the way for optimizing of concrete structures

    Directory of Open Access Journals (Sweden)

    I. Laníková

    Full Text Available Some standards for the design of concrete structures (e.g. EC2 and the original ČSN 73 1201-86 allow a structure to be designed by several methods. This contribution documents the fact that even if a structure does not comply with the partial reliability factor method, according to EC2, it can satisfy the conditions during the application of the fully probabilistic approach when using the same standard. From an example of the reliability of a prestressed spun concrete pole designed by the partial factor method and fully probabilistic approach according to the Eurocode it is evident that an expert should apply a more precise (though unfortunately more complicated method in the limiting cases. The Monte Carlo method, modified by the Latin Hypercube Sampling (LHS method, has been used for the calculation of reliability. Ultimate and serviceability limit states were checked for the partial factor method and fully probabilistic design. As a result of fully probabilistic design it is possible to obtain a more efficient design for a structure.

  14. Damage detection monitoring applications in self-healing concrete structures using embedded piezoelectric transducers and recovery

    International Nuclear Information System (INIS)

    Karaiskos, G; Tsangouri, E; Aggelis, D G; Van Hemelrijck, D; Deraemaeker, A

    2015-01-01

    The ageing, operational and ambient loadings have a great impact in the operational and maintenance cost of concrete structures. Their service life prolongation is of utmost importance and this can be efficiently achieved by using reliable and low-cost monitoring and self-healing techniques. In the present study, the ultrasonic pulse velocity (UPV) method using embedded small-size and low-cost piezoelectric PZT (lead zirconate titanate) ceramic transducers in concrete with self-healing properties is implemented for monitoring not only the setting and hardening phases of concrete since casting time, but also for the detection of damage initiation, propagation and recovery of integrity after healing. A couple of small-scale notched unreinforced concrete beams are subjected to mode-I fracture through three-point bending tests. After a 24-hour healing agent curing period, the beams are reloaded using the same loading scenario. The results demonstrate the excellent performance of the proposed monitoring technique during the hydration, damage generation and recovery periods. (paper)

  15. Sensitivity of PZT Impedance Sensors for Damage Detection of Concrete Structures.

    Science.gov (United States)

    Yang, Yaowen; Hu, Yuhang; Lu, Yong

    2008-01-21

    Piezoelectric ceramic Lead Zirconate Titanate (PZT) based electro-mechanicalimpedance (EMI) technique for structural health monitoring (SHM) has been successfullyapplied to various engineering systems. However, fundamental research work on thesensitivity of the PZT impedance sensors for damage detection is still in need. In thetraditional EMI method, the PZT electro-mechanical (EM) admittance (inverse of theimpedance) is used as damage indicator, which is difficult to specify the effect of damage onstructural properties. This paper uses the structural mechanical impedance (SMI) extractedfrom the PZT EM admittance signature as the damage indicator. A comparison study on thesensitivity of the EM admittance and the structural mechanical impedance to the damages ina concrete structure is conducted. Results show that the SMI is more sensitive to the damagethan the EM admittance thus a better indicator for damage detection. Furthermore, this paperproposes a dynamic system consisting of a number of single-degree-of-freedom elementswith mass, spring and damper components to model the SMI. A genetic algorithm isemployed to search for the optimal value of the unknown parameters in the dynamic system.An experiment is carried out on a two-storey concrete frame subjected to base vibrations thatsimulate earthquake. A number of PZT sensors are regularly arrayed and bonded to the framestructure to acquire PZT EM admittance signatures. The relationship between the damageindex and the distance of the PZT sensor from the damage is studied. Consequently, thesensitivity of the PZT sensors is discussed and their sensing region in concrete is derived.

  16. Prestressed concrete nuclear reactor containment structures. Revision 3

    International Nuclear Information System (INIS)

    Reuter, H.R.; Chang-Lo, P.L.C.; Pfeifer, B.W.; Shah, G.H.; Whitcraft, J.S.

    1975-02-01

    A discussion of the techniques and procedures used for the design of prestressed concrete nuclear reactor containment structures is presented. A physical description of Bechtel designed containment structures is presented. The design bases and load combinations are given for anticipated conditions of service. Reference design documents which include industry codes, specifications, AEC Regulatory Guides, Bechtel Topical Reports and additional criteria as appropriate to containment design are listed. Stepwise procedures typically followed by Bechtel for design of containments is discussed and design examples are presented. A description of currently used analytical methods and the practical application of these methods for containment design is also presented. The principal containment construction materials are identified and codes of practice pertaining to construction procedures are listed. Preoperational structural testing procedures and post-operational surveillance programs are furnished along with results of tests on completed containment structures. (U.S.)

  17. Modelling reinforced concrete structures in DYNA3D

    International Nuclear Information System (INIS)

    Broadhouse, B.J.; Neilson, A.J.

    1987-10-01

    A material model for reinforced concrete has been implemented in the transient structural dynamics code DYNA3D. This paper outlines the constitutive material model, and presents comparisons of DYNA3D calculations and experiments on impulsively loaded panels, covering the full range of panel damage states from light cracking through to panel collapse or perforation. The results are presented using the post-processor code TAURUS, which has also been modified to provide mesh diagrams with superimposed crack patterns from the DYNA3D predictions. (author)

  18. 3D-finite element impact simulation on concrete structures

    Energy Technology Data Exchange (ETDEWEB)

    Heider, N.

    1989-12-15

    The analysis of impact processes is an interesting application of full 3D Finite Element calculations. This work presents a simulation of the penetration process of a Kinetic Energy projectile into a concrete target. Such a calculation requires an adequate FE model, especially a proper description of the crack opening process in front of the projectile. The aim is the prediction of the structural survival of the penetrator case with the help of an appropriate failure criterion. Also, the computer simulation allows a detailed analysis of the physical phenomena during impact. (orig.) With 4 refs., 14 figs.

  19. Contributions to reinforced concrete structures numerical simulations; Contributions a la simulation numerique de structures en beton arme

    Energy Technology Data Exchange (ETDEWEB)

    Badel, P.B

    2001-07-15

    In order to be able to carry out simulations of reinforced concrete structures, it is necessary to know two aspects: the behaviour laws have to reflect the complex behaviour of concrete and a numerical environment has to be developed in order to avoid to the user difficulties due to the softening nature of the behaviour. This work deals with these two subjects. After an accurate estimation of two behaviour models (micro-plan and mesoscopic models), two damage models (the first one using a scalar variable, the other one a tensorial damage of the 2 order) are proposed. These two models belong to the framework of generalized standard materials, which renders their numerical integration easy and efficient. A method of load control is developed in order to make easier the convergence of the calculations. At last, simulations of industrial structures illustrate the efficiency of the method. (O.M.)

  20. Strength development of concrete made with recycled glass aggregates subjected to frost curing conditions

    OpenAIRE

    Poutos, Konstantinos; Nwaubani, Sunny

    2013-01-01

    An experimental investigation was undertaken to study whether the strength behavior of concrete made with glass aggregate differed significantly from that made with natural aggregates when concretes cured in low temperatures. The aim of the research work presented is to examine the strength behavior of glass concrete when cured under freezing conditions at -15°C and -10°C. The results showed that when glass concrete is cured at low curing temperature, the 28 day compressive strength is higher...

  1. The structural neural substrate of subjective happiness.

    Science.gov (United States)

    Sato, Wataru; Kochiyama, Takanori; Uono, Shota; Kubota, Yasutaka; Sawada, Reiko; Yoshimura, Sayaka; Toichi, Motomi

    2015-11-20

    Happiness is a subjective experience that is an ultimate goal for humans. Psychological studies have shown that subjective happiness can be measured reliably and consists of emotional and cognitive components. However, the neural substrates of subjective happiness remain unclear. To investigate this issue, we used structural magnetic resonance imaging and questionnaires that assessed subjective happiness, the intensity of positive and negative emotional experiences, and purpose in life. We found a positive relationship between the subjective happiness score and gray matter volume in the right precuneus. Moreover, the same region showed an association with the combined positive and negative emotional intensity and purpose in life scores. Our findings suggest that the precuneus mediates subjective happiness by integrating the emotional and cognitive components of happiness.

  2. Structural integrity of power generating speed bumps made of concrete foam composite

    Science.gov (United States)

    Syam, B.; Muttaqin, M.; Hastrino, D.; Sebayang, A.; Basuki, W. S.; Sabri, M.; Abda, S.

    2018-02-01

    In this paper concrete foam composite speed bumps were designed to generate electrical power by utilizing the movements of commuting vehicles on highways, streets, parking gates, and drive-thru station of fast food restaurants. The speed bumps were subjected to loadings generated by vehicles pass over the power generating mechanical system. In this paper, we mainly focus our discussion on the structural integrity of the speed bumps and discuss the electrical power generating speed bumps in another paper. One aspect of structural integrity is its ability to support designed loads without breaking and includes the study of past structural failures in order to prevent failures in future designs. The concrete foam composites were used for the speed bumps; the reinforcement materials are selected from empty fruit bunch of oil palm. In this study, the speed bump materials and structure were subjected to various tests to obtain its physical and mechanical properties. To analyze the structure stability of the speed bumps some models were produced and tested in our speed bump test station. We also conduct a FEM-based computer simulation to analyze stress responses of the speed bump structures. It was found that speed bump type 1 significantly reduced the radial voltage. In addition, the speed bump is equipped with a steel casing is also suitable for use as a component component in generating electrical energy.

  3. 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.

  4. Effect of mineral additives on structure and properties of concrete for pavements

    Directory of Open Access Journals (Sweden)

    Sobol Khrystyna

    2017-12-01

    Full Text Available Concrete pavements is an attractive alternative to asphalt pavements because of its lower cost and higher durability. Major contribution to sustainable development can be made by partial replacement of cement in concrete pavement with supplementary cementitious materials of different nature and origin. In this paper, the effect of natural zeolite and perlite additives in complex with chemical admixtures on the structure and properties of concrete for pavement was studied. Compressive and flexural strength test was used to study the mechanical behavior of designed concrete under load. Generally, the compressive strength of both control concrete and concrete containing mineral additives levels at the later ages of hardening. The microstructure analysis of concrete with mineral additives of different nature activity showed the formation of additional amount of hydration products such as tobermorite type calcium hydrosilicate which provide self-reinforcement of hardening concrete system.

  5. Effect of mineral additives on structure and properties of concrete for pavements

    Science.gov (United States)

    Sobol, Khrystyna; Markiv, Taras; Hunyak, Oleksii

    2017-12-01

    Concrete pavements is an attractive alternative to asphalt pavements because of its lower cost and higher durability. Major contribution to sustainable development can be made by partial replacement of cement in concrete pavement with supplementary cementitious materials of different nature and origin. In this paper, the effect of natural zeolite and perlite additives in complex with chemical admixtures on the structure and properties of concrete for pavement was studied. Compressive and flexural strength test was used to study the mechanical behavior of designed concrete under load. Generally, the compressive strength of both control concrete and concrete containing mineral additives levels at the later ages of hardening. The microstructure analysis of concrete with mineral additives of different nature activity showed the formation of additional amount of hydration products such as tobermorite type calcium hydrosilicate which provide self-reinforcement of hardening concrete system.

  6. Rigid-plastic seismic design of reinforced concrete structures

    DEFF Research Database (Denmark)

    Costa, Joao Domingues; Bento, R.; Levtchitch, V.

    2007-01-01

    structural strength with respect to a pre-defined performance parameter using a rigid-plastic response spectrum, which is characteristic of the ground motion alone. The maximum strength demand at any point is solely dependent on the intensity of the ground motion, which facilitates the task of distributing......In this paper a new seismic design procedure for Reinforced Concrete (R/C) structures is proposed-the Rigid-Plastic Seismic Design (RPSD) method. This is a design procedure based on Non-Linear Time-History Analysis (NLTHA) for systems expected to perform in the non-linear range during a lifetime...... earthquake event. The theoretical background is the Theory of Plasticity (Rigid-Plastic Structures). Firstly, a collapse mechanism is chosen and the corresponding stress field is made safe outside the regions where plastic behaviour takes place. It is shown that this allows the determination of the required...

  7. Wireless and embedded carbon nanotube networks for damage detection in concrete structures

    International Nuclear Information System (INIS)

    Saafi, Mohamed

    2009-01-01

    Concrete structures undergo an uncontrollable damage process manifesting in the form of cracks due to the coupling of fatigue loading and environmental effects. In order to achieve long-term durability and performance, continuous health monitoring systems are needed to make critical decisions regarding operation, maintenance and repairs. Recent advances in nanostructured materials such as carbon nanotubes have opened the door for new smart and advanced sensing materials that could effectively be used in health monitoring of structures where wireless and real time sensing could provide information on damage development. In this paper, carbon nanotube networks were embedded into a cement matrix to develop an in situ wireless and embedded sensor for damage detection in concrete structures. By wirelessly measuring the change in the electrical resistance of the carbon nanotube networks, the progress of damage can be detected and monitored. As a proof of concept, wireless cement-carbon nanotube sensors were embedded into concrete beams and subjected to monotonic and cyclic loading to evaluate the effect of damage on their response. Experimental results showed that the wireless response of the embedded nanotube sensors changes due to the formation of cracks during loading. In addition, the nanotube sensors were able to detect the initiation of damage at an early stage of loading.

  8. Wireless and embedded carbon nanotube networks for damage detection in concrete structures

    Science.gov (United States)

    Saafi, Mohamed

    2009-09-01

    Concrete structures undergo an uncontrollable damage process manifesting in the form of cracks due to the coupling of fatigue loading and environmental effects. In order to achieve long-term durability and performance, continuous health monitoring systems are needed to make critical decisions regarding operation, maintenance and repairs. Recent advances in nanostructured materials such as carbon nanotubes have opened the door for new smart and advanced sensing materials that could effectively be used in health monitoring of structures where wireless and real time sensing could provide information on damage development. In this paper, carbon nanotube networks were embedded into a cement matrix to develop an in situ wireless and embedded sensor for damage detection in concrete structures. By wirelessly measuring the change in the electrical resistance of the carbon nanotube networks, the progress of damage can be detected and monitored. As a proof of concept, wireless cement-carbon nanotube sensors were embedded into concrete beams and subjected to monotonic and cyclic loading to evaluate the effect of damage on their response. Experimental results showed that the wireless response of the embedded nanotube sensors changes due to the formation of cracks during loading. In addition, the nanotube sensors were able to detect the initiation of damage at an early stage of loading.

  9. Assessment of Mechanical Properties and Damage of High Performance Concrete Subjected to Magnesium Sulfate Environment

    Directory of Open Access Journals (Sweden)

    Sheng Cang

    2017-01-01

    Full Text Available Sulfate attack is one of the most important problems affecting concrete structures, especially magnesium sulfate attack. This paper presents an investigation on the mechanical properties and damage evolution of high performance concrete (HPC with different contents of fly ash exposure to magnesium sulfate environment. The microstructure, porosity, mass loss, dimensional variation, compressive strength, and splitting tensile strength of HPC were investigated at various erosion times up to 392 days. The ultrasonic pulse velocity (UPV propagation in HPC at different erosion time was determined by using ultrasonic testing technique. A relationship between damage and UPV of HPC was derived according to damage mechanics, and a correlation between the damage of HPC and erosion time was obtained eventually. The results indicated that (1 the average increasing amplitude of porosity for HPCs was 34.01% before and after exposure to magnesium sulfate solution; (2 the damage evolution of HPCs under sulfate attack could be described by an exponential fitting; (3 HPC containing 20% fly ash had the strongest resistance to magnesium sulfate attack.

  10. Self-flowing underwater concrete mixtures for high rise structures

    International Nuclear Information System (INIS)

    Yousri, K.M.

    2005-01-01

    Placement of conventional concrete mixtures in underwater construction results in a high percentage of material loss due to washout of cement paste. This paper presents the influence of anti washout admixture (AWA) on various properties of concrete. Eleven self-flowing concrete (SFC) mixtures using type II cement were proportioned. A combination of low water cement (w/c), high cement contents, anti washout admixtures, fly ash, and silica fume were used to enhance the resistance of fresh concrete to washout. The concrete mixtures proportioned to be highly flow able, self-leveling and cohesive. The water-cementitious materials ratios ranged between 0.356 and 0.392 which correspond a typical underwater concrete mixture. The concrete mixtures were tested for slump, slump flow, washout resistance and compressive strength. The compressive strength of each concrete mixture cast underwater was determined at 3, 7, 28 days and compared with the compressive strength of the same concrete mixture cast in normal condition (in air). Test results indicated that the use of an AWA facilitates the production of flow able concrete mixtures with the added benefit of lower washout loss. Concrete mixture proportioned using Type II cement and fly ash at level of replacement of 15% was found to develop self flowing concrete with better fresh and hardened properties and more resistant to washout. The self-flowing underwater concretes developed a 28-day compressive strengths ranging from 20 to 28 MPa

  11. Structural behavior of concrete box bridge using embedded FBG sensors

    Science.gov (United States)

    Chung, Wonseok; Kang, Donghoon

    2012-04-01

    For the structural monitoring of railway bridges, electromagnetic interference (EMI) is a significant problem as modern railway lines are powered by high-voltage electric power feeding systems. Fiber optic sensing systems are free from EMI and have been successfully applied in civil engineering fields. This study presents the application of fiber Bragg grating (FBG)-based sensing systems to precast concrete box railway bridges. A 20 m long full-scale precast concrete box railway girder was fabricated and tested in order to identify its static performance. The experimental program involved the measurement of the nonlinear static behavior until failure. Multiplexed FBG strain sensors were embedded along the length of steel rebar and a strain-induced wavelength shift was measured in order to monitor internal strains. The measured values from the FBG-based sensors are compared with the results using electric signal-based sensors. The results show that the FBG sensing system is promising and can improve the efficiency of structural monitoring for modern railway bridges.

  12. System reliability of concrete structures subjected to chloride ingress

    DEFF Research Database (Denmark)

    Leira, B.J.; Thöns, Sebastian

    2017-01-01

    attack on the entire bridge, a system model with 90 components is next introduced. This model is employed in order to perform reliability updating based on observations at a number of sites along the bridge. An Enhanced Monte Carlo simulation method (EMC) is applied for this purpose. It is shown...... that application of this simulation method reduces computation times significantly as compared to crude Monte Carlo methods....... are obtained based on measurements from the Gimsøystraumen bridge in Norway. These probability distributions are subsequently employed as input to a prediction model for chloride concentration at the steel reinforcement for a single but arbitrary position along the reinforcement. In order to address chloride...

  13. Durability performance of submerged concrete structures - phase 2 : [summary].

    Science.gov (United States)

    2015-10-01

    Thousands of Florida bridges have steel-reinforced concrete piling foundations standing : in salt water. Over time, chloride ions in the water can migrate through the concrete to : attack the steel inside. The Florida Department of Transportation (FD...

  14. Structural design of nuclear power plant using stiffened steel plate concrete structure

    International Nuclear Information System (INIS)

    Moon, Ilhwan; Kim, Sungmin; Mun, Taeyoup; Kim, Keunkyeong; Sun, Wonsang

    2009-01-01

    Nuclear power is an alternative energy source that is conducive to mitigate the environmental strains. The countries having nuclear power plants are encouraging research and development sector to find ways to construct safer and more economically feasible nuclear power plants. Modularization using Steel Plate Concrete(SC) structure has been proposed as a solution to these efforts. A study of structural modules using SC structure has been performed for shortening of construction period and enhancement of structural safety of NPP structures in Korea. As a result of the research, the design code and design techniques based on limit state design method has been developed. The design code has been developed through various structural tests and theoretical studies, and it has been modified by application design of SC structure for NPP buildings. The code consists of unstiffened SC wall design, stiffened SC wall design, Half-SC slab design, stud design, connection design and so on. The stiffened steel plate concrete(SSC) wall is SC structure whose steel plates with ribs are composed on both sides of the concrete wall, and this structure was developed for improved constructability and safety of SC structure. This paper explains a design application of SC structure for a sample building specially devised to reflect all of major structural properties of main buildings of APR1400. In addition, Stiffening effect of SSC structure is evaluated and structural efficiency of SSC structure is verified in comparison with that of unstiffened SC structure. (author)

  15. Void structure of concrete with superabsorbent polymers and its relation to frost resistance of concrete

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jensen, Ole Mejlhede; Laustsen, Sara

    2013-01-01

    the difference between poor and satisfactory frost-resistance. Furthermore, the results indicate that voids created directly by SAP protect concrete against frost deterioration just like other air voids; if the concrete contains enough SAP voids, these alone can provide sufficient frost resistance. © 2013 RILEM....

  16. Durability of cracked fibre reinforced concrete structures exposed to chlorides

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Ekman, Tom; Hansen, Kurt Kielsgaard

    1999-01-01

    is used as environmental load. The chloride penetration is characterized both qualitatively (UV-test) and quantitatively (chloride profile) and by microscopy. The test programme involves three different concrete qualities. Both steel fibres and polypropylene fibres are used in the concrete beams as well...... as main reinforcement. The effect of the cracks, the fibres and the concrete quality on the chloride penetration is studied....

  17. Evaluation of structural systems in precast concrete buildings by ...

    African Journals Online (AJOL)

    In general, the precast concrete is the type of concrete that constructing, casting and curing in the standard factory conditions with high quality and then it will be transported with proper equipments and then it will be installed in the final position. In fact, the precast concrete buildings are the combined of several types of ...

  18. High-strength concrete and the design of power plant structures

    International Nuclear Information System (INIS)

    Puttonen, J.

    1991-01-01

    Based on the literature, the design of high-strength concrete structures and the suitability of high-strength concrete for the power plant structures have been studied. Concerning the behavior of structures, a basic difference between the high-strength concrete and the traditional one is that the ductility of the high-strength concrete is smaller. In the design, the non-linear stress-strain relationship of the high-strength concrete has to be taken into account. The use of the high-strength concrete is economical if the strength of the material can be utilized. In the long term, the good durability and wear resistance of the high-strength concrete increases the economy of the material. Because of the low permeability of the high-strength concrete, it is a potential material in the safety-related structures of nuclear power plants. The study discovered no particular power plant structure which would always be economical to design of high-strength concrete. However, the high-strength concrete was found to be a competitive material in general

  19. Effect of temperature on structural quality of the cement paste and high-strength concrete with silica fume

    International Nuclear Information System (INIS)

    Janotka, Ivan; Nuernbergerova, Terezia

    2005-01-01

    Experimental investigation conducted to study the thermo-mechanical properties of concrete at Temelin (Czech Republic), Mochovce (Slovakia), and Penly (France) nuclear power plants reveals structural integrity degradation between 100 and 200 deg C due to both a loss of water bound in hydrated cement minerals and subsequently air void formation. Test results indicate changes in strength, average pore radius and calculated permeability coefficients for Mochovce specimens exposed to temperatures up to 400 deg C. It demonstrates that the permeability coefficient measured on the basis of pore sizes using mercury intrusion porosimetry is suitable technique for the evaluation of concrete quality. It confirms that strength and permeability coefficient are equivalent structural quality variables of concrete. At 400 deg C gel-like hydration products are decomposed, at 600 deg C Ca(OH) 2 is dehydroxylated, and CaCO 3 dissociation to CaO and CO 2 accompanied with the re-crystallisation of non-binding phases from hydrated cement under re-combustion are dominant processes between 600 and 800 deg C. This stage of concrete is characterised by the collapse of its structural integrity, revealing residual compressive strength. This paper reports high-strength concrete behaviour subjected to temperatures up to 200 deg C. In accordance with previous results, research studies of structure-property relation show the changes in strength, dynamic modulus of elasticity, strain-stress behaviour, and shrinkage-induced deformations influenced by a hydrate phase decomposition. Volume reduction of the hydrate phase due to the loss of bound water mass is the cause of air void formation, and pore structure coarsening. The main attention is herein devoted to the evaluation of utility property decrease of high-strength concrete and microstructure degradation of the cement paste with the same composition than that in concrete when attacked by elevated temperatures

  20. Local damage to Ultra High Performance Concrete structures caused by an impact of aircraft engine missiles

    International Nuclear Information System (INIS)

    Riedel, Werner; Noeldgen, Markus; Strassburger, Elmar; Thoma, Klaus; Fehling, Ekkehard

    2010-01-01

    Research highlights: → Experimental series on UHPC panels subjected to aircraft engine impact. → Improved ballistic limit of fiber reinforced UHPC in comparison to conventional R/C. → Detailed investigation of failure mechanisms of fiber reinforced UHPC panel. - Abstract: The impact of an aircraft engine missile causes high stresses, deformations and a severe local damage to conventional reinforced concrete. As a consequence the design of R/C protective structural elements results in components with rather large dimensions. Fiber reinforced Ultra High Performance Concrete (UHPC) is a concrete based material which combines ultra high strength, high packing density and an improved ductility with a significantly increased energy dissipation capacity due to the addition of fiber reinforcement. With those attributes the material is potentially suitable for improved protective structural elements with a reduced need for material resources. The presented paper reports on an experimental series of scaled aircraft engine impact tests with reinforced UHPC panels. The investigations are focused on the material behavior and the damage intensity in comparison to conventional concrete. The fundamental work of is taken as reference for the evaluation of the results. The impactor model of a Phantom F4 GE-J79 engine developed and validated by Sugano et al. is used as defined in the original work. In order to achieve best comparability, the experimental configuration and method are adapted for the UHPC experiments. With 'penetration', 'scabbing' and 'perforation' all relevant damage modes defined in are investigated so that a full set of results are provided for a representative UHPC structural configuration.

  1. Local damage to reinforced concrete structures caused by impact of aircraft engine missiles. Pt. 1

    International Nuclear Information System (INIS)

    Sugano, T.; Tsubota, H.; Kasai, Y.; Koshika, N.; Ohnuma, H.; Von Riesemann, W.A.; Bickel, D.C.; Parks, M.B.

    1993-01-01

    Structural damage induced by an aircraft crashing into a reinforced concrete structure includes local damage caused by the deformable engines, and global damage caused by the entire aircraft. Local damage to the target may consist of spalling of concrete from its front face together with missile penetration into it, scabbing of concrete from its rear face, and perforation of missile through it. Until now, local damage to concrete structures has been mainly evaluated by rigid missile impact tests. Past research work regarding local damage caused by impact of deformable missiles has been limited. This paper presents the results of a series of impact tests of small-, intermediate-, and full-scale engine models into reinforced concrete panels. The purpose of the tests was to determine the local damage to a reinforced concrete structure caused by the impact of a deformable aircraft engine. (orig.)

  2. Use of recycled tires in non-structural concrete

    Directory of Open Access Journals (Sweden)

    Al Rawahi Zamzam

    2017-01-01

    Full Text Available This research addresses the issue of tire waste management and natural aggregate resource depletion. It investigates use of commercially produced recycled tire rubber as replacement for fine and coarse aggregate in non-structural concrete. Two replacement levels of 10% and 20% were considered for fine aggregate with 0% or 10% of coarse aggregate. The study employed a mix proportion of 1:5:4 (cement: fine aggregate: coarse aggregate with a water-to-cement ratio of 0.25, which is normally utilized in concrete block manufacturing in Oman. The mixes were tested for their thermal conductivity, water absorption and compressive strength. The behavior of mixes exposed to 100 and 200°C was also studied and the samples were later tested for compressive strength. The results showed improvements in compressive strength after exposure to heat. Thermal conductivity was reduced as the percentage replacement increased for both fine and coarse aggregate. During heat exposure, the temperature rise was faster in rubberized mixes, and the compressive strength of all mixes improved after the exposure to heat. Water absorption and void content increased with increase in replacement percentage. The compressive strength did not show a clear trend with the replacement and this is due to the sensitivity of the stiff mix used in the study and its inherent lean nature. The results indicate that the lean nature of the mix makes it insensitive to small replacement investigated in this research.

  3. 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)

  4. Reliability of structural systems subject to fatigue

    International Nuclear Information System (INIS)

    Rackwitz, R.

    1984-01-01

    Concepts and computational procedures for the reliability calculation of structural systems subject to fatigue are outlined. Systems are dealt with by approximately computing componential times to first failure. So-called first-order reliability methods are then used to formulate dependencies between componential failures and to evaluate the system failure probability. (Author) [pt

  5. Current state of knowledge on the behavior of steel liners in concrete containments subjected to overpressurization loads

    International Nuclear Information System (INIS)

    Riesemann, W.A. von; Parks, M.B.

    1995-01-01

    In the US, concrete containment buildings for commercial nuclear power plants have steel liners that act as the internal pressure boundary. The liner abuts the concrete, acting as the interior concrete form. The liner is attached to the concrete by either studs or by a continuous structural shape (such as a T-section or channel) that is either continuously or intermittently welded to the liner. Studs are commonly used in reinforced concrete containments, while prestressed containments utilize a structural element as the anchorage. The practice in some countries follows the US practice, while in other countries the containment does not have a steel liner. In this latter case, there is a true double containment, and the annular region between the two containments is vented.This paper will review the practice of design of the liner system prior to the consideration of severe accident loads (overpressurization loads beyond the design conditions).An overpressurization test of a 1:6 scale reinforced concrete containment at Sandia National Laboratories resulted in a failure mechanism in the liner that was not fully anticipated. Post-test analyses and experiments have been conducted to understand the failure better. This work and the activities that followed the test are reviewed. Areas in which additional research should be conducted are given. (orig.)

  6. Detecting alkali-silica reaction in thick concrete structures using linear array ultrasound

    Science.gov (United States)

    Bull Ezell, N. Dianne; Albright, Austin; Clayton, Dwight; Santos-Villalobos, Hector

    2018-03-01

    Commercial nuclear power plants (NPPs) depend heavily on concrete structures, making the long-term performance of these structures crucial for safe operation, especially with license period extensions to 60 years and possibly beyond. Alkali-silica reaction (ASR) is a reaction that occurs over time in concrete between alkaline cement paste and reactive, noncrystalline silica (aggregates). In the presence of water, an expansive gel is formed within the aggregates, which results in microcracks in aggregates and adjacent cement paste. ASR can potentially affect concrete properties and performance characteristics such as compressive strength, modulus of elasticity, flexural stiffness, shear strength, and tensile strength. Currently, no nondestructive evaluation methods have proven effective in identifying ASR before surface cracks form. ASR is identified visibly or by petrographic analysis. Although ASR definitely impacts concrete material properties, the performance of concrete structures exhibiting ASR depends on whether or not the concrete is unconfined or confined with reinforcing bars. Confinement by reinforcing bars restrainsthe expansion of ASR-affected concrete, similar to prestressing, thus improving the performance of a structure. Additionally, there is no direct correlation between the mechanical properties of concrete sample cores and the in-situ properties of the concrete. The University of Tennessee-Knoxville, Oak Ridge National Laboratory, and a consortium of universities have developed an accelerated ASR experiment. Three large concrete specimens, representative of NPP infrastructure, were constructed containing both embedded and surface instruments. This paper presents preliminary analysis of these specimens using a frequency-banded synthetic aperture focusing technique.

  7. Static reliability of concrete structures under extreme temperature, radiation, moisture and force loading

    International Nuclear Information System (INIS)

    Stepanek, P.; Stastnik, S.; Salajka, V.; Hradil, P.; Skolar, J.; Chlanda, V.

    2003-01-01

    The contribution presents some aspects of the static reliability of concrete structures under temperature effects and under mechanical loading. The mathematical model of a load-bearing concrete structure was performed using the FEM method. The temperature field and static stress that generated states of stress were taken into account. A brief description of some aspects of evaluation of the reliability within the primary circuit concrete structures is stated. The knowledge of actual physical and mechanical characteristics and chemical composition of concrete were necessary for obtaining correct results of numerical analysis. (author)

  8. Modelling concrete behaviour at early-age: multi-scale analysis and simulation of a massive disposal structure

    International Nuclear Information System (INIS)

    Honorio-De-Faria, Tulio

    2015-01-01

    The accurate prediction of the long and short-term behaviour of concrete structures in the nuclear domain is essential to ensure optimal performances (integrity, containment properties) during their service life. In the particular case of massive concrete structures, at early age the heat produced by hydration reactions cannot be evacuated fast enough so that high temperatures may be reached and the resulting gradients of temperature might lead to cracking according to the external and internal restraints to which the structures are subjected. The goals of this study are (1) to perform numerical simulations in order to describe and predict the thermo-chemo-mechanical behaviour at early-age of a massive concrete structure devoted to nuclear waste disposal on surface, and (2) to develop and apply up-scaling tools to estimate rigorously the key properties of concrete needed in an early-age analysis from the composition of the material. Firstly, a chemo-thermal analysis aims at determining the influence of convection, solar radiation, re-radiation and hydration heat on the thermal response of the structure. Practical recommendations regarding concreting temperatures are provided in order to limit the maximum temperature reached within the structure. Then, by means of a mechanical analysis, simplified and more complex (i.e. accounting for coupled creep and damage) modelling strategies are used to assess scenarios involving different boundary conditions defined from the previous chemo-thermal analysis. Secondly, a study accounting for the multi-scale character of concrete is performed. A simplified model of cement hydration kinetics is proposed. The evolution of the different phases at the cement paste level can be estimated. Then, analytical and numerical tools to upscale the ageing properties are presented and applied to estimate the mechanical and thermal properties of cement based materials. Finally, the input data used in the structural analysis are compared with

  9. Towards assuring the continued performance of safety-related concrete structures in nuclear power plants

    International Nuclear Information System (INIS)

    Naus, D.J.; Oland, C.B.; Ellingwood, B.; Mori, Y.; Arndt, E.G.

    1993-01-01

    The Structural Aging (SAG) Program is addressing the aging management of safety-related concrete structures in nuclear power plants for the purpose of providing improved technical bases for their continued service. Pertinent concrete structures are described in terms of their importance, design considerations, and materials of construction. Degradation factors which can potentially impact the ability of these structures to meet their functional and performance requirements are identified. A review of the performance history of the concrete components in nuclear power plants is provided. Accomplishments of the SLAG Program are summarized, i.e., development of the structural materials information center, development of a structural aging assessment methodology, evaluation of models for predicting the remaining life of in-service concrete, review of in-service inspection methods, and development of a methodology for reliability-based condition assessment and life prediction of concrete structures. On-going activities are also described

  10. Structural Integrity Assessment of Reactor Containment Subjected to Aircraft Crash

    International Nuclear Information System (INIS)

    Kim, Junyong; Chang, Yoonsuk

    2013-01-01

    When an accident occurs at the NPP, containment building which acts as the last barrier should be assessed and analyzed structural integrity by internal loading or external loading. On many occasions that can occur in the containment internal such as LOCA(Loss Of Coolant Accident) are already reflected to design. Likewise, there are several kinds of accidents that may occur from the outside of containment such as earthquakes, hurricanes and strong wind. However, aircraft crash that at outside of containment is not reflected yet in domestic because NPP sites have been selected based on the probabilistic method. After intentional aircraft crash such as World Trade Center and Pentagon accident in US, social awareness for safety of infrastructure like NPP was raised world widely and it is time for assessment of aircraft crash in domestic. The object of this paper is assessment of reactor containment subjected to aircraft crash by FEM(Finite Element Method). In this paper, assessment of structural integrity of containment building subjected to certain aircraft crash was carried out. Verification of structure integrity of containment by intentional severe accident. Maximum stress 61.21MPa of horizontal shell crash does not penetrate containment. Research for more realistic results needed by steel reinforced concrete model

  11. Internal inspection of reinforced concrete for nuclear structures using shear wave tomography

    International Nuclear Information System (INIS)

    Scott, David B.

    2013-01-01

    Highlights: • Aging of reinforced concrete used for worldwide nuclear structures is increasing and necessitating evaluation. • Nondestructive evaluation is a tool for assessing the condition of reinforced concrete of nuclear structures. • Ultrasonic shear wave tomography as a stress wave technique has begun to be utilized for investigation of concrete material. • A study using ultrasonic shear wave tomography indicates anomalies vital to the long-term operation of the structure. • The use of this technique has shown to successfully evaluate the internal state of reinforced concrete members. - Abstract: Reinforced concrete is important for nuclear related structures. Therefore, the integrity of structural members consisting of reinforced concrete is germane to the safe operation and longevity of these facilities. Many issues that reduce the likelihood of safe operation and longevity are not visible on the surface of reinforced concrete material. Therefore, an investigation of reinforced concrete material should include techniques which will allow peering into the concrete member and determining its internal state. The performance of nondestructive evaluations is pursuant to this goal. Some of the categories of nondestructive evaluations are electrochemical, magnetism, ground penetrating radar, and ultrasonic testing. A specific ultrasonic testing technique, namely ultrasonic shear wave tomography, is used to determine presence and extent of voids, honeycombs, cracks perpendicular to the surface, and/or delamination. This technique, and others similar to it, has been utilized in the nuclear industry to determine structural conditions

  12. Design Of A Laboratory Set-up For Evaluating Structural Strength Of Deteriorated Concrete Sewer Pipes

    NARCIS (Netherlands)

    Stanic, N.; Salet, T.; Langeveld, J.G.; Clemens, F.H.L.R.

    2014-01-01

    The principle of structural behaviour of buried concrete pipes is fairly understood, except for how material deterioration affects structural behaviour and performance. Consequently, information on the structural behaviour of deteriorated sewer pipes will contribute to better understanding of the

  13. Structural and mechanical study of concrete made from cementitious materials of low environmental impact

    Science.gov (United States)

    González, A. K.; Montaño, A. M.; González, C. P.; Santos, A.

    2017-12-01

    This work shows the results obtained by replacing Type I Portland®, by cementitious geopolymers materials, derived from minerals, in concrete mixtures. Synthesis of both geopolymers through alkaline activation of two alluminosilicates: Bentonite and Pumice with sodium silicate (Na2SiO3). XRD, SEM and XRDE are used to structural study of new geopolymers. Concrete mixtures with replacement of Portland have 10% and 30% of geopolymer. Finally, concrete mortars formed were mechanically analysed according to ICONTEC 220 at 7, 14, 28, 41, 90 and 120 days of cure. Results shows that compressive strength of concrete from Bentonite and Pumice are almost the same for the standard concrete at 28 days of cure. At 90 days of cure, compression resistance of concrete from Pumice at 10% is even higher than those that standard concrete shows.

  14. Crack width monitoring of concrete structures based on smart film

    International Nuclear Information System (INIS)

    Zhang, Benniu; Wang, Shuliang; Li, Xingxing; Zhang, Xu; Yang, Guang; Qiu, Minfeng

    2014-01-01

    Due to its direct link to structural security, crack width is thought to be one of the most important parameters reflecting damage conditions of concrete structures. However, the width problem is difficult to solve with the existing structural health monitoring methods. In this paper, crack width monitoring by means of adhering enameled copper wires with different ultimate strains on the surface of structures is proposed, based on smart film crack monitoring put forward by the present authors. The basic idea of the proposed method is related to a proportional relationship between the crack width and ultimate strain of the broken wire. Namely, when a certain width of crack passes through the wire, some low ultimate strain wires will be broken and higher ultimate strain wires may stay non-broken until the crack extends to a larger scale. Detection of the copper wire condition as broken or non-broken may indicate the width of the structural crack. Thereafter, a multi-layered stress transfer model and specimen experiment are performed to quantify the relationship. A practical smart film is then redesigned with this idea and applied to Chongqing Jiangjin Yangtze River Bridge. (paper)

  15. Crack width monitoring of concrete structures based on smart film

    Science.gov (United States)

    Zhang, Benniu; Wang, Shuliang; Li, Xingxing; Zhang, Xu; Yang, Guang; Qiu, Minfeng

    2014-04-01

    Due to its direct link to structural security, crack width is thought to be one of the most important parameters reflecting damage conditions of concrete structures. However, the width problem is difficult to solve with the existing structural health monitoring methods. In this paper, crack width monitoring by means of adhering enameled copper wires with different ultimate strains on the surface of structures is proposed, based on smart film crack monitoring put forward by the present authors. The basic idea of the proposed method is related to a proportional relationship between the crack width and ultimate strain of the broken wire. Namely, when a certain width of crack passes through the wire, some low ultimate strain wires will be broken and higher ultimate strain wires may stay non-broken until the crack extends to a larger scale. Detection of the copper wire condition as broken or non-broken may indicate the width of the structural crack. Thereafter, a multi-layered stress transfer model and specimen experiment are performed to quantify the relationship. A practical smart film is then redesigned with this idea and applied to Chongqing Jiangjin Yangtze River Bridge.

  16. Tensile Characterization of FRP Rods for Reinforced Concrete Structures

    Science.gov (United States)

    Micelli, F.; Nanni, A.

    2003-07-01

    The application of FRP rods as an internal or external reinforcement in new or damaged concrete structures is based on the development of design equations that take into account the mechanical properties of FRP material systems.The measurement of mechanical characteristics of FRP requires a special anchoring and protocol, since it is well known that these characteristics depend on the direction and content of fibers. In this study, an effective tensile test method is described for the mechanical characterization of FRP rods. Twelve types of glass and carbon FRP specimens with different sizes and surface characteristics were tested to validate the procedure proposed. In all, 79 tensile tests were performed, and the results obtained are discussed in this paper. Recommendations are given for specimen preparation and test setup in order to facilitate the further investigation and standardization of the FRP rods used in civil engineering.

  17. Stochastic modeling of reinforced concrete structures exposed to chloride attack

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Frier, Christian

    2004-01-01

    For many reinforced concrete structures corrosion of reinforcement is an important problem since it can result in expensive maintenance and repair actions. Further, a significant reduction of the load-bearing capacity can occur. One mode of corrosion initiation is that the chloride content around...... concentration and reinforcement cover depth are modeled by stochastic fields. The paper contains a description of the parameters to be included in a stochastic model and a proposal for the information needed to obtain values for the parameters in order to be able to perform reliability investigations....... The distribution of the time to initiation of corrosion is estimated by simulation. As an example a bridge pier in a marine environment is considered....

  18. Stochastic Modeling of Reinforced Concrete Structures Exposed to Chloride Attack

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Frier, Christian

    2003-01-01

    For many reinforced concrete structures corrosion of reinforcement is an important problem since it can result in expensive maintenance and repair actions. Further, a significant reduction of the load-bearing capacity can occur. One mode of corrosion initiation is that the chloride content around...... concentration and reinforcement cover depth are modeled by stochastic fields. The paper contains a description of the parameters to be included in a stochastic model and a proposal for the information needed to obtain values for the parameters in order to be ab le to perform reliability investigations....... The distribution of the time to initiation of corrosion is estimated by simulation. As an example a bridge pier in a marine environment is considered....

  19. Effect of Alkali-Silica Reaction on Shear Strength of Reinforced Concrete Structural Members

    Energy Technology Data Exchange (ETDEWEB)

    Hariri-Ardebili, Mohammad [Univ. of Colorado, Boulder, CO (United States); Saouma, Victor [Univ. of Colorado, Boulder, CO (United States); Le Pape, Yann [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-10-01

    Alkali-silica reaction (ASR) was discovered in the early 40s by Stanton (1940) of the California Division of Highways. Since, it has been recognized as a major degradation mechanism for concrete dams and transportation infrastructures. Sometimes described as the ’cancer of concrete’, this internal swelling mechanism causes expansion, cracking and loss of mechanical properties. There are no known economically viable solutions applicable to massive concrete to prevent the reaction once initiated. The e ciency of the mitigation strategies for ASR subjected structures is limited. Several cases of ASR in nuclear generating stations have been disclosed in Japan (Takatura et al. 2005), Canada at Gentilly 2 NPP (Tcherner and Aziz 2009) 1, and more recently, in the United States for which the U.S. Nuclear Regulatory Commission issued Information Notice (IN) 2011-20, ’Concrete Degradation by Alkali Silica Reaction,’ on November 18, 2011, to provide the industry with information related to the ASR identified at Seabrook. Considering that US commercial reactors in operation enter the age when ASR degradation can be visually detected and that numerous non nuclear infrastructures (transportation, energy production) have already experienced ASR in a large majority of the States (e.g., Department of Transportation survey reported by Touma (Touma 2000)), the susceptibility and significance of ASR for nuclear concrete structures must be addressed in the perspective of license renewal and long-term operation beyond 60 years. The aim of this report is to perform an extensive parametric series of 3D nonlinear finite element analyses of three di erent “beam-like” geometries, including two di erent depths, three di erent types of boundary conditions, and four other parameters: namely, the ASR volumetric expansion, the reinforcement ratio, the loss of elastic modulus induced by ASR and the loss of tensile strength caused by ASR.

  20. Concrete containment tests: Phase 2, Structural elements with liner plates: Interim report

    International Nuclear Information System (INIS)

    Hanson, N.W.; Roller, J.J.; Schultz, D.M.; Julien, J.T.; Weinmann, T.L.

    1987-08-01

    The tests described in this report are part of Phase 2 of the Electric Power Research Institute (EPRI) program. The overall objective of the EPRI program is to provide a test-verified analytical method of estimating capacities of concrete reactor containment buildings under internal overpressurization from postulated degraded core accidents. The Phase 2 testing included seven large-scale specimens representing structural elements from reinforced and prestressed concrete reactor containment buildings. Six of the seven test specimens were square wall elements. Of these six specimens, four were used for biaxial tension tests to determine strength, deformation, and leak-rate characteristics of full-scale wall elements representing prestressed concrete containment design. The remaining two square wall elements were used for thermal buckling tests to determine whether buckling of the steel liner plate would occur between anchorages when subjected to a sudden extreme temperature differential. The last of the seven test specimens for Phase 2 represented the region where the wall and the basemat intersect in a prestressed concrete containment building. A multi-directional loading scheme was used to produce high bending moments and shear in the wall/basemat junction region. The objective of this test was to determine if there is potential for liner plate tearing in the junction region. Results presented include observed behavior and extensive measurements of deformations and strains as a function of applied load. The data are being used to confirm analytical models for predicting strength and deformation of containment structures in a separate parallel analytical investigation sponsored by EPRI

  1. Design and Modeling of Structural Joints in Precast Concrete Structures

    DEFF Research Database (Denmark)

    Sørensen, Jesper Harrild

    and in the onsite construction speed. The challenges appear in the on-site assembly phase, where structural integrity has to be ensured by in-situ cast connections in narrow zones. These connections are essential for the overall structural behavior and for this reason, strong and ductile connections...... is the orientation of the U-bar loops and the use of a double T-headed rebar in the overlapping area of the Ubars. The investigation covers several independent research topics, which in combination provides a broad knowledge of the behavior of keyed shear connections. As the first topic, the structural behavior...... the loop connection in such a way, that the tensile capacity is governed by yielding of the U-bars and not by a brittle failure of the grout. This is important in order to obtain a ductile response when the connection is loaded in shear. The main focus of the thesis is test and modeling of keyed shear...

  2. Tensile strength of structural concrete repaired with hi-bond polymer modified mortar

    International Nuclear Information System (INIS)

    Khaskheli, G.B.

    2009-01-01

    Repair of cracks in concrete is often required to save the concrete structures. Appearance of crack in concrete is bound with the tensile strength of concrete. Recently a cement factory in Sindh has launched a HBPMM (Hi-Bond Polymer Modified Mortar) that can be used as a concrete repairing material instead of normal OPC (Ordinary Portland Cement). It is needed to investigate its performance compared to that of OPC. In total 144 concrete cylinders (150x300mm) having strength of 3000 and 5000 psi were manufactured. These cylinders were then splitted by using a UTM (Universal Testing Machine) and their actual tensile strength was obtained. The concrete cylinders were then repaired with different applications of HBPMM and arc. The repaired samples were again splitted at different curing ages (3, 7 and 28 days) and their tensile strength after repair was obtained. The results show that the concrete cylinders repaired with HBPMM could give better tensile strength than that repaired with arc, the tensile strength of concrete cylinders after repair could increase with increase in the application of repairing material i.e. HBPMM or OPC and with curing time, and HBPMM could remain more effective in case of rich mix concrete than that of normal mix concrete. (author)

  3. Structural recycled concrete: utilization of recycled aggregate from construction and demolition wastes

    International Nuclear Information System (INIS)

    Alaejos Gutierrez, P.; Sanchez de Juan, M.

    2015-01-01

    This paper aims to present the main results of CEDEX research works concerning the use of recycled aggregates for structural concretes. By way of conclusion, recommendations on the requirements of the recycled aggregates have been established, providing information about the influence of these aggregates on the properties of structural concrete. (Author)

  4. Analysis of time-dependent reliability of degenerated reinforced concrete structure

    Directory of Open Access Journals (Sweden)

    Zhang Hongping

    2016-07-01

    Full Text Available Durability deterioration of structure is a highly random process. The maintenance of degenerated structure involves the calculation of the reliability of time-dependent structure. This study introduced reinforced concrete structure resistance decrease model and related statistical parameters of uncertainty, analyzed resistance decrease rules of corroded bending element of reinforced concrete structure, and finally calculated timedependent reliability of the corroded bending element of reinforced concrete structure, aiming to provide a specific theoretical basis for the application of time-dependent reliability theory.

  5. Strain Behavior of Concrete Panels Subjected to Different Nose Shapes of Projectile Impact.

    Science.gov (United States)

    Lee, Sangkyu; Kim, Gyuyong; Kim, Hongseop; Son, Minjae; Choe, Gyeongcheol; Nam, Jeongsoo

    2018-03-09

    This study evaluates the fracture properties and rear-face strain distribution of nonreinforced and hooked steel fiber-reinforced concrete panels penetrated by projectiles of three different nose shapes: sharp, hemispherical, and flat. The sharp projectile nose resulted in a deeper penetration because of the concentration of the impact force. Conversely, the flat projectile nose resulted in shallower penetrations. The penetration based on different projectile nose shapes is directly related to the impact force transmitted to the rear face. Scabbing can be more accurately predicted by the tensile strain on the rear face of concrete due to the projectile nose shape. The tensile strain on the rear face of the concrete was reduced by the hooked steel fiber reinforcement because the hooked steel fiber absorbed some of the impact stress transmitted to the rear face of the concrete. Consequently, the strain behavior on the rear face of concrete according to the projectile nose shape was confirmed.

  6. Strain Behavior of Concrete Panels Subjected to Different Nose Shapes of Projectile Impact

    Directory of Open Access Journals (Sweden)

    Sangkyu Lee

    2018-03-01

    Full Text Available This study evaluates the fracture properties and rear-face strain distribution of nonreinforced and hooked steel fiber-reinforced concrete panels penetrated by projectiles of three different nose shapes: sharp, hemispherical, and flat. The sharp projectile nose resulted in a deeper penetration because of the concentration of the impact force. Conversely, the flat projectile nose resulted in shallower penetrations. The penetration based on different projectile nose shapes is directly related to the impact force transmitted to the rear face. Scabbing can be more accurately predicted by the tensile strain on the rear face of concrete due to the projectile nose shape. The tensile strain on the rear face of the concrete was reduced by the hooked steel fiber reinforcement because the hooked steel fiber absorbed some of the impact stress transmitted to the rear face of the concrete. Consequently, the strain behavior on the rear face of concrete according to the projectile nose shape was confirmed.

  7. POROSIMETRY BY RANDOM NODE STRUCTURING IN VIRTUAL CONCRETE

    Directory of Open Access Journals (Sweden)

    Piet Stroeven

    2012-05-01

    Full Text Available Two different porosimetry methods are presented in two successive papers. Inspiration for the development came from the rapidly-exploring random tree (RRT approach used in robotics. The novel methods are applied to virtual cementitious materials produced by a modern concurrent algorithm-based discrete element modeling system, HADES. This would render possible realistically simulating all aspects of particulate matter that influence structure-sensitive features of the pore network structure in maturing concrete, namely size, shape and dispersion of the aggregate and cement particles. Pore space is a complex tortuous entity. Practical methods conventionally applied for assessment of pore size distribution may fail or present biased information. Among them, mercury intrusion porosimetry and 2D quantitative image analysis are popular. The mathematical morphology operator “opening” can be applied to sections and even provide 3D information on pore size distribution, provided isotropy is guaranteed. However, aggregate grain surfaces lead to anisotropy in porosity. The presented methods allow exploration of pore space in the virtual material, after which pore size distribution is derived from star volume measurements. In addition to size of pores their continuity is of crucial importance for durability estimation. Double-random multiple tree structuring (DRaMuTS, introduced earlier in IA&S (Stroeven et al., 2011b and random node structuring (RaNoS provide such information.

  8. Design of reinforced concrete members based on structural mechanics

    International Nuclear Information System (INIS)

    Diaz, B.E.; Schulz, M.

    1984-01-01

    Up to now the design of reinforced concrete linear members is performed with the help of an inconsistent design theory, which nevertherless is sufficiently safe and simple to be used in the practice. The purpose of this paper is to present a rational reinforced concrete design method which is not too dissimilar to the present design rules, but is capable of defining consistently internal stresses along a reinforced concrete section. The present status of the completed computer procedures allows the analysis of linear reinforced concrete members formed by laminar reinforced concrete plates presenting variable thickness. A practical approach is presented for which the concrete and steel section is constant along the member axis. In this case, the concept of the equivalent section is introduced, which allows a simple analysis of the stress pattern along the member section. (Author) [pt

  9. 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)

  10. Strain measurements of temperatures up to 3000C in a concrete structure

    International Nuclear Information System (INIS)

    Schittenhelm, Ch.

    1975-10-01

    Strain measurements in a concrete structure representing a cylindrical section of a Prestressed Concrete Reactor Vessel with hot liner, were made. In order to interpret these values in terms of strain and stress in a three dimensional structure, the gauge characteristics as well as the material date of the concrete have to be known in great detail. The paper deals with the performance of different gauges embedded in small concrete blocks and others of the same type embedded in the test ring. Temperature resistance, long-time performance, electrical drift and hysteresis of the gauges were investigated. (author)

  11. Topology optimization of reinforced concrete structures considering control of shrinkage and strength failure

    DEFF Research Database (Denmark)

    Luo, Yangjun; Wang, Michael Yu; Zhou, Mingdong

    2015-01-01

    To take into account the shrinkage effect in the early stage of Reinforced Concrete (RC) design, an effective continuum topology optimization method is presented in this paper. Based on the power-law interpolation, shrinkage of concrete is numerically simulated by introducing an additional design......-dependent force. Under multi-axial stress conditions, the concrete failure surface is well fitted by two Drucker-Prager yield functions. The optimization problem aims at minimizing the cost function under yield strength constraints on concrete elements and a structural shrinkage volume constraint. In conjunction...... to ensure the structural safety under the combined action of external loads and shrinkage....

  12. Experimental study on the cracking behavior of reinforced concrete hollow cylinders subjected to temperature gradient and the assessment of decrease in flexural rigidity due to cracking

    International Nuclear Information System (INIS)

    Aoyagi, Yukio; Onuma, Hiroshi; Okazawa, Takao

    1976-01-01

    Altough the consideration of thermal stress constitutes one of the primary factors governing the design of the hollow cylindrical structures made of reinforced concrete and subjected to temperature gradient, such as radiation-shielding walls and reactor containment vessels, the method of rationally evaluating the safety to such stress has not been established so far. The purposes of this study are to investigate the conditions under which cracks initiate in reinforced concrete structures due to temperature gradient, and to evaluate the decreases in the flexural rigidity after cracking, mainly on the basis of experiment. Three hollow cylinders with top and bottom slabs, 120 cm height and 100 cm outside diameter, were tested. The cylinders were externally cooled by being immersed in water, and internally heated by circulating hot water through the cavities. The maximum temperature difference of 65 deg C was attained. The strain was measured, and the crack patterns were observed. A reinforced concrete beam of 3.8 m length was subjected to temperature difference of 65 deg C. Horizontal cracks appeared first at 27 deg C, and vertical cracks followed at 31 deg C difference at the middle of cylindrical walls. It was assumed that the first cracks appear at the tensile strain of 100 x 10 -6 , and the calculated result was agreed fairly well with the observed temperature difference. The rational method for evaluating the decrease in flexural rigidity due to cracking was proposed by the authors. (Kako, I.)

  13. Composite Behavior of Insulated Concrete Sandwich Wall Panels Subjected to Wind Pressure and Suction

    Directory of Open Access Journals (Sweden)

    Insub Choi

    2015-03-01

    Full Text Available A full-scale experimental test was conducted to analyze the composite behavior of insulated concrete sandwich wall panels (ICSWPs subjected to wind pressure and suction. The experimental program was composed of three groups of ICSWP specimens, each with a different type of insulation and number of glass-fiber-reinforced polymer (GFRP shear grids. The degree of composite action of each specimen was analyzed according to the load direction, type of the insulation, and number of GFRP shear grids by comparing the theoretical and experimental values. The failure modes of the ICSWPs were compared to investigate the effect of bonds according to the load direction and type of insulation. Bonds based on insulation absorptiveness were effective to result in the composite behavior of ICSWP under positive loading tests only, while bonds based on insulation surface roughness were effective under both positive and negative loading tests. Therefore, the composite behavior based on surface roughness can be applied to the calculation of the design strength of ICSWPs with continuous GFRP shear connectors.

  14. Reinforced concrete membrane elements subjected to reversed cyclic in-plane shear stress

    International Nuclear Information System (INIS)

    Ohmori, N.; Tsubota, H.; Inoue, N.; Watanabe, S.; Kurihara, K.

    1987-01-01

    The response of reinforced concrete elements subjected to reversed cyclic in-plane shear stresses can be predicted by an analytical model, which considers equilibrium, compatibility and stress-strain relationships including hysteresis loop of unloading and reloading stages all expressed in terms of average stresses and average strains. The analytical results show that the dominant hysteretic behaviours in regard to decrease of stiffness during unloading, successive slip phenomena and restoration of compressive stiffness at the reloading stages are well simulated analytically. The results agree quite well with the observed behaviours. As for the envelope curve of the hysteretic response there remain the discrepancies that the stiffness and ultimate strength are a bit larger than the observed results, especially in the case of a panel with a large reinforcement ratio. Such descrepancies are also found in the predicted results of monotonic loading and more precise studies are necessary to evaluate more accurate envelope curves under not only reversed cyclic loading but also monotonic loading. (orig./HP)

  15. Cracking in reinforced concrete structures due to imposed deformations

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, A.

    1997-04-01

    This thesis is concerned with modeling of the cracking process in reinforced concrete due to imposed deformations. Cracking is investigated both at early ages, during hydration, and at mature age when the final properties of the concrete are reached. One of the most important material characteristics of the concrete at early ages, the Young`s modulus is determined by means of a dynamic method called the resonance frequency method. 40 refs

  16. Contrastive Numerical Investigations on Thermo-Structural Behaviors in Mass Concrete with Various Cements

    Science.gov (United States)

    Zhou, Wei; Feng, Chuqiao; Liu, Xinghong; Liu, Shuhua; Zhang, Chao; Yuan, Wei

    2016-01-01

    This work is a contrastive investigation of numerical simulations to improve the comprehension of thermo-structural coupled phenomena of mass concrete structures during construction. The finite element (FE) analysis of thermo-structural behaviors is used to investigate the applicability of supersulfated cement (SSC) in mass concrete structures. A multi-scale framework based on a homogenization scheme is adopted in the parameter studies to describe the nonlinear concrete behaviors. Based on the experimental data of hydration heat evolution rate and quantity of SSC and fly ash Portland cement, the hydration properties of various cements are studied. Simulations are run on a concrete dam section with a conventional method and a chemo-thermo-mechanical coupled method. The results show that SSC is more suitable for mass concrete structures from the standpoint of temperature control and crack prevention. PMID:28773517

  17. Quality control of concrete structures in nuclear power plant, (4)

    International Nuclear Information System (INIS)

    Takahashi, Hisao; Kawaguchi, Tohru; Oike, Takeshi; Morimoto, Shoichi; Takeshita, Shigetoshi.

    1979-01-01

    This report describes the result of an investigation to clarify the effect of concrete temperature as mixed in the summer season on the strength gain characteristics of mass concrete such as used in construction of nuclear power plants. It is pointed out that the low strength gain of control cylinders in summer is caused by two main factors, viz., the absence of water modification in the mix design according to concrete temperature as mixed and high curing temperature after placing up to mold removal rather than concrete temperature itself as mixed. On the other hand, it has been clarified that high strength gain in mass concrete can be realized by lowering concrete temperature as mixed so as to lower the subsequent curing temperature at early age. Furthermore, it is explained that the larger the size of the member is, the more effect can be expected from lowering concrete temperature. The effect of concrete temperature as mixed on high strength concrete to be used in PCCV is discussed in the Appendix. (author)

  18. 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.

  19. Structural Response to Blast Loading: The Effects of Corrosion on Reinforced Concrete Structures

    Directory of Open Access Journals (Sweden)

    Hakan Yalciner

    2014-01-01

    Full Text Available Structural blast design has become a necessary part of the design with increasing terrorist attacks. Terrorist attacks are not the one to make the structures important against blast loading where other explosions such as high gas explosions also take an important place in structural safety. The main objective of this study was to verify the structural performance levels under the impact of different blast loading scenarios. The blast loads were represented by using triangular pulse for single degree of freedom system. The effect of blast load on both corroded and uncorroded reinforced concrete buildings was examined for different explosion distances. Modified plastic hinge properties were used to ensure the effects of corrosion. The results indicated that explosion distance and concrete strength were key parameters to define the performance of the structures against blast loading.

  20. 2.4. Kinetics of voids structure change according to the specific properties of the concrete mix

    International Nuclear Information System (INIS)

    Saidov, D.Kh.

    2011-01-01

    This work is devoted to kinetics of voids structure changes according to the specific properties of concrete mix. The influence of concrete mix mobility on durability and watertightness of concrete was studied. The influence of cement expenditure on concrete durability was examined.

  1. Partial Prestress Concrete Beams Reinforced Concrete Column Joint Earthquake Resistant On Frame Structure Building

    Science.gov (United States)

    Astawa, M. D.; Kartini, W.; Lie, F. X. E.

    2018-01-01

    Floor Building that requires a large space such as for the meeting room, so it must remove the column in the middle of the room, then the span beam above the room will be long. If the beam of structural element with a span length reaches 15.00 m, then it is less effective and efficient using a regular Reinforced Concrete Beam because it requires a large section dimension, and will reduce the beauty of the view in terms of aesthetics of Architecture. In order to meet these criteria, in this design will use partial prestressing method with 400/600 mm section dimension, assuming the partial Prestressed Beam structure is still able to resist the lateral force of the earthquake. The design of the reinforcement has taken into account to resist the moment due to the gravitational load and lateral forces. The earthquake occurring on the frame structure of the building. In accordance with the provisions, the flexural moment capacity of the tendon is permitted only by 25% of the total bending moment on support of the beam, while the 75% will be charged to the reinforcing steel. Based on the analysis result, bring ini 1 (one) tendon contains 6 strand with diameter 15,2 mm. On the beam pedestal, requires 5D25 tensile reinforcement and 3D25 for the compression reinforcement, for shear reinforcement on the pedestal using Ø10-100 mm. Dimensional column section are 600/600 mm with longitudinal main reinforcement of 12D25, and transverse reinforcement Ø10-150. At the core of the beam-column joint, use the transversal reinforcement Ø10-100 mm. The moment of Column versus Beam Moment ∑Me > 1.2 Mg, with a value of 906.99 kNm > 832.25 kNm, qualify for ductility and Strong Columns-weak beam. Capacity of contribution bending moment of Strand Tendon’s is 23.95% from the total bending moment capacity of the beam, meaning in accordance with the provisions. Thus, the stability and ductility structure of Beam-Column joint is satisfy the requirements of SNI 2847: 2013 and ACI 318-11.

  2. Procedure for getting safety classed concrete structures approved by Finnish Radiation and Nuclear Safety Authority

    International Nuclear Information System (INIS)

    Halme, Ville-Juhani

    2015-01-01

    Posiva is preparing geological final disposal in the Finnish bedrock in Olkiluoto, Eurajoki. The final disposal facility includes encapsulation plant and underground repository. Most of the main civil structures are concrete structures. STUK is the supervising authority in civil structures. The National Building Code of Finland and STUK's Regulatory Guide on nuclear safety (YVL) are the most important instructions when constructing concrete structures into nuclear installation. Posiva has classified concrete structures in two classes according STUK's YVL-guidance: EYT (non-nuclear) and Safety Class 3 (SC 3, nuclear safety significance). When building SC 3 concrete structures, specific protocol must be followed. Protocol includes planned routines for design, construction, supervision, quality control (QC) and quality assurance (QA) activities. Documents relating concrete structures must be approved by Posiva and STUK before construction work. After structures have been designed and actual building is ongoing, there are two main steps. Before concreting, readiness inspection for concreting must be arranged. Readiness inspection will be arranged according to a specific plan and the date must be informed to STUK. After establishing readiness for concreting, casting work can begin. Once concrete structures are done, inspected and approved, final documentation according to a quality control plan will be reviewed by Posiva. After Posiva's approval, final documentation will be sent for STUK's approval. In the end STUK will give the permission for commissioning of the concrete structures after approved commissioning inspection. The document is made up of an abstract and a poster

  3. Damage detection in concrete structures with smart piezoceramic transducers

    Science.gov (United States)

    Naidu, Akshay S. K.; Bhalla, Suresh

    2003-10-01

    Detection of damages and progressive deterioration in structures is a critical issue. Visual inspections are tedious and unreliable. Incipient damages are often not discernible by low frequency dynamic response and other NDE techniques. Smart piezoelectric ceramic (PZT) transducers are emerging as an effective alternative in health monitoring of structures. The electro-mechanical impedance method employs the self-actuating and sensing characteristics of the PZT, without having to use actuators and sensors separately. When excited by an ac source, the PZT transducers bonded to the host structure activates the higher modes of vibration locally. Changes in the admittance response of the transducer serves as an indicator of damage around the transducer. In this paper, the effectiveness of PZT transducers for characterizing damages in concrete, in terms of the damage extent and location, is experimentally examined. The root mean square deviation (RMSD) index, adopted to quantify the changes in the admittance signatures, correlates with the damage extent. The damages on the surface that is not mounted by the PZT are also discernible. An array of transducers proves effective in detecting the damaged zone. The progressive incipient crack can be detected much before it actually becomes visible to the naked eye.

  4. Tests and calculation of the seismic behaviour of concrete structures

    International Nuclear Information System (INIS)

    Gauvain, J.; Hoffman, A.; Jeandidier, C.; Livolant, M.

    1979-01-01

    This paper deals with the frame type buildings, which are generally the most sensible to earthquakes. Its objectives are to describe the main phenomena governing the behaviour of such structures, when the earthquake level increases up to the structure collapse, to point out what type of calculation model shall be used to obtain good results and to give an estimation of the safety factors corresponding to the usual design practice. Extended experimental research on the behaviour of reinforced concrete beams and frames submitted to monotonic or cyclic loading has been done. These tests are very useful to build constitutive laws models, but as they do not reproduce the earthquake loads, they do not simulate directly what happens to the structure during an earthquake. For that reason, since 1966, dynamics tests were performed using vibration generators or shaking-tables. As an example of that type of test and of the corresponding results, we describe here with more details the tests made at the Saclay Center, on a shaking-table called VESUVE, on simple beams and frames

  5. Structural health monitoring for DOT using magnetic shape memory alloy cables in concrete

    Science.gov (United States)

    Davis, Allen; Mirsayar, Mirmilad; Sheahan, Emery; Hartl, Darren

    2018-03-01

    Embedding shape memory alloy (SMA) wires in concrete components offers the potential to monitor their structural health via external magnetic field sensing. Currently, structural health monitoring (SHM) is dominated by acoustic emission and vibration-based methods. Thus, it is attractive to pursue alternative damage sensing techniques that may lower the cost or increase the accuracy of SHM. In this work, SHM via magnetic field detection applied to embedded magnetic shape memory alloy (MSMA) is demonstrated both experimentally and using computational models. A concrete beam containing iron-based MSMA wire is subjected to a 3-point bend test where structural damage is induced, thereby resulting in a localized phase change of the MSMA wire. Magnetic field lines passing through the embedded MSMA domain are altered by this phase change and can thus be used to detect damage within the structure. A good correlation is observed between the computational and experimental results. Additionally, the implementation of stranded MSMA cables in place of the MSMA wire is assessed through similar computational models. The combination of these computational models and their subsequent experimental validation provide sufficient support for the feasibility of SHM using magnetic field sensing via MSMA embedded components.

  6. Structure soil structure interaction effects: Seismic analysis of safety related collocated concrete structures

    International Nuclear Information System (INIS)

    Joshi, J.R.

    2000-01-01

    The Process, Purification and Stack Buildings are collocated safety related concrete shear wall structures with plan dimensions in excess of 100 feet. An important aspect of their seismic analysis was the determination of structure soil structure interaction (SSSI) effects, if any. The SSSI analysis of the Process Building, with one other building at a time, was performed with the SASSI computer code for up to 50 frequencies. Each combined model had about 1500 interaction nodes. Results of the SSSI analysis were compared with those from soil structure interaction (SSI) analysis of the individual buildings, done with ABAQUS and SASSI codes, for three parameters: peak accelerations, seismic forces and the in-structure floor response spectra (FRS). The results may be of wider interest due to the model size and the potential applicability to other deep soil layered sites. Results obtained from the ABAQUS analysis were consistently higher, as expected, than those from the SSI and SSSI analyses using the SASSI. The SSSI effect between the Process and Purification Buildings was not significant. The Process and Stack Building results demonstrated that under certain conditions a massive structure can have an observable effect on the seismic response of a smaller and less stiff structure

  7. Strategy for 100-year life of the ACR-1000 concrete containment structure

    International Nuclear Information System (INIS)

    Abrishami, H.; Elgohary, M.

    2006-01-01

    The purpose of this paper is to present the Plant Life Management (PLiM) strategy for the concrete containment structure of the ACR-1000 (Advanced CANDU Reactor) designed by AECL. The ACR-1000 is designed for 100-year plant life including 60-year operating life and additional 40-year decommissioning period of time. The approach adopted for the PLiM strategy of the concrete containment structure is a preventive one, key areas being: 1) design methodology, 2) material performance and 3) life cycle management and ageing management program. In the design phase, in addition to strength and serviceability, durability is a major requirement during the service life and decommissioning phase of the ACR structure. Parameters affecting durability design include: a) concrete performance, b) structural application, and c) environmental conditions. Due to the complex nature of the environmental effects acting on structures during the service life of project, it is considered that true improved performance during the service life can be achieved by improving the material characteristics. Many recent innovations in advanced concrete materials technology have made it possible to produce modern concrete such as high-performance concrete with exceptional performance characteristics. In this paper, the PLiM strategy for the ACR-1000 concrete containment is presented. In addition to addressing the design methodology and material performance areas, a systematic approach for ageing management program for the concrete containment structure is presented. (author)

  8. Study on the influence of Alkali-Silica reaction on structural behavior of reinforced concrete members

    International Nuclear Information System (INIS)

    Murazumi, Y.; Watanabe, Y.; Matsumoto, N.; Mitsugi, S.; Takiguchi, K.; Masuda, Y.

    2005-01-01

    Expansion produced by alkali-silica reaction (ASR) has been observed in the turbine generator foundation of the unit 1, Ikata nuclear power station, Japan. The foundation is a reinforced concrete frame structure. This paper, as a part of the series of investigation and experiments, discusses tests on structural behavior of concrete members affected by ASR. The purpose of the study is to obtain experimental results on the effects of ASR on bending and shear behavior of reinforced concrete beams and shear walls, and compare with the calculated results by present evaluation methods for normal concrete structures For the experiments on bending/shear behavior of beam, bending test models with a small amount of rebar and shear test models with larger amount were made of concrete in which ASR was induced by adding alkali or concrete without ASR. It was found from the results that bending strength of the bending test models and shear strength of the shear test models did not fall, nor was it lower than the calculated strength for concrete members without ASR. In the shear wall test, the two test models were made of either concrete with ASR or one without it. Horizontal load was applied with actuators on the test model fixed on the test floor, while vertical load was applied with oil jacks. The results did not indicate that ASR lowered the stiffness or strength of the wall test models, showing the strength was able to be calculated with the same formula for reinforced concrete wall without ASR. (authors)

  9. Proceedings of the NEA workshop on development priorities for NDE of concrete structures in nuclear plants

    International Nuclear Information System (INIS)

    1998-01-01

    The first session's objectives of this conference were to identify the perspectives of national regulators and plant operators on what is required of NDE. The second session objectives were to provide opportunity for NDE practitioners to share experience and views on the status of development of key NDE techniques: tomographic imaging for investigation of concrete structures, four examples of modern NDE techniques applied to the investigation of nuclear and non-nuclear concrete structures and a vision of future improvements, investigating concrete structures by 3D Radar imaging and imaging using mechanical impact, synopsis NDT of concrete using ultrasonics and radar. The third session objectives were to prioritise development of NDE techniques for safety related concrete structures in nuclear installations: key conclusions from earlier sessions, proposed priorities and next steps

  10. The study on the mechanical characteristics of concrete of nuclear reactor containment structure

    International Nuclear Information System (INIS)

    Jung, W. S.; Kwon, K. J.; Cho, M. S.; Song, Y. C.

    2000-01-01

    Reactor containment structure of nuclear power plant designed by prestressed concrete causes time-dependent prestress loss due to the mechanical characteristics of concrete. Prestress loss strongly affects to the safety factor of structure under the circumstances of designing, construction and inspection. Thus, this study is to investigate the mechanical characteristics of reactor containment concrete structure of Yonggwang No. 5 and 6. In this study, the compressive strength, modulus of elasticity, poisson's ratio and creep test followed by ASTM code are performed to investigate the mechanical characteristics of concrete made by V type cement. Additionally, since creep causes more time-dependent prestress loss than the other, the measurement value from the creep test is compared with the results from the creep prediction equations by KSCE, JSCE, Hansen, ACI and CEB-FIP model for the effective application. Hereafter, the results of this study may enable to assist the calculation effective stress considering time-dependent prestress loss of the prestressed concrete structures

  11. Survey of Experience Using Reinforced Concrete in Floating Marine Structures.

    Science.gov (United States)

    1983-01-01

    analyzed in several steps. The load history can be simulated by .. using load increments and independent load vectors . 4.31 NTH is not only active in...NILSEN, N., " FEILD TEST OF REINFORCEMENT CORROSION IN CONCRETE", PERFORMANCE OF CONCRETE IN MARINE ENVIRONMENT, ACI SPECIAL PUBLICATION SP-65, 1980. 136

  12. History of service life design of concrete structures

    NARCIS (Netherlands)

    Siemes, A.J.M.

    1999-01-01

    After the introduction of reinforced concrete it was believed that the material was extremely durable. Soon it was found that reinforced concrete could have serious durability problems and that special care should be taken to avoid them. Durability became a design issue. Based on experience from

  13. A risk management process for reinforced concrete structures by coupling modelling, monitoring and Bayesian approaches

    International Nuclear Information System (INIS)

    Capra, Bruno; Li, Kefei; Wolff, Valentin; Bernard, Olivier; Gerard, Bruno

    2004-01-01

    The impact of steel corrosion on the durability of reinforced concrete structures has since a long time been a major concern in civil engineering. The main electrochemical mechanisms of the steel corrosion are know well known. The material and structure degradation is attributed to the progressive formation of an expansive corrosion product at the steel-concrete interface. To assess quantitatively the structure lifetime, a two-stage service life model has been accepted widely. So far, the research attention is mainly given to the corrosion in an un-cracked concrete. However. practically one is often confronted to the reinforcement corrosion in an already cracked concrete. How to quantify the corrosion risk is of great interest for the long term durability of these cracked structures. To this end, this paper proposes a service life modeling for the corrosion process by carbonation in a cracked or un-cracked concrete depending on the observation or monitoring data available. Some recent experimental investigations are used to calibrate the models. Then, the models are applied to a shell structure to quantify the corrosion process and determine the optimal maintenance strategy. As corrosion processes are very difficult to model and subjected to material and environmental random variations, an example of structure reassessment is presented taking into account in situ information by the mean of Bayesian approaches. The coupling of monitoring, modelling and updating leads to a new global maintenance strategy of infrastructure. In conclusion: This paper presents an unified methodology coupling predictive models, observations and Bayesian approaches in order to assess the degradation degree of an ageing structure. The particular case of corrosion is treated on an innovative way by the development of a service life model taking into account cracking effects on the kinetics of the phenomena. At a material level, the dominant factors are the crack opening and the crack nature

  14. Bond slip model for the simulation of reinforced concrete structures

    International Nuclear Information System (INIS)

    Casanova, A.; Jason, L.; Davenne, L.

    2012-01-01

    This paper presents a new finite element approach to model the steel-concrete bond effects. This model proposes to relate steel, represented by truss elements, with the surrounding concrete in the case where the two meshes are not necessary coincident. The theoretical formulation is described and the model is applied on a reinforced concrete tie. A characteristic stress distribution is observed, related to the transfer of bond forces from steel to concrete. The results of this simulation are compared with a computation in which a perfect relation between steel and concrete is supposed. It clearly shows how the introduction of the bond model can improve the description of the cracking process (finite number of cracks). (authors)

  15. Explosive Spalling of Fire Exposed Resource Saving Concrete Structures

    DEFF Research Database (Denmark)

    Sørensen, Lars Schiøtt; Hertz, Kristian Dahl; Kristiansen, Finn Harken

    2003-01-01

    The paper describes briefly a new test facility, which has been developed within the project “Resource Saving Concrete Structures”, also called “Green Concrete” and some test results from the project. A full report is available from the home page of the Department of Civil Engineering Kristiansen......, Hertz, Sørensen [1]. The main idea was to establish a test method by means of which it should be possible to assess whether a particular concrete has an increased risk of spalling compared to traditional concretes as defined in Hertz [2] and only using ordinary standard cylinders as test specimens....... The method has been applied on the green concretes of the project and later also as a first indicator in other projects. The method appears to be a valuable tool for the first investigation of new concretes...

  16. An Experimental Investigation On Minimum Compressive Strength Of Early Age Concrete To Prevent Frost Damage For Nuclear Power Plant Structures In Cold Climates

    International Nuclear Information System (INIS)

    Koh, Kyungtaek; Kim, Dogyeum; Park, Chunjin; Ryu, Gumsung; Park, Jungjun; Lee, Janghwa

    2013-01-01

    Concrete undergoing early frost damage in cold weather will experience significant loss of not only strength, but also of permeability and durability. Accordingly, concrete codes like ACI-306R prescribe a minimum compressive strength and duration of curing to prevent frost damage at an early age and secure the quality of concrete. Such minimum compressive strength and duration of curing are mostly defined based on the strength development of concrete. However, concrete subjected to frost damage at early age may not show a consistent relationship between its strength and durability. Especially, since durability of concrete is of utmost importance in nuclear power plant structures, this relationship should be imperatively clarified. Therefore, this study verifies the feasibility of the minimum compressive strength specified in the codes like ACI-306R by evaluating the strength development and the durability preventing the frost damage of early age concrete for nuclear power plant. The results indicate that the value of 5 MPa specified by the concrete standards like ACI-306R as the minimum compressive strength to prevent the early frost damage is reasonable in terms of the strength development, but seems to be inappropriate in the viewpoint of the resistance to chloride ion penetration and freeze-thaw. Consequently, it is recommended to propose a minimum compressive strength preventing early frost damage in terms of not only the strength development, but also in terms of the durability to secure the quality of concrete for nuclear power plants in cold climates

  17. An Experimental Investigation On Minimum Compressive Strength Of Early Age Concrete To Prevent Frost Damage For Nuclear Power Plant Structures In Cold Climates

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Kyungtaek; Kim, Dogyeum; Park, Chunjin; Ryu, Gumsung; Park, Jungjun; Lee, Janghwa [Korea Institute Construction Technology, Goyang (Korea, Republic of)

    2013-06-15

    Concrete undergoing early frost damage in cold weather will experience significant loss of not only strength, but also of permeability and durability. Accordingly, concrete codes like ACI-306R prescribe a minimum compressive strength and duration of curing to prevent frost damage at an early age and secure the quality of concrete. Such minimum compressive strength and duration of curing are mostly defined based on the strength development of concrete. However, concrete subjected to frost damage at early age may not show a consistent relationship between its strength and durability. Especially, since durability of concrete is of utmost importance in nuclear power plant structures, this relationship should be imperatively clarified. Therefore, this study verifies the feasibility of the minimum compressive strength specified in the codes like ACI-306R by evaluating the strength development and the durability preventing the frost damage of early age concrete for nuclear power plant. The results indicate that the value of 5 MPa specified by the concrete standards like ACI-306R as the minimum compressive strength to prevent the early frost damage is reasonable in terms of the strength development, but seems to be inappropriate in the viewpoint of the resistance to chloride ion penetration and freeze-thaw. Consequently, it is recommended to propose a minimum compressive strength preventing early frost damage in terms of not only the strength development, but also in terms of the durability to secure the quality of concrete for nuclear power plants in cold climates.

  18. 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%

  19. Finite element analysis of smart reinforced concrete beam with super elastic shape memory alloy subjected to static loading for seismic mitigation

    Science.gov (United States)

    Hamid, Nubailah Abd; Ismail, Muhammad Hussain; Ibrahim, Azmi; Adnan, Azlan

    2018-05-01

    Reinforced concrete beam has been among major applications in construction nowadays. However, the application of nickel titanium alloy as a replacement for steel rebar in reinforced concrete beam is a new approach nowadays despite of their ability to undergo large deformations and return to their undeformed shape by removal of stresses. In this paper, the response of simply supported reinforced concrete (RC) beams with smart rebars, control beam subjected to static load has been numerically studied, and highlighted, using finite element method (FEM) where the material employed in this study is the superelastic shape memory alloys (SESMA). The SESMA is a unique alloy that has the ability to undergo large deformations and return to their undeformed shape by removal of stresses. The size of the analysed beam is 125 mm × 270 mm × 2800 mm with 2 numbers of 12 mm diameter bars as main reinforcement for compression and 12 numbers of 12 as tension or hanger bars while 6 mm diameter at 100 mm c/c used as shear reinforcement bars respectively. The concrete was modelled using solid 65 element (in ANSYS) and rebars were modelled using beam 188 elements (in ANSYS). The result for reinforced concrete with nickel titanium alloy rebar is compared with the result obtained for reinforced concrete beam with steel rebar in term of flexural behavior, load displacement relationship, crack behaviour and failure modes for various loading conditions starting from 10kN to 100kN using 3D FE modelling in ANSYS v 15. The response and result obtained from the 3D finite element analysis used in this study is load-displacement curves, residual displacements, Von-Misses, strain and stiffness are suitable for the corresponding result showed a satisfactory performance in the structural analysis. Resultant displacement, Von-Mises stress and maximum strain were influenced by the factors of the material properties, load increments and the mesh size. Nickel titanium alloy was superior to the

  20. Model - including thermal creep effects - for the analysis of three-dimensional concrete structures

    International Nuclear Information System (INIS)

    Rodriguez, C.; Rebora, B.; Favrod, J.D.

    1979-01-01

    This article presents the most recent developments and results of research carried out by IPEN to establish a mathematical model for the non-linear rheological three-dimensional analysis of massive prestressed concrete structures. The main point of these latest developments is the simulation of the creep of concrete submitted to high temperatures over a long period of time. This research, financed by the Swiss National Science Foundation, has taken an increased importance with the advent of nuclear reactor vessels of the HHT type and new conceptions concerning the cooling of their concrete (replacement of the thermal insulation by a zone of hot concrete). (orig.)

  1. A 3D analysis of reinforced concrete structures by the finite element method

    International Nuclear Information System (INIS)

    Claure, J.D.; Campos Filho, A.

    1995-01-01

    Fundamental features of a computational model, based on the finite element methods, for the analysis of concrete structure are presented. The study comprehends short and long-term loading situations, where creep and shrinkage in concrete are considered. The reinforcement is inserted in the finite element model using an embedded model. A smeared crack model is used for the concrete cracking, which considers the contribution of concrete between cracks and allows the closing the cracks closing. The computational code MPGS (Multi-Purpose Graphic System) is used, to make easy the analysis and interpretation of the numeric results. (author). 8 refs., 4 figs

  2. Development of a low activation concrete shielding wall by multi-layered structure for a fusion reactor

    International Nuclear Information System (INIS)

    Sato, Satoshi; Maegawa, Toshio; Yoshimatsu, Kenji; Sato, Koichi; Nonaka, Akira; Takakura, Kosuke; Ochiai, Kentaro; Konno, Chikara

    2011-01-01

    A multi-layered concrete structure has been developed to reduce induced activity in the shielding for neutron generating facilities such as a fusion reactor. The multi-layered concrete structure is composed of: (1) an inner low activation concrete, (2) a boron-doped low activation concrete as the second layer, and (3) ordinary concrete as the outer layer of the neutron shield. With the multi-layered concrete structure the volume of boron is drastically decreased compared to a monolithic boron-doped concrete. A 14 MeV neutron shielding experiment with multi-layered concrete structure mockups was performed at FNS and several reaction rates and induced activity in the mockups were measured. This demonstrated that the multi-layered concrete effectively reduced low energy neutrons and induced activity.

  3. Development of laboratory acceleration test method for service life prediction of concrete structures

    International Nuclear Information System (INIS)

    Cho, M. S.; Song, Y. C.; Bang, K. S.; Lee, J. S.; Kim, D. K.

    1999-01-01

    Service life prediction of nuclear power plants depends on the application of history of structures, field inspection and test, the development of laboratory acceleration tests, their analysis method and predictive model. In this study, laboratory acceleration test method for service life prediction of concrete structures and application of experimental test results are introduced. This study is concerned with environmental condition of concrete structures and is to develop the acceleration test method for durability factors of concrete structures e.g. carbonation, sulfate attack, freeze-thaw cycles and shrinkage-expansion etc

  4. Method on the aging evaluation in nuclear power plant concrete structures

    International Nuclear Information System (INIS)

    Kitsutaka, Yoshinori; Tsukagoshi, Masayuki

    2014-01-01

    In this paper, method on the durability evaluation in nuclear power plant concrete structures was investigated. In view of the importance of evaluating the degree of deterioration of reinforced concrete structures, relationships should be formulated among the number of years elapsed, t, the amount of action of a deteriorative factor, F, the degree of material deterioration, D, and the performance of the structure, P. Evaluation by PDFt diagrams combining these relationships may be effective. A detailed procedure of durability evaluation for a reinforced concrete structure using PDFt concept is presented for the deterioration factors of thermal effect, irradiation, neutralization and penetration of salinity by referring to the recent papers

  5. Biaxial failure criteria and stress-strain response for concrete of containment structure

    International Nuclear Information System (INIS)

    Lee, S. K.; Woo, S. K.; Song, Y. C.; Kweon, Y. K.; Cho, C. H.

    2001-01-01

    Biaxial failure criteria and stress-strain response for plain concrete of containment structure on nuclear power plants are studied under uniaxial and biaxial stress(compression-compression, compression-tension, and tension-tension combined stress). The concrete specimens of a square plate type are used for uniaxial and biaxial loading. The experimental data indicate that the strength of concrete under biaxial compression, f 2 /f 1 =-1/-1, is 17 percent larger than under uniaxial compression and the poisson's ratio of concrete is 0.1745. On the base of the results, a biaxial failure envelope for plain concrete that the uniaxial strength is 5660 psi are provided, and the biaxial failure behaviors for three biaxial loading areas are plotted respectively. And, various analytical equations having the reliability are proposed for representations of the biaxial failure criteria and stress-strain response curves of concrete

  6. Importance of modeling beam-column joints for seismic safety of reinforced concrete structures

    International Nuclear Information System (INIS)

    Sharma, Akanshu; Reddy, G.R.; Vaze, K.K.; Eligehausen, R.; Hofmann, J.

    2011-01-01

    Almost all structures, except the containment building, in a NPP can be classified as reinforced concrete (RC) framed structures. In case of such structures subjected to seismic loads, beam-column joints are recognized as the critical and vulnerable zone. During an earthquake, the global behavior of the structure is highly governed by the behavior of the joints. If the joints behave in a ductile manner, the global behavior generally will be ductile, whereas if the joints behave in a brittle fashion then the structure will display a brittle behavior. The joints of old and non-seismically detailed structures are more vulnerable and behave poorly under the earthquakes compared to the joints of new and seismically detailed structures. Modeling of these joint regions is very important for correct assessment of the seismic performance of the structures. In this paper, it is shown with the help of a recently developed joint model that not modeling the inelastic behavior of the joints can lead to significantly misleading and unsafe results in terms of the performance assessment of the structures under seismic loads. Comparison of analytical and experimental results is shown for two structures, tested under lateral monotonic seismic pushover loads. It is displayed that the model can predict the inelastic seismic response of structures considering joint distortion with high accuracy by little extra effort in modeling. (author)

  7. The behavior of reinforced concrete barriers subjected to the impact of tornado generated deformable missiles

    International Nuclear Information System (INIS)

    McMahon, P.M.; Meyers, B.L.; Buchert, K.P.

    1977-01-01

    The paper presents a general model for the evaluation of local effects damage including, penetration and backface spalling, of reinforced concrete barriers subjected to the impact of deformable tornado generated missiles. The model is based on an approximte force time history which assumes: 1) the initial penetration of the missile occurs without significant deformation of the missile if the strength of the missile is greater than that of the barrier. This portion of the time history is represented by a linear and finite rise time; 2) wrinkling or collapse of the missile occurs when the critical stress of the missile is exceeded. This portion of the time histroy is represented by a constant force-time relationship, although a decreaseing force might be more accurate; 3) while the missile is penetrating and wrinkling both elastic and plastic stress waves are developed in the missile, and compressive and shear stress waves are generated in he target. When the shear waves reach the backface of the slab, doagonal cracks initiating at the end of the penetrating missile are formed. These cracks propagate to the backface reinforcing where splitting cracks are formed. Finally, yield hinge lines form in the plane of reinforcing; 4) repenetration of the missile occurs after the wrinkling has caused a change in missile cross section. This repenetration results from moving the failure cone described in three above, and is also represented by the costant force time history. Using the assumptions, relationships for the penetration depth of the missile the wrinkling length of the missile, the critical missile stress, the time history of the impact and the spalling of the target are developed. (Auth.)

  8. Sub-Frequency Interval Approach in Electromechanical Impedance Technique for Concrete Structure Health Monitoring

    Directory of Open Access Journals (Sweden)

    Bahador Sabet Divsholi

    2010-12-01

    Full Text Available The electromechanical (EM impedance technique using piezoelectric lead zirconate titanate (PZT transducers for structural health monitoring (SHM has attracted considerable attention in various engineering fields. In the conventional EM impedance technique, the EM admittance of a PZT transducer is used as a damage indicator. Statistical analysis methods such as root mean square deviation (RMSD have been employed to associate the damage level with the changes in the EM admittance signatures, but it is difficult to determine the location of damage using such methods. This paper proposes a new approach by dividing the large frequency (30–400 kHz range into sub-frequency intervals and calculating their respective RMSD values. The RMSD of the sub-frequency intervals (RMSD-S will be used to study the severity and location of damage. An experiment is carried out on a real size concrete structure subjected to artificial damage. It is observed that damage close to the PZT changes the high frequency range RMSD-S significantly, while the damage far away from the PZT changes the RMSD-S in the low frequency range significantly. The relationship between the frequency range and the PZT sensing region is also presented. Finally, a damage identification scheme is proposed to estimate the location and severity of damage in concrete structures.

  9. 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.

  10. 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.

  11. Concrete structural analysis tools and properties for Hanford site waste tank evaluation

    International Nuclear Information System (INIS)

    Moore, C.J.; Peterson, W.S.; Winkel, B.V.; Weiner, E.O.

    1995-09-01

    As Hanford Site Contractors address maintenance and future structural demands on nuclear waste tanks built as early as 1943, it is necessary to address their current safety margins and ensure safe margins are maintained. Although the current civil engineering practice has building codes for reinforced concrete design guidelines, the tanks were not constructed to today's building codes and future demands potentially result in loads and modifications to the tanks that are outside the original design basis and current practice. The Hanford Site engineering staff has embraced nonlinear finite-element modeling of concrete in an effort to obtain a more accurate understanding of the actual tank margins. This document brings together and integrates past Hanford Site nonlinear reinforced concrete analysis methods, past Hanford Site concrete testing, public domain research testing, and current concrete research directions. This document, including future revisions, provides the structural engineering overview (or survey) for a consistent, accurate approach to nonlinear finite-element modeling of reinforced concrete for Hanford Site waste storage tanks. This report addresses concrete strength and modulus degradation with temperature, creep, shrinkage, long-term sustained loads, and temperature degradation of rebar and concrete bonds. Recommendations are given for parameter studies and evaluation techniques for review of nonlinear finite-element analysis of concrete

  12. Stress-based topology optimization of concrete structures with prestressing reinforcements

    Science.gov (United States)

    Luo, Yangjun; Wang, Michael Yu; Deng, Zichen

    2013-11-01

    Following the extended two-material density penalization scheme, a stress-based topology optimization method for the layout design of prestressed concrete structures is proposed. The Drucker-Prager yield criterion is used to predict the asymmetrical strength failure of concrete. The prestress is considered by making a reasonable assumption on the prestressing orientation in each element and adding an additional load vector to the structural equilibrium function. The proposed optimization model is thus formulated as to minimize the reinforcement material volume under Drucker-Prager yield constraints on elemental concrete local stresses. In order to give a reasonable definition of concrete local stress and prevent the stress singularity phenomenon, the local stress interpolation function and the ɛ -relaxation technique are adopted. The topology optimization problem is solved using the method of moving asymptotes combined with an active set strategy. Numerical examples are given to show the efficiency of the proposed optimization method in the layout design of prestressed concrete structures.

  13. Connecting to concrete: wireless monitoring of chloride ions in concrete structures

    NARCIS (Netherlands)

    Abbas, Yawar; ten Have, Bas; Hoekstra, Gerrit I.; Douma, Arjan; de Bruijn, Douwe; Olthuis, Wouter; van den Berg, Albert

    2015-01-01

    For the first time, chloride ions are measured wirelessly in concrete. The half-cell potential of a silver/silver chloride (Ag/AgCl) electrode, which corresponds to the concentration of chloride ions, is measured wirelessly. The sensor system (the Ag/AgCl and a reference electrode) is embedded in

  14. Material model for non-linear finite element analyses of large concrete structures

    NARCIS (Netherlands)

    Engen, Morten; Hendriks, M.A.N.; Øverli, Jan Arve; Åldstedt, Erik; Beushausen, H.

    2016-01-01

    A fully triaxial material model for concrete was implemented in a commercial finite element code. The only required input parameter was the cylinder compressive strength. The material model was suitable for non-linear finite element analyses of large concrete structures. The importance of including

  15. General requirements for concrete containment structures for CANDU nuclear power plants

    International Nuclear Information System (INIS)

    1993-07-01

    This standard provides the general requirements used in the design, construction, testing, and commissioning of concrete containment structures for CANDU nuclear power plants designated as class containment and is directed to the owners, designers, manufacturers, fabricators, and constructors of the concrete components and parts

  16. A degradation model for stray current induced corrosion in underground reinforced concrete structures

    NARCIS (Netherlands)

    Polder, R.B.; Peelen, W.H.A.

    2003-01-01

    This paper describes the effects of stray currents on durability and reinforcement corrosion of underground concrete structures. Cathodic protection of underground pipelines are stationary sources of stray current interference with concrete, and rail traction systems are non-stationary sources. The

  17. PHYSICAL AND CHEMICAL PRINCIPLES OF REPAIR TECHNOLOGY PERTAINING TO REINFORCED CONCRETE STRUCTURES

    Directory of Open Access Journals (Sweden)

    S. N. Leonovich

    2008-01-01

    Full Text Available The paper presents a brief review of new methods for repair of concrete and reinforced concrete products, structures etc. The review demonstrates that the usage of diffusion processes proceeding in the porous materials makes it possible to obtain positive effects while performing  repair works. 

  18. Realisation of complex precast concrete structures through the integration of algorithmic design and novel fabrication techniques

    DEFF Research Database (Denmark)

    Larsen, Niels Martin; Egholm Pedersen, Ole; Pigram, Dave

    2012-01-01

    This paper describes a novel method for constructing complex concrete structures from small-scale individualized elements. The method was developed through the investigation of laser cutting, folding and concrete casting in PETG plastic sheets and funicular grid shell simulations as a generator o...

  19. Working life of cathodic protection systems for concrete structures - Analysis of field data

    NARCIS (Netherlands)

    Polder, R.B.; Leegwater, G.; Worm, D.; Courage, W.

    2012-01-01

    Corrosion of reinforcing steel in concrete structures causes concrete cracking, steel diameter reduction and eventually loss of safety. In infrastructure this is mainly due to penetration of chloride ions from de-icing or marine salts. Conventional repair means heavy, labour intensive and costly

  20. Service life and life cycle cost modelling of cathodic protection systems for concrete structures

    NARCIS (Netherlands)

    Polder, R.B.; Leegwater, G.; Worm, D.; Courage, W.

    2012-01-01

    Corrosion of reinforcing steel in concrete structures causes concrete cracking, steel diameter reduction and eventually loss of safety. In infrastructure this is mainly due to penetration of chloride ions from de-icing or marine salts. Conventional repair means heavy, labour intensive and costly

  1. Design of concrete structures for durability. Example: Chloride penetration in the lining of a bored tunnel

    NARCIS (Netherlands)

    Siemes, A.J.M.

    1998-01-01

    The present design method for durability of concrete is based on a set of rules that give no objective in-sight in the service life to expect from the concrete structure. An objective comparison between different durability measures is therefor not possible. Especially if the lack of durability can

  2. 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.

  3. Effect Of Age And Concrete Cover Thickness On Steel Reinforcement Corrosion At Splash Zone In Reinforced Concrete Hydraulic Structures

    Directory of Open Access Journals (Sweden)

    Nada M. Al- Galawi

    2015-08-01

    Full Text Available Corrosion of reinforcing steel bars in reinforced concrete is considered as one of the biggest problems that face countries overlooking to the Arabian Gulf including Iraq. The research aims to study the effect of the corrosion of steel bars in concrete structures that are exposed to wetting and drying via waves. Reinforced concrete samples were exposed to marine simulated environment for 90 days using prepared system for this purpose. At the end of exposure period polarization test was implemented to measure the actual corrosion rate in each sample. After that the corrosion process was accelerated using impressed current technique by applying a constant electric current DC to the reinforcing bars. Depending on the corrosion current in natural conditions which was measured in polarization test periods of exposing samples to accelerated corrosion current so as to maintain virtual exposure ages of 5 and 25 years of exposure to natural corrosion were calculated. The results showed a remarkable increase in the corrosion current of steel bars in samples that had lower concrete cover thickness. The increase in the cover thickness from 20mm to 40 and 65 mm had a significant effect on reducing the corrosion current at the age of 90 days to about 70 of its original value in both cases. At the virtual exposure age of 5 years the reduction percentage in the corrosion current resulted from increasing cover thickness from 20mm to 40 and 65 mm were 43 and 79 respectively.

  4. 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.

  5. Reliability-based design code calibration for concrete containment structures

    International Nuclear Information System (INIS)

    Han, B.K.; Cho, H.N.; Chang, S.P.

    1991-01-01

    In this study, a load combination criteria for design and a probability-based reliability analysis were proposed on the basis of a FEM-based random vibration analysis. The limit state model defined for the study is a serviceability limit state of the crack failure that causes the emission of radioactive materials, and the results are compared with the case of strength limit state. More accurate reliability analyses under various dynamic loads such as earthquake loads were made possible by incorporating the FEM and random vibration theory, which is different from the conventional reliability analysis method. The uncertainties in loads and resistance available in Korea and the references were adapted to the situation of Korea, and especially in case of earthquake, the design earthquake was assessed based on the available data for the probabilistic description of earthquake ground acceleration in the Korea peninsula. The SAP V-2 is used for a three-dimensional finite element analysis of concrete containment structure, and the reliability analysis is carried out by modifying HRAS reliability analysis program for this study. (orig./GL)

  6. Corrosion of reinforcing bars embedded in alkali-activated slag concrete subjected to chloride attack

    Directory of Open Access Journals (Sweden)

    William Aperador Chaparro

    2012-02-01

    Full Text Available Steel bar embedded in an alkali-activated slag (AAS concrete was tested under complete immersion, in 3.5% NaCl solution by weight of the slag. Ordinary Portland cement (OPC was also tested for comparative purposes and exposed to the same solution. Monitoring of open-circuit potential, polarization resistance measurement and electrochemical impedance spectroscopy (EIS were used to evaluate the corrosion behavior of steel bar. The corrosion resistances of AAS and OPC concretes were performed at 0, 3, 6, 9 and 12 months. Electrochemical measurements shows that AAS concrete presents passive corrosion behavior the first 3 months, after this period of time, it presents corrosion resistance decreased due to the chlorides presence at the steel/AAS interface. For 0 months immersion (28 days of curing the AAS and OPC concretes presented a 10% of corrosion probability. After 3 months of immersion the tested AAS and OPC concretes showed similar behavior, the active potentials in the range from "0.2 to "0.6 V vs. Cu/CuSO4, indicate a 90% probability of corrosion.

  7. Study on Seismic Behavior of Recycled Concrete Energy-efficient Homes Structure Wall

    Directory of Open Access Journals (Sweden)

    Dong Lan

    2016-01-01

    Full Text Available The main point is to study the seismic behavior of the lattice type recycled concrete energy saving wall under low-cyclic loading,to provide the basis for the seismic performance of application of recycled concrete lattice wall in energy-saving residential structure. Design two walls with the same structure measures, include Lattice type recycled concrete wall and natural concrete wall, they are tested under low-cycle repetitive loading, compared failure mode and seismic performance in different reinforcement conditions of side column. The bearing capacity and ductility of recycled aggregate concrete are better than natural aggregate concrete, The stiffness degradation curves and the skeleton curves of the walls are basically the same, both of them have better seismic energy dissipation capacity. Lattice type concrete wall is good at seismic performance, recycled aggregate concrete is good at plastic deformation ability, it is advantageous to seismic energy dissipation of wall, it can be applied in energy efficient residential structure wall.

  8. Overview of ORNL/NRC programs addressing durability of concrete structures

    International Nuclear Information System (INIS)

    Naus, D.J.; Oland, C.B.

    1994-01-01

    The role of reinforced concrete relative to its applications as either safety-related structures in nuclear power or engineered barriers of low-level radioactive waste disposal facilities is described. Factors that can affect the long-term durability of reinforced concrete are identified. Overviews are presented of the Structural Aging Program, which is addressing the aging management of safety-related concrete structures in nuclear power plants, and the Permeability Test Methods and Data Program, which is identifying pertinent data and information for use in performance assessments of engineered barriers for low-level radioactive waste disposal

  9. Effect of chloride-based deicers on reinforced concrete structures.

    Science.gov (United States)

    2012-07-01

    We conducted an extensive literature review and performed laboratory tests to assess the effect of chloride-based deicers on the rebars and dowel bars in concrete and to determine whether or not deicer corrosion inhibitors help preserve the transport...

  10. Corrosion of reinforcement bars in steel ibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Solgaard, Anders Ole Stubbe

    and the influence of steel fibres on initiation and propagation of cracks in concrete. Moreover, the impact of fibres on corrosion-induced cover cracking was covered. The impact of steel fibres on propagation of reinforcement corrosion was investigated through studies of their impact on the electrical resistivity...... of concrete, which is known to affect the corrosion process of embedded reinforcement. The work concerning the impact of steel fibres on initiation and propagation of cracks was linked to corrosion initiation and propagation of embedded reinforcement bars via additional studies. Cracks in the concrete cover...... are known to alter the ingress rate of depassivating substances and thereby influence the corrosion process. The Ph.D. study covered numerical as well as experimental studies. Electrochemically passive steel fibres are electrically isolating thus not changing the electrical resistivity of concrete, whereas...

  11. Leaching of concrete : the leaching process : extrapolation of deterioration : effect on the structural stability

    OpenAIRE

    Fagerlund, Göran

    2000-01-01

    The leaching process when water attacks concrete, and the effect of leaching on the strength and durability of a concrete structure, is analysed theoretically. Technique for prediction of the future leaching and structural stability is outlined. The analysis is to a certain extent supported by data from literature. The leaching process is divided in five different types: 1: Pure surface leaching 2: Surface leaching involving erosion 3: Homogeneous leaching over the entire structure 4...

  12. Structural performance evaluation on aging underground reinforced concrete structures. Part 5

    International Nuclear Information System (INIS)

    Matsumura, Takuro; Matsuo, Toyofumi; Miyagawa, Yoshinori

    2009-01-01

    When we evaluate the soundness of reinforced concrete structures, it is important to assess the chloride induced deterioration. We conducted the reinforcing steel corrosion tests of reinforced concrete specimens under simulated tidal environment of sea. Parameters of the tests were water cement ratio, cement type and crack width of concrete. Periods of the tests were eighty month. The obtained results were summarized at follows: (a) The chloride ion concentration at the initiation of reinforcing steel corrosion was about 3.0 kg/m 3 in case of reinforcing steel in non-crack concrete used ordinary cement. (b) The corrosion rate of reinforcing steels was almost constant at any cement type specimens after causing crack by reinforcing steel corrosion. (c) The corrosion rate of reinforcing steels in specimens, which caused cracks by bending load, increased as crack width. In the same type specimens, the corrosion rate of reinforcing steels in fly ash cement specimens was larger than that of ordinary cement specimens. In this case, the corrosion rate of reinforcing steels was evaluated about 0.18 mm/year. (author)

  13. Analytical capability for predicting structural response of NPP concrete containments to severe loads

    International Nuclear Information System (INIS)

    Planas, J.; Guinea, G.; Trbojevic, V.M.; Marti, J.; Martinez, F.; Cortes, P.

    1989-12-01

    A survey has been conducted on the state-of-the-art of analytical techniques for predicting the structural response of concrete containment buildings under severe accident conditions. The validity of inelastic analysis is often limited by the inadequacy of the material models adopted. This is specially true in the case of materials which undergo localization phenomena in the course of the deformation process. Because of this, the Joint Research Centre at Ispra has given a high priority to the review of existing constitutive models for concrete. Such models must be able to describe concrete behaviour with and without steel reinforcement across the complete stress range, from initial elastic behaviour to and beyond the point of failure. For reinforced and prestressed concrete, segregated models (where concrete and steel are independently simulated) are preferred. A review of existing constitutive models for mass concrete has been conducted. The review focused on necessary features for describing the near-peak and post-peak stages of deformation. Special attention was dedicated to the localization of strains in tension and the post-peak softening behaviour. Existing models for representing the concrete steel bond were also reviewed. These models are still relatively simplistic and incorporate seldom a number of effects of considerable importance: sustained, dynamic and cyclic loading, environmental effects, etc. Finally, the computational procedures currently available for modelling problems involving the ultimate capacity of concrete containments have also been reviewed. This includes methodologies for modelling amongst other mass concrete, cracking procedures, bond behaviour, in existing computer codes

  14. 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.

  15. A realistic structural analysis of the integrity of the liner of reinforced and prestressed concrete containments

    International Nuclear Information System (INIS)

    Buchhardt, F.; Brandl, P.

    1979-01-01

    The BWR Gundremmingen II is the first German nuclear power plant with a concrete containment having a thin steel plate liner directly attached to the interior concrete surface to provide an air-tight seal. Due to this monolithic way of anchorage a bonded system of concrete and metal liner membrane is obtained so that the same deformations of the loading or strain conditions are induced to the very stiff concrete hull as well as to the liner. Because of the complex structural behaviour of the bonded system the evaluation is carried out by the finite element method. The overall system is decoupled in several steps. Due to its considerable stiffness the concrete structure can be regarded as the liner supporting basis. The liner system itself might be subdivided into perfect and imperfect sections discretized by plain or curved elements which are supported by point-wise spring elements representing the stud anchors. (orig.)

  16. Structural-functional integrated concrete with macro-encapsulated inorganic PCM

    Science.gov (United States)

    Mohseni, Ehsan; Tang, Waiching; Wang, Zhiyu

    2017-09-01

    Over the last few years the application of thermal energy storage system incorporating phase change materials (PCMs) to foster productivity and efficiency of buildings energy has grown rapidly. In this study, a structural-functional integrated concrete was developed using macro-encapsulated PCM-lightweight aggregate (LWA) as partial replacement (25 and 50% by volume) of coarse aggregate in control concrete. The PCM-LWA was prepared by incorporation of an inorganic PCM into porous LWAs through vacuum impregnation. The mechanical and thermal performance of PCM-LWA concrete were studied. The test results revealed that though the compressive strength of concrete with PCM-LWA was lower than the control concrete, but ranged from 22.02 MPa to 42.88 MPa which above the minimum strength requirement for structural application. The thermal performance test indicated that macro-encapsulated PCM-LWA has underwent the phase change transition reducing the indoor temperature.

  17. Viscoelastic and thermal behavior of structural concrete with reference to containment vessels

    International Nuclear Information System (INIS)

    Stefanou, G.D.

    1981-01-01

    A method of numerical viscoelastic stress analysis is described suitable for concrete structures operating at elevated temperatures. The paper describes how approximate numerical methods of elastic analysis of the finite element type can be extended to incorporate the viscoelastic behavior of structural concrete of the quasi-static type. A new eight parameter viscoelastic model is proposed to represent concrete behavior in the loaded and unloaded stage. The deformational expressions for the proposed viscoelastic analogue are also developed. Finally, as a result of courve-fitting procedures, the evaluation of the creep law coefficients are obtained for creep laws appropriate to a test regime. The proposed method is of general application providing that the properties of concrete are assessed reasonably well. The analytical predictions are compared with experimental results obtained on concrete model specimens loaded for 3 1/2 months, at a temperature of 80 0 C. (author)

  18. Performance of asphaltic concrete incorporating styrene butadiene rubber subjected to varying aging condition

    Science.gov (United States)

    Salah, Faisal Mohammed; Jaya, Ramadhansyah Putra; Mohamed, Azman; Hassan, Norhidayah Abdul; Rosni, Nurul Najihah Mad; Mohamed, Abdullahi Ali; Agussabti

    2017-12-01

    The influence of styrene butadiene rubber (SBR) on asphaltic concrete properties at different aging conditions was presented in this study. These aging conditions were named as un-aged, short-term, and long-term aging. The conventional asphalt binder of penetration grade 60/70 was used in this work. Four different levels of SBR addition were employed (i.e., 0 %, 1 %, 3 %, and 5 % by binder weight). Asphalt concrete mixes were prepared at selected optimum asphalt content (5 %). The performance was evaluated based on Marshall Stability, resilient modulus, and dynamic creep tests. Results indicated the improving stability and permanent deformation characteristics that the mixes modified with SBR polymer have under aging conditions. The result also showed that the stability, resilient modulus, and dynamic creep tests have the highest rates compared to the short-term aging and un-aged samples. Thus, the use of 5 % SBR can produce more durable asphalt concrete mixtures with better serviceability.

  19. Activities in Support of Continuing the Service of Nuclear Power Plant Safety-Related Concrete Structures

    International Nuclear Information System (INIS)

    Naus, Dan J.

    2010-01-01

    Nuclear power plant concrete structures are described. In-service inspection and testing requirements in the U.S. are summarized. The license renewal process in the U.S. is outlined and its current status provided. Operating experience related to performance of the concrete structures is presented. Basic components of a program to manage aging of the concrete structures are identified and described: degradation mechanisms, damage models, and material performance; assessment and remediation (i.e., component selection, in-service inspection, non-destructive examinations, and remedial actions); and estimation of performance at present or some future point in time (i.e., application of structural reliability theory to the design and optimization of in-service inspection/maintenance strategies, and determination of the effects of degradation on plant risk). Finally, areas are noted where additional research would be of benefit to aging management of nuclear power plant concrete structures.

  20. An improved basis for evaluating continued service of Category I concrete structures in nuclear power plants

    International Nuclear Information System (INIS)

    Naus, D.J.; Oland, C.B.; Ellingwood, B.; Mori, Y.; Arndt, E.G.

    1992-01-01

    The Structural Aging (SAG) Program has the overall objective of preparing technical bases for regulatory criteria which will provide the NRC with potential structural safety issues and acceptance criteria for use in nuclear power plant evaluations for continued service. In meeting this objective three primary activities are underway: (1) development of a structural materials information center containing data and information on the variation of concrete and concrete-related material properties over time; (2) establishment of procedures to make quantitative evaluations of the presence, magnitude, and significance of environmental stressors or aging factors that can impact critical component performance, as well as techniques which can be used for repair of degraded concrete structures; and (3) formulation of a quantitative methodology for performing current condition assessments and making reliability-based life predictions of critical concrete structures in nuclear power plants. Accomplishments to date under each of these tasks are presented

  1. A Reusable PZT Transducer for Monitoring Initial Hydration and Structural Health of Concrete

    Science.gov (United States)

    Yang, Yaowen; Divsholi, Bahador Sabet; Soh, Chee Kiong

    2010-01-01

    During the construction of a concrete structure, strength monitoring is important to ensure the safety of both personnel and the structure. Furthermore, to increase the efficiency of in situ casting or precast of concrete, determining the optimal time of demolding is important for concrete suppliers. Surface bonded lead zirconate titanate (PZT) transducers have been used for damage detection and parameter identification for various engineering structures over the last two decades. In this work, a reusable PZT transducer setup for monitoring initial hydration of concrete and structural health is developed, where a piece of PZT is bonded to an enclosure with two bolts tightened inside the holes drilled in the enclosure. An impedance analyzer is used to acquire the admittance signatures of the PZT. Root mean square deviation (RMSD) is employed to associate the change in concrete strength with changes in the PZT admittance signatures. The results show that the reusable setup is able to effectively monitor the initial hydration of concrete and the structural health. It can also be detached from the concrete for future re-use. PMID:22399929

  2. A Reusable PZT Transducer for Monitoring Initial Hydration and Structural Health of Concrete

    Directory of Open Access Journals (Sweden)

    Yaowen Yang

    2010-05-01

    Full Text Available During the construction of a concrete structure, strength monitoring is important to ensure the safety of both personnel and the structure. Furthermore, to increase the efficiency of in situ casting or precast of concrete, determining the optimal time of demolding is important for concrete suppliers. Surface bonded lead zirconate titanate (PZT transducers have been used for damage detection and parameter identification for various engineering structures over the last two decades. In this work, a reusable PZT transducer setup for monitoring initial hydration of concrete and structural health is developed, where a piece of PZT is bonded to an enclosure with two bolts tightened inside the holes drilled in the enclosure. An impedance analyzer is used to acquire the admittance signatures of the PZT. Root mean square deviation (RMSD is employed to associate the change in concrete strength with changes in the PZT admittance signatures. The results show that the reusable setup is able to effectively monitor the initial hydration of concrete and the structural health. It can also be detached from the concrete for future re-use.

  3. A reusable PZT transducer for monitoring initial hydration and structural health of concrete.

    Science.gov (United States)

    Yang, Yaowen; Divsholi, Bahador Sabet; Soh, Chee Kiong

    2010-01-01

    During the construction of a concrete structure, strength monitoring is important to ensure the safety of both personnel and the structure. Furthermore, to increase the efficiency of in situ casting or precast of concrete, determining the optimal time of demolding is important for concrete suppliers. Surface bonded lead zirconate titanate (PZT) transducers have been used for damage detection and parameter identification for various engineering structures over the last two decades. In this work, a reusable PZT transducer setup for monitoring initial hydration of concrete and structural health is developed, where a piece of PZT is bonded to an enclosure with two bolts tightened inside the holes drilled in the enclosure. An impedance analyzer is used to acquire the admittance signatures of the PZT. Root mean square deviation (RMSD) is employed to associate the change in concrete strength with changes in the PZT admittance signatures. The results show that the reusable setup is able to effectively monitor the initial hydration of concrete and the structural health. It can also be detached from the concrete for future re-use.

  4. A study on shear behavior of reinforced concrete beams subjected to long-term heating

    International Nuclear Information System (INIS)

    Maruta, M.; Yamazaki, M.; Miyashita, T.

    1995-01-01

    A study has been undertaken to determine the shear behavior of reinforced concrete members in nuclear power plant facilities following sustained heating to high temperatures. A total of nine specimens was tested. The parameters of the tests were (1) heating temperature (65, 90 and 175 C) and (2) heating period (1, 3, 6 or 12 months). Different combinations of these parameters were employed, and the shear strength deterioration rate was evaluated. The test results were confirmed by a non-linear finite element analysis. The relationship between the concrete compressive strengths, which varied from heating face to upper portion, and the shear strength in specimens was evaluated. (orig.)

  5. Primer on Durability of Nuclear Power Plant Reinforced Concrete Structures - A Review of Pertinent Factors

    Energy Technology Data Exchange (ETDEWEB)

    Naus, Dan J [ORNL

    2007-02-01

    The objective of this study was to provide a primer on the environmental effects that can affect the durability of nuclear power plant concrete structures. As concrete ages, changes in its properties will occur as a result of continuing microstructural changes (i.e., slow hydration, crystallization of amorphous constituents, and reactions between cement paste and aggregates), as well as environmental influences. These changes do not have to be detrimental to the point that concrete will not be able to meet its performance requirements. Concrete, however, can suffer undesirable changes with time because of improper specifications, a violation of specifications, or adverse performance of its cement paste matrix or aggregate constituents under either physical or chemical attack. Contained in this report is a discussion on concrete durability and the relationship between durability and performance, a review of the historical perspective related to concrete and longevity, a description of the basic materials that comprise reinforced concrete, and information on the environmental factors that can affect the performance of nuclear power plant concrete structures. Commentary is provided on the importance of an aging management program.

  6. A Review of the Effects of Elevated Temperature on Concrete Materials and Structures

    International Nuclear Information System (INIS)

    Naus, D.J.; Graves, H.L. III

    2006-01-01

    Concrete's properties are more complex than those of most materials because not only is concrete a composite material whose constituents have different properties, but its properties depend upon moisture and porosity. Exposure of concrete to elevated temperature affects its mechanical and physical properties. Elements could distort and displace, and, under certain conditions, the concrete surfaces could spall due to the buildup of steam pressure. Because thermally-induced dimensional changes, loss of structural integrity, and release of moisture and gases resulting from the migration of free water could adversely affect plant operations and safety, a complete understanding of the behavior of concrete under long-term elevated-temperature exposure as well as both during and after a thermal excursion resulting from a postulated design-basis accident condition is essential for reliable design evaluations and assessments of nuclear power plant structures. As the properties of concrete change with respect to time and the environment to which it is exposed, an assessment of the effects of concrete aging is also important in performing safety evaluations. The effects of elevated temperature on Portland cement concretes and constituent materials are summarized, design codes and standards identified, and considerations for elevated temperature service noted. (authors)

  7. Studies on limestone concrete as a low-activation structural material for nuclear power plants

    International Nuclear Information System (INIS)

    Uematsu, Mikio; Nagano, Hiroshi; Naito, Yasuhiro

    2000-01-01

    Because of low content of Li, Co and Eu, the target nuclides of activation reaction, limestone concrete is considered to be effective in reducing the decommissioning cost of nuclear plants. Induced activity calculation and structural strength test were performed for limestone concrete and the results were compared with the data obtained for sandstone concrete, which is generally used in nuclear plants. Minor elements, which are important from the viewpoint of activation, were measured with elementary analysis for limestone samples from three different quarries in Japan. Induced activity in biological shield walls (BSW) of Boiling Water Reactor (BWR) plants was calculated with the isotope generation code ORIGEN-79 using neutron flux data obtained with the one-dimensional Sn transport code ANISN and MGCL 137-group activation cross section library based on JENDL-3. Estimated total radioactivity accumulated in limestone concrete BSW was 5 times lower than that in the sandstone concrete BSW. Structural strength were compared between limestone concrete and sandstone concrete, and limestone concrete was found to have enough compressive strength and tensile strength. (author)

  8. Primer on Durability of Nuclear Power Plant Reinforced Concrete Structures - A Review of Pertinent Factors

    International Nuclear Information System (INIS)

    Naus, Dan J.

    2007-01-01

    The objective of this study was to provide a primer on the environmental effects that can affect the durability of nuclear power plant concrete structures. As concrete ages, changes in its properties will occur as a result of continuing microstructural changes (i.e., slow hydration, crystallization of amorphous constituents, and reactions between cement paste and aggregates), as well as environmental influences. These changes do not have to be detrimental to the point that concrete will not be able to meet its performance requirements. Concrete, however, can suffer undesirable changes with time because of improper specifications, a violation of specifications, or adverse performance of its cement paste matrix or aggregate constituents under either physical or chemical attack. Contained in this report is a discussion on concrete durability and the relationship between durability and performance, a review of the historical perspective related to concrete and longevity, a description of the basic materials that comprise reinforced concrete, and information on the environmental factors that can affect the performance of nuclear power plant concrete structures. Commentary is provided on the importance of an aging management program

  9. The effect of crack width on the service life of reinforced concrete structures

    Science.gov (United States)

    Van Hung, Nguyen; Viet Hung, Vu; Viet, Tran Bao

    2018-04-01

    Reinforced concrete has become a widely used construction material around the world. Nowadays, the assessment of deterioration and life expectancy of reinforced concrete structure is very important and necessary as concrete is a complex material with brittle failure. Under the effect of load and over time, cracks occur in the structure, significantly reducing its performance and durability. Therefore, a number of models for predicting the penetration of chloride ions into the concrete were proposed to assess the durability of the structure. In the study performed by T B Viet (2016) [1], the author proposed a new theoretical model, especially considering the effects of macro and micro cracking on the diffusion coefficient of chloride ion in the cracked concrete. The following experimental results, in term of electrical indication of concrete’s ability to resist chloride ion penetration, are used to calculate the lifespan of a reinforced concrete structure according to Dura Crete approach [8] with different crack widths to evaluate the accuracy and reliability of the above model in the range of concrete compressive strength of 30-70MPa.

  10. Recovery and residual stress of SMA wires and applications for concrete structures

    International Nuclear Information System (INIS)

    Choi, Eunsoo; Cho, Sung-Chul; Park, Taehyo; Hu, Jong Wan; Chung, Young-Soo

    2010-01-01

    In general, NiTi shape memory alloys are used for applications in civil structures. NiTi SMAs show good superelasticity and shape memory effect properties. However, for application of the shape memory effect, it is desirable for SMAs to show a wide temperature hysteresis, especially for civil structures which are exposed to severe environmental conditions. NiTiNb SMAs, in general, show a wider temperature hysteresis than NiTi SMAs and are more applicable for civil structures. This study examines the temperature hysteresis of NiTiNb and NiTi SMAs, and their recovery and residual stress are investigated. In addition, the tensile behaviors of SMA wires under residual stress are evaluated. This study explains the possible applications for concrete structures with the shape memory effect and illustrates two experimental results of concrete cylinders and reinforced concrete columns. For both tests, SMA wires of NiTiNb and NiTi are used to confine concrete using residual stress. The SMA wire jackets on the concrete cylinders increase the peak strength and the ductility compared to the plain concrete cylinders. In addition, the SMA wire jackets on reinforced concrete columns increase the ductility greatly without flexural strength degradation

  11. 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.

  12. A method for three-dimensional structural analysis of reinforced concrete containment

    International Nuclear Information System (INIS)

    Kulak, R.F.; Fiala, C.

    1989-01-01

    A finite element method designed to assist reactor safety analysts in the three-dimensional numerical simulation of reinforced concrete containments to normal and off-normal mechanical loadings is presented. The development of a lined reinforced concrete plate element is described in detail, and the implementation of an empirical transverse shear failure criteria is discussed. The method is applied to the analysis of a 1/6th scale reinforced concrete containment model subjected to static internal pressurization. 11 refs., 14 figs., 1 tab

  13. Probabilistic Seismic Performance Model for Tunnel Form Concrete Building Structures

    Directory of Open Access Journals (Sweden)

    S. Bahram Beheshti Aval

    2016-12-01

    Full Text Available Despite widespread construction of mass-production houses with tunnel form structural system across the world, unfortunately no special seismic code is published for design of this type of construction. Through a literature survey, only a few studies are about the seismic behavior of this type of structural system. Thus based on reasonable numerical results, the seismic performance of structures constructed with this technique considering the effective factors on structural behavior is highly noteworthy in a seismic code development process. In addition, due to newness of this system and observed damages in past earthquakes, and especially random nature of future earthquakes, the importance of probabilistic approach and necessity of developing fragility curves in a next generation Performance Based Earthquake Engineering (PBEE frame work are important. In this study, the seismic behavior of 2, 5 and 10 story tunnel form structures with a regular plan is examined. First, the performance levels of these structures under the design earthquake (return period of 475 years with time history analysis and pushover method are assessed, and then through incremental dynamic analysis, fragility curves are extracted for different levels of damage in walls and spandrels. The results indicated that the case study structures have high capacity and strength and show appropriate seismic performance. Moreover, all three structures subjected were in immediate occupancy performance level.

  14. Structural design guidelines for concrete bridge decks reinforced with corrosion-resistant reinforcing bars.

    Science.gov (United States)

    2014-10-01

    This research program develops and validates structural design guidelines and details for concrete bridge decks with : corrosion-resistant reinforcing (CRR) bars. A two-phase experimental program was conducted where a control test set consistent : wi...

  15. Particulate structure and microstructure evolution of concrete investigated by DEM : Part 2: Porosimetry in hydrating binders

    NARCIS (Netherlands)

    Huan He, H.; Le, N.L.B.; Stroeven, P.

    2012-01-01

    Durability of concrete in engineering structures is becoming more and more of a major problem. Research into such problems is complicated and expensive, however. Developments in computer technology make it possible nowadays realistically simulating cementitious materials and studying its pore

  16. Screening life cycle assessment study of a sisal fibre reinforced micro-concrete structural insulated panel

    CSIR Research Space (South Africa)

    Ampofo-Anti, N

    2013-12-01

    Full Text Available First international conference on composites, biocomposites and nanocomposites, DUT, Durban, South Africa, 2-4 December 2013 SCREENING LIFE CYCLE ASSESSMENT STUDY OFA SISAL FIBRE REINFORCED MICRO-CONCRETE STRUCTURAL INSULATED PANEL Naa Lamkai Ampofo...

  17. Load-carrying capacity of lightly reinforced, prefabricated walls of lightweight aggregate concrete with open structure

    DEFF Research Database (Denmark)

    Goltermann, Per

    2009-01-01

    The paper presents and evaluates the results of a coordinated testing of prefabricated, lightly reinforced walls of lightweight aggregate concrete with open structure. The coordinated testing covers all wall productions in Denmark and will therefore provide a representative assessment...

  18. ON SHEAR BEHAVIOR OF STRUCTURAL ELEMENTS MADE OF STEEL FIBER REINFORCED CONCRETE

    OpenAIRE

    Cuenca Asensio, Estefanía

    2013-01-01

    Cuenca Asensio, E. (2012). ON SHEAR BEHAVIOR OF STRUCTURAL ELEMENTS MADE OF STEEL FIBER REINFORCED CONCRETE [Tesis doctoral no publicada]. Universitat Politècnica de València. doi:10.4995/Thesis/10251/18326. Palancia

  19. Conceptual design of reinforced concrete structures using topology optimization with elastoplastic material modeling

    DEFF Research Database (Denmark)

    Bogomolny, Michael; Amir, Oded

    2012-01-01

    Design of reinforced concrete structures is governed by the nonlinear behavior of concrete and by its different strengths in tension and compression. The purpose of this article is to present a computational procedure for optimal conceptual design of reinforced concrete structures on the basis...... response must be considered. Optimized distribution of materials is achieved by introducing interpolation rules for both elastic and plastic material properties. Several numerical examples illustrate the capability and potential of the proposed procedure. Copyright © 2012 John Wiley & Sons, Ltd....

  20. New Fiber Reinforced Waterless Concrete for Extraterrestrial Structural Applications

    Science.gov (United States)

    Toutanji, H.; Tucker, D.; Ethridge, E.

    2005-01-01

    Commercial use of sulfur concrete on Earth is well established, particularly in corrosive, e.g., acid and salt, environments. Having found troilite (FeS) on the Moon raises the question of using extracted sulfur as a lunar construction mate: iii an attractive alternative to conventional concrete as it does not require water For the purpose of this paper it is assumed that lunar ore is mined, refined, and the raw sulfur processed with appropriate lunar regolith to form, for example, brick and beam elements. Glass fibers produced from regolith were used as a reinforcement to improve the mechanical properties of the sulfur concrete. Glass fibers and glass rebar were produced by melting the lunar regolith simulant. Lunar regolith stimulant was melted in a 25 cc Pt-Rh crucible in a Sybron Thermoline 46100 high temperature MoSi2 furnace at melting temperatures of 1450 to 1600G. The glass melt wets the ceramic rod and long continuous glass fibers were easily hand drawn. The glass fibers were immediately coated with a protective polymer to maintain the mechanical strength. The viability of sulfur concrete as a construction material for extraterrestrial application is presented. The mechanical properties of the glass fiber reinforced sulfur concrete were investigated.