Research on Durability of Big Recycled Aggregate Self-Compacting Concrete Beam

Science.gov (United States)

Gao, Shuai; Liu, Xuliang; Li, Jing; Li, Juan; Wang, Chang; Zheng, Jinkai

2018-03-01

Deflection and crack width are the most important durability indexes, which play a pivotal role in the popularization and application of the Big Recycled Aggregate Self-Compacting Concrete technology. In this research, comparative study on the Big Recycled Aggregate Self-Compacting Concrete Beam and ordinary concrete beam were conducted by measuring the deflection and crack width index. The results show that both kind of concrete beams have almost equal mid-span deflection value and are slightly different in the maximum crack width. It indicates that the Big Recycled Aggregate Self-Compacting Concrete Beam will be a good substitute for ordinary concrete beam in some less critical structure projects.

Flexural Behavior of Corroded Reinforced Recycled Aggregate Concrete Beams

Directory of Open Access Journals (Sweden)

Taoping Ye

2018-01-01

Full Text Available Recycling concrete not only reduces the use of virgin aggregate but also decreases the pressure on landfills. As a result, recycled coarse aggregate (RCA is extensively recommended for new construction projects. However, the flexural behavior of corroded reinforced recycled aggregate concrete (RAC beams is uncertain. The experimental research presented in this paper was performed to investigate the flexural behavior of corroded reinforced RAC beams compared to that of corroded reinforced natural aggregate concrete (NAC beams and consequently explore the possibility of using RAC beams in corrosive environments. Four different percentages of RCA in total mass of coarse aggregate in concrete mixtures (0%, 33%, 66%, and 100% and two different concrete strengths (C30, C60 were the governing parameters. The electrochemical method was adopted to accelerate steel corrosion. Full-scale tests were performed on eight simply supported beams until the failure load was reached. Comparison of load-deflection behavior, crack patterns, failure modes, ductility, and ultimate flexural capacity of corroded reinforced NAC and RAC beams was made based on the experimental results obtained. The comparison results show that the flexural behavior of corroded reinforced RAC beams with an appropriate percentage of RCA is satisfactory compared to the behavior of NAC beams.

Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

Energy Technology Data Exchange (ETDEWEB)

Alferjani, M. B. S.; Samad, A. A. Abdul; Mohamad, Noridah [Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia, Batu Pahat (Malaysia); Elrawaff, Blkasem S.; Elzaroug, Omer [Faculty of Civil Engineering Omar Al Mukhtar University, Bayda, Libya, Africa (Libya)

2015-05-15

Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results.

Behavior of corroded bonded partially prestressed concrete beams

Directory of Open Access Journals (Sweden)

Mohamed Moawad

2018-04-01

Full Text Available Prestressed concrete is widely used in the construction industry in buildings. And corrosion of reinforcing steel is one of the most important and prevalent mechanisms of deterioration for concrete structures. Consequently the capacity of post-tension elements decreased after exposure to corrosion. This study presents results of the experimental investigation of the performance and the behavior of partially prestressed beams, with 40 and 80 MPa compressive strength exposed to corrosion. The experimental program of this study consisted of six partially prestressed beams with overall dimensions equal to 150 × 400 × 4500 mm. The variables were considered in terms of concrete compressive strength, and corrosion location effect. The mode of failure, and strain of steel reinforcement, cracking, yield, ultimate load and the corresponding deflection of each beam, and crack width and distribution were recorded. The results showed that the partially prestressed beam with 80 MPa compressive strength has higher resistance to corrosion exposure than that of partially prestressed concrete beam with 40 MPa compressive strength. Not big difference in deterioration against fully/partially corrosion exposure found between partially prestressed beams at the same compressive strength. The most of deterioration incident in partially prestressed beam acts on non prestressed steel reinforcement. Because the bonded tendons are less likely to corrode, cement grout and duct act as a barrier to moisture and chloride penetration, especially plastic duct without splices and connections. The theoretical analysis based on strain compatibility and force equilibrium gave a good prediction of the deformational behavior for high/normal partially prestressed beams. Keywords: Beam, Corrosion, Deterioration, Partially prestressed, High strength concrete

Damage Detection In Laboratory Concrete Beams

DEFF Research Database (Denmark)

Brincker, Rune; Andersen, Palle; Kirkegaard, Poul Henning

1995-01-01

The aim of the investigation reported in this paper is to clarify to what extent damages in reinforced concrete can be detected by estimating changes in the vibrational properties. A series of damages were introduced by applying static load cycles of increasing magnitude to two concrete beams...

Damage Detection in Laboratory Concrete Beams

DEFF Research Database (Denmark)

Brincker, Rune; Andersen, P.; Kirkegaard, Poul Henning

The aim of the investigation reported in this paper is to clarify to what extent damages in reinforced concrete can be detected by estimating changes in the vibrational properties. A series of damages were introduced by applying static load cycles of increasing magnitude to two concrete beams...

Performance based design of reinforced concrete beams under impact

Directory of Open Access Journals (Sweden)

S. Tachibana

2010-06-01

Full Text Available The purpose of this research is to collect fundamental data and to establish a performance-based design method for reinforced concrete beams under perpendicular impact load.

Series of low speed impact experiments using reinforced concrete beams were performed varying span length, cross section and main reinforcement.

The experimental results are evaluated focusing on the impact load characteristics and the impact behaviours of reinforced concrete beams. Various characteristic values and their relationships are investigated such as the collision energy, the impact force duration, the energy absorbed by the beams and the beam response values. Also the bending performance of the reinforced concrete beams against perpendicular impact is evaluated.

An equation is proposed to estimate the maximum displacement of the beam based on the collision energy and the static ultimate bending strength. The validity of the proposed equation is confirmed by comparison with experimental results obtained by other researchers as well as numerical results obtained by FEM simulations. The proposed equation allows for a performance based design of the structure accounting for the actual deformation due to the expected impact action.

Flexural Behavior of Self-Compacting RC Continuous Beams Strengthened by CFRP Sheets

Directory of Open Access Journals (Sweden)

Sabih Z. Al-Sarraf

2018-01-01

Full Text Available This search presented an experimental study of the flexural behavior of self-compacting reinforced concrete continuous beams externally strengthened by carbon fiber reinforced polymer (CFRP Sheets. The practical study contained eight self-compacting reinforced concrete continuous beams (with two span, each span had (1500 mm length and (150x250 mm cross sectional dimensions. Seven of these beams strengthened externally by CFRP sheets with and without external anchorage. The experimental variables included location of CFRP sheets and anchor type and location. The results, shows that the beams strengthened externally by CFRP sheets provided improvement in ultimate loads reached (60.71%. The usage of CFRP in the anchorage zone indicated an effective method in comparison to increasing the CFRP sheets lengths or extending them up to the support or under the loading points. Test results also showed that side strengthening provided an effective tool for increasing the load at the cracking stage and also the load capacity and reducing flexural crack widths.

Strengthening and repairing of damaged concrete beams

International Nuclear Information System (INIS)

Mahmoud, M.K.; Ebrahiem, G.T.A.; Hassanein, S.A.

2005-01-01

The main part in this investigation is concerned with the advanced techniques of retrofitting damaged reinforced concrete (RC) beams. Glass fiber reinforced plastics (GFRP) were employed for this purpose. The aim of this paper is to investigate the advantage of using glass fiber .reinforced plastics (GFRP) to retrofit and repair damaged reinforced concrete beams. In this investigation, concrete beam specimens were preloaded up to the 60%, 70% arid 80% of their ultimate load capacity. The damaged beams were then repaired with one layer of FRP composite wraps and re-tested. Plastic reinforced by glass fibers 20% fiber volume fractions and with various fiber arrangement unidirectional, bi-directional and chopped were also considered. Four points bending test was adopted. The bending tests were performed on fourteen RC beams in addition to a two control, all of them were (225 30 15) cm in dimensions, and with a typical reinforcement details. Test results were indicative of the merit of using GFRP, as the ultimate loads were almost restored and the modes of failure were of ductile nature. Even more an increase in the ultimate bearing capacity was recorded for some of the retrofitted beams. The effects of the previously mentioned parameters on the cracking pattern and failure mode were reported and thoroughly discussed

Study on reinforced lightweight coconut shell concrete beam behavior under torsion

International Nuclear Information System (INIS)

Gunasekaran, K.; Ramasubramani, R.; Annadurai, R.; Prakash Chandar, S.

2014-01-01

Highlights: • Use of coconut shell as aggregate in concrete production. • Behavior of coconut shell concrete under torsion. • Pre and post cracking behavior and analysis. • Torsional reinforcement and ductility. • Crack width and stiffness. - Abstract: This research investigates and evaluates the results of coconut shell concrete beams subjected to torsion and compared with conventional concrete beams. Eight beams, four with coconut shell concrete and four with conventional concrete were fabricated and tested. Study includes the general cracking characteristics, pre cracking behavior and analysis, post cracking behavior and analysis, minimum torsional reinforcement, torsional reinforcement, ductility, crack width and stiffness. It was observed that the torsional behavior of coconut shell concrete is comparable to that of conventional concrete. Compare to ACI prediction, equation suggested by Macgregor is more conservative in calculating cracking torsional resistance. But for the calculation of ultimate torque strength ACI prediction is more conservative compared to the equation suggested by Macgregor. Indian standard is also conservative in this regard, but it was under estimated compared to ACI and Macgregor equations. Minimum torsional reinforcement in beams is necessary to ensure that the beam do not fail at cracking. Compared to conventional concrete specimens, coconut shell concrete specimens have more ductility. Crack width at initial cracking torque for both conventional and coconut shell concrete with corresponding reinforcement ratios is almost similar

Application of a Reinforced Self-Compacting Concrete Jacket in Damaged Reinforced Concrete Beams under Monotonic and Repeated Loading

Directory of Open Access Journals (Sweden)

Constantin E. Chalioris

2013-01-01

Full Text Available This paper presents the findings of an experimental study on the application of a reinforced self-compacting concrete jacketing technique in damaged reinforced concrete beams. Test results of 12 specimens subjected to monotonic loading up to failure or under repeated loading steps prior to total failure are included. First, 6 beams were designed to be shear dominated, constructed by commonly used concrete, were initially tested, damaged, and failed in a brittle manner. Afterwards, the shear-damaged beams were retrofitted using a self-compacting concrete U-formed jacket that consisted of small diameter steel bars and U-formed stirrups in order to increase their shear resistance and potentially to alter their initially observed shear response to a more ductile one. The jacketed beams were retested under the same loading. Test results indicated that the application of reinforced self-compacting concrete jacketing in damaged reinforced concrete beams is a promising rehabilitation technique. All the jacketed beams showed enhanced overall structural response and 35% to 50% increased load bearing capacities. The ultimate shear load of the jacketed beams varied from 39.7 to 42.0 kN, whereas the capacity of the original beams was approximately 30% lower. Further, all the retrofitted specimens exhibited typical flexural response with high values of deflection ductility.

The influence of the damaged reinforcing bars on the stress-strain state of the rein-forced concrete beams

Directory of Open Access Journals (Sweden)

Zenoviy Blikharskyy

2017-04-01

Full Text Available The article is devoted to the overall view of experimental research of reinforced concrete beams with the simultaneous influence of the corrosion environment and loading. The tests have been carried out upon the reinforced concrete specimens considering the corrosion in the acid environment, namely 10 % H2SO4 that have been taken as a model of the aggressive environment. The beams are with span equalling to 1,9m with different series of tensile armature, concrete compressive strength and different length of impact of corrosion (continuous and local. The influence of simultaneous action of the aggressive environment and loading on strength of reinforced-concrete beams has been described. For a detailed study of the effect of individual components there was suggested additional experimental modelling of the only tensile armature damage without concrete damage. It will investigate the influence of this factor irrespective of the concrete.

Identifying location and severity of multiple cracks in reinforced concrete cantilever beams using modal and wavelet analysis

Directory of Open Access Journals (Sweden)

Tahere Arefzade

2016-06-01

Full Text Available In this paper, a method of multiple cracks detection in a cantilever reinforced concrete beam based on wavelet transform is presented. For this purpose, different damage scenarios in concrete beam were considered. Then, the four first mode shapes of undamaged and damaged beam using ABAQUS software were extracted. The estimated mode shapes of the beam are analyzed by the continuous and discrete wavelet transform (CWT & DWT to detect the damage scenarios. It was found that DWT is more sensitive to damage location than CWT in the concrete beam which introduced in this paper. Also, the influence of the mode order and the effect of damage distance from support on the effectiveness of damage detection was evaluated. It was observed that the distance of cracks to each other have no effect on identifying their location.

Study on reinforced lightweight coconut shell concrete beam behavior under flexure

International Nuclear Information System (INIS)

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

2013-01-01

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

Steel fiber replacement of mild steel in prestressed concrete beams

Science.gov (United States)

2010-10-01

In traditional prestressed concrete beams, longitudinal prestressed tendons serve to resist bending moment and : transverse mild steel bars (or stirrups) are used to carry shear forces. However, traditional prestressed concrete I-beams : exhibit earl...

Steel fiber replacement of mild steel in prestressed concrete beams.

Science.gov (United States)

2011-01-01

In traditional prestressed concrete beams, longitudinal prestressed tendons serve to resist bending moment and transverse mild : steel bars (or stirrups) are used to carry shear forces. However, traditional prestressed concrete I-beams exhibit early-...

Flexural behavior of bonded post-tensioned concrete beams under strand corrosion

International Nuclear Information System (INIS)

Zhang, Xuhui; Wang, Lei; Zhang, Jianren; Ma, Yafei; Liu, Yongming

2017-01-01

Highlights: • Flexural behavior of bonded PT beams with strand corrosion is experimental tested. • Cracking, stiffness, ultimate strength, failure & ductility of beams are clarified. • A coefficient is proposed to measure incompatible strain between strand & concrete. - Abstract: An experimental test is performed to investigate the flexural behavior of bonded post-tensioned concrete beams under strand corrosion. Eight beams are designed and subjected to accelerated method to different corrosion levels. The initial stiffness of beams is observed by cyclic loading-unloading test during the corrosion procedure. Corrosion effects on concrete cracking, post-cracking stiffness, ultimate strength, failure mode and ductility are then clarified by the flexural test. And, a coefficient is introduced to quantify the incompatible strain between corroded strand and concrete. Results show that the prestress force loss of strand has almost the linear relation with corrosion loss. Strand corrosion affects slightly the initial stiffness of beam before flexural cracking, but degrades significantly the post-cracking stiffness of beam as the corrosion loss exceeds 27.0%. Slight corrosion of strand has little effects on beams flexural behavior. The severe corrosion, however, decreases the number of crack, changes the failure mode form the concrete crushing to strand rupture, degrades the ductility and the ultimate strength of beams, and leads to the incompatible strain between strand and concrete. In the present test, the incompatible strain decreases about 20% of the flexural strength as the corrosion loss exceeds 27.0%.

Flexural behavior of bonded post-tensioned concrete beams under strand corrosion

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xuhui [College of Civil Engineering and Mechanics, Xiangtan University, 411105 Xiangtan (China); School of Civil Engineering and Architecture, Changsha University of Science & Technology, 410114 Changsha (China); Industry Key Laboratory of Traffic Infrastructure Security Risk Management (CSUST), 410114 Changsha (China); Wang, Lei, E-mail: leiwlei@hotmail.com [School of Civil Engineering and Architecture, Changsha University of Science & Technology, 410114 Changsha (China); Industry Key Laboratory of Traffic Infrastructure Security Risk Management (CSUST), 410114 Changsha (China); Zhang, Jianren; Ma, Yafei [School of Civil Engineering and Architecture, Changsha University of Science & Technology, 410114 Changsha (China); Industry Key Laboratory of Traffic Infrastructure Security Risk Management (CSUST), 410114 Changsha (China); Liu, Yongming [School for Engineering of Matter, Transport and Energy, Arizona State University, 85281 Tempe, AZ (United States)

2017-03-15

Highlights: • Flexural behavior of bonded PT beams with strand corrosion is experimental tested. • Cracking, stiffness, ultimate strength, failure & ductility of beams are clarified. • A coefficient is proposed to measure incompatible strain between strand & concrete. - Abstract: An experimental test is performed to investigate the flexural behavior of bonded post-tensioned concrete beams under strand corrosion. Eight beams are designed and subjected to accelerated method to different corrosion levels. The initial stiffness of beams is observed by cyclic loading-unloading test during the corrosion procedure. Corrosion effects on concrete cracking, post-cracking stiffness, ultimate strength, failure mode and ductility are then clarified by the flexural test. And, a coefficient is introduced to quantify the incompatible strain between corroded strand and concrete. Results show that the prestress force loss of strand has almost the linear relation with corrosion loss. Strand corrosion affects slightly the initial stiffness of beam before flexural cracking, but degrades significantly the post-cracking stiffness of beam as the corrosion loss exceeds 27.0%. Slight corrosion of strand has little effects on beams flexural behavior. The severe corrosion, however, decreases the number of crack, changes the failure mode form the concrete crushing to strand rupture, degrades the ductility and the ultimate strength of beams, and leads to the incompatible strain between strand and concrete. In the present test, the incompatible strain decreases about 20% of the flexural strength as the corrosion loss exceeds 27.0%.

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

OpenAIRE

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

2012-01-01

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

0-6722 : spread prestressed concrete slab beam bridges.

Science.gov (United States)

2014-08-01

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

Study on reinforced concrete beams with helical transverse reinforcement

Science.gov (United States)

Kaarthik Krishna, N.; Sandeep, S.; Mini, K. M.

2018-02-01

In a Reinforced Concrete (R.C) structure, major reinforcement is used for taking up tensile stresses acting on the structure due to applied loading. The present paper reports the behavior of reinforced concrete beams with helical reinforcement (transverse reinforcement) subjected to monotonous loading by 3-point flexure test. The results were compared with identically similar reinforced concrete beams with rectangular stirrups. During the test crack evolution, load carrying capacity and deflection of the beams were monitored, analyzed and compared. Test results indicate that the use of helical reinforcement provides enhanced load carrying capacity and a lower deflection proving to be more ductile, clearly indicating the advantage in carrying horizontal loads. An analysis was also carried out using ANSYS software in order to compare the test results of both the beams.

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)

Flexural Cracking Behavior Of Steel Fiber Reinforced Concrete Beams

Directory of Open Access Journals (Sweden)

Ashraf Abdalkader

2017-08-01

Full Text Available Steel fibers are added to concrete due to its ability to improve the tensile strength and control propagation of cracks in reinforced concrete members. Steel fiber reinforced concrete is made of cement fine water and coarse aggregate in addition to steel fibers. In this experimental work flexural cracking behavior of reinforced concrete beams contains different percentage of hooked-end steel fibers with length of 50 mm and equivalent diameter of 0.5 mm was studied. The beams were tested under third-point loading test at 28 days. First cracking load maximum crack width cracks number and load-deflection relations were investigated to evaluate the flexural cracking behavior of concrete beams with 34 MPa target mean strength. Workability wet density compressive and splitting tensile strength were also investigated. The results showed that the flexural crack width is significantly reduced with the addition of steel fibers. Fiber contents of 1.0 resulted in 81 reduction in maximum crack width compared to control concrete without fiber. The results also showed that the first cracking load and maximum load are increased with the addition of steel fibers.

Comparison of performance of partial prestressed beam-column subassemblages made of reactive powder concrete and normal concrete materials using finite element models

Science.gov (United States)

Nurjannah, S. A.; Budiono, B.; Imran, I.; Sugiri, S.

2016-04-01

Research on concrete material continues in several countries and had produced a concrete type of Ultra High Performance Concrete (UHPC) which has a better compressive strength, tensile strength, flexural strength, modulus of elasticity, and durability than normal concrete (NC) namely Reactive Powder Concrete (RPC). Researches on structures using RPC material showed that the RPC structures had a better performance than the NC structures in resisting gravity and lateral cyclic loads. In this study, an experiment was conducted to apply combination of constant axial and lateral cyclic loads to a prototype of RPC interior partial prestressed beam-column subassemblage (prototype of BCS-RPC) with a value of Partial Prestressed Ratio (PPR) of 31.72% on the beam. The test results were compared with finite element model of beam-column subassemblage made of RPC by PPR of 31.72% (BCS-RPC-31.72). Furthermore, there was BCS-RPC modeling with PPR of 21.39% (BCS-RPC-21.39) and beam-column subassemblages made of NC materials modeling with a value of PPR at 21.09% (BCS-NC-21.09) and 32.02% (BCS-NC-32.02). The purpose of this study was to determine the performance of the BCS-RPC models compared to the performance of the BCS-NC models with PPR values below and above 25%, which is the maximum limit of permitted PPR. The results showed that all models of BCS-RPC had a better performance than all models of BCS-NC and the BCS-RPC model with PPR above 25% still behaved ductile and was able to dissipate energy well.

Flexural behavior of reinforced concrete beam with polymer coated pumice

Science.gov (United States)

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

2017-09-01

Sustainable development has become an important issue due to the increasing consideration of preserving the nature. Many alternative for coarse aggregate replacement have been investigated ranging from natural and fabricated aggregates. In this study, natural aggregate pumice was investigated since it offers lower density that give paramount benefit in reducing total building weight and hence reducing the earthquake excitation effect and optimizing the structural dimension. However, the characteristic of porous surfaces of pumice causes excessive water absorption during concrete mixing process. Therefore, to reduce the additional water, the pumice aggregates were coated with polymer. The tested specimens consisted of normal concrete beams (NCB), uncoated pumice aggregate concrete beam (UPA) and polymer coated pumice aggregate concrete beam (PCP). The objective of the research was to obtain the effect of coating on the pumice aggregate to the flexural behavior of concrete beams. The lateral load-displacement behavior, ductility and collapse mechanism were studied. The results showed that there were only marginal drop on the load-carrying capacity of the pumice aggregate beam compared to those of normal beam. Additionally, the ductility coefficient of specimens UPA and PCP decreased of 11,97% and 14,03% respectively compared to NCB, and the ultimate load capacity decreased less than 1%. Overall, the pumice aggregate showed good characteristic for replacing normal coarse aggregate.

Finite element modelling of concrete beams reinforced with hybrid fiber reinforced bars

Science.gov (United States)

Smring, Santa binti; Salleh, Norhafizah; Hamid, NoorAzlina Abdul; Majid, Masni A.

2017-11-01

Concrete is a heterogeneous composite material made up of cement, sand, coarse aggregate and water mixed in a desired proportion to obtain the required strength. Plain concrete does not with stand tension as compared to compression. In order to compensate this drawback steel reinforcement are provided in concrete. Now a day, for improving the properties of concrete and also to take up tension combination of steel and glass fibre-reinforced polymer (GFRP) bars promises favourable strength, serviceability, and durability. To verify its promise and support design concrete structures with hybrid type of reinforcement, this study have investigated the load-deflection behaviour of concrete beams reinforced with hybrid GFRP and steel bars by using ATENA software. Fourteen beams, including six control beams reinforced with only steel or only GFRP bars, were analysed. The ratio and the ordinate of GFRP to steel were the main parameters investigated. The behaviour of these beams was investigated via the load-deflection characteristics, cracking behaviour and mode of failure. Hybrid GFRP-Steel reinforced concrete beam showed the improvement in both ultimate capacity and deflection concomitant to the steel reinforced concrete beam. On the other hand, finite element (FE) modelling which is ATENA were validated with previous experiment and promising the good result to be used for further analyses and development in the field of present study.

Serviceability behavior of Reinforcement Concrete beams with polypropylene and steel fibers

OpenAIRE

NaserKabashi; Cenë Krasniqi

2015-01-01

Serviceability Limit States (SLS) may lead to the design of concrete elements internally reinforced with Fiber Reinforced Polymer (FRP).In many types of concrete structure loss the serviceability due to wide cracks, number of cracks or large deflection is not uncommon behaviour in concrete structures or concrete beams.The flexural ductility affects the serviceability deflection of RC beams once flexural cracking take place.Imprvement will be focused on the use of polypropilene fib...

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.

NONLINEAR ANALYSIS OF CFRP- PRESTRESSED CONCRETE BEAMS SUBJECTED TO INCREMENTAL STATIC LOADING BY FINITE ELEMENTS

Directory of Open Access Journals (Sweden)

Husain M. Husain

2013-05-01

Full Text Available In this work a program is developed to carry out the nonlinear analysis (material nonlinearity of prestressed concrete beams using tendons of carbon fiber reinforced polymer (CFRP instead of steel. The properties of this material include high strength, light weight, and insusceptibility to corrosion and magnetism. This material is still under investigation, therefore it needs continuous work to make it beneficial in concrete design. Four beams which are tested experimentally by Yan et al. are examined by the developed computer program to reach a certain analytical approach of the design and analysis of such beams because there is no available restrictions or recommendations covering this material in the codes. The program uses the finite element analysis by dividing the beams into isoparametric 20-noded brick elements. The results obtained are good in comparison with experimental results.

Process of cracking in reinforced concrete beams (simulation and experiment

Directory of Open Access Journals (Sweden)

I. N. Shardakov

2016-10-01

Full Text Available The paper presents the results of experimental and theoretical investigations of the mechanisms of crack formation in reinforced concrete beams subjected to quasi-static bending. The boundary-value problem has been formulated in the framework of brittle fracture mechanics and solved using the finite-element method. Numerical simulation of the vibrations of an uncracked beam and a beam with cracks of different size serves to determine the pattern of changes in the spectrum of eigenfrequencies observed during crack evolution. A series of sequential quasi-static 4-point bend tests leading to the formation of cracks in a reinforced concrete beam were performed. At each loading step, the beam was subjected to an impulse load to induce vibrations. Two stages of cracking were detected. During the first stage the nonconservative process of deformation begins to develope, but has not visible signs. The second stage is an active cracking, which is marked by a sharp change in eingenfrequencies. The boundary of a transition from one stage to another is well registered. The vibration behavior was examined for the ordinary concrete beams and the beams strengthened with a carbon-fiber polymer. The obtained results show that the vibrodiagnostic approach is an effective tool for monitoring crack formation and assessing the quality of measures aimed at strengthening concrete structures

FEM performance of concrete beams reinforced by carbon fiber bars

Directory of Open Access Journals (Sweden)

Hasan Hashim

2018-01-01

Full Text Available Concrete structures may be vulnerable to harsh environment, reinforcement with Fiber Reinforced Polymer (FRP bars have an increasing acceptance than normal steel. The nature of (FRP bar is (non-corrosive which is very beneficial for increased durability as well as the reinforcement of FRP bar has higher strength than steel bar. FRP usage are being specified more and more by public structural engineers and individual companies as main reinforcement and as strengthening of structures. Steel reinforcement as compared to (FRP reinforcement are decreasingly acceptable for structural concrete reinforcement including precast concrete, cast in place concrete, columns, beams and other components. Carbon Fiber Reinforcement Polymer (CFRP have a very high modulus of elasticity “high modulus” and very high tensile strength. In aerospace industry, CFRP with high modulus are popular among all FRPs because it has a high strength to weight ratio. In this research, a finite element models will be used to represent beams with Carbon Fiber Reinforcement and beams with steel reinforcement. The primary objective of the research is the evaluation of the effect of (CFR on beam reinforcement.

Prestressed concrete bridge beams with microsilica admixture : final report.

Science.gov (United States)

1998-01-01

Microsilica fume admixture in concrete beams was used in two coastal bridges to reduce chloride permeability. Cylinders were cast from the beam mixture for strength and permeability tests. : The fabricator found no problems with making these beams, e...

Flexural strength of self compacting fiber reinforced concrete beams using polypropylene fiber: An experimental study

Science.gov (United States)

Lisantono, Ade; Praja, Baskoro Abdi; Hermawan, Billy Nouwen

2017-11-01

One of the methods to increase the tensile strength of concrete is adding a fiber material into the concrete. While to reduce a noise in a construction project, a self compacting concrete was a good choices in the project. This paper presents an experimental study of flexural behavior and strength of self compacting fiber reinforced concrete (RC) beams using polypropylene fiber. The micro monofilament polypropylene fibers with the proportion 0.9 kg/m3 of concrete weight were used in this study. Four beam specimens were cast and tested in this study. Two beams were cast of self compacting reinforced concrete without fiber, and two beams were cast of self compacting fiber reinforced concrete using polypropylene. The beams specimen had the section of (180×260) mm and the length was 2000 mm. The beams had simple supported with the span of 1800 mm. The longitudinal reinforcements were using diameter of 10 mm. Two reinforcements of Ø10 mm were put for compressive reinforcement and three reinforcements of Ø10 mm were put for tensile reinforcement. The shear reinforcement was using diameter of 8 mm. The shear reinforcements with spacing of 100 mm were put in the one fourth near to the support and the spacing of 150 mm were put in the middle span. Two points loading were used in the testing. The result shows that the load-carrying capacity of the self compacting reinforced concrete beam using polypropylene was a little bit higher than the self compacting reinforced concrete beam without polypropylene. The increment of load-carrying capacity of self compacting polypropylene fiber reinforced concrete was not so significant because the increment was only 2.80 % compare to self compacting non fiber reinforced concrete. And from the load-carrying capacity-deflection relationship curves show that both the self compacting polypropylene fiber reinforced concrete beam and the self compacting non fiber reinforced concrete beam were ductile beams.

Flexural Behaviour Of Reinforced Concrete Beams Containing Expanded Glass As Lightweight Aggregates

Directory of Open Access Journals (Sweden)

Khatib Jamal

2015-12-01

Full Text Available The flexural properties of reinforced concrete beams containing expanded glass as a partial fine aggregate (sand replacement are investigated. Four concrete mixes were employed to conduct this study. The fine aggregate was replaced with 0%, 25%, 50% and 100% (by volume expanded glass. The results suggest that the incorporation of 50% expanded glass increased the workability of the concrete. The compressive strength was decreasing linearly with the increasing amount of expanded glass. The ductility of the concrete beam significantly improved with the incorporation of the expanded glass. However, the load-carrying capacity of the beam and load at which the first crack occurs was reduced. It was concluded that the inclusion of expanded glass in structural concrete applications is feasible.

Shear behavior of concrete beams externally prestressed with Parafil ropes

Directory of Open Access Journals (Sweden)

A.H. Ghallab

2013-03-01

Full Text Available Although extensive work has been carried out investigating the use of external prestressing system for flexural strengthening, a few studies regarding the shear behavior of externally prestressed beams can be found. Five beams, four of them were externally strengthened using Parafil rope, were loaded up to failure to investigate the effect of shear span/depth ratio, external prestressing force and concrete strength on their shear behavior. Test results showed that the shear span to depth ratio has a significant effect on both the shear strength and failure mode of the strengthened beams and the presence of external prestressing force increased the ultimate load of the tested beams by about 75%. Equations proposed by different codes for both the conventional reinforced concrete beams and for ordinary prestressed beams were used to evaluate the obtained experimental results. In general, codes equations showed a high level of conservatism in predicting the shear strength of the beams. Also, using the full strength rather than half of the concrete shear strength in the Egyptian code PC-method improves the accuracy of the calculated ultimate shear strength.

FINITE ELEMENT MODELING OF CAMBER OF PRESTRESSED CONCRETE BEAMS

Directory of Open Access Journals (Sweden)

Peter P. Gaigerov

2017-12-01

Full Text Available For large-span reinforced concrete beam structures developed by the method of determining the camber due to the prestressing of a steel rope on the concrete. Performed numerical experiments to study the impact of various schemes layout prestressed reinforcement without bonding with concrete on the distribution of the relief efforts along the path of the reinforcement.

Nonlinear analysis of reinforced concrete beam with/without tension stiffening effect

International Nuclear Information System (INIS)

Dede, T.; Ayvaz, Y.

2009-01-01

The aim of this paper is to do materially nonlinear failure analysis of RC beam by using finite element method. In the finite element modeling, two different approaches and different tension stress-strain models with/without tension stiffening effect are used by considering two different mesh sizes. In the first approach, the material matrices of concrete and reinforcement are constructed separately, and then superimposed to obtain the element stiffness matrix. In the second approach, the reinforcement is assumed to be uniformly distributed throughout the beam. So, the beam is modeled as a single composite element with increasing the modulus of elasticity of concrete by considering the reinforcement ratio. For these two approaches, elastic-perfectly plastic stress-strain relationship is used for concrete in compression. For the concrete in tension, a stress-strain relationship with/without tension stiffening is used. It is concluded that the approaches and the models considered in this study can be effectively used in the materially nonlinear analysis of RC beams.

Prestress Force Identification for Externally Prestressed Concrete Beam Based on Frequency Equation and Measured Frequencies

Directory of Open Access Journals (Sweden)

Luning Shi

2014-01-01

Full Text Available A prestress force identification method for externally prestressed concrete uniform beam based on the frequency equation and the measured frequencies is developed. For the purpose of the prestress force identification accuracy, we first look for the appropriate method to solve the free vibration equation of externally prestressed concrete beam and then combine the measured frequencies with frequency equation to identify the prestress force. To obtain the exact solution of the free vibration equation of multispan externally prestressed concrete beam, an analytical model of externally prestressed concrete beam is set up based on the Bernoulli-Euler beam theory and the function relation between prestress variation and vibration displacement is built. The multispan externally prestressed concrete beam is taken as the multiple single-span beams which must meet the bending moment and rotation angle boundary conditions, the free vibration equation is solved using sublevel simultaneous method and the semi-analytical solution of the free vibration equation which considered the influence of prestress on section rigidity and beam length is obtained. Taking simply supported concrete beam and two-span concrete beam with external tendons as examples, frequency function curves are obtained with the measured frequencies into it and the prestress force can be identified using the abscissa of the crosspoint of frequency functions. Identification value of the prestress force is in good agreement with the test results. The method can accurately identify prestress force of externally prestressed concrete beam and trace the trend of effective prestress force.

Strengthening Reinforced Concrete Beams with CFRP and GFRP

Directory of Open Access Journals (Sweden)

Mehmet Mustafa Önal

2014-01-01

Full Text Available Concrete beams were strengthened by wrapping the shear edges of the beams twice at 45° in opposite directions by either carbon fiber reinforced polymer (CFRP or glass fiber reinforced polymer (GFRP. The study included 3 CFRP wrapped beams, 3 GFRP wrapped beams, and 3 control beams, all of which were 150 × 250 × 2200 mm and manufactured with C20 concrete and S420a structural steel at the Gazi University Technical Education Faculty labs, Turkey. Samples in molds were cured by watering in the open air for 21 days. Four-point bending tests were made on the beam test specimens and the data were collected. Data were evaluated in terms of load displacement, bearing strength, ductility, and energy consumption. In the CFRP and GFRP reinforced beams, compared to controls, 38% and 42%, respectively, strength increase was observed. In all beams, failure-flexural stress occurred in the center as expected. Most cracking was observed in the flexural region 4. A comparison of CFRP and GFRP materials reveals that GFRP enforced parts absorb more energy. Both materials yielded successful results. Thicker epoxy application in both CFRP and GFRP beams was considered to be effective in preventing break-ups.

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.

Flexural behaviour of reinforced concrete beams with discrete steel – polypropylene fibres

Directory of Open Access Journals (Sweden)

Amizah Wan Jusoh Wan

2017-01-01

Full Text Available This paper discusses the experimental results on the flexural test of concrete containing different proportions of steel fibre (SF and polypropylene fibre (PPF. The flexural test was carried out under 4-point bending load and followed the relevant standards to FRC. Hooked-end deformed SF fibre with 60 mm length and fibrillated virgin PPF fibre with 19 mm length were used in this study. Meanwhile, the concrete was designed for high strength concrete of C60. The mixture included both single SF and PPF, and also the combination of both fibres; Control beam (PC, beam with 75%SF, beam with 75%SF + 25%PPF and beam with 25%PPF. The total fibre volume fraction (Vf was fixed at 1.5%. The experimental results show that the percentage proportion of combined SF-PPF at 75-25% had the best performance for its flexural capacity. Mixture with single PPF was also found not effective in delaying the onset of tension cracks and to increase the tensile strength of the concrete. Experimental result also shows beam with 75%SF +25%PPF had their structural stiffness improved the most as compared with the others. For the compressive strength, beam with 75%SF + 25%PPF also revealed comparable performance with the control for high strength composite concrete.

Prediction of the behavior of reinforced concrete deep beams with web openings using the finite ele

Directory of Open Access Journals (Sweden)

Ashraf Ragab Mohamed

2014-06-01

Full Text Available The exact analysis of reinforced concrete deep beams is a complex problem and the presence of web openings aggravates the situation. However, no code provision exists for the analysis of deep beams with web opening. The code implemented strut and tie models are debatable and no unique solution using these models is available. In this study, the finite element method is utilized to study the behavior of reinforced concrete deep beams with and without web openings. Furthermore, the effect of the reinforcement distribution on the beam overall capacity has been studied and compared to the Egyptian code guidelines. The damaged plasticity model has been used for the analysis. Models of simply supported deep beams under 3 and 4-point bending and continuous deep beams with and without web openings have been analyzed. Model verification has shown good agreement to literature experimental work. Results of the parametric analysis have shown that web openings crossing the expected compression struts should be avoided, and the depth of the opening should not exceed 20% of the beam overall depth. The reinforcement distribution should be in the range of 0.1–0.2 beam depth for simply supported deep beams.

Ultimate stress increase in unbonded tendons in post-tensioned indeterminate I-beams cast with high strength normal and self compacting concrete

Directory of Open Access Journals (Sweden)

Yousef Askari Dolatabad

2018-06-01

Full Text Available The use of un-bonded tendons is prevalent in post-tensioned concrete structures. Equations for prediction of stress in un-bonded tendons of post-tensioned normal (vibrating concrete flexural members have been given in various codes. They are based on experience and don’t account all of important parameters such as concrete strength (normal and high strength and its type (vibrating and non-vibrating concrete. Since self-compacting concrete (SCC is nearly a new innovation therefore, understanding the implementation of this type of non-vibrating concrete on the ultimate unbonded tendon stress is critical. For this aim, in this paper there are presented experimental results of six continuous un-bonded post-tensioned I-beams in two groups were casted and monitored by different electrical strain gauges. In the first tested group, the beams (UPN1-12, UPN1-18, UPN1-22 were consisting of high strength normal concrete (HSNC where as in the second group (UPS1-12, UPS1-18, UPS1-22 high strength self-compacting concrete (HSSCC were tested. The variables included the type of concrete and percentage of bounded non-prestressed steel. Experimental monitored results of ultimate stress increase in unbonded tendons are compared with predicted equations of different researchers and standards. It was found that, the proposed equation is in better agreement with the test results. The results of standard error of estimate Sy/x, indicates that for two types of HSCs, the ACI 318-2011 provides better estimates than AASHTO-2010 model whereas this model provides better estimates than BS 8110-97. Keywords: Post-tensioned, Unbonded tendons, Stress increase, High strength normal and self-compacting concrete, Continuous beams

Experimental testing of a self-sensing FRP-concrete composite beam using FBG sensors

Science.gov (United States)

Wang, Yanlei; Hao, Qingduo; Ou, Jinping

2009-03-01

A new kind of self-sensing fiber reinforced polymer (FRP)-concrete composite beam, which consists of a FRP box beam combined with a thin layer of concrete in the compression zone, was developed by using two embedded FBG sensors in the top and bottom flanges of FRP box beam at mid-span section along longitudinal direction, respectively. The flexural behavior of the proposed self-sensing FRP-concrete composite beam was experimentally studied in four-point bending. The longitudinal strains of the composite beam were recorded using the embedded FBG sensors as well as the surfacebonded electric resistance strain gauges. Test results indicate that the FBG sensors can faithfully record the longitudinal strain of the composite beam in tension at bottom flange of the FRP box beam or in compression at top flange over the entire load range, as compared with the surface-bonded strain gauges. The proposed self-sensing FRP-concrete composite beam can monitor its longitudinal strains in serviceability limit state as well as in strength limit state, and will has wide applications for long-term monitoring in civil engineering.

Numerical simulation of impact tests on reinforced concrete beams

International Nuclear Information System (INIS)

Jiang, Hua; Wang, Xiaowo; He, Shuanhai

2012-01-01

Highlights: ► Predictions using advanced concrete model compare well with the impact test results. ► Several important behavior of concrete is discussed. ► Two mesh ways incorporating rebar into concrete mesh is also discussed. ► Gives a example of using EPDC model and references to develop new constitutive models. -- Abstract: This paper focuses on numerical simulation of impact tests of reinforced concrete (RC) beams by the LS-DYNA finite element (FE) code. In the FE model, the elasto-plastic damage cap (EPDC) model, which is based on continuum damage mechanics in combination with plasticity theory, is used for concrete, and the reinforcement is assumed to be elasto-plastic. The numerical results compares well with the experimental values reported in the literature, in terms of impact force history, mid-span deflection history and crack patterns of RC beams. By comparing the numerical and experimental results, several important behavior of concrete material is investigated, which includes: damage variable to describe the strain softening section of stress–strain curve; the cap surface to describe the plastic volume change; the shape of the meridian and deviatoric plane to describe the yield surface as well as two methods of incorporating rebar into concrete mesh. This study gives a good example of using EPDC model and can be utilized for the development new constitutive models for concrete in future.

Behaviour of Steel Fibre Reinforced Rubberized Continuous Deep Beams

Science.gov (United States)

Sandeep, MS; Nagarajan, Praveen; Shashikala, A. P.

2018-03-01

Transfer girders and pier caps, which are in fact deep beams, are critical structural elements present in high-rise buildings and bridges respectively. During an earthquake, failure of lifeline structures like bridges and critical structural members like transfer girders will result in severe catastrophes. Ductility is the key factor that influences the resistance of any structural member against seismic action. Structural members cast using materials having higher ductility will possess higher seismic resistance. Previous research shows that concrete having rubber particles (rubcrete) possess better ductility and low density in comparison to ordinary concrete. The main hindrance to the use of rubcrete is the reduction in compressive and tensile strength of concrete due to the presence of rubber. If these undesirable properties of rubcrete can be controlled, a new cementitious composite with better ductility, seismic performance and economy can be developed. A combination of rubber particles and steel fibre has the potential to reduce the undesirable effect of rubcrete. In this paper, the effect of rubber particles and steel fibre in the behaviour of two-span continuous deep beams is studied experimentally. Based on the results, optimum proportions of steel fibre and rubber particles for getting good ductile behaviour with less reduction in collapse load is found out.

Effect of flexural crack on plain concrete beam failure mechanism A numerical simulation

Directory of Open Access Journals (Sweden)

Abdoullah Namdar

2016-03-01

Full Text Available The flexural failure of plain concrete beam occurs along with development of flexural crack on beam. In this paper by using ABAQUS, mechanism failure of plain concrete beam under three steps have been simulated. The cracking moment has been analytically calculated and applied on the both sides of the fixed beam, and flexural crack has been simulated on beam. Displacement, von Mises, load reaction, displacementcrack length, von Mises-crack length and von Mises-displacement of beams have been graphical depicted. Results indicated that, the flexural crack governs beam mechanism failure and its effects on beam resistance failure. It has been found that the flexural crack in initial stage it developed slowly and changes to be fast at the final stage of collapsing beam due to reduction of the flexural resistance of beam. Increasing mechanical properties of concrete, collapse displacement is reduced.

The effect of concrete strength and reinforcement on toughness of reinforced concrete beams

OpenAIRE

Carneiro, Joaquim A. O.; Jalali, Said; Teixeira, Vasco M. P.; Tomás, M.

2005-01-01

The objective pursued with this work includes the evaluating of the strength and the total energy absorption capacity (toughness) of reinforced concrete beams using different amounts of steel-bar reinforcement. The experimental campaign deals with the evaluation of the threshold load prior collapse, ultimate load and deformation, as well as the beam total energy absorption capacity, using a three point bending test. The beam half span displacement was measured using a displacement transducer,...

Numerical Analysis on the High-Strength Concrete Beams Ultimate Behaviour

Science.gov (United States)

Smarzewski, Piotr; Stolarski, Adam

2017-10-01

Development of technologies of high-strength concrete (HSC) beams production, with the aim of creating a secure and durable material, is closely linked with the numerical models of real objects. The three-dimensional nonlinear finite element models of reinforced high-strength concrete beams with a complex geometry has been investigated in this study. The numerical analysis is performed using the ANSYS finite element package. The arc-length (A-L) parameters and the adaptive descent (AD) parameters are used with Newton-Raphson method to trace the complete load-deflection curves. Experimental and finite element modelling results are compared graphically and numerically. Comparison of these results indicates the correctness of failure criteria assumed for the high-strength concrete and the steel reinforcement. The results of numerical simulation are sensitive to the modulus of elasticity and the shear transfer coefficient for an open crack assigned to high-strength concrete. The full nonlinear load-deflection curves at mid-span of the beams, the development of strain in compressive concrete and the development of strain in tensile bar are in good agreement with the experimental results. Numerical results for smeared crack patterns are qualitatively agreeable as to the location, direction, and distribution with the test data. The model was capable of predicting the introduction and propagation of flexural and diagonal cracks. It was concluded that the finite element model captured successfully the inelastic flexural behaviour of the beams to failure.

Acoustic emission monitoring of concrete columns and beams strengthened with fiber reinforced polymer sheets

Science.gov (United States)

Ma, Gao; Li, Hui; Zhou, Wensong; Xian, Guijun

2012-04-01

Acoustic emission (AE) technique is an effective method in the nondestructive testing (NDT) field of civil engineering. During the last two decades, Fiber reinforced polymer (FRP) has been widely used in repairing and strengthening concrete structures. The damage state of FRP strengthened concrete structures has become an important issue during the service period of the structure and it is a meaningful work to use AE technique as a nondestructive method to assess its damage state. The present study reports AE monitoring results of axial compression tests carried on basalt fiber reinforced polymer (BFRP) confined concrete columns and three-point-bending tests carried on BFRP reinforced concrete beams. AE parameters analysis was firstly utilized to give preliminary results of the concrete fracture process of these specimens. It was found that cumulative AE events can reflect the fracture development trend of both BFRP confined concrete columns and BFRP strengthened concrete beams and AE events had an abrupt increase at the point of BFRP breakage. Then the fracture process of BFRP confined concrete columns and BFRP strengthened concrete beams was studied through RA value-average frequency analysis. The RA value-average frequency tendencies of BFRP confined concrete were found different from that of BFRP strengthened concrete beams. The variation tendency of concrete crack patterns during the loading process was revealed.

Bending Moment Decrease of Reinforced Concrete Beam Supported by Additional CFRP

Directory of Open Access Journals (Sweden)

Mykolas Daugevičius

2011-04-01

Full Text Available The calculation method of reinforced concrete beam with additional CFRP composite is proposed in this article. This method estimates tangential angular concrete deformations in tensioned beam layers between steel and bonded carbon fiber reinforced polymer. The horizontal slip of CFRP composite reduce beam bending moment capacity. An additional coefficient to reduce CFRP resultant force is necessary for better precision of bending moment capacity. Also, various calculation methods of bending moment capacity are considered. Article in Lithuanian

Numerical estimation of concrete beams reinforced with FRP bars

Directory of Open Access Journals (Sweden)

Protchenko Kostiantyn

2016-01-01

Full Text Available This paper introduces numerical investigation on mechanical performance of a concrete beam reinforced with Fibre Reinforced Polymer (FRP bars, which can be competitive alternative to steel bars for enhancing concrete structures. The objective of this work is being identified as elaborating of reliable numerical model for predicting strength capacity of structural elements with implementation of Finite Element Analysis (FEA. The numerical model is based on experimental study prepared for the beams, which were reinforced with Basalt FRP (BFRP bars and steel bars (for comparison. The results obtained for the beams reinforced with steel bars are found to be in close agreement with the experimental results. However, the beams reinforced with BFRP bars in experimental programme demonstrated higher bearing capacity than those reinforced with steel bars, which is not in a good convergence with numerical results. Authors did attempt to describe the reasons on achieving experimentally higher bearing capacity of beams reinforced with BFRP bars.

Diagonal Cracking and Shear Strength of Reinforced Concrete Beams

DEFF Research Database (Denmark)

Zhang, Jin-Ping

1997-01-01

The shear failure of non-shear-reinforced concrete beams with normal shear span ratios is observed to be governed in general by the formation of a critical diagonal crack. Under the hypothesis that the cracking of concrete introduces potential yield lines which may be more dangerous than the ones...

Economic impact of multi-span, prestressed concrete girder bridges designed as simple span versus continuous span : final report.

Science.gov (United States)

2016-10-01

The objective of this study was to determine the economic impact of designing pre-tensioned prestressed concrete beam (PPCB) : bridges utilizing the continuity developed in the bridge deck as opposed to the current Iowa Department of Transportation (...

Reliability Analysis of Corroded Reinforced Concrete Beams Using Enhanced HL-RF Method

Directory of Open Access Journals (Sweden)

Arash Mohammadi Farsani

2015-12-01

Full Text Available Steel corrosion of bars in concrete structures is a complex process which leads to the reduction of the cross-section bars and decreasing the resistance of the concrete and steel materials. In this study, reliability analysis of a reinforced concrete beam with corrosion defects under the distributed load was investigated using the enhanced Hasofer-Lind and Rackwitz-Fiessler (EHL-RF method based on relaxed approach. Robustness of the EHL-RF algorithm was compared with the HL-RF using a complicated example. It was seen that the EHL-RF algorithm is more robust than the HL-RF method. Finally, the effects of corrosion time were investigated using the EHL-RF algorithm for a reinforced concrete beam based on flexural strength in the pitting and general corrosion. The model uncertainties were considered in the resistance and load terms of flexural strength limit state function. The results illustrated that increasing the corrosion time-period leads to increase in the failure probability of the corroded concrete beam.

Interfacial shear behavior of composite flanged concrete beams

Directory of Open Access Journals (Sweden)

Moataz Awry Mahmoud

2014-08-01

Full Text Available Composite concrete decks are commonly used in the construction of highway bridges due to their rapid constructability. The interfacial shear transfer between the top slab and the supporting beams is of great significance to the overall deck load carrying capacity and performance. Interfacial shear capacity is directly influenced by the distribution and the percentage of shear connectors. Research and design guidelines suggest the use of two different approaches to quantify the required interfacial shear strength, namely based on the maximum compressive forces in the flange at mid span or the maximum shear flow at the supports. This paper investigates the performance of flanged reinforced concrete composite beams with different shear connector’s distribution and reinforcing ratios. The study incorporated both experimental and analytical programs for beams. Key experimental findings suggest that concentrating the connectors at the vicinity of the supports enhances the ductility of the beam. The paper proposes a simple and straight forward approach to estimate the interfacial shear capacity that was proven to give good correlation with the experimental results and selected code provisions. The paper presents a method to predict the horizontal shear force between precast beams and cast in-situ slabs.

Flexural Behaviour of Reinforced Fibrous Concrete Beams: Experiments and Analytical Modelling

International Nuclear Information System (INIS)

Hameed, R.; Sellier, A.; Turatsinze, A.; Duprat, F.

2013-01-01

Flexural behaviour of reinforced fibrous concrete beams was investigated in this research study. Two types of metallic fibers were studied: amorphous metallic fibers (FibraFlex fibers), and carbon steel hooked-end fibers (Dramix fibers). Four types of reinforced concretes were made: one control (without fibers) and three fibrous. Among three reinforced fibrous concretes, two contained fibers in mono form and one contained fibers in hybrid form. The total quantity of fibers in mono and hybrid forms was 20 kg/m3 and 40 kg/m3, respectively. Three point bending tests were performed according to European standards NF EN 14651 on beams of 150 x 150 mm cross section and length of 550 mm. The results showed that due to positive synergetic interaction between the two metallic fibers used, reinforced fibrous concret (RFC) beams containing fibers in hybrid form exhibited better response at all loading stages. Analytical model to predict ultimate moment capacity of the RFC beam of rectangular section was developed and is presented in this paper. Analytical results for ultimate moment were found to be in good agreement with experimental results. (author)

Experimental Study and Shear Strength Prediction for Reactive Powder Concrete Beams

Directory of Open Access Journals (Sweden)

Maha M.S. Ridha

2018-06-01

Full Text Available Eighteen reactive powder concrete (RPC beams subjected to monotonic loading were tested to quantify the effect of a novel cementitious matrix materials on the shear behavior of longitudinally reinforced RPC beams without web reinforcement. The main test variables were the ratio of the shear span-to- effective depth (a/d, the ratio of the longitudinal reinforcement (ρw, the percentage of steel fibers volume fractions (Vf and the percentage of silica fume powder (SF. A massive experimental program was implemented with monitoring the concrete strain, the deflection and the cracking width and pattern for each RPC beam during the test at all the stages of the loading until failure. The findings of this paper showed that the addition of micro steel fibers (Lf/Df = 13/0.2 into the RPC mixture did not dramatically influence the initial diagonal cracking load whereas it improved the ultimate load capacity, ductility and absorbed energy. The shear design equations proposed by Ashour et al. and Bunni for high strength fiber reinforced concrete (HSFRC beams have been modified in this paper to predict the shear strength of slender RPC beams without web reinforcement and with a/d ≥ 2.5. The predictions of the modified equations are compared with Equations of Shine et al., Kwak et al. and Khuntia et al. Both of the modified equations in this paper gave satisfied predictions for the shear strength of the tested RPC beams with COV of 7.9% and 10%. Keywords: Beams, Ductility, Crack width, Absorbed energy, Reactive powder concrete, Steel fibers

Nondestructive estimation of depth of surface opening cracks in concrete beams

International Nuclear Information System (INIS)

Arne, Kevin; In, Chiwon; Kurtis, Kimberly; Kim, Jin-Yeon; Jacobs, Laurence J.

2014-01-01

Concrete is one of the most widely used construction materials and thus assessment of damage in concrete structures is of the utmost importance from both a safety point of view and a financial point of view. Of particular interest are surface opening cracks that extend through the concrete cover, as this can expose the steel reinforcement bars underneath and induce corrosion in them. This corrosion can lead to significant subsequent damage in concrete such as cracking and delamination of the cover concrete as well as rust staining on the surface of concrete. Concrete beams are designed and constructed in such a way to provide crack depths up to around 13 cm. Two different types of measurements are made in-situ to estimate depths of real surface cracks (as opposed to saw-cut notches) after unloading: one based on the impact-echo method and the other one based on the diffuse ultrasonic method. These measurements are compared to the crack depth visually observed on the sides of the beams. Discussions are given as to the advantages and disadvantages of each method

Reinforced concrete beams with web openings: A state of the art review

International Nuclear Information System (INIS)

Ahmed, A.; Fayyadh, M.M.; Naganathan, S.; Nasharuddin, K.

2012-01-01

Highlights: ► Present paper highlights the gaps in the work related RC beams with web opening. ► There is limited work on comparing of design approaches of RC beams with opening. ► Strengthening with externally bonded steel or FRP sheets needs to be investigated. ► There is no repair work been done on the RC beams with opening. -- Abstract: The construction of modern buildings requires many pipes and ducts in order to accommodate essential services such as air conditioning, electricity, telephone, and computer network. Web openings in concrete beams enable the installation of these services. A number of studies have been conducted with regards to reinforced concrete beams which contain web openings. The present paper aims to compile this state of the art work on the behaviour, analysis and design of Reinforced Concrete (RC) beams with transverse web openings. A variety of aspects will be highlighted and discussed including the classification of openings, guidelines for opening location, and the structural behaviour of RC beams with web openings. Various design approaches will also be detailed, for example the American Concrete Institute (ACI) approach, the Architectural Institute of Japan (AIJ) approach and the strut and tie method. Moreover, the strengthening of RC beams with openings using Fibre Reinforced Polymer (FRP) material and steel plates is presented. Finally, directions for future research based on the gaps which exist in the present work are presented.

Variation of Shrinkage Strain within the Depth of Concrete Beams

Directory of Open Access Journals (Sweden)

Jong-Hyun Jeong

2015-11-01

Full Text Available The variation of shrinkage strain within beam depth was examined through four series of time-dependent laboratory experiments on unreinforced concrete beam specimens. Two types of beam specimens, horizontally cast and vertically cast, were tested; shrinkage variation was observed in the horizontally cast specimens. This indicated that the shrinkage variation within the beam depth was due to water bleeding and tamping during the placement of the fresh concrete. Shrinkage strains were measured within the beam depth by two types of strain gages, surface-attached and embedded. The shrinkage strain distribution within the beam depth showed a consistent tendency for the two types of gages. The test beams were cut into four sections after completion of the test, and the cutting planes were divided into four equal sub-areas to measure the aggregate concentration for each sub-area of the cutting plane. The aggregate concentration increased towards the bottom of the beam. The shrinkage strain distribution was estimated by Hobbs’ equation, which accounts for the change of aggregate volume concentration.

Determination of residual load-bearing capacity of concrete beams at the operation stage by the strength reinforcement and concrete criterion

OpenAIRE

V.S. Utkin

2015-01-01

An experimental theoretical method was considered for estimating the residual load-bearing capacity of an individual reinforced concrete beam at the operational stage according to the criteria of the working strength and durability of concrete reinforcement compressed zone of the beam. Integrated methods of beam testing and probabilistic methods of random variables definition were used. Ultimate load in the form of interval during the operational phase was accepted as the measure of carr...

Economic impact of multi-span, prestressed concrete girder bridges designed as simple span versus continuous span : tech transfer summary.

Science.gov (United States)

2016-10-01

The objective of this study was to determine the economic impact of : designing pre-tensioned prestressed concrete beam (PPCB) bridges : utilizing the continuity developed in the bridge deck as opposed to the : current Iowa Department of Transportati...

Long-term deflection and flexural behavior of reinforced concrete beams with recycled aggregate

International Nuclear Information System (INIS)

Choi, Won-Chang; Yun, Hyun-Do

2013-01-01

Highlights: • Long-term deformation of recycled aggregate concrete beams was examined. • Three beams were monitored for over 380 days. • Influence of recycled aggregate on the long-term performance. • Comparison of that between normal and recycled aggregate concrete beams. - Abstract: This paper presents experimental results on the long-term deformations of recycled aggregate concrete (RAC) beams for over 1 year (380 days) and flexural behavior of RAC beams after exposure to sustained loading. Three reinforced concrete (RC) beam specimens were fabricated with replacement percentage of aggregate (100% natural aggregate, 100% recycled coarse aggregate, and 50% recycled fine aggregate) and subjected to sustained loading that is 50% of the nominal flexural capacity. During the sustained loading period (380 days), the long-term deflection due to creep and shrinkage was recorded and compared with predicted behavior that was determined based on current specifications (ACI 318 Code). After measuring the long-term deflection for 380 days, four-point bending tests were conducted to investigate the flexural behavior of RC beams after exposure to sustained loading and determine any reduction in flexural capacity. A modified equation to predict the long-term deflection values for RC beams with recycled aggregate is proposed, and the experimental results are compared with the predictions calculated using the ACI 318 Code provisions

Beam Shear Design According to Eurocode 2 - Limitations for the Concrete Strut Inclinations

DEFF Research Database (Denmark)

Hagsten, Lars German; Hestbech, Lars; Fisker, Jakob

2011-01-01

and are presented. These beams are all designed to fail in shear and the shear reinforcement is designed for different values of the concrete strut inclinations (cot θ varies from 1.5 to 3.4). These tests indicate a clear connection between the values of the concrete strut inclinations and crack width in the SLS......The beam shear design method adopted in Eurocode 2 is based on a lower bound plastic solution. This method is combined with limitations on the concrete strut inclination, θ. These limitations are introduced to ensure acceptable crack width in the SLS. 7 full scale beams have been tested....... In cases where larger crack widths (w > 0.4 mm) can be accepted, larger values of the concrete strut inclinations can be chosen. This will lead to less shear reinforcements. The results are also compared with analytical analysis based on energy methods. At the SLS the beams are expected to be cracked...

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

Directory of Open Access Journals (Sweden)

Jankowiak Iwona

2017-12-01

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

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

Science.gov (United States)

Jankowiak, Iwona; Madaj, Arkadiusz

2017-12-01

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

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

Directory of Open Access Journals (Sweden)

M. N. Kataoka

Full Text Available Due to the large increase in the use of precast concrete structures in multistory buildings, this work covers a study on the behavior of beam-column connection with emphasis on the continuity provided by the slab reinforcement. Two prototypes were tested, each one with a different detail of the continuity reinforcement distribution. In both connections, the steel area used on the concrete cover of the hollow core slab was the same, varying the amount of bars that passed through the column and the ones that were placed adjacent to the column. The experimental results showed that the connection with bars adjacent to the column presented stiffness increase and a better cracking control. According to the classification the two tested connections can be considered semi-rigid.

Shear strength of reinforced concrete circular cross-section beams

Directory of Open Access Journals (Sweden)

P. W. G. N. Teixeira

Full Text Available A proposed adequation of NBR 6118, Item 7.4, related to shear strength of reinforced concrete beams is presented with aims to application on circular cross-section. The actual expressions are most suitable to rectangular cross-section and some misleading occurs when applied to circular sections at determination of VRd2, Vc and Vsw, as consequence of bw (beam width and d (effective depth definitions as well as the real effectiveness of circular stirrups. The proposed adequation is based on extensive bibliographic review and practical experience with a great number of infrastructure elements, such as anchored retaining pile walls, where the use of circular reinforced concrete members is frequent.

High strength oil palm shell concrete beams reinforced with steel fibres

Directory of Open Access Journals (Sweden)

S. Poh-Yap

2017-10-01

Full Text Available The utilization of lightweight oil palm shell to produce high strength lightweight sustainable material has led many researchers towards its commercialization as structural concrete. However, the low tensile strength of Oil Palm Shell Concrete (OPSC has hindered its development. This study aims to enhance the mechanical properties and flexural behaviours of OPSC by the addition of steel fibres of up to 3% by volume, to produce oil palm shell fibre-reinforced concrete (OPSFRC. The experimental results showed that the steel fibres significantly enhanced the mechanical properties of OPSFRC. The highest compressive strength, splitting tensile and flexural strengths of 55, 11.0 and 18.5 MPa, respectively, were achieved in the OPSFRC mix reinforced with 3% steel fibres. In addition, the flexural beam testing on OPSFRC beams with 3% steel fibres showed that the steel fibre reinforcement up to 3% produced notable increments in the moment capacity and crack resistance of OPSFRC beams, but accompanied by reduction in the ductility.

Flexure Behavior of Hybrid Continuous Deep Beam Strengthened by Carbon Fiber Reinforced Polymer

Directory of Open Access Journals (Sweden)

Hayder M.K.Al-Mutairee

2017-08-01

Full Text Available This study present an experimental investigation for overall flexure behavior of reinforced concrete continuous deep beams (RCCDB made of hybrid concrete, normal strength concrete (NSC and high strength concrete (HSC at different location and percentage. The experimental work includes testing of sixteen specimens of RCCDB under two points loads. The effects of HSC layer thickness and CFRP on strength of RCCDB had been studied. The experimental results showed that the strengthening of RCCDB by HSC layer from top is better than from bottom, where the increment in the ultimate flexural strength increased by (14,21,27% for top strengthening and (12,15,13% for bottom strengthening for (25,50,75% thickness of total depth of beam respectively. The optimal strengthening of RCCDB by HSC layer at top was of 25%. The results also proved that the strengthening of hybrid RCCDB by (10,15cm CFRP strip at the bottom for flexure gave increment in the ultimate strength by (32, 29% respectively, and the strengthening by CFRP strip for flexure at the bottom is better than at top for hybrid RCCDB. The shear strengthening of hybrid RCCDB increases the ultimate strength by 23.4% and 13.8% if the strengthening has O and U shape respectively

Nonlinear Analysis of External Prestressed Reinforced Concrete Beams with BFRP and CFRP

Directory of Open Access Journals (Sweden)

Haleem K. Hussain

2017-05-01

Full Text Available The traditional strengthening methods for concrete structure (girders, beams, columns…. consuming time and could be an economical, a new modern repair methods using the Carbon Fiber Reinforced Polymers (CFRP and Basalt Fiber Reinforced Polymer (BFRP as a laminate strips or bars,and considered a competitive solution that will increase the life-cycle of repaired structures. This study investigated the strengthen reinforced concrete girder. Nonlinear analysis have been adopted to the models using FEM analysis (ANSYS to simulate the theoretical results compared with experimental results.Using finite element packages, more efficient and better analyses can be made to fully understand the response of individual structural components and their contribution to a structure as a whole.Three type of material are used in this study as an external prestressed wire (steel, CFRP and BFRP. The prestressed beam is modeled as simply supported beam with two concentrated point load. The results showed that all tested strengthening beam increased the load carryingcapacity of the beams depend on prestressing force. Obtained Result was compared for different type of beam.This study also was enlarged to include using CFRP and BFRPbarwhich are light weight and moredurable, lead to ease of handling and maintenance. The research conducted analytical work to evaluate the effectiveness of concrete beams reinforced normally by the use of CFRP and BFRP bars. The results showed a significant gain in the beam’s ultimate capacities using CFRP bars comparing with beam reinforced with BFRP bar and reference beam

Theoretical and numerical analysis of reinforced concrete beams with confinement reinforcement

Directory of Open Access Journals (Sweden)

R. G. Delalibera

Full Text Available This paper discusses the use of confinement in over-reinforced concrete beams. This reinforcement consists of square stirrups, placed in the compression zone of the beam cross-section, in order to improve its ductility. A parametric numerical study is initially performed, using a finite element computational program that considers the material nonlinearities and the confinement effect. To investigate the influence of the transverse reinforcing ratio on the beam ductility, an experimental program was also conducted. Four over-reinforced beams were tested; three beam specimens with additional transverse reinforcement to confine the beams, and one without it. All specimens were fabricated with a concrete designed for a compressive strength of 25 MPa. The experimental results show that the post-peak ductility factor is proportional to the confining reinforcement ratio, however the same is not observed for the pre-peak ductility factor, which varied randomly with changes in the confining reinforcement ratio. It was also observed from the experiments that the confinement effect tends to be smaller close to the beam neutral axis.

A design method for two-layer beams consisting of normal and fibered high strength concrete

International Nuclear Information System (INIS)

Iskhakov, I.; Ribakov, Y.

2007-01-01

Two-layer fibered concrete beams can be analyzed using conventional methods for composite elements. The compressed zone of such beam section is made of high strength concrete (HSC), and the tensile one of normal strength concrete (NSC). The problems related to such type of beams are revealed and studied. An appropriate depth of each layer is prescribed. Compatibility conditions between HSC and NSC layers are found. It is based on the shear deformations equality on the layers border in a section with maximal depth of the compression zone. For the first time a rigorous definition of HSC is given using a comparative analysis of deformability and strength characteristics of different concrete classes. According to this definition, HSC has no download branch in the stress-strain diagram, the stress-strain function has minimum exponent, the ductility parameter is minimal and the concrete tensile strength remains constant with an increase in concrete compression strength. The application fields of two-layer concrete beams based on different static schemes and load conditions make known. It is known that the main disadvantage of HSCs is their low ductility. In order to overcome this problem, fibers are added to the HSC layer. Influence of different fiber volume ratios on structural ductility is discussed. An upper limit of the required fibers volume ratio is found based on compatibility equation of transverse tensile concrete deformations and deformations of fibers

Flexural strengthening of reinforced lightweight polystyrene aggregate concrete beams with near-surface mounted GFRP bars

Energy Technology Data Exchange (ETDEWEB)

Tang, W.C.; Balendran, R.V.; Nadeem, A.; Leung, H.Y. [City University of Hong Kong (China). Department of Building and Construction

2006-10-15

Application of near-surface mounted (NSM) fibre reinforced polymer (FRP) bars is emerging as a promising technology for increasing flexural and shear strength of deficient reinforced concrete (RC) members. In order for this technique to perform effectively, the structural behaviour of RC elements strengthened with NSM FRP bars needs to be fully characterized. This paper focuses on the characterization of flexural behaviour of RC members strengthened with NSM glass-FRP bars. Totally, 10 beams were tested using symmetrical two-point loads test. The parameters examined under the beam tests were type of concretes (lightweight polystyrene aggregate concrete and normal concrete), type of reinforcing bars (GFRP and steel), and type of adhesives. Flexural performance of the tested beams including modes of failure, moment-deflection response and ultimate moment capacity are presented and discussed in this paper. Results of this investigation showed that beams with NSM GFRP bars showed a reduction in ultimate deflection and an improvement in flexural stiffness and bending capacity, depending on the PA content of the beams. In general, beams strengthened with NSM GFRP bars overall showed a significant increase in ultimate moment ranging from 23% to 53% over the corresponding beams without NSM GFRP bars. The influence of epoxy type was found conspicuously dominated the moment-deflection response up to the peak moment. Besides, the ultimate moment of concrete beams reinforced with GFRP bars could be predicted satisfactorily using the equation provided in ACI 318-95 Building Code. (author)

A Numerical Analysis of the Resistance and Stiffness of the Timber and Concrete Composite Beam

Science.gov (United States)

Szumigała, Ewa; Szumigała, Maciej; Polus, Łukasz

2015-03-01

The article presents the results of a numerical analysis of the load capacity and stiffness of the composite timber and concrete beam. Timber and concrete structures are relatively new, they have not been thoroughly tested and they are rarely used because of technological constraints. One of the obstacles to using them is difficulty with finding a method which would allow successful cooperation between concrete and timber, which has been proposed by the authors of the present article. The modern idea of sustainable construction design requires the use of new more environmentally-friendly solutions. Wood as an ecological material is easily accessible, less energy-consuming, and under certain conditions more corrosion-resistant than steel. The analysis presented in the article showed that cooperation between a wooden beam and a concrete slab on profiled steel sheeting is possible. The analysed composite beam has a greater load capacity and stiffness than the wooden beam.

Shear Capacity of Steel and Polymer Fibre Reinforced Concrete Beams

DEFF Research Database (Denmark)

Kragh-Poulsen, Jens C.; Hoang, Cao Linh; Goltermann, Per

2011-01-01

This paper deals with the application of a plasticity model for shear strength estimation of fibre reinforced concrete beams without stirrups. When using plastic theory to shear problems in structural concrete, the so-called effective strengths are introduced, usually determined by calibrating...... the plastic solutions with tests. This approach is, however, problematic when dealing with fibre reinforced concrete (FRC), as the effective strengths depend also on the type and the amount of fibres. In this paper, it is suggested that the effective tensile strength of FRC can be determined on the basis...

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.

Shear Strength of Concrete I-Beams - Contributions of Flanges

DEFF Research Database (Denmark)

Teoh, B. K.; Hoang, Cao Linh; Nielsen, Mogens Peter

1999-01-01

The contribution of flanges to the shear strength of reinforced concrete beams has up to now either been neglected or evaluated by very simple empirical formulas. However, the contribution may sometimes be large, up to 20-30%. In this paper the flange contribution for shear reinforced I-beams has...... range of geometrical parameters. The comparisons show that the method suggested does indeed lead to very accurate results....

Flexural Strength Of Prestressed Concrete Beams With Openings And Strengthened With CFRP Sheets

Directory of Open Access Journals (Sweden)

Dr. Mustafa B. Dawood

2015-06-01

Full Text Available Abstract This paper presents an experimental investigation of flexural strength of pretensioned prestressed concrete beams with openings and strengthened with CFRP sheets tested as simply supported span subjected under two-point loading. The experimental work includes testing of nine prestressed concrete beams specimens with dimensions effective length 1800mm depth 300mm width 130mm two of which were without openings as a control beams one without and the other with strengthening by CFRP three were with openings and the remaining four with openings and strengthened with CFRP sheets. The opening was made at square shape 100100 mm in flexure zone at mid span of beam. Several design parameters were varied such as opening width opening depth and strengthening of openings of beams by CFRP sheets at compression and tension zone. Experimental results showed that the presence of square opening with ratio hH 0.333 and rectangular opening with ratio hH from 0.333-0.5 at mid span of beams decreased the ultimate load about 5.5 and 5.5-33.1 respectively when compared with beam without openings control beam. The externally strengthened prestressed concrete beams with bonded CFRP sheets showed a significant increase at the ultimate load this increase was about 10.9-28.8 for flexure beams when compared with the unstrengthened beams. Moreover the load-deflection curves for flexure beams strengthened with CFRP sheets were stiffer than the unstrengthened beams. Therefore this results gave a good indication about using CFRP sheets in improvement of deflection.

Comparative analysis of the influence of creep of concrete composite beams of steel - concrete model based on Volterra integral equation

Directory of Open Access Journals (Sweden)

Partov Doncho

2017-01-01

Full Text Available The paper presents analysis of the stress-strain behaviour and deflection changes due to creep in statically determinate composite steel-concrete beam according to EUROCODE 2, ACI209R-92 and Gardner&Lockman models. The mathematical model involves the equation of equilibrium, compatibility and constitutive relationship, i.e. an elastic law for the steel part and an integral-type creep law of Boltzmann - Volterra for the concrete part considering the above mentioned models. On the basis of the theory of viscoelastic body of Maslov-Arutyunian-Trost-Zerna-Bažant for determining the redistribution of stresses in beam section between concrete plate and steel beam with respect to time 't', two independent Volterra integral equations of the second kind have been derived. Numerical method based on linear approximation of the singular kernel function in the integral equation is presented. Example with the model proposed is investigated.

Thermal analysis of reinforced concrete beams and frames

Directory of Open Access Journals (Sweden)

Essam H. El-Tayeb

2017-04-01

The obtained results of the studied cases reveal that material modeling of reinforced concrete beams and frames plays a major role in how these structures react to temperature variation. Cracking contributes to the release of significant portion of temperature restrain and in some cases this restrain is almost eliminated. The response of beams and frames deviates significantly based on the temperature gradient, linear or nonlinear; hence, the nonlinear temperature gradient which is the realistic profile is important to implement in the analysis.

Finite element analysis of composite concrete-timber beams

Directory of Open Access Journals (Sweden)

N. C. S. FORTI

Full Text Available AbstractIn the search for sustainable construction, timber construction is gaining in popularity around the world. Sustainably harvested wood stores carbon dioxide, while reforestation absorbs yet more CO2. One technique involves the combination of a concrete slab and a timber beam, where the two materials are assembled by the use of flexible connectors. Composite structures provide reduced costs, environmental benefits, a better acoustic performance, when compared to timber structures, and maintain structural safety. Composite structures combine materials with different mechanical properties. Their mechanical performance depends on the efficiency of the connection, which is designed to transmit shear longitudinal forces between the two materials and to prevent vertical detachment. This study contributes with the implementation of a finite element formulation for stress and displacement determination of composite concrete-timber beams. The deduced stiffness matrix and load vector are presented along to numerical examples. Numerical examples are compared to the analytical equations available in Eurocode 5 and to experimental data found in the literature.

Finite Element Analysis of Reinforced Concrete Beam-Column Connections with Governing Joint Shear Failure Mode

Directory of Open Access Journals (Sweden)

M.A. Najafgholipour

Full Text Available Abstract Reinforced concrete (RC beam-column connections especially those without transverse reinforcement in joint region can exhibit brittle behavior when intensive damage is concentrated in the joint region during an earthquake event. Brittle behavior in the joint region can compromise the ductile design philosophy and the expected overall performance of structure when subjected to seismic loading. Considering the importance of joint shear failure influences on strength, ductility and stability of RC moment resisting frames, a finite element modeling which focuses on joint shear behavior is presented in this article. Nonlinear finite element analysis (FEA of RC beam-column connections is performed in order to investigate the joint shear failure mode in terms of joint shear capacity, deformations and cracking pattern. A 3D finite element model capable of appropriately modeling the concrete stress-strain behavior, tensile cracking and compressive damage of concrete and indirect modeling of steel-concrete bond is used. In order to define nonlinear behavior of concrete material, the concrete damage plasticity is applied to the numerical model as a distributed plasticity over the whole geometry. Finite element model is then verified against experimental results of two non-ductile beam-column connections (one exterior and one interior which are vulnerable to joint shear failure. The comparison between experimental and numerical results indicates that the FE model is able to simulate the performance of the beam-column connections and is able to capture the joint shear failure in RC beam-column connections.

A Numerical Analysis of the Resistance and Stiffness of the Timber and Concrete Composite Beam

Directory of Open Access Journals (Sweden)

Szumigała Ewa

2015-03-01

Full Text Available The article presents the results of a numerical analysis of the load capacity and stiffness of the composite timber and concrete beam. Timber and concrete structures are relatively new, they have not been thoroughly tested and they are rarely used because of technological constraints. One of the obstacles to using them is difficulty with finding a method which would allow successful cooperation between concrete and timber, which has been proposed by the authors of the present article. The modern idea of sustainable construction design requires the use of new more environmentally-friendly solutions. Wood as an ecological material is easily accessible, less energy-consuming, and under certain conditions more corrosion-resistant than steel. The analysis presented in the article showed that cooperation between a wooden beam and a concrete slab on profiled steel sheeting is possible. The analysed composite beam has a greater load capacity and stiffness than the wooden beam.

Modeling of interaction between steel and concrete in continuously reinforced concrete pavements : final report.

Science.gov (United States)

2016-01-01

Continuously reinforced concrete pavement (CRCP) contains continuous longitudinal reinforcement with no transverse : expansion within the early life of the pavement and can continue to develop cracks in the long-term. The : accurate modeling of CRCPs...

Experimental analysis of reinforced concrete beams strengthened in bending with carbon fiber reinforced polymer

Directory of Open Access Journals (Sweden)

M. M. VIEIRA

Full Text Available The use of carbon fiber reinforced polymer (CFRP has been widely used for the reinforcement of concrete structures due to its practicality and versatility in application, low weight, high tensile strength and corrosion resistance. Some construction companies use CFRP in flexural strengthening of reinforced concrete beams, but without anchor systems. Therefore, the aim of this study is analyze, through an experimental program, the structural behavior of reinforced concrete beams flexural strengthened by CFRP without anchor fibers, varying steel reinforcement and the amount of carbon fibers reinforcement layers. Thus, two groups of reinforced concrete beams were produced with the same geometric feature but with different steel reinforcement. Each group had five beams: one that is not reinforced with CFRP (reference and other reinforced with two, three, four and five layers of carbon fibers. Beams were designed using a computational routine developed in MAPLE software and subsequently tested in 4-point points flexural test up to collapse. Experimental tests have confirmed the effectiveness of the reinforcement, ratifying that beams collapse at higher loads and lower deformation as the amount of fibers in the reinforcing layers increased. However, the increase in the number of layers did not provide a significant increase in the performance of strengthened beams, indicating that it was not possible to take full advantage of strengthening applied due to the occurrence of premature failure mode in the strengthened beams for pullout of the cover that could have been avoided through the use of a suitable anchoring system for CFRP.

Static and dynamic testing of a damaged post tensioned concrete beam

Directory of Open Access Journals (Sweden)

Limongelli M.P.

2015-01-01

Full Text Available In this paper are reported the results of an experimental campaign carried out on a post tensioned concrete beam with the aim of investigating the possibility to detect early warning signs of deterioration basing on static and/or dynamic tests. The beam was tested in several configurations aimed to reproduce several different phases of the ‘life’ of the beam: the original undamaged state, increasing loss of tension in the post tensioning cables, a strengthening intervention carried out by means of a second tension cable, formation of further cracks on the strengthened beam. Responses of the beam were measured by an extensive set of instruments consisting of accelerometers, inclinometers, displacement transducers, strain gauges and optical fibres. The paper discusses the tests program and the dynamic characterization of the beam in the different damage scenarios. The modal properties of the beam in the different phases were recovered basing on the responses recorded on the beam during sine-sweep and impact hammer tests. The variation of the first modal frequency was studied to investigate the sensitivity of this parameter to both the cracking of the concrete section and the tension in the cables and also to compare results given by different types of experimental tests.

Modeling the dynamic stiffness of cracked reinforced concrete beams under low-amplitude vibration loads

Science.gov (United States)

Xu, Tengfei; Castel, Arnaud

2016-04-01

In this paper, a model, initially developed to calculate the stiffness of cracked reinforced concrete beams under static loading, is used to assess the dynamic stiffness. The model allows calculating the average inertia of cracked beams by taking into account the effect of bending cracks (primary cracks) and steel-concrete bond damage (i.e. interfacial microcracks). Free and forced vibration experiments are used to assess the performance of the model. The respective influence of bending cracks and steel-concrete bond damage on both static and dynamic responses is analyzed. The comparison between experimental and simulated deflections confirms that the effects of both bending cracks and steel-concrete bond loss should be taken into account to assess reinforced concrete stiffness under service static loading. On the contrary, comparison of experimental and calculated dynamic responses reveals that localized steel-concrete bond damages do not influence significantly the dynamic stiffness and the fundamental frequency.

Failure analysis of prestressed concrete beam under impact loading

International Nuclear Information System (INIS)

Ishikawa, N.; Sonoda, Y.; Kobayashi, N.

1993-01-01

This paper presents a failure analysis of prestressed concrete (PC) beam under impact loading. At first, the failure analysis of PC beam section is performed by using the discrete section element method in order to obtain the dynamic bending moment-curvature relation. Secondary, the failure analysis of PC beam is performed by using the rigid panel-spring model. Finally, the numerical calculation is executed and is compared with the experimental results. It is found that this approach can simulate well the experiments at the local and overall failure of the PC beam as well as the impact load and the displacement-time relations. (author)

Ductility and Ultimate Capacity of Prestressed Steel Reinforced Concrete Beams

Directory of Open Access Journals (Sweden)

Chengquan Wang

2017-01-01

Full Text Available Nonlinear numerical analysis of the structural behaviour of prestressed steel reinforced concrete (PSRC beams was carried out by using finite element analysis software ABAQUS. By comparing the load-deformation curves, the rationality and reliability of the finite element model have been confirmed; moreover, the changes of the beam stiffness and stress in the forcing process and the ultimate bearing capacity of the beam were analyzed. Based on the model, the effect of prestressed force, and H-steel to the stiffness, the ultimate bearing capacity and ductility of beam were also analyzed.

Calculating the Carrying Capacity of Flexural Prestressed Concrete Beams with Non-Metallic Reinforcement

Directory of Open Access Journals (Sweden)

Mantas Atutis

2011-04-01

Full Text Available The article reviews moment resistance design methods of prestressed concrete beams with fibre-reinforced polymer (FRP reinforcement. FRP tendons exhibit linear elastic response to rupture without yielding and thus failure is expected to be brittle. The structural behaviour of beams prestressed with FRP tendons is different from beams with traditional steel reinforcement. Depending on the reinforcement ratio, the flexural behaviour of the beam can be divided into several groups. The numerical results show that depending on the nature of the element failure, moment resistance calculation results are different by using reviewed methods. It was found, that the use of non-metallic reinforcement in prestressed concrete structures is effective: moment capacity is about 5% higher than that of the beams with conventional steel reinforcement.Article in Lithuanian

Experimental Study on Flexural Strength of Reinforced Geopolymer Concrete Beams

OpenAIRE

Khoa Tan Nguyen; Tuan Anh Le; Kihak Lee

2016-01-01

This paper presents the flexural response of Reinforced Geopolymer Concrete (RGPC) beams. A commercial finite element (FE) software ABAQUS has been used to perform a structural behavior of RGPC beams. Using parameters such: stress, strain, Young’s modulus, and Poisson’s ratio obtained from experimental results, a beam model has been simulated in ABAQUS. The results from experimental tests and ABAQUS simulation were compared. Due to friction forces at the supports and loading rollers; slip occ...

Performance of Reinforced Concrete Beam with Differently Positioned Replacement Zones of Block Infill under Low Impact Loads

Directory of Open Access Journals (Sweden)

Mokhatar Shahrul Niza

2017-01-01

Full Text Available This paper reveals a study performed on reinforced concrete with artificial aggregate concrete block infill composite beams to innovate a lightweight reinforced concrete utilizing polyethylene (PE waste materials, such as waste plastic bags. Six beam specimens of normal reinforced concrete (NRC and different block infill replacement zone positions RCAI (RZ1 beams containing 100% MAPEA with 50, 95, and 1,000 mm width, height, and length, respectively, were provided for the block infill, whereas RCAI (RZ2 with different block infill positions containing a 100% MAPEA with 50, 115, and 1000 mm width, height, and length were provided and tested under low impact load. The steel impactor with blunt nose dropped at 0.6 m height which equivalent to 3.5 m/s. The behaviors of the beams were studied relative to the impact force-time and displacement-time histories, the flexural/ bending cracks, and the impact failure. Results show that the overall failure modes of all the beam specimens were successfully recorded. In addition, the residual displacements of the RZ2 was almost same than those of the RZ1 and the significantly lower than those of the NRC. In the reinforced concrete beams, less stressed concrete near the neutral axis can be replaced by certain light weight material like waste plastic bags as modified artificial polyethylene aggregates to serve as an artificial aggregate.

Cohesive fracture model for functionally graded fiber reinforced concrete

International Nuclear Information System (INIS)

Park, Kyoungsoo; Paulino, Glaucio H.; Roesler, Jeffery

2010-01-01

A simple, effective, and practical constitutive model for cohesive fracture of fiber reinforced concrete is proposed by differentiating the aggregate bridging zone and the fiber bridging zone. The aggregate bridging zone is related to the total fracture energy of plain concrete, while the fiber bridging zone is associated with the difference between the total fracture energy of fiber reinforced concrete and the total fracture energy of plain concrete. The cohesive fracture model is defined by experimental fracture parameters, which are obtained through three-point bending and split tensile tests. As expected, the model describes fracture behavior of plain concrete beams. In addition, it predicts the fracture behavior of either fiber reinforced concrete beams or a combination of plain and fiber reinforced concrete functionally layered in a single beam specimen. The validated model is also applied to investigate continuously, functionally graded fiber reinforced concrete composites.

Structural Behavior of Concrete Beams Reinforced with Basalt Fiber Reinforced Polymer (BFRP) Bars

Science.gov (United States)

Ovitigala, Thilan

The main challenge for civil engineers is to provide sustainable, environmentally friendly and financially feasible structures to the society. Finding new materials such as fiber reinforced polymer (FRP) material that can fulfill the above requirements is a must. FRP material was expensive and it was limited to niche markets such as space shuttles and air industry in the 1960s. Over the time, it became cheaper and spread to other industries such as sporting goods in the 1980-1990, and then towards the infrastructure industry. Design and construction guidelines are available for carbon fiber reinforced polymer (CFRP), aramid fiber reinforced polymer (AFRP) and glass fiber reinforced polymer (GFRP) and they are currently used in structural applications. Since FRP is linear elastic brittle material, design guidelines for the steel reinforcement are not valid for FRP materials. Corrosion of steel reinforcement affects the durability of the concrete structures. FRP reinforcement is identified as an alternative to steel reinforcement in corrosive environments. Although basalt fiber reinforced polymer (BFRP) has many advantages over other FRP materials, but limited studies have been done. These studies didn't include larger BFRP bar diameters that are mostly used in practice. Therefore, larger beam sizes with larger BFRP reinforcement bar diameters are needed to investigate the flexural and shear behavior of BFRP reinforced concrete beams. Also, shear behavior of BFRP reinforced concrete beams was not yet studied. Experimental testing of mechanical properties and bond strength of BFRP bars and flexural and shear behavior of BFRP reinforced concrete beams are needed to include BFRP reinforcement bars in the design codes. This study mainly focuses on the use of BFRP bars as internal reinforcement. The test results of the mechanical properties of BFRP reinforcement bars, the bond strength of BFRP reinforcement bars, and the flexural and shear behavior of concrete beams

Experimental Evaluation of the Failure of a Seismic Design Category - B Precast Concrete Beam-Column Connection System

Science.gov (United States)

2014-12-01

Precast Concrete Beam - Column Connection ...ERDC TR-14-12 December 2014 Experimental Evaluation of the Failure of a Seismic Design Category – B Precast Concrete Beam - Column Connection ...systems in order to develop a methodology and obtain basic insight for predicting the brittle failure of precast beam - column connections under

The Effect of CFRP Length on the Failure Mode of Strengthened Concrete Beams

Directory of Open Access Journals (Sweden)

Jun Ding

2014-06-01

Full Text Available This paper reports the effects of carbon fiber-reinforced polymer (CFRP length on the failure process, pattern and crack propagation for a strengthened concrete beam with an initial notch. The experiments measuring load-bearing capacity for concrete beams with various CFRP lengths have been performed, wherein the crack opening displacements (COD at the initial notch are also measured. The application of CFRP can significantly improve the load-bearing capacity, and the failure modes seem different with various CFRP lengths. The stress profiles in the concrete material around the crack tip, at the end of CFRP and at the interface between the concrete and CFRP are then calculated using the finite element method. The experiment measurements are validated by theoretical derivation and also support the finite element analysis. The results show that CFRP can significantly increase the ultimate load of the beam, while such an increase stops as the length reaches 0.15 m. It is also concluded that the CFRP length can influence the stress distribution at three critical stress regions for strengthened concrete beams. However, the optimum CFRP lengths vary with different critical stress regions. For the region around the crack tip, it is 0.15 m; for the region at the interface it is 0.25 m, and for the region at the end of CFRP, it is 0.30 m. In conclusion, the optimum CFRP length in this work is 0.30 m, at which CFRP strengthening is fully functioning, which thus provides a good reference for the retrofitting of buildings.

Self-repairing performance of concrete beams strengthened using superelastic SMA wires in combination with adhesives released from hollow fibers

International Nuclear Information System (INIS)

Kuang Yachuan; Ou Jinping

2008-01-01

By taking advantage of the superelastic effect of shape memory alloy (SMA) and the cohering characteristic of repairing adhesive, a smart self-repairing concrete beam with damage self-repairing performance has been developed. In order to verify the potential self-repairing capacity of smart concrete beams reinforced with SMA wires and brittle fibers containing adhesives, static loading tests were conducted. Experimental results show that the superelastic SMA wires added self-restoration capacity to concrete beams, the deflection of the beams reversed and the crack closed almost completely after unloading. After the release of adhesive from the broken-open fibers into the cracks from the first loading, stress was redistributed to the uncracked section where a new crack was formed, while the sealed crack remained closed during reloading for the smart concrete beams reinforced with SMA wires and brittle fibers containing adhesives. While the original cracks experienced reopening, the load was carried directly by the wires during reloading for concrete beams reinforced with SMA wires

Finite element modeling of reinforced concrete beams with a hybrid combination of steel and aramid reinforcement

International Nuclear Information System (INIS)

Hawileh, R.A.

2015-01-01

Highlights: • Modeling of concrete beams reinforced steel and FRP bars. • Developed finite element models achieved good results. • The models are validated via comparison with experimental results. • Parametric studies are performed. - Abstract: Corrosion of steel bars has an adverse effect on the life-span of reinforced concrete (RC) members and is usually associated with crack development in RC beams. Fiber reinforced polymer (FRP) bars have been recently used to reinforce concrete members in flexure due to their high tensile strength and superior corrosion resistance properties. However, FRP materials are brittle in nature, thus RC beams reinforced with such materials would exhibit a less ductile behavior when compared to similar members reinforced with conventional steel reinforcement. Recently, researchers investigated the performance of concrete beams reinforced with a hybrid combination of steel and Aramid Fiber Reinforced Polymer (AFRP) reinforcement to maintain a reasonable level of ductility in such members. The function of the AFRP bars is to increase the load-carrying capacity, while the function of the steel bars is to ensure ductility of the flexural member upon yielding in tension. This paper presents a three-dimensional (3D) finite element (FE) model that predicted the load versus mid-span deflection response of tested RC beams conducted by other researchers with a hybrid combination of steel and AFRP bars. The developed FE models account for the constituent material nonlinearities and bond–slip behavior between the reinforcing bars and adjacent concrete surfaces. It was concluded that the developed models can accurately capture the behavior and predicts the load-carrying capacity of such RC members. In addition, a parametric study is conducted using the validated models to investigate the effect of AFRP bar size, FRP material type, bond–slip action, and concrete compressive strength on the performance of concrete beams when reinforced

Self-sensing CF-GFRP rods as mechanical reinforcement and sensors of concrete beams

Science.gov (United States)

Nanni, F.; Auricchio, F.; Sarchi, F.; Forte, G.; Gusmano, G.

2006-02-01

In this paper testing carried out on concrete beams reinforced with self-sensing composite rods is presented. Such concrete beams, whose peculiarity is to be reinforced by self-sensing materials able to generate an alarm signal when fixed loads are reached, were designed, manufactured and tested. The reinforcing rods were manufactured by pultrusion and consisted of self-sensing hybrid composites containing both glass and carbon fibres in an epoxy resin. The experimentation was carried out by performing simultaneously mechanical tests on the reinforced beams and electrical measurements on the composite rods. The results showed that the developed system reached the target proposed, giving an alarm signal.

Seismic performance of interior precast concrete beam-column connections with T-section steel inserts under cyclic loading

Science.gov (United States)

Ketiyot, Rattapon; Hansapinyo, Chayanon

2018-04-01

An experimental investigation was conducted to study the performance of precast beam-column concrete connections using T-section steel inserts into the concrete beam and joint core, under reversed cyclic loading. Six 2/3-scale interior beam-column subassemblies, one monolithic concrete specimen and five precast concrete specimens were tested. One precast specimen was a simple connection for a gravity load resistant design. Other precast specimens were developed with different attributes to improve their seismic performance. The test results showed that the performance of the monolithic specimen M1 represented ductile seismic behavior. Failure of columns and joints could be prevented, and the failure of the frame occurred at the flexural plastic hinge formation at the beam ends, close to the column faces. For the precast specimens, the splitting crack along the longitudinal lapped splice was a major failure. The precast P5 specimen with double steel T-section inserts showed better seismic performance compared to the other precast models. However, the dowel bars connected to the steel inserts were too short to develop a bond. The design of the precast concrete beams with lap splice is needed for longer lap lengths and should be done at the beam mid span or at the low flexural stress region.

Study of stiffness and bearing capacity degradation of reinforced concrete beams under constant-amplitude fatigue.

Science.gov (United States)

Liu, Fangping; Zhou, Jianting; Yan, Lei

2018-01-01

For a reinforced concrete beam subjected to fatigue loads, the structural stiffness and bearing capacity will gradually undergo irreversible degeneration, leading to damage. Moreover, there is an inherent relationship between the stiffness and bearing capacity degradation and fatigue damage. In this study, a series of fatigue tests are performed to examine the degradation law of the stiffness and bearing capacity. The results pertaining to the stiffness show that the stiffness degradation of a reinforced concrete beam exhibits a very clear monotonic decreasing "S" curve, i.e., the stiffness of the beam decreases significantly at the start of the fatigue loading, it undergoes a linear decline phase in the middle for a long loading period, and before the failure, the bearing capacity decreases drastically again. The relationship between the residual stiffness and residual bearing capacity is determined based on the assumption that the residual stiffness and residual bearing capacity depend on the same damage state, and then, the bearing capacity degradation model of the reinforced concrete beam is established based on the fatigue stiffness. Through the established model and under the premise of the known residual stiffness degradation law, the degradation law of the bearing capacity is determined by using at least one residual bearing capacity test data, for which the parameters of the stiffness degradation function are considered as material constants. The results of the bearing capacity show that the bearing capacity degradation of the reinforced concrete beam also exhibits a very clear monotonic decreasing "S" curve, which is consistent with the stiffness degradation process and in good agreement with the experiment. In this study, the stiffness and bearing capacity degradation expressions are used to quantitatively describe their occurrence in reinforced concrete beams. In particular, the expression of the bearing capacity degradation can mitigate numerous

Long term bending behavior of ultra-high performance concrete (UHPC beams

Directory of Open Access Journals (Sweden)

Gheorghe-Alexandru BARBOS

2015-12-01

Full Text Available Unlike normal concrete (NC the behavior of ultra-high performance concrete (UHPC is different under long-term efforts, if we refer to creep, shrinkage or long-term deflections. It is well known that UHPC has special properties, like compressive strength higher than 150 MPa and tensile strength higher than 20 MPa - in case of UHPC reinforced with steel-fibers. Nevertheless, UHPC behavior is not completely elucidated in what concerns creep straining or serviceability behavior in case of structural elements. Some studies made on UHPC samples shown that creep is significantly reduced if the concrete is subjected to heat treatment and if it contains steel-fiber reinforcement. Relating thereto, it is important to know how does structural elements made of this type of concrete works in service life under long-term loadings. The results obtained on UHPC samples, regarding creep straining from tension or compression efforts may not be generalized in case of structural elements (e.g. beams, slabs, columns subjected to bending. By performing this study, it was aimed to understand the influence of heat treatment and steel-fiber addition on the rheological phenomena of UHPC bended beams.

Dynamics of layered reinforced concrete beam on visco-elastic foundation with different resistances of concrete and reinforcement to tension and compression

Science.gov (United States)

Nemirovsky, Y. V.; Tikhonov, S. V.

2018-03-01

Originally, fundamentals of the theory of limit equilibrium and dynamic deformation of building metal and reinforced concrete structures were created by A. A. Gvozdev [1] and developed by his followers [4, 5, 6, 7, 11, 12]. Forming the basis for the calculation, the model of an ideal rigid-plastic material has enabled to determine in many cases the ultimate load bearing capacity and upper (kinematically possible) or lower (statically valid) values for a wide class of different structures with quite simple methods. At the same time, applied to concrete structures the most important property of concrete to significantly differently resist tension and compression was not taken into account [10]. This circumstance was considered in [3] for reinforced concrete beams under conditions of quasistatic loading. The deformation is often accompanied by resistance of the environment in construction practice [8, 9]. In [2], the dynamics of multi-layered concrete beams on visco-elastic foundation under the loadings of explosive type is considered. In this work we consider the case which is often encountered in practical applications when the loadings weakly change in time.

Markov chain modeling of evolution of strains in reinforced concrete flexural beams

Directory of Open Access Journals (Sweden)

Anoop, M. B.

2012-09-01

Full Text Available From the analysis of experimentally observed variations in surface strains with loading in reinforced concrete beams, it is noted that there is a need to consider the evolution of strains (with loading as a stochastic process. Use of Markov Chains for modeling stochastic evolution of strains with loading in reinforced concrete flexural beams is studied in this paper. A simple, yet practically useful, bi-level homogeneous Gaussian Markov Chain (BLHGMC model is proposed for determining the state of strain in reinforced concrete beams. The BLHGMC model will be useful for predicting behavior/response of reinforced concrete beams leading to more rational design.A través del análisis de la evolución de la deformación superficial observada experimentalmente en vigas de hormigón armado al entrar en carga, se constata que dicho proceso debe considerarse estocástico. En este trabajo se estudia la utilización de cadenas de Markov para modelizar la evolución estocástica de la deformación de vigas flexotraccionadas. Se propone, para establecer el estado de deformación de estas, un modelo con distribución gaussiana tipo cadena de Markov homogénea de dos niveles (BLHGMC por sus siglas en inglés, cuyo empleo resulta sencillo y práctico. Se comprueba la utilidad del modelo BLHGMC para prever el comportamiento de estos elementos, lo que determina a su vez una mayor racionalidad a la hora de su cálculo y diseño

Investigation on the flexural behaviour of reinforced concrete beams using phyllite aggregates from mining waste

International Nuclear Information System (INIS)

Adom-Asamoah, Mark; Afrifa, Russell Owusu

2011-01-01

Highlights: → Most parts of the world's geology is underlain by phyllite rocks. → Crack widths not well predicted so may not be used in water retaining structures. → Shear failure mode and low displacement ductility often observed in beams. → Concrete shear capacity observed lower than code values. -- Abstract: This paper investigated the flexural behaviour of 12 reinforced concrete (RC) beams made of phyllite coarse aggregates produced as by-product of underground gold mining activity. The beams were tested to failure under four point test. Collapse of the beams which were adequately designed against shear failure occurred mostly through either flexural-shear failure and/or diagonal tension failure. The experimental failure loads averaged approximately 115% of the theoretical failure loads. It was observed that the beams developed early shear cracks and higher flexural crack widths than allowable at service loads. Deflections compared reasonably well with the design code requirement but displacement ductility was low. It is recommended that British Standard (BS) 8110 design concrete shear stress values be multiplied by 0.8 to assure that the predicted shear capacity of phyllite concrete would be low and reasonable as compared to flexural capacity. In that case, BS 8110 can be used to provide adequate load factor against flexural failure for under-reinforced RC beams made of phyllite coarse aggregates.

Experimental investigation of steel fiber-reinforced concrete beams under cyclic loading

Science.gov (United States)

Ranjbaran, Fariman; Rezayfar, Omid; Mirzababai, Rahmatollah

2018-03-01

An experimental study has been conducted to study the cyclic behavior of reinforced concrete beams in which steel fibers were added to the concrete mix. Seven similar geometrically specimens in full scale were studied under four- point bending test in the form of slow cyclic loading. One sample as a control specimen was made without steel fibers or 0% volume fraction (vf) and six other samples with 1, 2 and 4% vf of steel fibers in twin models. The maximum and ultimate resistance, ductility, degradation of loading and unloading stiffness, absorption and dissipation of energy and equivalent viscous damping were studied in this investigation and the effect of steel fibers on the cyclic behavior was compared with each other. Generally, the addition of steel fibers up to a certain limit value (vf = 2%) improves the cyclic behavior of reinforced concrete beams and results in the increase of maximum strength and ultimate displacement.

Vibration Analysis of Steel-Concrete Composite Box Beams considering Shear Lag and Slip

Directory of Open Access Journals (Sweden)

Zhou Wangbao

2015-01-01

Full Text Available In order to investigate dynamic characteristics of steel-concrete composite box beams, a longitudinal warping function of beam section considering self-balancing of axial forces is established. On the basis of Hamilton principle, governing differential equations of vibration and displacement boundary conditions are deduced by taking into account coupled influencing of shear lag, interface slip, and shear deformation. The proposed method shows an improvement over previous calculations. The central difference method is applied to solve the differential equations to obtain dynamic responses of composite beams subjected to arbitrarily distributed loads. The results from the proposed method are found to be in good agreement with those from ANSYS through numerical studies. Its validity is thus verified and meaningful conclusions for engineering design can be drawn as follows. There are obvious shear lag effects in the top concrete slab and bottom plate of steel beams under dynamic excitation. This shear lag increases with the increasing degree of shear connections. However, it has little impact on the period and deflection amplitude of vibration of composite box beams. The amplitude of deflection and strains in concrete slab reduce as the degree of shear connections increases. Nevertheless, the influence of shear connections on the period of vibration is not distinct.

Shear strength of non-shear reinforced concrete elements

DEFF Research Database (Denmark)

Hoang, Cao linh

1997-01-01

is based upon the hypothesis that cracks can be transformed into yield lines, which have lower sliding resistance than yield lines formed in uncracked concrete.Proposals have been made on how the derived standard solutions may be applied to more complicated cases, such as continuous beams, beams......The report deals with the shear strength of statically indeterminate reinforced concrete beams without shear reinforcement. Solutions for a number of beams with different load and support conditions have been derived by means of the crack sliding model developed by Jin- Ping Zhang.This model...

Influence of steel fibers on the shear and flexural performance of high-strength concrete beams tested under blast loads

Science.gov (United States)

Algassem, O.; Li, Y.; Aoude, H.

2017-09-01

This paper presents the results of a study examining the effect of steel fibres on the blast behaviour of high-strength concrete beams. As part of the study, a series of three large-scale beams built with high-strength concrete and steel fibres are tested under simulated blast loading using the shock-tube testing facility at the University of Ottawa. The specimens include two beams built with conventional high-strength concrete (HSC) and one beam built with high-strength concrete and steel fibres (HSFRC). The effect of steel fibres on the blast behaviour is examined by comparing the failure mode, mid-span displacements and, overall blast resistance of the specimens. The results show that the addition of steel fibres in high-strength concrete beams can prevent shear failure and substitute for shear reinforcement if added in sufficient quantity. Moreover, the use of steel fibres improves flexural response under blast loading by reducing displacements and increasing blast capacity. Finally, the provision of steel fibres is found to improve the fragmentation resistance of high-strength concrete under blast loads.

SDOF models for reinforced concrete beams under impulsive loads accounting for strain rate effects

Energy Technology Data Exchange (ETDEWEB)

Stochino, F., E-mail: fstochino@unica.it [Department of Civil and Environmental Engineering and Architecture, University of Cagliari, Via Marengo 2, 09123 Cagliari (Italy); Carta, G., E-mail: giorgio_carta@unica.it [Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Via Marengo 2, 09123 Cagliari (Italy)

2014-09-15

Highlights: • Flexural failure of reinforced concrete beams under blast and impact loads is studied. • Two single degree of freedom models are formulated to predict the beam response. • Strain rate effects are taken into account for both models. • The theoretical response obtained from each model is compared with experimental data. • The two models give a good estimation of the maximum deflection at collapse. - Abstract: In this paper, reinforced concrete beams subjected to blast and impact loads are examined. Two single degree of freedom models are proposed to predict the response of the beam. The first model (denoted as “energy model”) is developed from the law of energy balance and assumes that the deformed shape of the beam is represented by its first vibration mode. In the second model (named “dynamic model”), the dynamic behavior of the beam is simulated by a spring-mass oscillator. In both formulations, the strain rate dependencies of the constitutive properties of the beams are considered by varying the parameters of the models at each time step of the computation according to the values of the strain rates of the materials (i.e. concrete and reinforcing steels). The efficiency of each model is evaluated by comparing the theoretical results with experimental data found in literature. The comparison shows that the energy model gives a good estimation of the maximum deflection of the beam at collapse, defined as the attainment of the ultimate strain in concrete. On the other hand, the dynamic model generally provides a smaller value of the maximum displacement. However, both approaches yield reliable results, even though they are based on some approximations. Being also very simple to implement, they may serve as an useful tool in practical applications.

Delamination of carbon-fiber strengthening layer from concrete beam during deformation (infrared thermography)

OpenAIRE

Shardakov, I. N.; Shestakov, A. P.; Bykov, A.A.

2016-01-01

Technology of strengthening reinforced concrete structures with composite materials has found wide application. The effectiveness of strengthening of concrete structures with externally bonded reinforcement is supported by a great deal of experimental evidence. However, the problem of serviceability of such structures has not been adequately explored. The present work describes the results of experimental studies on the loadcarrying capacity of concrete beams strengthened with carbon fiber re...

Investigation of the behavior of connection of reduced-beam-section steel beam to reinforced concrete column

Directory of Open Access Journals (Sweden)

Ali Babaeenezhad

2017-11-01

Full Text Available After recent earthquakes that caused major damages in beam-column connections, scientists and engineers proposed new types of connections to postpone such brittle failures. One of these new connections is the connection of steel beam to concrete column and connection of reduced- beam-section to steel column. However, these new connections have some defects. The aim of this paper is to investigate the combination of RCS and RBS connection and assess the behavior of new combined connection. In this type of connection, a beam with reduced section at the end is connected to a concrete column. In such a detail, the main defect of RCS and RBS connection disappears. The connection was modeled using Abaqus finite element package and the effect of cut of the flange, cover-plate thickness and stiffener thickness in the new system were investigated and compared with those in RCS connection.  The results show that cut of flange has a great influence on compressive damage and tensile damage. Furthermore, cut of flange decreases the stress in the cover-plate, stiffener and reinforcements. Increasing the thickness of cover-plate, reduces stress in cover-plate. The use of reduced-beam-section instead of ordinary connection improves the connection overall performance.

FLEXURAL TESTING OF WOOD-CONCRETE COMPOSITE BEAM MADE FROM KAMPER AND BANGKIRAI WOOD

Directory of Open Access Journals (Sweden)

Fengky Satria Yoresta

2015-07-01

Full Text Available Certain wood has a tensile strength that almost equal with steel rebar in reinforced concrete beams. This research aims to understand the capacity and flexural behavior of concrete beams reinforced by wood (wood-concrete composite beam. Two different types of beams based on placement positions of wood layers are proposed in this study. Two kinds of wood used are consisted of Bangkirai (Shorea laevifolia and Kamper (Cinnamomum camphora, meanwhile the concrete mix ratio for all beams is 1 cement : 2 fine aggregates : 3 coarse aggregates. Bending test is conducted by using one-point loading method. The results show that composite beam using Bangkirai wood is stronger than beams using Kamper wood. More thicker wood layer in tensile area will increase the flexural strength of beams. Crack patterns identified could be classified into flexural cracks, shear cracks, and split on wood layer   Beberapa jenis kayu tertentu memiliki kekuatan tarik yang hampir sama dengan tulangan baja pada balok beton bertulang. Penelitian ini bertujuan memahami kapasitas dan perilaku lentur balok beton bertulang yang diperkuat menggunakan kayu (balok komposit beton-kayu. Dua tipe balok yang berbeda berdasarkan posisi penempatan kayu digunakan dalam penelitian ini. Dua jenis kayu yang digunakan adalah kayu Bangkirai (Shorea laevifolia and Kamper (Cinnamomum camphora, sementara itu rasio campuran beton untuk semua balok menggunakan perbandingan 1 semen : 2 agregat halus : 3 agregat kasar. Pengujian lentur dilakukan menggunakan metode one-point loading. Hasil penelitian menunjukkan bahwa balok komposit dengan kayu Bangkirai lebih kuat dibandingkan balok dengan kayu Kamper. Semakin tebal lapisan kayu yang berada di daerah tarik akan meningkatkan kekuatan lentur balok. Pola kerusakan yang teridentifikasi dapat diklasifikasikan menjadi retak lentur, retak geser, dan pecah pada kayu REFERENCES Boen T. (2010. Retrofitting Simple Buildings Damaged by Earthquakes. World Seismic

Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

Science.gov (United States)

Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

2016-12-16

In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

An experiment on the use of disposable plastics as a reinforcement in concrete beams

Science.gov (United States)

Chowdhury, Mostafiz R.

1992-01-01

Illustrated here is the concept of reinforced concrete structures by the use of computer simulation and an inexpensive hands-on design experiment. The students in our construction management program use disposable plastic as a reinforcement to demonstrate their understanding of reinforced concrete and prestressed concrete beams. The plastics used for such an experiment vary from plastic bottles to steel reinforced auto tires. This experiment will show the extent to which plastic reinforcement increases the strength of a concrete beam. The procedure of using such throw-away plastics in an experiment to explain the interaction between the reinforcement material and concrete, and a comparison of the test results for using different types of waste plastics are discussed. A computer analysis to simulate the structural response is used to compare the test results and to understand the analytical background of reinforced concrete design. This interaction of using computers to analyze structures and to relate the output results with real experimentation is found to be a very useful method for teaching a math-based analytical subject to our non-engineering students.

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

Flexural and Shear Behavior of RC Concrete Beams Reinforced with Fiber Wire Mesh

Directory of Open Access Journals (Sweden)

Rafea Flaih Hassan

2018-02-01

Full Text Available This work aims to study  the effect of using fiber wire mesh on the flexural and shear properties of RC concrete beams. Six reinforced concrete beams (120*180*1220mm were tested under two load points. Fiber wire mesh was applied with two manners, first one is three layers as U shape around the section of the beam, the second one is four layers around overall section of beam. The test results indicated that using of fiber wire mesh as additional reinforcement can increase the ultimate load of about (1.85-3.58% in the case of flexural and (17.7-23.7% in case of shear. Also,  results showed that an increasing in  first cracking  load is obtained from  (42.8-85.7% in case of flexural and from (41.2-76.5% in case of shear. Also the shear behavior of beams becomes more ductile when the fiber wire mesh was used in beams. The cracks of shrinkage was disappeared when the fiber wire mesh surround the section of the beam. 

Behavior and strength of beams cast with ultra high strength concrete containing different types of fibers

Directory of Open Access Journals (Sweden)

M.M. Kamal

2014-04-01

Full Text Available Ultra-high performance concrete (UHPC is a special type of concrete with extraordinary potentials in terms of strength and durability performance. Its production and application implement the most up-to-date knowledge and technology of concrete manufacturing. Sophisticated structural designs in bridges and high-rise buildings, repair works and special structures like nuclear facilities are currently the main fields of applications of UHPC. This paper aimed to evaluate the behavior of ultra-high strength concrete beams. This paper also aimed to determine the effect of adding fibers and explore their effect upon the behavior and strength of the reinforced concrete beams. A total of twelve simple concrete beams with and without shear reinforcements were tested in flexure. The main variables taken into consideration in this research were the type of fibers and the percentage of longitudinal reinforcement as well as the existence or absence of the web reinforcement. Two types of fibers were used including steel and polypropylene fibers. The behavior of the tested beams was investigated with special attention to the deflection under different stages of loading, initial cracking, cracking pattern, and ultimate load. Increased number of cracks was observed at the end of loading due to the use of fibers, which led to the reduced width of cracks. This led to increased stiffness and higher values of maximum loads.

Influence of reinforcement's corrosion into hyperstatic reinforced concrete beams: a probabilistic failure scenarios analysis

Directory of Open Access Journals (Sweden)

G. P. PELLIZZER

Full Text Available AbstractThis work aims to study the mechanical effects of reinforcement's corrosion in hyperstatic reinforced concrete beams. The focus is the probabilistic determination of individual failure scenarios change as well as global failure change along time. The limit state functions assumed describe analytically bending and shear resistance of reinforced concrete rectangular cross sections as a function of steel and concrete resistance and section dimensions. It was incorporated empirical laws that penalize the steel yield stress and the reinforcement's area along time in addition to Fick's law, which models the chloride penetration into concrete pores. The reliability theory was applied based on Monte Carlo simulation method, which assesses each individual probability of failure. The probability of global structural failure was determined based in the concept of failure tree. The results of a hyperstatic reinforced concrete beam showed that reinforcements corrosion make change into the failure scenarios modes. Therefore, unimportant failure modes in design phase become important after corrosion start.

Effect of tension lap splice on the behavior of high strength concrete (HSC beams

Directory of Open Access Journals (Sweden)

Ahmed El-Azab

2014-12-01

Full Text Available In the recent years, many research efforts have been carried out on the bond strength between normal strength concrete (NSC and reinforcing bars spliced in tension zones in beams. Many codes gave a minimum splice length for tension and compression reinforcement as a factor of the bar diameter depending on many parameters such as concrete strength, steel yield stress, shape of bar end, shape of bar surface and also bar location. Also, codes gave another restriction about the percentage of total reinforcement to be spliced at the same time. Comparatively limited attention has been directed toward the bond between high strength concrete (HSC and reinforcing bars spliced in tension zones in beams. HSC has high modulus of elasticity, high density and long-term durability. This research presents an experimental study on the bond between high strength concrete (HSC and reinforcing bars spliced in tension zones in beams. It reports the influence of several parameters on bond in splices. The parameters covered are casting position, splice length as a factor of bar diameter, bar diameter and reinforcement ratio. The research involved tests on sixteen simply-supported beams of 1800 mm span, 200 mm width and 400 mm thickness made of HSC. In each beam, the total tensile steel bars were spliced in the constant moment zone. Crack pattern, crack propagation, cracking load, failure load and mi span deflection were recorded and analyzed to study the mentioned parameters effect.

Behavior of bonded and unbonded prestressed normal and high strength concrete beams

Directory of Open Access Journals (Sweden)

O.F. Hussien

2012-12-01

This paper presents an experimental program conducted to study the behavior of bonded and unbounded prestressed normal strength (NSC and high strength concrete (HSC beams. The program consists of a total of nine beams; two specimens were reinforced with non-prestressed reinforcement, four specimens were reinforced with bonded tendons, and the remaining three specimens were reinforced with unbonded tendons. The overall dimensions of the beams are 160 × 340 × 4400-mm. The beams were tested under cyclic loading up to failure to examine its flexural behavior. The main variables in this experimental program are nominal concrete compressive strength (43, 72 and 97 MPa, bonded and unbonded tendons and prestressing index (0%, 70% and 100%. Theoretical analysis using rational approach was also carried out to predict the flexural behavior of the specimens. Evaluation of the analytical work is introduced and compared to the results of the experimental work.

Effect of total cementitious content on shear strength of high-volume fly ash concrete beams

International Nuclear Information System (INIS)

Arezoumandi, Mahdi; Volz, Jeffery S.; Ortega, Carlos A.; Myers, John J.

2013-01-01

Highlights: ► Existing design standards conservatively predicted the capacity of the HVFAC beams. ► In general, the HVFAC beams exceeded the code predicted shear strengths. ► The cementitious content did not have effect on the shear behavior of the HVFAC beams. - Abstract: The production of portland cement – the key ingredient in concrete – generates a significant amount of carbon dioxide. However, due to its incredible versatility, availability, and relatively low cost, concrete is the most consumed manmade material on the planet. One method of reducing concrete’s contribution to greenhouse gas emissions is the use of fly ash to replace a significant amount of the cement. This paper compares two experimental studies that were conducted to investigate the shear strength of full-scale beams constructed with high-volume fly ash concrete (HVFAC) – concrete with at least 50% of the cement replaced with fly ash. The primary difference between the two studies involved the amount of cementitious material, with one mix having a relatively high total cementitious content (502 kg/m 3 ) and the other mix having a relatively low total cementitious content (337 kg/m 3 ). Both mixes utilized a 70% replacement of portland cement with a Class C fly ash. Each of these experimental programs consisted of eight beams (six without shear reinforcing and two with shear reinforcing in the form of stirrups) with three different longitudinal reinforcement ratios. The beams were tested under a simply supported four-point loading condition. The experimental shear strengths of the beams were compared with both the shear provisions of selected standards (US, Australia, Canada, Europe, and Japan) and a shear database of conventional concrete (CC) specimens. Furthermore, statistical data analyses (both parametric and nonparametric) were performed to evaluate whether or not there is any statistically significant difference between the shear strength of both mixes. Results of these

Ultra thin continuously reinforced concrete pavement research in south Africa

CSIR Research Space (South Africa)

Perrie, BD

2007-08-01

Full Text Available Ultra thin continuously reinforced concrete pavements (UTCRCP), in literature also referred to as Ultra Thin Reinforced High Performance Concrete (UTHRHPC), have been used in Europe successfully as a rehabilitation measure on steel bridge decks...

Digital-image-correlation-based experimental stress analysis of reinforced concrete beams strengthened using carbon composites

Science.gov (United States)

Helm, Jeffrey; Kurtz, Stephen

2005-01-01

The strengthening of reinforced concrete beams through the use of epoxy-bonded carbon composites has been widely researched in the United States since 1991. Despite the widespread attention of researchers, however, there are no reliable methods of predicting the failure of the repaired and strengthened beams by peeling of the fiber reinforced polymer (FRP) material from the parent concrete. To better understand peeling failure, several investigators have presented analytical work to predict the distribution of stresses along the interface between the FRP and the concrete. Several closed-form solutions can be found in the literature to predict the levels of shear stress present between the bonded composite plate and the parent concrete beam. However, there has been very little experimental verification of these analytical predictions because few experiments on large-scale beams have had sufficient instrumentation to facilitate the comparison. Some experiments have been presented1 in which electrical resistance strain gages were placed along the length of the carbon plate in order to deduce the interfacial shear stress using first differences. This method, though very crude, demonstrated that there are substantial differences between the distributions of interfacial shear stresses in actual repaired beams versus the analytical predictions. This paper presents a new test program in which large-scale carbon-fiber-strengthened reinforced concrete beams are load-tested to failure, while employing digital image correlation (DIC) to record the strains in the carbon fiber plate. Relying on the linear elasticity of carbon fiber, the interfacial shear can be determined and compared with the analytical predictions of the literature. The focus of this paper is the presentation of the experimental shear stress distributions and comparisons of these distributions with previous results available in the literature.

Nonlinear micromechanics-based finite element analysis of the interfacial behaviour of FRP-strengthened reinforced concrete beams

Science.gov (United States)

Abd El Baky, Hussien

This research work is devoted to theoretical and numerical studies on the flexural behaviour of FRP-strengthened concrete beams. The objectives of this research are to extend and generalize the results of simple experiments, to recommend new design guidelines based on accurate numerical tools, and to enhance our comprehension of the bond performance of such beams. These numerical tools can be exploited to bridge the existing gaps in the development of analysis and modelling approaches that can predict the behaviour of FRP-strengthened concrete beams. The research effort here begins with the formulation of a concrete model and development of FRP/concrete interface constitutive laws, followed by finite element simulations for beams strengthened in flexure. Finally, a statistical analysis is carried out taking the advantage of the aforesaid numerical tools to propose design guidelines. In this dissertation, an alternative incremental formulation of the M4 microplane model is proposed to overcome the computational complexities associated with the original formulation. Through a number of numerical applications, this incremental formulation is shown to be equivalent to the original M4 model. To assess the computational efficiency of the incremental formulation, the "arc-length" numerical technique is also considered and implemented in the original Bazant et al. [2000] M4 formulation. Finally, the M4 microplane concrete model is coded in FORTRAN and implemented as a user-defined subroutine into the commercial software package ADINA, Version 8.4. Then this subroutine is used with the finite element package to analyze various applications involving FRP strengthening. In the first application a nonlinear micromechanics-based finite element analysis is performed to investigate the interfacial behaviour of FRP/concrete joints subjected to direct shear loadings. The intention of this part is to develop a reliable bond--slip model for the FRP/concrete interface. The bond

Articularities of Analysis and Behaviour of Concrete Beams Reinforced with Fibrous Polymer Composite Bars

Directory of Open Access Journals (Sweden)

N. Ţăranu

2006-01-01

Full Text Available Traditional steel based reinforcement systems for concrete elements are facing with serious problems mainly caused by corrosion due to chemically aggressive environments and salts used in deicing procedures, especially in case of bridge steel reinforced concrete girders. Also in some cases special applications require structural members with magnetic transparency. An alternative to this major problem has recently become the use of fiber reinforced polymer (FPR composite bars as internal reinforcement for concrete beams. The particularities of their mechanical properties are making the design process a difficult task for engineers, numerous research centers being involved in correcting this situation. The general aspects concerning the conceiving of FR.P reinforced concrete beams are firstly analyzed, compared to those reinforced with steel bars. Some results of a Finite Element Analysis, as part of a complex program which also implies full scale testing of FRP reinforced beams subjected to bending, are given and discussed in the paper. The low elasticity modulus presented by glass fiber reinforced polymer (GFRP bars does not justify its use from structural point of view when deflection is the limiting condition but for corrosive resistance reasons and special electromagnetic properties this system can be promoted.

Stay-in-Place Formwork of TRC Designed as Shear Reinforcement for Concrete Beams

Directory of Open Access Journals (Sweden)

S. Verbruggen

2013-01-01

Full Text Available In order to reduce on-site building time, the construction industry shows an increasing interest in stay-in-place formwork with a reinforcement function after concrete hardening, such as CFRP formwork confinement for columns. The current combined systems however do not answer the demand of the building industry for a material system that is both lightweight and fire safe. High performance textile reinforced cement (TRC composites can address this need. They can be particularly interesting for the shear reinforcement of concrete beams. This paper describes a preliminary analysis and feasibility study on structural stay-in-place formwork made of TRC. Comparative bending experiments demonstrate that a fully steel reinforced beam and an equivalent beam with shear reinforcement in TRC formwork show similar yielding behaviour, indicating that the TRC shear reinforcement system actually works. Moreover, the cracking moment of the concrete was more or less doubled, resulting in a much lower deflection in serviceability limit state than calculated. Digital image correlation measurements show that the latter is due to the crack bridging capacity of the external TRC shear reinforcement.

Analytical Model for Fictitious Crack Propagation in Concrete Beams

DEFF Research Database (Denmark)

Ulfkjær, J. P.; Krenk, S.; Brincker, Rune

An analytical model for load-displacement curves of unreinforced notched and un-notched concrete beams is presented. The load displacement-curve is obtained by combining two simple models. The fracture is modelled by a fictitious crack in an elastic layer around the mid-section of the beam. Outside...... the elastic layer the deformations are modelled by the Timoshenko beam theory. The state of stress in the elastic layer is assumed to depend bi-lineary on local elongation corresponding to a linear softening relation for the fictitious crack. For different beam size results from the analytical model...... is compared with results from a more accurate model based on numerical methods. The analytical model is shown to be in good agreement with the numerical results if the thickness of the elastic layer is taken as half the beam depth. Several general results are obtained. It is shown that the point on the load...

Topology optimization of reinforced concrete beams by a spread-over reinforcement model with fixed grid mesh

Directory of Open Access Journals (Sweden)

Benjapon Wethyavivorn

2011-02-01

Full Text Available For this investigation, topology optimization was used as a tool to determine the optimal reinforcement for reinforcedconcrete beam. The topology optimization process was based on a unit finite element cell with layers of concrete and steel.The thickness of the reinforced steel layer of this unit cell was then adjusted when the concrete layer could not carry thetensile or compressive stress. At the same time, unit cells which carried very low stress were eliminated. The process wasperformed iteratively to create a topology of reinforced concrete beam which satisfied design conditions.

Prestressing Effects on the Performance of Concrete Beams with Near-surface-mounted Carbon-fiber-reinforced Polymer Bars

Science.gov (United States)

Hong, Sungnam; Park, Sun-Kyu

2016-07-01

The effects of various prestressing levels on the flexural behavior of concrete beams strengthened with prestressed near-surface-mounted (NSM) carbon-fiber-reinforced polymer (CFRP) bars were investigated in this study. Four-point flexural tests up to failure were performed using a total of six strengthened prestressed and nonprestressed concrete beams. The nonprestressed strengthened beam failed by premature debonding at the interface of concrete and the epoxy adhesive, but the prestressed one failed owing due to rupture of the CFRP bar. As the prestressing level of the CFRP bar increased, the cracking and yield loads of the prestressed beams increased, but its effect on their deflections was insignificant. The ultimate load was constant regardless of prestressing level, but the ultimate deflection was almost inversely proportional to the level.

Damage detection of simply supported reinforced concrete beam by S transform

Science.gov (United States)

Liu, Ning; Xi, Jiaxin; Zhang, Xuebing; Liu, Zhenzhou

2017-08-01

Signal processing is the key component of vibration-based structural damage detection. The S transform is variable window of short time Fourier transform (STFT) or an extension of wavelet transform (WT). The goal of using S transform is to extract subtle changes in the vibration signals in order to detect and quantify the damage in the structure. This paper presents the concentrated load is applied to the simply supported reinforced concrete beam and adopting the stepwise loading method, the vibration signals of each loading and unloading state is obtained by using the hammer impact. Then the vibration data of the reinforced concrete beam pre-damage and post-damage is analysed by S transform. Experimental result shows the potential ability of S transform in identifying peak energy changes and multiple reflections with different loading force state.

Determination of Bond Capacity in Reinforced Concrete Beam and Its Influence on the Flexural Strength

Directory of Open Access Journals (Sweden)

Mohammad Rashidi

2016-05-01

Full Text Available This paper presents results of an experimental investigation of actual performance of the reinforced concrete beam in bond under flexure, when reinforced with tension steel is going to consider. In this experiment four specimens of beam and a bar in the middle of the width of the beam has been used and 2.5 cm of concrete cover has been considered from the center of the bar. In addition, transverse bars have been used to reassure lack of shear yield at the two ends of the beam. Flexural bar has been put in the middle of the beam symmetrically and the length of the flexural bar in each of the samples shall be: 15, 20, 30 and 40 cm. Three cylindrical samples were made in order to determine f’c and were examined at 28 days and the compressive strength of concrete used in this study was about 35 MPa. The beam samples were examined after 28 days via two-point loading system. Based on the results, increasing the length of bar causes increase of flexural strength. The presence of longitudinal rebar resulted in the ultimate momentum to be more than the crack momentum of the cross-section in parts which have broken at the point of longitudinal bar cut.

COED Transactions, Vol. IX, No. 7, July 1977. Heuristic Design of Prestressed Concrete Beams.

Science.gov (United States)

Marcovitz, Alan B., Ed.

This document provides a computer program which produces a graphical determination of admissible solutions for engineering problems relating to the design of prestressed concrete beams. Included is a generalized section for describing beam sections. (Author/SL)

Analytical Model for Fictitious Crack Propagation in Concrete Beams

DEFF Research Database (Denmark)

Ulfkjær, J. P.; Krenk, Steen; Brincker, Rune

1995-01-01

An analytical model for load-displacement curves of concrete beams is presented. The load-displacement curve is obtained by combining two simple models. The fracture is modeled by a fictitious crack in an elastic layer around the midsection of the beam. Outside the elastic layer the deformations...... are modeled by beam theory. The state of stress in the elastic layer is assumed to depend bilinearly on local elongation corresponding to a linear softening relation for the fictitious crack. Results from the analytical model are compared with results from a more detailed model based on numerical methods...... for different beam sizes. The analytical model is shown to be in agreement with the numerical results if the thickness of the elastic layer is taken as half the beam depth. It is shown that the point on the load-displacement curve where the fictitious crack starts to develop and the point where the real crack...

The Overall Research Results of Prestressed I-beams Made of Ultra-high Performance Concrete

Science.gov (United States)

Tej, P.; Kolísko, J.; Kněž, P.; Čech, J.

2017-09-01

The design process of short-term and long-term loading of prestressed I-beams made of ultra-high performance concrete (UHPC) and the overall research results are presented in this article. The prestressed I-beams are intended and designed to replace steel HEB beams mainly in the construction of railway bridges with fully concreted height of the beams. These types of structures have the advantage of a low construction height. The prestressed I-beams were made of UHPC with dispersed steel fibres and are reinforced by prestressing cables in the bottom flange. Two specimens of 9 m span, three specimens of 7 m span and two specimens of 12 m span were made for the short-term loading. For the purpose of the long-term loading, two specimens of 12 m span were made and subsequently loaded for 450 days. All specimens were tested in four-point bending tests in the laboratory. The article presents also comparison of results of the experiments with computer simulations.

Finite Element Model for Nonlinear Analysis of Reinforced Concrete Beams and Plane Frames

Directory of Open Access Journals (Sweden)

R.S.B. STRAMANDINOLI

Full Text Available Abstract In this work, a two-dimensional finite element (FE model for physical and geometric nonlinear analysis of reinforced concrete beams and plane frames, developed by the authors, is presented. The FE model is based on the Euler-Bernoulli Beam Theory, in which shear deformations are neglected. The bar elements have three nodes with a total of seven degrees of freedom. Three Gauss-points are utilized for the element integration, with the element section discretized into layers at each Gauss point (Fiber Model. It is assumed that concrete and reinforcing bars are perfectly bonded, and each section layer is assumed to be under a uniaxial stress-state. Nonlinear constitutive laws are utilized for both concrete and reinforcing steel layers, and a refined tension-stiffening model, developed by the authors, is included. The Total Lagrangean Formulation is adopted for geometric nonlinear consideration and several methods can be utilized to achieve equilibrium convergence of the nonlinear equations. The developed model is implemented into a computer program named ANEST/CA, which is validated by comparison with some tests on RC beams and plane frames, showing an excellent correlation between numerical and experimental results.

Finite Element Simulation of GFRP Reinforced Concrete Beam Externally Strengthened With CFRP Plates

Directory of Open Access Journals (Sweden)

Salleh Norhafizah

2017-01-01

Full Text Available The construction technology now has become more and more advanced allowing the development of new technologies or material to replace the previous one and also solved some of the troubles confronted by construction experts. The Glass Fibre Reinforced Polymer (GFRP composite is an alternative to replace the current usage of steel as it is rust proof and stronger in terms of stiffness compared to steel. Furthermore, GFRP bars have a high strength-to-weight ratio, making them attractive as reinforcement for concrete structures. However, the tensile behavior of GFRP bars is characterized by a linear elastic stress–strain relationship up to failure and, therefore, concrete elements reinforced with GFRP reinforcement exhibit brittle failure without warning. Design codes encourage over-reinforced GFRP design since it is more progressive and leads to a less catastrophic failure with a higher degree of deformability. Moreover, because of GFRP low modulus of elasticity, GFRP reinforced concrete members exhibit larger deflections and wider cracks width than steel reinforced concrete. This aims of this paper is to developed 2D Finite Element (FE models that can accurately simulate the respond on an improvement in the deflection of GFRP reinforced concrete beam externally strengthened with CFRP plates on the tension part of beam. The prediction of flexural response according to RCCSA software was also discussed. It was observed that the predicted FE results are given similar result with the experimental measured test data. Base on this good agreement, a parametric study was the performed using the validation FE model to investigate the effect of flexural reinforcement ratio and arrangement of the beams strengthened with different regions of CFRP plates.

Numerical Study on Deflection Behaviour of Concrete Beams Reinforced with GFRP Bars

Science.gov (United States)

Mohamed, Osama A.; Khattab, Rania; Hawat, Waddah Al

2017-10-01

Fiber-Reinforced Polymer (FRP) bars are gaining popularity as sustainable alternatives to conventional reinforcing steel bars in reinforced concrete applications. The production of FRP bars has lower environmental impact compared to steel reinforcing bars. In addition, the non-corroding FRP materials can potentially decrease the cost or need for maintenance of reinforced concrete structural elements, especially in harsh environmental conditions that can impact both concrete and reinforcement. FRP bars offer additional favourable properties including high tensile strength and low unit weight. However, the mechanical properties of FRP bars can lead to large crack widths and deflections. The objective of this study is to investigate the deflection behaviour of concrete beams reinforced with Glass FRP (GFRP) bars as a longitudinal main reinforcement. Six concrete beams reinforced with GFRP bars were modelled using the finite element computer program ANSYS. The main variable considered in the study is the reinforcement ratio. The deflection equations in current North American codes including ACI 440.1R-06, ACI 440.1R-15 and CSA S806-12 are used to compute deflections, and these are compared to numerical results. It was concluded in this paper that deflections predicted by ACI 440.1R-06 equations are lower than the numerical analysis results while ACI 440.1R-15 is in agreement with numerical analysis with tendency to be conservative. The values of deflections estimated by CSA S806-12 formulas are consistent with results of numerical analysis.

Development of connecting method for mechanically cut reinforced concrete blocks

International Nuclear Information System (INIS)

Nishiuchi, Tatsuo

2005-01-01

The purpose of the study is to develop a practical method of disposing and recycling in dismantled reinforced concrete structures. We have devised a new method in which mechanically cut reinforced concrete blocks are connected and they are reused as a structural beam. In this method, concrete blocks are connected with several steel bars and the connected surface is wrapped with a fiber sheet. We verified that the load capacity of renewal beams was considerably large as same as that of continuous structural beams on the basis of experimental as well as numerical analysis results. As far as construction cost of reinforced concrete walls are concerned, we demonstrated that the cost of this method is slightly lower than that of the plan to use new and recycle materials. (author)

Repair of reinforced concrete beams using carbon fiber reinforced polymer

Directory of Open Access Journals (Sweden)

Karzad Abdul Saboor

2017-01-01

Full Text Available This research paper is part of an ongoing research on the behaviour of Reinforced Concrete (RC beams retrofitted with Externally Bonded Carbon Fiber Reinforced Polymer (EB-CFRP. A total of 5 large-scale rectangular beams, previously damaged due to shear loading, were repaired and strengthened with EB-CFRP and tested in this study. The major cracks of the damaged beams were injected with epoxy and the beams were wrapped with 2 layers of EB-CFRP discrete strips with 100mm width and 150mm center to center spacing. The beams were instrumented and tested to failure under three points loading in simply supported configuration. The measured test parameters were the beams deflection, maximum load, and the strain in the FRP strips. The failure mode was also observed. The results showed that applying EB-FRP strips increased the shear strength significantly relative to the original shear capacity of the beam. The results demonstrate that the application of EB-FRP strips used in this study is an effective repair method that can be used to repair and strengthen damaged beams.

Performance of Retrofitted Self-Compacting Concrete-Filled Steel Tube Beams Using External Steel Plates

Directory of Open Access Journals (Sweden)

Ahmed A. M. AL-Shaar

2018-01-01

Full Text Available Self-compacting concrete-filled steel tube (SCCFST beams, similar to other structural members, necessitate retrofitting for many causes. However, research on SCCFST beams externally retrofitted by bolted steel plates has seldom been explored in the literature. This paper aims at experimentally investigating the retrofitting performance of square self-compacting concrete-filled steel tube (SCCFST beams using bolted steel plates with three different retrofitting schemes including varied configurations and two different steel plate lengths under flexure. A total of 18 specimens which consist of 12 retrofitted SCCFST beams, three unretrofitted (control SCCFST beams, and three hollow steel tubes were used. The flexural behaviour of the retrofitted SCCFST beams was examined regarding flexural strength, failure modes, and moment versus deflection curves, energy absorption, and ductility. Experimental results revealed that the implemented retrofitting schemes efficiently improve the moment carrying capacity and stiffness of the retrofitted SCCFST beams compared to the control beams. The increment in flexural strength ranged from 1% to 46%. Furthermore, the adopted retrofitting schemes were able to restore the energy absorption and ductility of the damaged beams in the range of 35% to 75% of the original beam ductility. Furthermore, a theoretical model was suggested to predict the moment capacity of the retrofitted SCCFST beams. The theoretical model results were in good agreement with the test results.

Mechanical Behavior of Steel Fiber-Reinforced Concrete Beams Bonded with External Carbon Fiber Sheets.

Science.gov (United States)

Gribniak, Viktor; Tamulenas, Vytautas; Ng, Pui-Lam; Arnautov, Aleksandr K; Gudonis, Eugenijus; Misiunaite, Ieva

2017-06-17

This study investigates the mechanical behavior of steel fiber-reinforced concrete (SFRC) beams internally reinforced with steel bars and externally bonded with carbon fiber-reinforced polymer (CFRP) sheets fixed by adhesive and hybrid jointing techniques. In particular, attention is paid to the load resistance and failure modes of composite beams. The steel fibers were used to avoiding the rip-off failure of the concrete cover. The CFRP sheets were fixed to the concrete surface by epoxy adhesive as well as combined with various configurations of small-diameter steel pins for mechanical fastening to form a hybrid connection. Such hybrid jointing techniques were found to be particularly advantageous in avoiding brittle debonding failure, by promoting progressive failure within the hybrid joints. The use of CFRP sheets was also effective in suppressing the localization of the discrete cracks. The development of the crack pattern was monitored using the digital image correlation method. As revealed from the image analyses, with an appropriate layout of the steel pins, brittle failure of the concrete-carbon fiber interface could be effectively prevented. Inverse analysis of the moment-curvature diagrams was conducted, and it was found that a simplified tension-stiffening model with a constant residual stress level at 90% of the strength of the SFRC is adequate for numerically simulating the deformation behavior of beams up to the debonding of the CFRP sheets.

Photogrammetric Assessment of Flexure Induced Cracking of Reinforced Concrete Beams under Service Loads

DEFF Research Database (Denmark)

Pease, Bradley Justin; Geiker, Mette Rica; Stang, Henrik

2006-01-01

Reinforced concrete structures are known to crack due to restrained shrinkage, temperature gradients, application of load, and expansive reactions. Cracks provide paths for rapid ingress of moisture, chlorides, and other aggressive substances, which may affect the long-term durability...... of the structure. For example, concrete cracks located at the reinforcing steel may contribute to a rapid corrosion initiation and propagation. Previous research has shown that cracked reinforced concrete under static flexural loading may have an increased ingress of chloride ions along the reinforcement....../concrete interface. The aim of this paper is to provide a detailed description of the development of cracks in reinforced concrete under flexural load. Cracking at both realistic service load levels (1.0-1.8 times estimated cracking load) and unrealistically high service load levels (> 0.5 times beam capacity) has...

The Efficiency of Basalt Fibres in Strengthening the Reinforced Concrete Beams

OpenAIRE

Şerbescu, Andreea; Kypros, Pilakoutas; Ţăranu, N.

2006-01-01

The technique of externally bonding fibre reinforced polymer (FRP) composite laminates on the tension side of reinforced concrete (RC) beams is already widely accepted as an easy to apply, corrosion resistant and effective solution due to the high strength as well as the low weight of the composite material. The basalt fibres are produced from volcano rocks by a simple process; their applicability as reinforcing material composites utilized for plate bonding of RC beams was not enough researc...

Corrosion characteristics of a 4-year naturally corroded reinforced concrete beam with load-induced transverse cracks

International Nuclear Information System (INIS)

Fu, Chuanqing; Jin, Nanguo; Ye, Hailong; Jin, Xianyu; Dai, Wei

2017-01-01

Highlights: • A comprehensive study of corrosion characteristics of a naturally corroded RC beam. • New insights on the role of cracks in corrosion propagation of steel in concrete. • EMPA and 3D laser scanning provide quantitative analysis of corroded rebar. - Abstract: This work studies the corrosion characteristics of reinforcement in a 4-year naturally corroded concrete beam after accelerated chloride penetration. The results show that the presence of transverse cracks in the tension surface of reinforced concrete beam can globally exacerbate the loss of cross-sectional area of rebar. However, there is no strong correlation between the width of transverse cracks, with the width of longitudinal cracks and loss of cross-sectional area of corroded rebar at a specific location. The self-healing of cracks and sacrificing roles of stirrups at crack tips seem to reduce the impacts of cracks on the corrosion propagation.

Numerical approach of the bond stress behavior of steel bars embedded in self-compacting concrete and in ordinary concrete using beam models

Directory of Open Access Journals (Sweden)

F.M. Almeida Filho

Full Text Available The present study evaluates the bond behavior between steel bars and concrete by means of a numerical analysis based on Finite Element Method. Results of a previously conducted experimental program on reinforced concrete beams subjected to monotonic loading are also presented. Two concrete types, self-compacting concrete and ordinary concrete, were considered in the study. Non-linear constitutive relations were used to represent concrete and steel in the proposed numerical model, aiming to reproduce the bond behavior observed in the tests. Experimental analysis showed similar results for the bond resistances of self-compacting and ordinary concrete, with self-compacting concrete presenting a better performance in some cases. The results given by the numerical modeling showed a good agreement with the tests for both types of concrete, especially in the pre-peak branch of the load vs. slip and load vs. displacement curves. As a consequence, the proposed numerical model could be used to estimate a reliable development length, allowing a possible reduction of the structure costs.

Exploring the relationship between structurally defined geometrical parameters of reinforced concrete beams and the thermal comfort on indoor environment

DEFF Research Database (Denmark)

Lee, Daniel Sang-Hoon; Naboni, Emanuele

2017-01-01

mass effect (and the implication on thermal comfort) and the given geometrical parameters of exposed soffit reinforced concrete beams are explored. The geometrical parameters of the beams are initially defined in means of structural optimisation. The beams consist of flange and web in likeness of T...... the resultant heat exchange behaviour, and the implication on thermal comfort indoor environment. However, the current paper presents the thermal mass characteristics of one geometrical type. The study is based on results derived from computational fluid dynamics (CFD) analysis, where Rhino 3D is used......The paper presents a research exploring the thermal mass effect of reinforced concrete beams with structurally optimised geometrical forms. Fully exposed concrete soffits in architectural contexts create more than just visual impacts on the indoor climate through their possible interferences...

Influence of Connection Placement to the Behavior of Precast Concrete Exterior Beam-Column Joint

OpenAIRE

Elly Tjahjono; Heru Purnomo

2010-01-01

This paper presents an experimental study on the influence of connection placement to the behaviour of exterior beamcolumn joint of precast concrete structure under semi cyclic loading. Four half-scale beam-column specimens were investigated. Three beam-columns were jointed through connection that are placed in beam-column joint region and the forth is connected at the plastic hinge potensial region of the beam. Crack patterns, strength, stiffness and ductility of the test specimens have been...

The implementation of unit price of work standard SNI 7394: 2008 for the construction of reinforced concrete beam

Science.gov (United States)

Tripoli; Mubarak; Nurisra; Mahmuddin

2018-05-01

This paper discusses the implementation of Indonesian National Standard (SNI) 7394: 2008 on procedures for calculating the unit price of concrete work for the construction of building and housing. The standard provides some reinforced concrete constructions unit price (UP) analysis by specified the total number of reinforcing uses. Related to reinforced concrete beam work (Analysis No. 6.31), the reinforcement requirement is stated at 200 kg/m3 of concrete. Once the implementation considers various earthquake zoning, the question will arise about the extent to which the standard is feasible to apply. Therefore, this research aimed to analyze the possibility of UP standard implementation by certain earthquake zonation. This research is focused on the construction of reinforced concrete beam for buildings with function as educational, residential and office buildings. The data used are sourced from 21 buildings in two zones in Aceh Province, covering Zone 10 and Zone 15 based on earthquake map of SNI 1726: 2012. The analysis results indicate that the UP standard for reinforced concrete beam cannot be applied to all zoning. The UP standard is only possible on buildings constructed in Zone 10 or zonation with seismic spectral response 0.6g to 0.7g or lower.

Development of Vegetation-Pervious Concrete in Grid Beam System for Soil Slope Protection

Science.gov (United States)

Bao, Xiaohua; Liao, Wenyu; Dong, Zhijun; Wang, Shanyong; Tang, Waiching

2017-01-01

One of the most efficient and environmentally friendly methods for preventing a landslide on a slope is to vegetate it. Vegetation-pervious concretes have a promising potential for soil protection. In this study, the vegetation-pervious concrete with low alkalinity was developed and studied. Combined with a grid beam structure system, the stability and strength between the vegetation-pervious concrete and base soil are believed to be enhanced effectively. For improving plant adaptability, the alkalinity of concrete can be decreased innovatively by adding a self-designed admixture into the cement paste. The effects of the admixture content on alkalinity and compressive strength of the hardened pervious concrete were investigated using X-ray diffraction (XRD) and compression test, respectively. Meanwhile, the permeability of the vegetation-pervious concrete was studied as well. Through comparing with ordinary pervious concrete, the effect of low alkaline pervious concrete on vegetation growth was investigated in a small-scale field for ten weeks. The test results indicated that the alkalinity of the cement samples decreased with the increase of admixture content, and the vegetation grew successfully on previous concrete. By increasing the admixture content to approximately 3.6%, the compressive strength of pervious concrete was more than 25 MPa. PMID:28772454

Nonlinear finite element modeling of concrete deep beams with openings strengthened with externally-bonded composites

International Nuclear Information System (INIS)

Hawileh, Rami A.; El-Maaddawy, Tamer A.; Naser, Mohannad Z.

2012-01-01

Highlights: ► A 3D nonlinear FE model is developed of RC deep beams with web openings. ► We used cohesion elements to simulate bond. ► The developed FE model is suitable for analysis of such complex structures. -- Abstract: This paper aims to develop 3D nonlinear finite element (FE) models for reinforced concrete (RC) deep beams containing web openings and strengthened in shear with carbon fiber reinforced polymer (CFRP) composite sheets. The web openings interrupted the natural load path either fully or partially. The FE models adopted realistic materials constitutive laws that account for the nonlinear behavior of materials. In the FE models, solid elements for concrete, multi-layer shell elements for CFRP and link elements for steel reinforcement were used to simulate the physical models. Special interface elements were implemented in the FE models to simulate the interfacial bond behavior between the concrete and CFRP composites. A comparison between the FE results and experimental data published in the literature demonstrated the validity of the computational models in capturing the structural response for both unstrengthened and CFRP-strengthened deep beams with openings. The developed FE models can serve as a numerical platform for performance prediction of RC deep beams with openings strengthened in shear with CFRP composites.

Efficacy of Thermally Conditioned Sisal FRP Composite on the Shear Characteristics of Reinforced Concrete Beams

Directory of Open Access Journals (Sweden)

Tara Sen

2013-01-01

Full Text Available The development of commercially viable composites based on natural resources for a wide range of applications is on the rise. Efforts include new methods of production and the utilization of natural reinforcements to make biodegradable composites with lignocellulosic fibers, for various engineering applications. In this work, thermal conditioning of woven sisal fibre was carried out, followed by the development of woven sisal fibre reinforced polymer composite system, and its tensile and flexural behaviour was characterized. It was observed that thermal conditioning improved the tensile strength and the flexural strength of the woven sisal fibre composites, which were observed to bear superior values than those in the untreated ones. Then, the efficacy of woven sisal fibre reinforced polymer composite for shear strengthening of reinforced concrete beams was evaluated using two types of techniques: full and strip wrapping techniques. Detailed analysis of the load deflection behaviour and fracture study of reinforced concrete beams strengthened with woven sisal under shearing load were carried out, and it was concluded that woven sisal FRP strengthened beams, underwent very ductile nature of failure, without any delamination or debonding of sisal FRP, and also increased the shear strength and the first crack load of the reinforced concrete beams.

Measurements of resonance frequencies on prestressed concrete beams during post-tensioning

International Nuclear Information System (INIS)

Lundqvist, P.; Ryden, N.

2011-01-01

The reactor containment, which is a concrete structure prestressed vertically and horizontally, is the most essential safety barrier in a nuclear power plant and is designed to withstand a severe internal accident. The safety of the containment depends on the induced compressive stresses in the concrete, however due to various long-term mechanisms the tendon forces will decrease with time. Today, no methods exist for measuring these prestress losses in containments with bonded tendons and thus there is a need for non-destructive methods for estimating the losses in these structures. Recent results from non-linear ultrasonic measurements during uniaxial loading have demonstrated a strong acoustic and elastic effect in concrete. The present research applies resonant acoustic spectroscopy (RAS) during static loading and unloading of three prestressed concrete beams. At each load step multiple modes of vibration are measured using an accelerometer and a small impact source. Measured resonant frequencies increase with increasing compressive stress. The stress dependency of the modulus of elasticity indicates that the change in state of stress in a simple concrete structure can be estimated by simply measuring the resonance frequency

Behaviour of steel-concrete composite beams using bolts as shear connectors

Science.gov (United States)

Tran, Minh-Tung; Nguyen Van Do, Vuong; Nguyen, Tuan-Anh

2018-04-01

The paper presents an experimental program on the application of bolts as shear connectors for steel-composite beams. Four steel- concrete composite beams and a reference steel beam were made and tested. The aim of the testing program is to examine which forms of the steel bolts can be used effectively for steel-composite beams. The four types of the bolts include: Type 1 the bolt with the nut at the end; Type 2 the bolt bending at 900 hook; Type 3 the bolt without the nut at the end and Type 4 the bolt with the nut at the end but connected with the steel beam by hand welding in other to be connected with the steel beam by bolt connection as in the first three types. The test results showed that beside the traditional shear connectors like shear studs, angle type, channel type, bolts can be used effectively as the shear connectors in steel-composite beams and the application of bolts in Types 1 and 2 in the composite beams gave the better performance for the tested beam.

Strengthening Performance of PALF-Epoxy Composite Plate on Reinforced Concrete Beams

Science.gov (United States)

Chin, Siew C.; Tong, Foo S.; Doh, Shu I.; Gimbun, Jolius; Ong, Huey R.; Serigar, Januar P.

2018-03-01

This paper presents the effective strengthening potential of pineapple leaves fiber (PALF)-epoxy composite plate on reinforced concrete (RC) beam. At first the PALF is treated with alkali (NaOH) and its morphology is observed via scanning electron microscope (SEM). The composite plates made of PALF and epoxy with fiber loading ranging from 0.1 to 0.4 v/v was tested for its flexural behaviour. The composite was then used for external RC beam strengthening. The structural properties of RC beams were evaluated and all the beams were tested under four-point bending. It was found that the flexural strength increased as the fiber volume ratio increases. The maximum flexural strength (301.94 MPa) was obtained at the fiber volume ratio of 40%. The beam strengthened with PALF-epoxy composite plate has a 7% higher beam capacity compared to the control beam. Cracks formed at the edge of the plate of PALF-strengthened beams resulted in diagonal cracking. Result from this work shows that the PALF-epoxy composite plate has the potential to be used as external strengthening material for RC beam.

Temperature measurement and damage detection in concrete beams exposed to fire using PPP-BOTDA based fiber optic sensors

Science.gov (United States)

Bao, Yi; Hoehler, Matthew S.; Smith, Christopher M.; Bundy, Matthew; Chen, Genda

2017-10-01

In this study, Brillouin scattering-based distributed fiber optic sensor is implemented to measure temperature distributions and detect cracks in concrete structures subjected to fire for the first time. A telecommunication-grade optical fiber is characterized as a high temperature sensor with pulse pre-pump Brillouin optical time domain analysis (PPP-BODTA), and implemented to measure spatially-distributed temperatures in reinforced concrete beams in fire. Four beams were tested to failure in a natural gas fueled compartment fire, each instrumented with one fused silica, single-mode optical fiber as a distributed sensor and four thermocouples. Prior to concrete cracking, the distributed temperature was validated at locations of the thermocouples by a relative difference of less than 9%. The cracks in concrete can be identified as sharp peaks in the temperature distribution since the cracks are locally filled with hot air. Concrete cracking did not affect the sensitivity of the distributed sensor but concrete spalling broke the optical fiber loop required for PPP-BOTDA measurements.

Influence of Connection Placement to the Behavior of Precast Concrete Exterior Beam-Column Joint

Directory of Open Access Journals (Sweden)

Elly Tjahjono

2010-10-01

Full Text Available This paper presents an experimental study on the influence of connection placement to the behaviour of exterior beamcolumn joint of precast concrete structure under semi cyclic loading. Four half-scale beam-column specimens were investigated. Three beam-columns were jointed through connection that are placed in beam-column joint region and the forth is connected at the plastic hinge potensial region of the beam. Crack patterns, strength, stiffness and ductility of the test specimens have been evaluated. The test result indicated that all beam-column specimens show good ductility behavior.

Study on Flexural Behaviour of Ternary Blended Reinforced Self Compacting Concrete Beam with Conventional RCC Beam

Science.gov (United States)

Marshaline Seles, M.; Suryanarayanan, R.; Vivek, S. S.; Dhinakaran, G.

2017-07-01

The conventional concrete when used for structures having dense congested reinforcement, the problems such as external compaction and vibration needs special attention. In such case, the self compacting concrete (SCC) which has the properties like flow ability, passing and filling ability would be an obvious answer. All those SCC flow behavior was governed by EFNARC specifications. In present study, the combination type of SCC was prepared by replacing cement with silica fume (SF) and metakaolin (MK) along with optimum dosages of chemical admixtures. From the fresh property test, cube compressive strength and cylinder split tensile strength, optimum ternary mix was obtained. In order to study the flexural behavior, the optimum ternary mix was taken in which beam specimens of size 1200 mm x 100 mm x 200 mm was designed as singly reinforced section according to IS: 456-2000, Limit state method. Finally the comparative experimental analysis was made between conventional RCC and SCC beams of same grade in terms of flexural strength namely yield load & ultimate load, load- deflection curve, crack size and pattern respectively.

Flexural strengthening of Reinforced Concrete (RC) Beams Retrofitted with Corrugated Glass Fiber Reinforced Polymer (GFRP) Laminates

Science.gov (United States)

Aravind, N.; Samanta, Amiya K.; Roy, Dilip Kr. Singha; Thanikal, Joseph V.

2015-01-01

Strengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.

Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

Science.gov (United States)

Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

2015-01-01

Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

Moment-Curvature Behaviors of Concrete Beams Singly Reinforced by Steel-FRP Composite Bars

Directory of Open Access Journals (Sweden)

Zeyang Sun

2017-01-01

Full Text Available A steel-fiber-reinforced polymer (FRP composite bar (SFCB is a kind of rebar with inner steel bar wrapped by FRP, which can achieve a better anticorrosion performance than that of ordinary steel bar. The high ultimate strength of FRP can also provide a significant increase in load bearing capacity. Based on the adequate simulation of the load-displacement behaviors of concrete beams reinforced by SFCBs, a parametric analysis of the moment-curvature behaviors of concrete beams that are singly reinforced by SFCB was conducted. The critical reinforcement ratio for differentiating the beam’s failure mode was presented, and the concept of the maximum possible peak curvature (MPPC was proposed. After the ultimate curvature reached MPPC, it decreased with an increase in the postyield stiffness ratio (rsf, and the theoretical calculation method about the curvatures before and after the MPPC was derived. The influence of the reinforcement ratio, effective depth, and FRP ultimate strain on the ultimate point was studied by the dimensionless moment and curvature. By calculating the envelope area under the moment-curvature curve, the energy ductility index can obtain a balance between the bearing capacity and the deformation ability. This paper can provide a reference for the design of concrete beams that are reinforced by SFCB or hybrid steel bar/FRP bar.

Durability of reinforced concrete beams strengthened with fiber reinforced polymers under varying environmental conditions

International Nuclear Information System (INIS)

El-Sadani, R.A.M.G

2008-01-01

Fiber reinforced polymers (FRP) materials were adopted by the aerospace and marine industries, not only for their lightweight and high strength characteristics but also due to their tough and durable nature . As the engineering community has become more familiar with the performance advantages of these materials, new applications have been investigated and implemented. Researches and design guidelines concluded that externally bonded FRP to concrete elements could efficiently increase the capacity of RC elements. Long-term exposure to harsh environments deteriorates concrete and the need for repair and rehabilitation is evident. In order to accept these FRP materials, they must be evaluated for durability in harsh environments. An experimental program was conducted at the materials laboratory- faculty of engineering-Ain Shams university to study the durability of RC beams strengthened with FRP sheets and to compare them with un strengthened beams.The effect of gamma rays on FRP materials and concrete specimens bonded to FRP sheets were also investigated.

Cyclic behavior of non-seismically designed interior reinforced concrete beam-column connections

Directory of Open Access Journals (Sweden)

Amorn Pimanmas

2008-05-01

Full Text Available This paper presents a test of non-seismically detailed reinforced concrete beam-column connections under reversedcyclic load. The tested specimens represented those of the actual mid-rise reinforced concrete frame buildings, designedaccording to the non-seismic provisions of the ACI building code. The evaluation of 10 existing reinforced concrete frameswas conducted to identify key structural and geometrical indices. It was found that there existed correlation VS structuraland geometrical characteristics and the column tributary area. Hence, the column tributary area was chosen as a parameterfor classifying the specimens. The test results showed that specimens representing small and medium column tributary areafailed by brittle joint shear, while specimen representing large column tributary area failed by ductile flexure, even thoughno ductile seismic details were provided.

The improved design method of shear strength of reinforced concrete beams without transverse reinforcement

Directory of Open Access Journals (Sweden)

Vegera Pavlo

2017-12-01

Full Text Available In this article, results of experimental testing of reinforced concrete beams without transverse shear reinforcement are given. Three prototypes for improved testing methods were tested. The testing variable parameter was the shear span to the effective depth ratio. In the result of the tests we noticed that bearing capacity of RC beams is increased with the decreasing shear span to the effective depth ratio. The design method according to current codes was applied to test samples and it showed a significant discrepancy results. Than we proposed the improved design method using the adjusted value of shear strength of concrete CRd,c. The results obtained by the improved design method showed satisfactory reproducibility.

Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors.

Science.gov (United States)

Montanini, Roberto; Recupero, Antonino; De Domenico, Fabrizio; Freni, Fabrizio

2016-09-22

Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data.

A comparative experimental study of steel fibre-additive reinforced concrete beams

Directory of Open Access Journals (Sweden)

Altun, F.

2004-12-01

Full Text Available Five different batches of class C20 concrete, containing Dramix-RC-80/60-BN steel fibers (SFs as additives at doses of 0, 30, 40, 50 and 60 kg/m3, and six Ø 15x30 cm prisms were poured from each batch. Standard crushing tests were run on all the specimens and the respective load-displacement and stress-strain curves were plotted. Toughness, ultimate compressive strength and the modulus of elasticity were determined for all specimens. The compressive strength and modulus of elasticity declined in 30 kg/m3 steel-fiber-additive concrete (SFAC by 9% and 7% compared to the reference C20 concrete without SFs, and the area under the load-deflection curve grew more than twofold. In concrete with a higher SF dosage, the differences in strength and elasticity were around I0% whilst toughness was about the same. Because toughness values were similar in 30, 40, 50 and 60 kg/m3 plain SF-additive concrete and the strength and modulus of elasticity were slightly better in the mixes with the smallest proportion of SF for reasons of economy, 30 kg/m3 was taken as the optimum dose of steel fiber to be added to the reinforced concrete used in a second phase of the study. Hence, of the six reinforced concrete (RC beams made, all of equal size and with the same under-reinforced tensile reinforcement design, three were made with concrete containing the above-mentioned dose of SF. In addition to compressive strength, these beams were tested for flexural strength, which was found to be 18% greater for the SFARC beams than the ordinary RC beams, and the upper arms of the load versus mid-span deflection curves prior to ultimate failure of the SFARC beams were considerably longer than the same arms on the curves for ordinary RC beams.

Se han utilizado cinco lotes diferentes de hormigón clase C20 cuatro de ellos con fibras de acero (FA, identificadas como Dramix-CR-80/60-BN, en cuatro proporciones diferentes: 30, 40, 50 y 60 kg/m³ y el quinto exento de

Performance of IBS Precast Concrete Beam-Column Connections Under Earthquake Effects: A Literature Review

OpenAIRE

Patrick T.L. Yee; Azlan B. Adnan; Abdul K. Mirasa; Ahmad B.A. Rahman

2011-01-01

Problem statement: Despite demonstrating rather much benefits comparing to the conventional cast-in-place construction, the acceptance level of precast concrete building is still reportedly low in Malaysia. The implication imposed by stricter seismic design provisions would only worsen the matter. Approach: The main objective of this study was to identify the most appropriate type of beam-column connections to be introduced to precast concrete industry, particularly for re...

Crack growth and fracture in fiber reinforced concrete beams under static and fatigue loading

International Nuclear Information System (INIS)

Jeanfreau, J.; Arockiasamy, M.; Reddy, D.V.

1987-01-01

The paper presents the results of a two-phase experimental investigation on the fatigue and fracture of six different types of concrete: plain, 0.5%, 1.0%, 1.5%, and 2.0% steel fibers and 0.5% kevlar fibers. In the first phase the J-integral was evaluated for different types of concrete from load-displacement curves. The value shows a marked increase in the energy required to fracture concrete when fibers are added. The values did not vary substantially for different notch depths. In the second phase concrete beams were subjected to fatigue by applying a pure bending on the notch. The effect of fiber addition was examined with emphasis on the crack propagation and the increase in the fatigue strength. The crack pattern was mainly influenced by the presence, amount, and the distribution of the fibers in the concrete. (orig./HP)

The Continuous Electron Beam Accelerator Facility

International Nuclear Information System (INIS)

Grunder, H.A.; Bisognano, J.J.; Diamond, W.I.; Hartline, B.K.; Leemann, C.W.; Mougey, J.; Sundelin, R.M.; York, R.C.

1987-01-01

On February 13, 1987, construction started on the Continuous Electron Beam Accelerator Facility - a 4-GeV, 200-μA, continuous beam, electron accelerator facility designed for nuclear physics research. The machine has a racetrack configuration with two antiparallel, 500-MeV, superconducting linac segments connected by beam lines to allow four passes of recirculation. The accelerating structure consists of 1500-MHz, five-cell niobium cavities developed at Cornell University. A liquid helium cryogenic system cools the cavities to an operating temperature of 2 K. Beam extraction after any three of the four passes allows simultaneous delivery of up to three beams of independently variable currents and different, but correlated, energies to the three experimental areas. Beam breakup thresholds exceed the design current by nearly two orders of magnitude. Project completion and the start of physics operations are scheduled for 1993. The total estimated cost is $255 million

Improving resistance of high strength concrete (HSC) bridge beams to frost and defrosting salt attack by application of hydrophobic agent

Science.gov (United States)

Kolisko, Jiri; Balík, Lukáš; Kostelecka, Michaela; Pokorný, Petr

2017-09-01

HSC (High Strength Concrete) is increasingly used for bearing bridge structures nowadays. Bridge structures in the Czech Republic are exposed to severe conditions in winter time and durability of the concrete is therefore a crucial requirement. The high strength and low water absorption of HSC suggests that the material will have high durability. However, the situation may not be so straightforward. We carried out a study of the very poor durability of HSC concrete C70/85 used to produce prestresed beams 37.1 m in length to build a 6-span highway bridge. After the beams were cast, a production control test indicated some problems with the durability of the concrete. There was a danger that 42 of the beams would not be suitable for use. All participants in the bridge project finally decided, after extensive discussions, to attempt to improve the durability of the concrete by applying a hydrophobic agent. Paper will present the results of comparative tests of four hydrophobic agents in order to choose one for real application and describes this application on construction site.

Dismantling of metallic components of a concrete structure with a laser beam

International Nuclear Information System (INIS)

Migliorati, B.; Manassero, G.; Tarroni, G.

1985-01-01

Experimental tests have been performed using CO 2 laser with output power 1-15 kW to evaluate the effect of varying the following parameters: material (carbon steel Fe42C, stainless steel AISI 304, concrete), laser power, beam characteristics, work piece velocity, gas type and distribution on the laser interaction zone. In the case of concrete, drilling depths of 80 mm were obtained in a few seconds using a 10 kW laser beam and pieces of 160 mm were cut at 0.01 meters per minute. Results with carbon steel indicated maximum thicknesses of 110 mm, cut at 0.01 meters per minute with 10 kW, while depths of about 20% lower were obtained with the AISI 304 stainless steel. A parallel investigation was aimed at characterising particles emission during the laser cutting process. At the end of the research, it was possible to elaborate a preliminary proposal concerning a laser based dismantling system for a typical Nuclear Power Station PWR

Cracking behavior of reinforced concrete beams: experiment and simulations on the numerical influence of the steel-concrete bond

International Nuclear Information System (INIS)

Jason, L.; Torre-Casanova, A.; Pinelli, X.; Davenne, L.

2013-01-01

Experimental and numerical results are provided in this contribution to study the global and cracking behaviors of two reinforced concrete beams subjected to four point bending. Experimentally, the use of image correlation technique enables to obtain precise information concerning the cracking properties (spacing, cumulated, maximum and mean values of the opening). Numerically, two simulations are compared taking into account a bond model between steel and concrete or supposing a perfect relation between the two materials. In both cases, a good agreement is achieved between numerical and experimental results even if the introduction of the bond effects has a direct influence during the development of the cracks (better agreement during the 'active' cracking phase). (authors)

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

Behaviour of Nano Silica in Tension Zone of High Performance Concrete Beams

Science.gov (United States)

Jaishankar, P.; Vivek, D.

2017-07-01

High performance concrete (HPC) is similar to High strength concrete (HSC).It is because of lowering of water to cement ratio, which is needed to attain high strength and generally improves other properties. This concrete contains one or more cementitious materials such as fly ash, Silica fume or ground granulated blast furnace slag and usually a super plasticizer. The term ‘high performance’ is somewhat different because the essential feature of this concrete is that it’s ingredients and proportions are specifically chosen so as to have particularly appropriate properties for the expected use of the structure such as high strength and low permeability. Usage of nano scale properties such as Nano SiO2 can result in dramatically improved properties from conventional grain size materials of same chemical composition. This project is more interested in evaluate the behaviour of nano silica in concrete for 5%, 10%, and 15% volume fraction of cement. Flexural test for beams were conducted with two point loads, at different percentage as mentioned above. From results interpolated, Nano silica with higher order replacement gives optimized results compared to control specimens.

Flexural and Thermal Properties of Novel Energy Conservation Slotted Reinforced Concrete Beams

Directory of Open Access Journals (Sweden)

Gao Ma

2016-01-01

Full Text Available Conventional solid reinforced concrete (RC beams were modified to slotted beams for consideration as thermal insulation structural components. The slotted beam consisted of an outer and an inner beam, respectively, with a slot located near the middle of the beam along its width direction for filling thermal insulation material. Flexural and thermal behavior of the slotted beams were investigated. Three RC reference solid beams and six slotted beams were fabricated and tested under four-point bending tests. The test results indicated that the failure mode of both slotted beams and the solid beams was flexural failure. However, the damage process of the slotted beams was different from that of the solid beams at the final loading stage. The moment curvature analysis indicated that the tensile reinforcement ratio of the outer and inner beams had an important effect on the flexural behavior, especially the ductility of the slotted beams. Thermal study indicated that the heat transfer coefficient of the slotted beam was greatly reduced and the thermal inertia factor increased a lot, compared with the solid beam. In addition, FE simulation results showed that a new frame structure using slotted beams exhibited obvious and attractive thermal insulation property.

Enhancement of shear strength and ductility for reinforced concrete wide beams due to web reinforcement

Directory of Open Access Journals (Sweden)

M. Said

2013-12-01

Full Text Available The shear behavior of reinforced concrete wide beams was investigated. The experimental program consisted of nine beams of 29 MPa concrete strength tested with a shear span-depth ratio equal to 3.0. One of the tested beams had no web reinforcement as a control specimen. The flexure mode of failure was secured for all of the specimens to allow for shear mode of failure. The key parameters covered in this investigation are the effect of the existence, spacing, amount and yield stress of the vertical stirrups on the shear capacity and ductility of the tested wide beams. The study shows that the contribution of web reinforcement to the shear capacity is significant and directly proportional to the amount and spacing of the shear reinforcement. The increase in the shear capacity ranged from 32% to 132% for the range of the tested beams compared with the control beam. High grade steel was more effective in the contribution of the shear strength of wide beams. Also, test results demonstrate that the shear reinforcement significantly enhances the ductility of the wide beams. In addition, shear resistances at failure recorded in this study are compared to the analytical strengths calculated according to the current Egyptian Code and the available international codes. The current study highlights the need to include the contribution of shear reinforcement in the Egyptian Code requirements for shear capacity of wide beams.

Experimental Investigation of Static Behavior of Fibrous Concrete Simply Supported Deep Beams under Patch Loading

Directory of Open Access Journals (Sweden)

Thamer Hanna

2015-02-01

Full Text Available This paper investigates the effect of steel and polypropylene fibers on static behavior of simply supported deep beams of normal concrete strength under patch loading. Also the paper studied the effect of web opening and its positions on shear capacity and mode of failures for steel fiber concrete deep beams under the same conditions of loading and strength.       Sixteen beams of (1000*300*100mm, eighteen cubes (150*150*150mm and thirty cylinders (150*300mm in dimensions were cast with different fiber volume content (0, 0.4, 0.64 and 0.89% as additives. Shear capacity, mode of failure and three of mechanical strengths were tested.       After testing, the results indicate that shear capacity increases with increasing volume of steel fiber content with change on mode of failure while midspan displacement decreases.

Damage induced by continued corrosion in concrete repair systems

NARCIS (Netherlands)

Luckovic, M.; Savija, B.; Schlangen, E.

2014-01-01

Corrosion of steel reinforcement is the main cause of deterioration in reinforced concrete structures. After the repair, corrosion of the steel might continue and even accelerate. While the development of the corrosion cell depends on many parameters and is difficult to control, the occurrence of

Deflection of Steel Reinforced Concrete Beam Prestressed With CFRP Bar

Directory of Open Access Journals (Sweden)

Selvachandran P.

2017-09-01

Full Text Available Carbon Fiber Reinforced polymer (CFRP bars are weak in yielding property which results in sudden failure of structure at failure load. Inclusion of non-pretensioned steel reinforcement in the tension side of CFRP based prestressed concrete beam will balance the yielding requirements of member and it will show the definite crack failure pattern before failure. Experimental investigation has been carried out to study the deflection behavior of partially prestressed beam. Experimental works includes four beam specimens stressed by varying degree of prestressing. The Partial Prestressing Ratio (PPR of specimen is considered for experimental works in the range of 0.6 to 0.8. A new deflection model is recommended in the present study considering the strain contribution of CFRP bar and steel reinforcement for the fully bonded member. New deflection model converges to experimental results with the error of less than 5% .

Nonlinear finite element analysis of a test on the mechanical mechanism of the half-steel-concrete composite beam in HTR-PM

International Nuclear Information System (INIS)

Sun Feng; Pan Rong

2014-01-01

According to a large-span half-steel-concrete (HSC) composited beam in the composited roof in the HTR-PM, a 1:3 scale specimen is investigated by the static load test. By analyzing the loading, deflection, strain and fracture development of the specimen in the process, studying the mechanical characteristics and failure pattern of such components. The ANSYS finite element software is utilized in this paper to analyze the nonlinearity behavior of the HSC beam specimen, and through comparing the experimental results and the numerical simulation, it can be illustrated that the finite element model can simulate the HSC beam accurately. From the test results, it can be concluded that by means of appropriate shear connection and anchorage length, steel plate and concrete can work together very well and the HSC beam has good load carrying capacity and ductility. These conclusions can serve as a preliminary design reference for the large span half-steel-concrete composite beam in NPP. (author)

Research of Effective Width of FRP U-shaped Hoop Reinforcement Properties of Concrete Beams by Shear

Directory of Open Access Journals (Sweden)

Li Baokun

2015-01-01

Full Text Available The paste fiber reinforced composite material (hereinafter referred to as FRP U-shaped hoop of reinforced concrete beams interfacial debonding is an important reinforcement technology research. For the effective width of the CFRP U-shaped hoop reinforcement, it is still a lack of in-depth research, only relying on the test research huge workload, this article (ANSYS and the numerical simulation in the whole process of the shear load release properties of finite element calculation software. According to the results of finite element analysis, the author studied the CFRP U-shaped hoop to increase the width of the shear capacity of reinforced concrete beams by the impact.

Damage location and quantification of a pretensioned concrete beam using stochastic subspace identification

Science.gov (United States)

Cancelli, Alessandro; Micheli, Laura; Laflamme, Simon; Alipour, Alice; Sritharan, Sri; Ubertini, Filippo

2017-04-01

Stochastic subspace identification (SSID) is a first-order linear system identification technique enabling modal analysis through the time domain. Research in the field of structural health monitoring has demonstrated that SSID can be used to successfully retrieve modal properties, including modal damping ratios, using output-only measurements. In this paper, the utilization of SSID for indirectly retrieving structures' stiffness matrix was investigated, through the study of a simply supported reinforced concrete beam subjected to dynamic loads. Hence, by introducing a physical model of the structure, a second-order identification method is achieved. The reconstruction is based on system condensation methods, which enables calculation of reduced order stiffness, damping, and mass matrices for the structural system. The methods compute the reduced order matrices directly from the modal properties, obtained through the use of SSID. Lastly, the reduced properties of the system are used to reconstruct the stiffness matrix of the beam. The proposed approach is first verified through numerical simulations and then validated using experimental data obtained from a full-scale reinforced concrete beam that experienced progressive damage. Results show that the SSID technique can be used to diagnose, locate, and quantify damage through the reconstruction of the stiffness matrix.

Study of the shear behaviour of fibre reinforced concrete beams

Directory of Open Access Journals (Sweden)

Barragán, B.

2008-12-01

Full Text Available This study presents a series of tests for characterizing the structural behaviour of fibre reinforced concrete beams subjected to shear loading. The experimental program involves three types of fibres; two steel fibres and a polypropylene fibre. As a reference, plain concrete and conventionally reinforced concrete specimens have also been tested. The ultimate shear capacity of the beams is calculated and these values compared with those predicted by existing formulations. The study confirms that the toughness and shear crack resistance of the material is greatly enhanced by the fibres. However, the incorporation of 1% of fibres yielded lower shear strength than conventionally reinforced beams with the same amount of steel in the form of transversal stirrups. Existing design methods seem sufficiently robust to estimate the maximum shear load, even when using material properties (toughness, tensile strength extrapolated from code formulae.Este trabajo presenta una serie de ensayos para caracterizar el comportamiento estructural de vigas realizadas con hormigón reforzado con fibras sometidas a cortante. El programa de ensayos incluía tres tipos de fibras, dos de acero y una de polipropileno. Asimismo, se realizó una serie de ensayos con una viga confeccionada con hormigón armado convencional. La resistencia a cortante de las vigas es comparada con los valores que la formulación existente predice. El estudio confirma que la tenacidad y la resistencia a cortante son incrementadas tras la adición de fibras al hormigón. Sin embargo, la incorporación de un 1% en volumen de fibras conduce a valores de resistencia última a cortante inferiores a los obtenidos con vigas de hormigón convencional con la misma cantidad de acero dispuesta en forma de cercos de cortante. Los actuales métodos de cálculo parecen lo suficientemente precisos para evaluar la carga de cortante último, incluso cuando los parámetros mecánicos utilizados en las f

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.

Experimental Study on Full-Scale Beams Made by Reinforced Alkali Activated Concrete Undergoing Flexure.

Science.gov (United States)

Monfardini, Linda; Minelli, Fausto

2016-08-30

Alkali Activated Concrete (AAC) is an alternative kind of concrete that uses fly ash as a total replacement of Portland cement. Fly ash combined with alkaline solution and cured at high temperature reacts to form a binder. Four point bending tests on two full scale beams made with AAC are described in this paper. Companion small material specimens were also casted with the aim of properly characterizing this new tailored material. The beam's length was 5000 mm and the cross section was 200 mm × 300 mm. The AAC consisted of fly ash, water, sand 0-4 mm and coarse aggregate 6-10 mm; and the alkaline solution consisted of sodium hydroxide mixed with sodium silicate. No cement was utilized. The maximum aggregate size was 10 mm; fly ash was type F, containing a maximum calcium content of 2%. After a rest period of two days, the beam was cured at 60 °C for 24 h. Data collected and critically discussed included beam deflection, crack patterns, compressive and flexural strength and elastic modulus. Results show how AAC behavior is comparable with Ordinary Portland Cement (OPC) based materials. Nonlinear numerical analyses are finally reported, promoting a better understanding of the structural response.

Combined effect of high curing temperature and crack width on chloride migration in reinforced concrete beams

Science.gov (United States)

Elkedrouci, L.; Diao, B.; Pang, S.; Li, Y.

2018-03-01

Deterioration of reinforced concrete structures is a serious concern in the construction engineering, largely due to chloride induced corrosion of reinforcement. Chloride penetration is markedly influenced by one or several major factors at the same time such as cuing in combination with different crack widths which have spectacular effect on reinforced concrete structures. This research presents the results of an experimental investigation involving reinforced concrete beams with three different crack widths ranging from 0 to 0.2mm, curing temperatures of 20°C or 40°C and water-to-cement of 0.5. Chloride content profiles were determined under non-steady state diffusion at 20°C. Based on the obtained results, higher chloride content was obtained under condition of high curing temperature in combination with large crack more than 0.1mm and there are no significant differences between narrow crack width (less than 0.1 mm) and beams without crack (0 mm).

Numerical Study Of The Effects Of Preloading, Axial Loading And Concrete Shrinkage On Reinforced Concrete Elements Strengthened By Concrete Layers And Jackets

International Nuclear Information System (INIS)

Lampropoulos, A. P.; Dritsos, S. E.

2008-01-01

In this study, the technique of seismic strengthening existing reinforced concrete columns and beams using additional concrete layers and jackets is examined. The finite element method and the finite element program ATENA is used in this investigation. When a reinforced jacket or layer is being constructed around a column it is already preloaded due to existing service loads. This effect has been examined for different values of the axial load normalized to the strengthened column. The techniques of strengthening with a concrete jacket or a reinforced concrete layer on the compressive side of the column are examined. Another phenomenon that is examined in this study is the shrinkage of the new concrete of an additional layer used to strengthen an existing member. For this investigation, a simply supported beam with an additional reinforced concrete layer on the tensile side is examined. The results demonstrate that the effect of preloading is important when a reinforced concrete layer is being used with shear connectors between the old and the new reinforcement. It was also found that the shrinkage of the new concrete reduces the strength of the strengthened beam and induces an initial sliding between the old and the new concrete

THE STRENGTH OF REINFORCED CONCRETE BEAM ELEMENTS UNDER CYCLIC ALTERNATING LOADING AND LOW CYCLE LOAD OF CONSTANT SIGN

Directory of Open Access Journals (Sweden)

Semina Yuliya Anatol'evna

2015-09-01

Full Text Available The behavior of reinforced concrete elements under some types of cyclic loads is described in the paper. The main aim of the investigations is research of the stress-strain state and strength of the inclined sections of reinforced concrete beam elements in conditions of systemic impact of constructive factors and the factor of external influence. To spotlight the problem of cyclic loadings three series of tests were conducted by the author. Firstly, the analysis of the tests showed that especially cyclic alternating loading reduces the bearing capacity of reinforced concrete beams and their crack resistance by 20 % due to the fatigue of concrete and reinforcement. Thus the change of load sign creates serious changes of stress-strain state of reinforced concrete beam elements. Low cycle loads of constant sign effect the behavior of the constructions not so adversely. Secondly, based on the experimental data mathematical models of elements’ strength were obtained. These models allow evaluating the impact of each factor on the output parameter not only separately, but also in interaction with each other. Furthermore, the material spotlighted by the author describes stress-strain state of the investigated elements, cracking mechanism, changes of deflection values, the influence of mode cyclic loading during the tests. Since the data on the subject are useful and important to building practice, the ultimate aim of the tests will be working out for improvement of nonlinear calculation models of span reinforced concrete constructions taking into account the impact of these loads, and also there will be the development of engineering calculation techniques of their strength, crack resistance and deformability.

Fire Flame Influence on the Behavior of reinforced Concrete Beams Affected by Repeated

Directory of Open Access Journals (Sweden)

Shatha Dheyaa Mohammed

2016-09-01

Full Text Available The influence and hazard of fire flame are one of the most important parameters that affecting the durability and strength of structural members. This research studied the influence of fire flame on the behavior of reinforced concrete beams affected by repeated load. Nine self- compacted reinforced concrete beams were castellated, all have the same geometric layout (0.15x0.15x1.00 m, reinforcement details and compressive strength (50 Mpa. To estimate the effect of fire flame disaster, four temperatures were adopted (200, 300, 400 and 500 oC and two method of cooling were used (graduated and sudden. In the first cooling method, graduated, the tested beams were leaved to cool in air while in the second method, sudden, water splash was used to reduce the temperature. Eight of the tested beams were divided in to four groups, each were burned to one of the adopted temperature for about half an hour and cooled by the adopted cooling methods (one by sudden cooling and the other by graduated cooling. After burning and cooling the beams were tested under the effect of repeated load (loading – unloading for five cycle and then up to failure. As a compared with the non- burned beam, the results indicated that the ultimate load capacity of the tested beams were reduced by (16, 23, 54 and 71% after being burned to (200, 300, 400 and 500 oC , respectively, for a case of sudden cooling and by (8, 14, 36 and 64% , respectively, for a case of graduated cooling. It was also found that the effect of sudden cooling was greater than that in a case of graduated cooling. Regarding the failure mode, there was a different between the non-burred beam and the other ones even that all of them had the same geometric layout, compressive strength and reinforcement details. The failure mode for all burned beams was combined shear- flexure failure which was belong to the reduction in the compressive strength of the concrete due to the effect of the temperature rising , while

Shear strength estimation of the concrete beams reinforced with FRP; comparison of artificial neural network and equations of regulations

Directory of Open Access Journals (Sweden)

Mahmood Akbari

2017-12-01

Full Text Available In recent years, numerous experimental tests were done on the concrete beams reinforced with the fiber-reinforced polymer (FRP. In this way, some equations were proposed to estimate the shear strength of the beams reinforced with FRP. The aim of this study is to explore the feasibility of using a feed-forward artificial neural network (ANN model to predict the ultimate shear strength of the beams strengthened with FRP composites. For this purpose, a database consists of 304 reinforced FRP concrete beams have been collected from the available articles on the analysis of shear behavior of these beams. The inputs to the ANN model consists of the 11 variables including the geometric dimensions of the section, steel reinforcement amount, FRP amount and the properties of the concrete, steel reinforcement and FRP materials while the output variable is the shear strength of the FRP beam. To assess the performance of the ANN model for estimating the shear strength of the reinforced beams, the outputs of the ANN are compared to those of equations of the Iranian code (Publication No. 345 and the American code (ACI 440. The comparisons between the outputs of Iran and American regulations with those of the proposed model indicates that the predictive power of this model is much better than the experimental codes. Specifically, for under study data, mean absolute relative error (MARE criteria is 13%, 34% and 39% for the ANN model, the American and the Iranian codes, respectively.

Shear reinforced beams in autoclaved aerated concrete

DEFF Research Database (Denmark)

Cornelius, Thomas

2010-01-01

Shear behaviour in concrete materials is very well documented, for normal density concrete materials. In this paper results of various tests on low density concrete materials like aerated autoclaved concrete (in the following denoted aircrete) will be presented and analyzed for different combinat....... Codes for designing prefabricated reinforced components of aircrete structures have adopted these recently developed approaches.......Shear behaviour in concrete materials is very well documented, for normal density concrete materials. In this paper results of various tests on low density concrete materials like aerated autoclaved concrete (in the following denoted aircrete) will be presented and analyzed for different...

Shear design and assessment of reinforced and prestressed concrete beams based on a mechanical model

OpenAIRE

Marí Bernat, Antonio Ricardo; Bairán García, Jesús Miguel; Cladera Bohigas, Antoni; Oller Ibars, Eva

2016-01-01

Safe and economical design and assessment of reinforced (RC) and prestressed concrete (PC) beams requires the availability of accurate but simple formulations which adequately capture the structural response. In this paper, a mechanical model for the prediction of the shear-flexural strength of PC and RC members with rectangular, I, or T sections, with and without shear reinforcement, is presented. The model is based on the principles of concrete mechanics and on assumptions supported by the ...

A Modified Model for Deflection Calculation of Reinforced Concrete Beam with Deformed GFRP Rebar

OpenAIRE

Ju, Minkwan; Oh, Hongseob; Lim, Junhyun; Sim, Jongsung

2016-01-01

The authors carried out experimental and analytical research to evaluate the flexural capacity and the moment-deflection relationship of concrete beams reinforced with GFRP bars. The proposed model to predict the effective moment of inertia for R/C beam with GFRP bars was developed empirically, based on Branson’s equation to have better accuracy and a familiar approach to a structural engineer. For better prediction of the moment-deflection relationship until the ultimate strength is reached,...

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.

Optimisation of the Crack Pattern in Continuously Reinforced Concrete Pavements

NARCIS (Netherlands)

Ren, D.

2015-01-01

Recent field investigations on several new Continuously Reinforced Concrete Pavements (CRCP) in Belgium indicate that its crack pattern is characterized by low mean crack spacing along with a high percentage of clusters of closely spaced cracks. Field surveys also indicate that it is difficult to

Investigation on Failures of Composite Beam and Substrate Concrete due to Drying Shrinkage Property of Repair Materials

Science.gov (United States)

Pattnaik, Rashmi Ranjan

2017-06-01

A Finite Element Analysis (FEA) and an experimental study was conducted on composite beam of repair material and substrate concrete to investigate the failures of the composite beam due to drying shrinkage property of the repair materials. In FEA, the stress distribution in the composite beam due to two concentrate load and shrinkage of repair materials were investigated in addition to the deflected shape of the composite beam. The stress distributions and load deflection shapes of the finite element model were investigated to aid in analysis of the experimental findings. In the experimental findings, the mechanical properties such as compressive strength, split tensile strength, flexural strength, and load-deflection curves were studied in addition to slant shear bond strength, drying shrinkage and failure patterns of the composite beam specimens. Flexure test was conducted to simulate tensile stress at the interface between the repair material and substrate concrete. The results of FEA were used to analyze the experimental results. It was observed that the repair materials with low drying shrinkage are showing compatible failure in the flexure test of the composite beam and deform adequately in the load deflection curves. Also, the flexural strength of the composite beam with low drying shrinkage repair materials showed higher flexural strength as compared to the composite beams with higher drying shrinkage value of the repair materials even though the strength of those materials were more.

Ductility and performance assessment of high strength self compacting concrete (HSSCC) deep beams: An experimental investigation

International Nuclear Information System (INIS)

Mohammadhassani, Mohammad; Jumaat, Mohd Zamin; Jameel, Mohammed; Badiee, Hamid; Arumugam, Arul M.S.

2012-01-01

Highlights: ► Ductility decreased with increase in tensile reinforcement ratio. ► The width of the load point and the support point influences premature failure. ► Load–deflection relationship is linear till 85% of the ultimate load. ► The absorbed energy increases with the increase of tensile reinforcement ratios. - Abstract: The behavior of deep beams is significantly different from that of normal beams. Because of their proportions, deep beams are likely to have strength controlled by shear. This paper discusses the results of eight simply supported high strength self compacting concrete (HSSCC) deep beams having variation in ratio of web reinforcement and tensile reinforcement. The deflection at two points along the beam length, web strains, tensile bars strains and the strain at concrete surface are recorded. The results show that the strain distribution at the section height of mid span is nonlinear. Ductility decreased with increase in tensile reinforcement ratio. The effect of width of load point and the support point is more important than the effect of tensile reinforcement ratio in preventing premature failure. Load–deflection graphs confirm linear relationship up to 85% of the ultimate load for HSSCC over-reinforcement web sections. The absorbed energy index increases with the increase in tensile reinforcement ratios.

Distributed Strain Measurement along a Concrete Beam via Stimulated Brillouin Scattering in Optical Fibers

Directory of Open Access Journals (Sweden)

Romeo Bernini

2011-01-01

Full Text Available The structural strain measurement of tension and compression in a 4 m long concrete beam was demonstrated with a distributed fiber-optic sensor portable system based on Brillouin scattering. Strain measurements provided by the fiber-optic sensor permitted to detect the formation of a crack in the beam resulting from the external applied load. The sensor system is valuable for structural monitoring applications, enabling the long-term performance and health of structures to be efficiently monitored.

Prediction of Mean and Design Fatigue Lives of Self Compacting Concrete Beams in Flexure

Science.gov (United States)

Goel, S.; Singh, S. P.; Singh, P.; Kaushik, S. K.

2012-02-01

In this paper, result of an investigation conducted to study the flexural fatigue characteristics of self compacting concrete (SCC) beams in flexure are presented. An experimental programme was planned in which approximately 60 SCC beam specimens of size 100 × 100 × 500 mm were tested under flexural fatigue loading. Approximately 45 static flexural tests were also conducted to facilitate fatigue testing. The flexural fatigue and static flexural strength tests were conducted on a 100 kN servo-controlled actuator. The fatigue life data thus obtained have been used to establish the probability distributions of fatigue life of SCC using two-parameter Weibull distribution. The parameters of the Weibull distribution have been obtained by different methods of analysis. Using the distribution parameters, the mean and design fatigue lives of SCC have been estimated and compared with Normally vibrated concrete (NVC), the data for which have been taken from literature. It has been observed that SCC exhibits higher mean and design fatigue lives compared to NVC.

Pretreatment of Woven Jute FRP Composite and Its Use in Strengthening of Reinforced Concrete Beams in Flexure

Directory of Open Access Journals (Sweden)

Tara Sen

2013-01-01

Full Text Available Environmental awareness motivates researchers worldwide to perform studies of natural fibre reinforced polymer composites, as they come with many advantages and are primarily sustainable. The present study aims at evaluating the mechanical characteristics of natural woven jute fibre reinforced polymer (FRP composite subjected to three different pretreatments, alkali, benzyl chloride, and lastly heat treatment. It was concluded that heat treatment is one of the most suitable treatment methods for enhancing mechanical properties of jute FRP. Durability studies on Jute FRP pertaining to some common environmental conditions were also carried out such as effect of normal water and thermal aging on the tensile strength of jute FRP followed by fire flow test. The heat treated woven jute FRP composites were subsequently used for flexural strengthening of reinforced concrete beams in full and strip wrapping configurations. The study includes the effect of flexural strengthening provided by woven jute FRP, study of different failure modes, load deflection behavior, effect on the first crack load, and ultimate flexural strength of concrete beams strengthened using woven jute FRP subjected to bending loads. The study concludes that woven jute FRP is a suitable material which can be used for flexural upgradation of reinforced concrete beams.

Behavior of Equipment Support Beam Joint Directly Connected to A Steel-plate Concrete(SC) Wall

International Nuclear Information System (INIS)

Kim, K. S.; Kwon, K. J.

2008-01-01

To decrease the time for building nuclear power plants, a modular construction method, 'Steel-plate Concrete(SC)', has been investigated for over a decade. To construct a SC wall, a pair of steel plates are placed in parallel similar to a form-work in conventional reinforced concrete (RC) structures, and concrete is filled between the steel plates. Instead of removing the steel plates after the concrete has cured, the steel plates serve as components of the structural member. The exposed steel plate of SC structures serves as the base plate for the equipment support, and the headed studs welded to the steel plates are used as anchor bolts. Then, a support beam can be directly welded to the surface of the steel plate in any preferred position. In this study, we discuss the behavior and evaluation method of the equipment support joint directly connected to exposed steel plate of SC wall

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.

Nonlinear Analysis for the Crack Control of SMA Smart Concrete Beam Based on a Bidirectional B-Spline QR Method

Directory of Open Access Journals (Sweden)

Yan Li

2018-01-01

Full Text Available A bidirectional B-spline QR method (BB-sQRM for the study on the crack control of the reinforced concrete (RC beam embedded with shape memory alloy (SMA wires is presented. In the proposed method, the discretization is performed with a set of spline nodes in two directions of the plane model, and structural displacement fields are constructed by the linear combination of the products of cubic B-spline interpolation functions. To derive the elastoplastic stiffness equation of the RC beam, an explicit form is utilized to express the elastoplastic constitutive law of concrete materials. The proposed model is compared with the ANSYS model in several numerical examples. The results not only show that the solutions given by the BB-sQRM are very close to those given by the finite element method (FEM but also prove the high efficiency and low computational cost of the BB-sQRM. Meanwhile, the five parameters, such as depth-span ratio, thickness of concrete cover, reinforcement ratio, prestrain, and eccentricity of SMA wires, are investigated to learn their effects on the crack control. The results show that depth-span ratio of RC beams and prestrain and eccentricity of SMA wires have a significant influence on the control performance of beam cracks.

Analysis of concrete beams using applied element method

Science.gov (United States)

Lincy Christy, D.; Madhavan Pillai, T. M.; Nagarajan, Praveen

2018-03-01

The Applied Element Method (AEM) is a displacement based method of structural analysis. Some of its features are similar to that of Finite Element Method (FEM). In AEM, the structure is analysed by dividing it into several elements similar to FEM. But, in AEM, elements are connected by springs instead of nodes as in the case of FEM. In this paper, background to AEM is discussed and necessary equations are derived. For illustrating the application of AEM, it has been used to analyse plain concrete beam of fixed support condition. The analysis is limited to the analysis of 2-dimensional structures. It was found that the number of springs has no much influence on the results. AEM could predict deflection and reactions with reasonable degree of accuracy.

X-Ray Investigation and Strength Measurement of Steel Fibre Reinforced Self-Compacting Concrete Beams

Directory of Open Access Journals (Sweden)

Ponikiewski Tomasz

2016-12-01

Full Text Available The paper presents a study on self-compacting concrete with two types of steel fibres. Under consideration was the effect the method of forming of beam elements has on the distribution of steel fibres. Formed we beams of dimensions 120×15×15 cm3 and 180×15×15 cm3. The self-compacting mixture contained steel fibres of varying lengths (35 and 50 mm and varying levels of their volume ratio in the mix (0.5% - 1.0% - 1.5%.

Pedogenic Carbonate Concretions in the Russian Chernozem

Energy Technology Data Exchange (ETDEWEB)

Mikhailova, E. A.; Post, C. J.; Magrini-Bair, K.; Castle, J. W.

2006-12-01

Pedogenic carbonate concretions are commonly found in grassland soils, but their origin is not fully understood. This study was conducted to determine the radiocarbon age, the stable isotope geochemistry, and chemical composition of carbonate concretions in the Russian Chernozem, one of the typical soils in grasslands. Three sites were sampled: a native grassland field (not cultivated for at least 300 years), an adjacent 50-year continuous fallow field in the V. V. Alekhin Central-Chernozem Biosphere State Reserve in the Kursk region of Russia, and a continuously cropped field in the Experimental Station of the Kursk Institute of Agronomy and Soil Erosion Control. All sampled soils were classified as fine-silty, mixed, frigid Pachic Hapludolls. The mineralogical composition of concretions varies from low-magnesium calcite to pure calcite. The concretion contains 0.05% N, 6.4% C, and has [delta]13C and [delta]18O values of -10.9[per mille sign] (the per mill symbol, parts per thousand) and -7.8[per mille sign], respectively. The outside part of the carbonate concretion is 1909 +/- 40 14C age Before Present (B.P.) compared with 1693 +/- 40 14C age B.P. for the inside part of the same concretion, even though the concretion is found in the C horizon of much older age (10,902 +/- 63 14C age B.P.). Remnants of soil organic matter in concretions are closely associated with the cropped and fallow/plowed soils by pyrolysis molecular beam mass spectrometry.

Interfacial damage identification of steel and concrete composite beams based on piezoceramic wave method.

Science.gov (United States)

Yan, Shi; Dai, Yong; Zhao, Putian; Liu, Weiling

2018-01-01

Steel-concrete composite structures are playing an increasingly important role in economic construction because of a series of advantages of great stiffness, good seismic performance, steel material saving, cost efficiency, convenient construction, etc. However, in service process, due to the long-term effects of environmental impacts and dynamic loading, interfaces of a composite structure might generate debonding cracks, relative slips or separations, and so on, lowering the composite effect of the composite structure. In this paper, the piezoceramics (PZT) are used as transducers to perform experiments on interface debonding slips and separations of composite beams, respectively, aimed at proposing an interface damage identification model and a relevant damage detection innovation method based on PZT wave technology. One part of various PZT patches was embedded in concrete as "smart aggregates," and another part of the PZT patches was pasted on the surface of the steel beam flange, forming a sensor array. A push-out test for four specimens was carried out and experimental results showed that, under the action of the external loading, the received signal amplitudes will increasingly decrease with increase of debonding slips along the interface. The proposed signal energy-based interface damage detection algorithm is highly efficient in surface state evaluations of composite beams.

Static Analysis of Steel Fiber Concrete Beam With Heterosis Finite Elements

Directory of Open Access Journals (Sweden)

James H. Haido

2014-08-01

Full Text Available Steel fiber is considered as the most commonly used constructional fibers in concrete structures. The formulation of new nonlinearities to predict the static performance of steel fiber concrete composite structures is considered essential. Present study is devoted to investigate the efficiency of utilizing heterosis finite elements analysis in static analysis of steel fibrous beams. New and simple material nonlinearities are proposed and used in the formulation of these elements. A computer program coded in FORTRAN was developed to perform current finite element static analysis with considering four cases of elements stiffness matrix determination. The results are compared with the experimental data available in literature in terms of central deflections, strains, and failure form, good agreement was found. Suitable outcomes have been observed in present static analysis with using of tangential stiffness matrix and stiffness matrix in second iteration of the load increment.

Investigation of in-plane moment connections of I-beams to square concrete-filled steel tube columns under gravity loads

Directory of Open Access Journals (Sweden)

Abdelrahim K. Dessouki

2015-04-01

Full Text Available This paper focuses on experimental and analytical behavior of the ultimate moment of the connections of steel I-beams to square concrete-filled steel tube columns. External stiffeners around the columns are used at the beam flange levels. Five specimens are tested monotonically. The test parameters are the column stiffener dimensions and filling the steel tube column with concrete. Two types of failure modes are observed; beam flange failure and stiffener failure. The experimental results show that the ultimate moment of the connection is increased by increasing stiffener’s dimensions and filling the steel tube column with concrete. ANSYS finite element program is used to simulate the behavior, taking into account both geometric and material nonlinearities. Analytical results that are in fair agreement with the experimental ones are then used to discuss the influence of the main geometric parameters on the connection behavior. The parameters are the stiffener and column dimensions as well as filling the steel tube column with concrete. Different square column cross sections are chosen to cover the three classes of section classifications according to Egyptian code of practice, which are: compact, non compact or slender. The increase in the ultimate moment of the connections is based upon both column cross sections’ compactness and stiffener dimensions while the maximum advantages occur with slender columns.

Strengthening of self-compacting reinforced concrete deep beams containing circular openings with CFRP

Directory of Open Access Journals (Sweden)

Al-Bayati Nabeel

2018-01-01

Full Text Available This paper shows the behavior of reinforced self-compacting concrete deep beams with circular openings strengthened in shear with various arrangements of externally bonded Carbon Fibre Reinforced Polymer (CFRP. Six simply supported deep beams were constructed and tested under two points load up to the failure for this purpose. All tested beams had same geometry, compressive strength, shear span to depth ratio, main flexural and web reinforcement. The variables considered in this study include the influence of fiber orientation, utilizing longitudinal CFRP strips with vertical strips and area of CFRP. The test results indicated that the presence of the circular openings in center of load path reduce stiffness and ultimate strength by about 50% when compared with solid one, also it was found that the externally bonded CFRP can significantly increase the ultimate load and enhance the stiffness of deep beam with openings.

Ductility and performance assessment of high strength self compacting concrete (HSSCC) deep beams: An experimental investigation

Energy Technology Data Exchange (ETDEWEB)

Mohammadhassani, Mohammad, E-mail: mmh356@yahoo.com [Department of Civil Engineering, University of Malaya, Kuala Lumpur (Malaysia); Jumaat, Mohd Zamin; Jameel, Mohammed [Department of Civil Engineering, University of Malaya, Kuala Lumpur (Malaysia); Badiee, Hamid [Department of Civil Engineering, University of Kerman (Iran, Islamic Republic of); Arumugam, Arul M.S. [Department of Civil Engineering, University of Malaya, Kuala Lumpur (Malaysia)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Ductility decreased with increase in tensile reinforcement ratio. Black-Right-Pointing-Pointer The width of the load point and the support point influences premature failure. Black-Right-Pointing-Pointer Load-deflection relationship is linear till 85% of the ultimate load. Black-Right-Pointing-Pointer The absorbed energy increases with the increase of tensile reinforcement ratios. - Abstract: The behavior of deep beams is significantly different from that of normal beams. Because of their proportions, deep beams are likely to have strength controlled by shear. This paper discusses the results of eight simply supported high strength self compacting concrete (HSSCC) deep beams having variation in ratio of web reinforcement and tensile reinforcement. The deflection at two points along the beam length, web strains, tensile bars strains and the strain at concrete surface are recorded. The results show that the strain distribution at the section height of mid span is nonlinear. Ductility decreased with increase in tensile reinforcement ratio. The effect of width of load point and the support point is more important than the effect of tensile reinforcement ratio in preventing premature failure. Load-deflection graphs confirm linear relationship up to 85% of the ultimate load for HSSCC over-reinforcement web sections. The absorbed energy index increases with the increase in tensile reinforcement ratios.

NON-LINEAR ANALYSIS OF AN EXPERIMENTAL JOINT OF COLUMN AND BEAMS OF ARMED CONCRETE-STEEL COLUMN FOR FRAME

Directory of Open Access Journals (Sweden)

Nelson López

2017-12-01

Full Text Available In this research, the nonlinear behavior of a real-scale experimental joint (node is studied, consisting of three reinforced concrete elements, one column and two beams joined to a structural steel column at the upper level. In the numerical analysis the model of the union was analyzed in the inelastic range, this model was elaborated with the finite element program based on fibers, SeismoStruct to analyze as a function of time, the traction and compression efforts in the confined area and not confined area of the concrete column and in the longitudinal reinforcement steel, as well as verification of the design of the base plate that joins the two columns. The results showed that tensile stresses in the unconfined zone surpassed the concrete breaking point, with cracking occurring just below the lower edge of the beams; in the confined area the traction efforts were much lower, with cracks occurring later than in the non-confined area. The concrete column-steel column joint behaved as a rigid node, so the elastic design was consistent with the calculation methodology of base plates for steel columns.

Temperature Measurement and Damage Detection in Concrete Beams Exposed to Fire Using PPP-BOTDA Based Fiber Optic Sensors.

Science.gov (United States)

Bao, Yi; Hoehler, Matthew S; Smith, Christopher M; Bundy, Matthew; Chen, Genda

2017-10-01

In this study, distributed fiber optic sensors based on pulse pre-pump Brillouin optical time domain analysis (PPP-BODTA) are characterized and deployed to measure spatially-distributed temperatures in reinforced concrete specimens exposed to fire. Four beams were tested to failure in a natural gas fueled compartment fire, each instrumented with one fused silica, single-mode optical fiber as a distributed sensor and four thermocouples. Prior to concrete cracking, the distributed temperature was validated at locations of the thermocouples by a relative difference of less than 9 %. The cracks in concrete can be identified as sharp peaks in the temperature distribution since the cracks are locally filled with hot air. Concrete cracking did not affect the sensitivity of the distributed sensor but concrete spalling broke the optical fiber loop required for PPP-BOTDA measurements.

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.

Nonlinear fracture mechanics investigation on the ductility of reinforced concrete beams

Directory of Open Access Journals (Sweden)

A. Carpinteri

Full Text Available In the present paper, a numerical algorithm based on the finite element method is proposed for the prediction of the mechanical response of reinforced concrete (RC beams under bending loading. The main novelty of such an approach is the introduction of the Overlapping Crack Model, based on nonlinear fracture mechanics concepts, to describe concrete crushing. According to this model, the concrete dam- age in compression is represented by means of a fictitious interpenetration. The larger is the interpenetration, the lower are the transferred forces across the damaged zone. The well-known Cohesive Crack Model in tension and an elastic-perfectly plastic stress versus crack opening displacement relationship describing the steel reinforcement behavior are also integrated into the numerical algorithm. The application of the proposed Cohesive-Overlapping Crack Model to the assessment of the minimum reinforcement amount neces- sary to prevent unstable tensile crack propagation and to the evaluation of the rotational capacity of plastic hinges, permits to predict the size-scale effects evidenced by several experimental programs available in the literature. According to the obtained numerical results, new practical design formulae and diagrams are proposed for the improvement of the current code provisions which usually disregard the size effects.

Nonlinear earthquake analysis of reinforced concrete frames with fiber and Bernoulli-Euler beam-column element.

Science.gov (United States)

Karaton, Muhammet

2014-01-01

A beam-column element based on the Euler-Bernoulli beam theory is researched for nonlinear dynamic analysis of reinforced concrete (RC) structural element. Stiffness matrix of this element is obtained by using rigidity method. A solution technique that included nonlinear dynamic substructure procedure is developed for dynamic analyses of RC frames. A predicted-corrected form of the Bossak-α method is applied for dynamic integration scheme. A comparison of experimental data of a RC column element with numerical results, obtained from proposed solution technique, is studied for verification the numerical solutions. Furthermore, nonlinear cyclic analysis results of a portal reinforced concrete frame are achieved for comparing the proposed solution technique with Fibre element, based on flexibility method. However, seismic damage analyses of an 8-story RC frame structure with soft-story are investigated for cases of lumped/distributed mass and load. Damage region, propagation, and intensities according to both approaches are researched.

An experimental investigation on bending stiffness and neutral axis depth variation of over-reinforced high strength concrete beams

International Nuclear Information System (INIS)

Mohammadhassani, Mohammad; Bin Jumaat, Mohd Zamin; Chemrouk, Mohamed; Akbar Maghsoudi, Ali; Jameel, Mohammed; Akib, Shatirah

2011-01-01

Highlights: → Improvement of the assessment of correspond stress for calculation of modules of elasticity → better evaluation of cracked moment of inertia. → Low distinction of neutral axis depth → low bending stiffness variation. → Rate of slope in the line connecting the origin of first crack to yield point of N.A.D-LOAD graph → rate of ductility of beam section. - Abstract: The present work is an attempt to study the neutral axis variation and the evolution of the moment inertia with the loading of over reinforced high strength concrete sections in conjunction with ACI 318-05. In this sense, four high strength concrete beams, having different tension reinforcement quantities expressed as proportions of the balanced steel ratio (0.75ρ b , 0.85ρ b , ρ b , 1.2ρ b ) were tested. Measurements of the deflection and the reinforcement and concrete strains of all specimens were made during the loading process. The load-neutral axis depth variation and the load-section stiffness curves were drawn. The slope of the line connecting the origin of the first crack to the initial yielding of the failure point in the neutral axis depth-load graphs shows the rate of ductility; ductile behaviour in the beam increases as the slope becomes steeper. Based on the results of this study, it is recommended that the modulus of elasticity of concrete E c be reviewed and evaluated at a stress higher than 0.5f ' c for the determination of the cracked moment of inertia.

Coupling creep and damage in concrete under high sustained loading: Experimental investigation on bending beams and application of Acoustic Emission technique

Directory of Open Access Journals (Sweden)

Grondin F.

2010-06-01

Full Text Available Creep and damage in concrete govern the long-term deformability of concrete. Thus, it is important to understand the interaction between creep and damage in order to design reliable civil engineering structures subjected to high level loading during a long time. Many investigations have been performed on the influence of concrete mixture, the effect of the bond between the matrix and the aggregates, temperature, aging and the size effect on the cracking mechanism and fracture parameters of concrete. But there is a lack of results on the influence of the creep loading history. In the present paper, an experimental investigation on the fracture properties of concrete beams submitted to three point bending tests with high levels of sustained load that deals with creep is reported. The results aim first to investigate the ranges of variation of the time response due to creep damage coupled effects under constant load and secondly to evaluate the residual capacity after creep. For this purpose a series of tests were carried out on geometrically similar specimens of size 100x200x800mm with notch to depth ratio of 0.2 in all the test specimens. The exchange of moisture was prevented and beams were subjected to a constant load of 70% and 90% of the maximum capacity. Three point bending test were realized on specimen at the age of 28 days to determine the characteristics of concrete and the maximum load so we could load the specimens in creep. Threepoint bend creep tests were performed on frames placed in a climate controlled chamber [1]. Then after four months of loading, the beams subjected to creep were removed from the creep frames and then immediately subjected to three-point bending test loading up to failure with a constant loading rate as per RILEM-FMC 50 recommendations. The residual capacity on the notched beams and the evolution of the characteristics of concrete due to the basic creep was considered. The results show that sustained loading

Coupling creep and damage in concrete under high sustained loading: Experimental investigation on bending beams and application of Acoustic Emission technique

Science.gov (United States)

Saliba, J.; Loukili, A.; Grondin, F.

2010-06-01

Creep and damage in concrete govern the long-term deformability of concrete. Thus, it is important to understand the interaction between creep and damage in order to design reliable civil engineering structures subjected to high level loading during a long time. Many investigations have been performed on the influence of concrete mixture, the effect of the bond between the matrix and the aggregates, temperature, aging and the size effect on the cracking mechanism and fracture parameters of concrete. But there is a lack of results on the influence of the creep loading history. In the present paper, an experimental investigation on the fracture properties of concrete beams submitted to three point bending tests with high levels of sustained load that deals with creep is reported. The results aim first to investigate the ranges of variation of the time response due to creep damage coupled effects under constant load and secondly to evaluate the residual capacity after creep. For this purpose a series of tests were carried out on geometrically similar specimens of size 100x200x800mm with notch to depth ratio of 0.2 in all the test specimens. The exchange of moisture was prevented and beams were subjected to a constant load of 70% and 90% of the maximum capacity. Three point bending test were realized on specimen at the age of 28 days to determine the characteristics of concrete and the maximum load so we could load the specimens in creep. Threepoint bend creep tests were performed on frames placed in a climate controlled chamber [1]. Then after four months of loading, the beams subjected to creep were removed from the creep frames and then immediately subjected to three-point bending test loading up to failure with a constant loading rate as per RILEM-FMC 50 recommendations. The residual capacity on the notched beams and the evolution of the characteristics of concrete due to the basic creep was considered. The results show that sustained loading had a strengthening

A new solution of measuring thermal response of prestressed concrete bridge girders for structural health monitoring

International Nuclear Information System (INIS)

Jiao, Pengcheng; Borchani, Wassim; Hasni, Hassene; Lajnef, Nizar

2017-01-01

This study develops a novel buckling-based mechanism to measure the thermal response of prestressed concrete bridge girders under continuous temperature changes for structural health monitoring. The measuring device consists of a bilaterally constrained beam and a piezoelectric polyvinylidene fluoride transducer that is attached to the beam. Under thermally induced displacement, the slender beam is buckled. The post-buckling events are deployed to convert the low-rate and low-frequency excitations into localized high-rate motions and, therefore, the attached piezoelectric transducer is triggered to generate electrical signals. Attaching the measuring device to concrete bridge girders, the electrical signals are used to detect the thermal response of concrete bridges. Finite element simulations are conducted to obtain the displacement of prestressed concrete girders under thermal loads. Using the thermal-induced displacement as input, experiments are carried out on a 3D printed measuring device to investigate the buckling response and corresponding electrical signals. A theoretical model is developed based on the nonlinear Euler–Bernoulli beam theory and large deformation assumptions to predict the buckling mode transitions of the beam. Based on the presented theoretical model, the geometry properties of the measuring device can be designed such that its buckling response is effectively controlled. Consequently, the thermally induced displacement can be designed as limit states to detect excessive thermal loads on concrete bridge girders. The proposed solution sufficiently measures the thermal response of concrete bridges. (paper)

A new solution of measuring thermal response of prestressed concrete bridge girders for structural health monitoring

Science.gov (United States)

Jiao, Pengcheng; Borchani, Wassim; Hasni, Hassene; Lajnef, Nizar

2017-08-01

This study develops a novel buckling-based mechanism to measure the thermal response of prestressed concrete bridge girders under continuous temperature changes for structural health monitoring. The measuring device consists of a bilaterally constrained beam and a piezoelectric polyvinylidene fluoride transducer that is attached to the beam. Under thermally induced displacement, the slender beam is buckled. The post-buckling events are deployed to convert the low-rate and low-frequency excitations into localized high-rate motions and, therefore, the attached piezoelectric transducer is triggered to generate electrical signals. Attaching the measuring device to concrete bridge girders, the electrical signals are used to detect the thermal response of concrete bridges. Finite element simulations are conducted to obtain the displacement of prestressed concrete girders under thermal loads. Using the thermal-induced displacement as input, experiments are carried out on a 3D printed measuring device to investigate the buckling response and corresponding electrical signals. A theoretical model is developed based on the nonlinear Euler-Bernoulli beam theory and large deformation assumptions to predict the buckling mode transitions of the beam. Based on the presented theoretical model, the geometry properties of the measuring device can be designed such that its buckling response is effectively controlled. Consequently, the thermally induced displacement can be designed as limit states to detect excessive thermal loads on concrete bridge girders. The proposed solution sufficiently measures the thermal response of concrete bridges.

A Modified Model for Deflection Calculation of Reinforced Concrete Beam with Deformed GFRP Rebar

Directory of Open Access Journals (Sweden)

Minkwan Ju

2016-01-01

Full Text Available The authors carried out experimental and analytical research to evaluate the flexural capacity and the moment-deflection relationship of concrete beams reinforced with GFRP bars. The proposed model to predict the effective moment of inertia for R/C beam with GFRP bars was developed empirically, based on Branson’s equation to have better accuracy and a familiar approach to a structural engineer. For better prediction of the moment-deflection relationship until the ultimate strength is reached, a nonlinear parameter (k was also considered. This parameter was introduced to reduce the effect of the cracked moment of inertia for the reinforced concrete member, including a lower reinforcement ratio and modulus of elasticity of the GFRP bar. In a comparative study using six equations suggested by others, the proposed model showed better agreement with the experimental test results. It was confirmed that the empirical modification based on Branson’s equation was valid for predicting the effective moment of inertia of R/C beams with GFRP bar in this study. To evaluate the generality of the proposed model, a comparative study using previous test results from the literature and the results from this study was carried out. It was found that the proposed model had better accuracy and was a familiar approach to structural engineers to predict and evaluate the deflection behavior.

Design and experimental study on columns and beams connection in the precast prestressed concrete structure. Precast PC acchaku setsugo ni kansuru sekkeiho to jikkenteki kenkyu

Energy Technology Data Exchange (ETDEWEB)

Tanabe, K. (Kurosawa Construction Co. Ltd., Tokyo (Japan))

1993-07-30

Design engineering and experimental study were made of precast PC clad connection. The clad connection method between the columns and beams is classified into bracket method, shearing key method, corbel method and reinforcing structure-jointing method, among which the corbel method is recommendable because of its simplicity without slip. The PC clad connection system is characterized by its possibility of structuring the continuous multi-rahmen structure, designing the highest strength concrete and easing the earthquake-proof design with a high toughness restoring force. The PC cable wiring method is classified into X-cross method and continuous method. The design of PC clad connection was experimentally proved by alternately loading the frame. Through the experiment, the interstory deformation angle, and stress behavior of the column and beam PC steel materials were made clear so that their destruction became able to be prevented. Also through the experiment, the interstory deformation angle and maximum column-shearing force were known at the yield point of beam, which had the frame-restoring force characteristics modeled by a trilinear elastoplastic type. 28 refs., 13 figs.

Nonlinear analysis of the progressive collapse of reinforced concrete plane frames using a multilayered beam formulation

Directory of Open Access Journals (Sweden)

C. E. M. Oliveira

Full Text Available This work investigates the response of two reinforced concrete (RC plane frames after the loss of a column and their potential resistance for progressive collapse. Nonlinear dynamic analysis is performed using a multilayered Euler/Bernoulli beam element, including elasto-viscoplastic effects. The material nonlinearity is represented using one-dimensional constitutive laws in the material layers, while geometrical nonlinearities are incorporated within a corotational beam formulation. The frames were designed in accordance with the minimum requirements proposed by the reinforced concrete design/building codes of Europe (fib [1-2], Eurocode 2 [3] and Brazil (NBR 6118 [4]. The load combinations considered for PC analysis follow the prescriptions of DoD [5]. The work verifies if the minimum requirements of the considered codes are sufficient for enforcing structural safety and robustness, and also points out the major differences in terms of progressive collapse potential of the corresponding designed structures.

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

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)

Continuing the service of safety-related concrete structures in nuclear power plants

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.; 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 (NPPs) for the purpose of providing improved technical bases for their continued service. The program consists of three technical tasks: materials property data base, structural component assessment/repair technologies, and quantitative methodologies for continued service determinations. Recent accomplishments under each of these tasks are summarized

Sub-Pixel Accuracy Crack Width Determination on Concrete Beams in Load Tests by Triangle Mesh Geometry Analysis

Science.gov (United States)

Liebold, F.; Maas, H.-G.

2018-05-01

This paper deals with the determination of crack widths of concrete beams during load tests from monocular image sequences. The procedure starts in a reference image of the probe with suitable surface texture under zero load, where a large number of points is defined by an interest operator. Then a triangulated irregular network is established to connect the points. Image sequences are recorded during load tests with the load increasing continuously or stepwise, or at intermittently changing load. The vertices of the triangles are tracked through the consecutive images of the sequence with sub-pixel accuracy by least squares matching. All triangles are then analyzed for changes by principal strain calculation. For each triangle showing significant strain, a crack width is computed by a thorough geometric analysis of the relative movement of the vertices.

AA, entrance of proton beam to antiproton production target

CERN Multimedia

CERN PhotoLab

1980-01-01

Please look up 8010295 first. The intense proton beam from the 26 GeV PS arrives from the right, through the vacuum chamber. The big flange contains a thin window, after which the proton beam continues through free air. A beam transformer, affixed to the shielding block, measures its intensity, before it enters the hole in the concrete to hit the target behind it.

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)

Overview of Activities in U.S. Related to Continued Service of Nuclear Power Plant Concrete Structures

International Nuclear Information System (INIS)

Naus, Dan J.

2011-01-01

Safety-related nuclear power plant concrete structures are described and commentary on continued service assessments of these structures is provided. 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 noted. A summary of operating experience related to U.S. nuclear power plant concrete structures is presented. Several candidate areas are identified where additional research would be of benefit to aging management of NPP concrete structures. Finally current ORNL activities related to aging-management of concrete structures are outlined: development of operating experience database, application of structural reliability theory, and compilation of elevated temperature concrete material property data and information.

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

Experimental study on beam for composite CES structural system

Science.gov (United States)

Matsui, Tomoya

2017-10-01

Development study on Concrete Encase Steel (CES) composite structure system has been continuously conducted toward the practical use. CES structure is composed of steel and fiber reinforced concrete. In previous study, it was found that CES structure has good seismic performance from experimental study of columns, beam - column joints, shear walls and a two story two span frame. However, as fundamental study on CES beam could be lacking, it is necessary to understand the structural performance of CES beam. In this study, static loading tests of CES beams were conducted with experimental valuable of steel size, the presence or absence of slab and thickness of slab. And restoring characteristics, failure behavior, deformation behavior, and strength evaluation method of CES beam were investigated. As the results, it was found that CES beam showed stable hysteresis behavior. Furthermore it was found that the flexural strength of the CES beam could be evaluated by superposition strength theory.

Full Scale Reinforced Concrete Beam-Column Joints Strengthened with Steel Reinforced Polymer Systems

Directory of Open Access Journals (Sweden)

Alessandro De Vita

2017-07-01

Full Text Available This paper presents the results of an experimental campaign performed at the Laboratory of Materials and Structural Testing of the University of Salerno (Italy in order to investigate the seismic performance of reinforced concrete (RC beam-column joints strengthened with steel reinforced polymer (SRP systems. With the aim to represent typical façade frames’ beam-column subassemblies found in existing RC buildings, specimens were provided with two short beam stubs orthogonal to the main beam and were designed with inadequate seismic details. Five members were strengthened by using two different SRP layouts while the remaining ones were used as benchmarks. Once damaged, two specimens were also repaired, retrofitted with SRP, and subjected to cyclic test again. The results of cyclic tests performed on SRP strengthened joints are examined through a comparison with the outcomes of the previous experimental program including companion specimens not provided with transverse beam stubs and strengthened by carbon fiber-reinforced polymer (CFRP systems. In particular, both qualitative and quantitative considerations about the influence of the confining effect provided by the secondary beams on the joint response, the suitability of all the adopted strengthening solutions (SRP/CFRP systems, the performances and the failure modes experienced in the several cases studied are provided.

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

CERN Document Server

Johnson, R P

2008-01-01

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

Rapid Strengthening of Full-Sized Concrete Beams with Powder-Actuated fastening Systems and Fiber-Reinforced Polymer (FRP) Composite Materials

National Research Council Canada - National Science Library

Bank, Lawrence

2002-01-01

A research study was conducted to determine if the method of retrofitting reinforced concrete beams with powder-actuated fasteners and composite materials was applicable to full-scale flexural members...

Vigas de concreto reforçadas com bambu Dendrocalamus giganteus. I: análise experimental Concrete beams reinforced with bamboo (Dendrocalamus giganteus. I: experimental analysis

Directory of Open Access Journals (Sweden)

Humberto C. Lima Júnior

2005-12-01

Full Text Available Neste trabalho, apresenta-se e se discute um estudo experimental sobre o comportamento estrutural de vigas de concreto reforçadas com bambu. Ensaiaram-se dez vigas de concreto armado, sendo oito vigas armadas longitudinalmente com varas de bambu Dendrocalamus giganteus e duas vigas de referência, armadas com barras de aço. Duas variáveis foram estudadas: a taxa de armadura longitudinal (1,6 e 3,2% e a relação área/perímetro das varas de bambu (0,25 e 0,33 cm. Para cada combinação de variáveis foram confeccionadas duas vigas. Curvas força vs. deslocamento e força vs. deformação dos materiais são apresentadas e discutidas. Constatou-se que o comportamento estrutural das vigas de concreto reforçadas com bambu segue a teoria de flexão de Bernoulli-Kirchoff, sendo possível a aplicação dos procedimentos usuais de dimensionamento do concreto armado no projeto desses elementos. Observou-se, também, que a capacidade de carga dessas vigas se assemelha à das vigas de aço; contudo, estas são mais rígidas que aquelas.In this paper, an experimental study about bamboo reinforced concrete beams is presented and discussed. Ten reinforced concrete beams were tested, where eight of them were reinforced with Dendrocalamus giganteus bamboo-splint and two reference beams were reinforced with steel bars. Two factors were studied: the longitudinal reinforcement ratio (1.6 and 3.2% and the area/perimeter ratio of the bamboo-splint (0.25 and 0.33 cm. For each factor combination, two beams were cast. Force vs. displacement and force vs. strain curves are presented and discussed. It was found out that the structural behaviour of bamboo-concrete beams follow the Bernoulli-Kirchoff bending theory. Therefore, the usual design procedures of reinforced concrete can be used to design the bamboo-concrete beams. The load capacity of the bamboo-concrete beams is almost the same as that of reinforced with steel; nevertheless, are more stiffer than those

Flexural strength using Steel Plate, Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) on reinforced concrete beam in building technology

Science.gov (United States)

Tarigan, Johannes; Patra, Fadel Muhammad; Sitorus, Torang

2018-03-01

Reinforced concrete structures are very commonly used in buildings because they are cheaper than the steel structures. But in reality, many concrete structures are damaged, so there are several ways to overcome this problem, by providing reinforcement with Fiber Reinforced Polymer (FRP) and reinforcement with steel plates. Each type of reinforcements has its advantages and disadvantages. In this study, researchers discuss the comparison between flexural strength of reinforced concrete beam using steel plates and Fiber Reinforced Polymer (FRP). In this case, the researchers use Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) as external reinforcements. The dimension of the beams is 15 x 25 cm with the length of 320 cm. Based on the analytical results, the strength of the beam with CFRP is 1.991 times its initial, GFRP is 1.877 times while with the steel plate is 1.646 times. Based on test results, the strength of the beam with CFRP is 1.444 times its initial, GFRP is 1.333 times while the steel plate is 1.167 times. Based on these test results, the authors conclude that beam with CFRP is the best choice for external reinforcement in building technology than the others.

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

Modulation of continuous electron beams in plasma wake-fields

International Nuclear Information System (INIS)

Rosenzweig, J.B.

1988-01-01

In this paper we discuss the interaction of a continuous electron beam with wake-field generated plasma waves. Using a one-dimensional two fluid model, a fully nonlinear analytical description of the interaction is obtained. The phenomena of continuous beam modulation and wave period shortening are discussed. The relationship between these effects and the two-stream instability is also examined. 12 refs., 1 fig

Evaluation of Strength Characteristics of Laterized Concrete with Corn Cob Ash (CCA) Blended Cement

Science.gov (United States)

Ikponmwosa, E. E.; Salau, M. A.; Kaigama, W. B.

2015-11-01

Agricultural wastes are dumped in landfills or left on land in which they constitute nuisance. This study presents the results of investigation of strength characteristics of reinforced laterized concrete beams with cement partially replaced with corn cob (agricultural wastes) ash (CCA). Laterized concrete specimen of 25% laterite and 75% sharp sand were made by blending cement with corn cob ash at 0 to 40% in steps of 10%. A concrete mix ratio of 1:2:4 was used to cast 54 cubes of 150×150×150mm size and 54 beams of dimension 750×150×150mm. The results show that the consistency and setting time of cement increased as the percentage replacement of cement with CCA increased while the workability and density of concrete decreased as the percentage of CCA increased. There was a decrease in compressive strength when laterite was introduced to the concrete from 25.04 to 22.96N/mm2 after 28 days and a continual reduction in strength when CCA was further added from 10% to 40% at steps of 10%. Generally, the beam specimens exhibited majorly shear failure with visible diagonal cracks extending from support points to the load points. The corresponding central deflection in beams, due to two points loading, increased as the laterite was added to the concrete mix but reduced and almost approaching that of the control as 10% CCA was added. The deflection then increased as the CCA content further increased to 20%, 30% and 40% in the mix. It was also noted that the deflection of all percentage replacement including 40% CCA is less than the standard recommended maximum deflection of the beam. The optimal flexural strength occurred with 10% CCA content.

Behavior of reinforcement SCC beams under elevated temperatures

Science.gov (United States)

Fathi, Hamoon; Farhang, Kianoosh

2015-09-01

This experimental study focuses on the behavior of heated reinforced concrete beams. Four types of concrete mixtures were used for the tested self-compacting concrete beams. A total of 72 reinforced concrete beams and 72 standard cylindrical specimens were tested. The compressive strength under uniaxial loading at 23 °C ranged from 30 to 45 MPa. The specimens were exposed to different temperatures. The test parameters of interest were the compressive strength and the temperature of the specimens. The effect of changes in the parameters was examined so as to control the behavior of the tested concrete and that of the reinforced concrete beam. The results indicated that flexibility and compressive strength of the reinforced concrete beams decreased at higher temperatures. Furthermore, heating beyond 400 °C produced greater variations in the structural behavior of the materials in both the cylindrical samples and the reinforced concrete beams.

Experimental continuously reinforced concrete pavement parameterization using nondestructive methods

Directory of Open Access Journals (Sweden)

L. S. Salles

Full Text Available ABSTRACT Four continuously reinforced concrete pavement (CRCP sections were built at the University of São Paulo campus in order to analyze the pavement performance in a tropical environment. The sections short length coupled with particular project aspects made the experimental CRCP cracking be different from the traditional CRCP one. After three years of construction, a series of nondestructive testing were performed - Falling Weight Deflectometer (FWD loadings - to verify and to parameterize the pavement structural condition based on two main properties: the elasticity modulus of concrete (E and the modulus of subgrade reaction (k. These properties estimation was obtained through the matching process between real and EverFE simulated basins with the load at the slab center, between two consecutive cracks. The backcalculation results show that the lack of anchorage at the sections end decreases the E and k values and that the longitudinal reinforcement percentage provides additional stiffness to the pavement. Additionally, FWD loadings tangential to the cracks allowed the load transfer efficiency (LTE estimation determination across cracks. The LTE resulted in values above 90 % for all cracks.

CEBAF [Continuous Electron Beam Accelerator Facility] design report

International Nuclear Information System (INIS)

1986-05-01

This book describes the conceptual design of, and the planning for, the Continuous Electron Beam Accelerator Facility (CEBAF), which will be a high-intensity, continuous-wave electron linear accelerator (linac) for nuclear physics. Its principal scientific goal is to understand the quark structure, behavior, and clustering of individual nucleons in the nuclear medium, and simultaneously to understand the forces governing this behavior. The linac will consist of 1 GeV of accelerating structure, split into two antiparallel 0.5-GeV segments. The segments will be connected by a beam transport system to circulate the electron beams from one segment to the other for up to four complete passes of acceleration. The maximum beam energy will be 4 GeV at a design current of 200 microamperes. The accelerator complex will also include systems to extract three continuous beams from the linac and to deliver them to three experimental halls equipped with detectors and instrumentation for nuclear physics research. The accelerating structure will be kept superconducting within insulated cryostats filled with liquid helium produced at a central helium refrigerator and distributed to the cryostats via insulated transfer lines. An injector, instrumentation and controls for the accelerator, radio-frequency power systems, and several support facilities will also be provided. A cost estimate based on the Work Breakdown Structure has been completed. Assuming a five-year construction schedule starting early in FY 1987, the total estimated cost is $236 million (actual year dollars), including contingency

Analysis of Flexural Fatigue Strength of Self Compacting Fibre Reinforced Concrete Beams

Science.gov (United States)

Murali, G.; Sudar Celestina, J. P. Arul; Subhashini, N.; Vigneshwari, M.

2017-07-01

This study presents the extensive statistical investigation ofvariations in flexural fatigue life of self-compacting Fibrous Concrete (FC) beams. For this purpose, the experimental data of earlier researchers were examined by two parameter Weibull distribution.Two methods namely Graphical and moment wereused to analyse the variations in experimental data and the results have been presented in the form of probability of survival. The Weibull parameters values obtained from graphical and method of moments are precise. At 0.7 stress level, the fatigue life shows 59861 cyclesfor areliability of 90%.

Optimisation of the Crack Pattern in Continuously Reinforced Concrete Pavements

OpenAIRE

Ren, D.

2015-01-01

Recent field investigations on several new Continuously Reinforced Concrete Pavements (CRCP) in Belgium indicate that its crack pattern is characterized by low mean crack spacing along with a high percentage of clusters of closely spaced cracks. Field surveys also indicate that it is difficult to significantly reduce the probability of a non-uniform crack pattern - such as closely spaced cracks, meandering, and Y-cracks - by only slightly adjusting the amount of longitudinal steel. Non-unifor...

APPLICATION OF FINITE ELEMENT METHOD TAKING INTO ACCOUNT PHYSICAL AND GEOMETRIC NONLINEARITY FOR THE CALCULATION OF PRESTRESSED REINFORCED CONCRETE BEAMS

Directory of Open Access Journals (Sweden)

Vladimir P. Agapov

2017-01-01

Full Text Available Abstract. Objectives Modern building codes prescribe the calculation of building structures taking into account the nonlinearity of deformation. To achieve this goal, the task is to develop a methodology for calculating prestressed reinforced concrete beams, taking into account physical and geometric nonlinearity. Methods The methodology is based on nonlinear calculation algorithms implemented and tested in the computation complex PRINS (a program for calculating engineering constructions for other types of construction. As a tool for solving this problem, the finite element method is used. Non-linear calculation of constructions is carried out by the PRINS computational complex using the stepwise iterative method. In this case, an equation is constructed and solved at the loading step, using modified Lagrangian coordinates. Results The basic formulas necessary for both the formation and the solution of a system of nonlinear algebraic equations by the stepwise iteration method are given, taking into account the loading, unloading and possible additional loading. A method for simulating prestressing is described by setting the temperature action on the reinforcement and stressing steel rod. Different approaches to accounting for physical and geometric nonlinearity of reinforced concrete beam rods are considered. A calculation example of a flat beam is given, in which the behaviour of the beam is analysed at various stages of its loading up to destruction. Conclusion A program is developed for the calculation of flat and spatially reinforced concrete beams taking into account the nonlinearity of deformation. The program is adapted to the computational complex PRINS and as part of this complex is available to a wide range of engineering, scientific and technical specialists. 

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...

Ultrasonic imaging in concrete

International Nuclear Information System (INIS)

Ribay, G.; Paris, O.; Rambach, J.M.

2009-01-01

The third and final protection barrier confining nuclear reactors is usually a concrete containment structure. Monitoring the structural integrity of these barriers is critical in ensuring the safety of nuclear power plants. The Institute for Radiological Protection and Nuclear Safety (IRSN) in France in collaboration with the French Atomic commission (CEA/LIST) has developed an ultrasonic phased-array technique capable of inspecting thick concrete walls. The non-destructive method is dedicated to detect cracks and bulk defects. Given the thickness of the structure (1.2 m) undergoing inspection and the heterogeneity of the concrete, the optimal frequency lies in the 50-300 kHz range. At these frequencies, the ultrasonic beam profiles are widespread (non-directive) with poor signal-to-noise ratio. Previous studies have shown the potential of using phased-array techniques (i.e., beam focusing and beam steering) in order to improve detection resolution and sizing accuracy. In this paper we present experimental studies performed with array up to 16 transducers working at 200 kHz. Experiments are carried out on representative concrete blocks containing artificial defects. One is a reinforced mock-up representative of the first reinforcing mesh of wall containment. Experimental results show that in spite of the reinforcement, artificial defects deep as half a meter can be detected. Reconstructed images resulting from phased array acquisitions on an artificial crack embedded in a concrete block are also presented and discussed. The presented method allows detecting oriented defects in concrete with improved signal to noise ratio and sensibility. A simulation model of the interaction of ultrasound with a heterogeneous medium like concrete is briefly commented. (authors)

Analytical Model for Fictitious Crack Propagation in Reinforced Concrete Beams without Debonding

DEFF Research Database (Denmark)

Ulfkjær, J. P.; Brincker, Rune

1994-01-01

, the crack growth is further simplified by introducing a continuous layer of springs at the midsection mainly representing a simplified material response around the fracture zone. In the reinforcement the strain condition is assumed to be equal to the strain condition in the concrete. the important question...

Fatigue testing of wood-concrete composite beams.

Science.gov (United States)

2013-05-01

Currently, wood-concrete composite structural members are usually applied in building structures. There are a relatively small number (in the low 100s) of known bridge applications involving wood-concrete composites. A problem with using these novel ...

Seismic behavior of two exterior beam-column connections made of normal-strength concrete developed for precast construction

NARCIS (Netherlands)

Yuksel, Ercan; Karadogan, H. Faruk; Bal, Ihsan Engin; Ilki, Alper; Bal, Ahmet; Inci, Pinar

2015-01-01

The lack of in-depth understanding of the seismic behavior and ductility of precast concrete structures makes it difficult to reach to ductility demand which could be exhibited during an earthquake. The limitations are mainly related to the beam-to-column connections as the main load transfer paths.

Continuing the service of aging concrete structures in nuclear power plants

International Nuclear Information System (INIS)

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

1993-01-01

Concrete structures play a vital role in the safe operation of all light-water reactor plants because they provide foundation, support, shielding and containment functions. History tells us that concrete is a durable material. However, a number of factors can compromise its performance, singly or in combination: (1) faulty design, (2) use of unsuitable materials, (3) improper workmanship, (4) exposure to aggressive environments, and (5) excessive structural loads. Furthermore, aging of nuclear power plant (NPP) concrete structures occurs with the passage of time and has the potential, if its effects are not controlled, to increase the risk to public health and safety. Although limited, incidences of degradation of concrete structures in NPPs indicate that there is a need for improved surveillance, inspection/testing, and maintenance to enhance the technical bases for assurance of continued safe operation of NPPs. Guidelines and criteria for use in evaluating the remaining structural margins (residual life) are required. Potential regulatory applications of this research include: improved predictions of long-term material and structural performance and available safety margins at future times; establishment of limits on exposure to environmental stressors; reduction in total reliance by licensing on inspection and surveillance through development of a methodology which will enable the integrity of structures to be assessed (either pre- or post-accident); and improvements in damage inspection methodology through potential incorporation of results into national standards which could be referenced by standard review plans

Effective Moment Of Inertia And Deflections Of Reinforced Concrete Beams Under Long-Term Loading

OpenAIRE

Mahmood, Khalid M.; Ashour, Samir A.; Al-Noury, Soliman I.

1995-01-01

The paper presents a method for estimating long-term deflections of reinforced concrete beams by considering creep and shrinkage effects separately. Based on equilibrium and compatibility conditions a method is developed for investigating the properties of a cracked transformed section under sustained load. The concept of effective moment of inertia is extended to predict initial-plus-creep deflections. Long-term deflections computed by the proposed method are compared with the experimental r...

The continuous electron beam accelerator facility

International Nuclear Information System (INIS)

Grunder, H.A.

1989-01-01

Tunnel construction and accelerator component development, assembly, and testing are under way at the Continuous Electron Beam Accelerator Facility. CEBAF's 4-GeV, 200-μA superconducting recirculating accelerator will provide cw beam to simultaneous experiments in three end stations for studies of the nuclear many-body system, its quark substructure, and the strong and electroweak interactions governing this form of matter. Prototype accelerating cavities, assembled in cryostats and tested on site, continue to exceed performance specifications. An on-site liquid helium capability supports cryostat development and cavity testing. Major elements of the accelerator instrumentation and control hardware and software are in use in cryogenics, rf, and injector tests. Prototype rf systems have been operated and prototype klystrons have been ordered. The initial, 100-keV, room-temperature region of the 45-MeV injector is operational and meets specifications. CEBAF's end stations have been conceptually designed; experimental equipment conceptual designs will be completed in 1989. 2 refs., 5 figs., 2 tabs

Biological shielding design and qualification of concreting process for construction of electron beam irradiation facility

International Nuclear Information System (INIS)

Petwal, V.C.; Kumar, P.; Suresh, N.; Parchani, G.; Dwivedi, J.; Thakurta, A.C.

2011-01-01

A technology demonstration facility for irradiation of food and agricultural products is being set-up by RRCAT at Indore. The facility design is based on linear electron accelerator with maximum beam power of 10 kW and can be operated either in electron mode at 10 MeV or photon modes at 5/7.5 MeV. Biological shielding has been designed in accordance with NCRP 51 to achieve dose rate at all accessible points outside the irradiation vault less than the permissible limit of 0.1 mR/hr. In addition to radiation attenuation property, concrete must have satisfactory mechanical properties to meet the structural requirements. There are number of site specific variables which affect the structural, thermal and radiological properties of concrete, leading to considerable difference in actual values and design values. Hence it is essential to establish a suitable site and environmental specific process to cast the concrete and qualify the process by experimental measurement. For process qualification we have cast concrete test blocks of different thicknesses up to 3.25 m and evaluated the radiological and mechanical properties by radiometry, ultrasonic and mechanical tests. In this paper we describe the biological shielding design of the facility and analyse the results of tests carried out for qualification of the process. (author)

Intermediate Crack Induced Debonding in Concrete Beams Strengthened with CFRP Plates - An Experimental Study

DEFF Research Database (Denmark)

Rusinowski, Piotr Michal; Täljsten, Björn

2009-01-01

, ductility and even durability. Design of structural strengthening applications using externally bonded FRP composites is usually based on conventional design approaches with improvement to account for the presence and characteristics of the FRP material. Non-conventional design issues that are specific...... of the strengthening method. End-peeling has governed a large interest and several debonding models have been presented. However, interfacial peeling at flexural cracks has not attained the same focus – even though this debonding failure is most likely more common. This paper presents laboratory tests of concrete...... beams strengthened in flexure with CFRP epoxy bonded plates. Wrapping with CFRP sheets was applied in order to try to localize the failure initiation. Concrete cracking as well as debonding initiation and propagation was possible to observe with help of advanced optical measuring system and high speed...

Assessment of permeation quality of concrete through mercury intrusion porosimetry

International Nuclear Information System (INIS)

Kumar, Rakesh; Bhattacharjee, B.

2004-01-01

Permeation quality of laboratory cast concrete beams was determined through initial surface absorption test (ISAT). The pore system characteristics of the same concrete beam specimens were determined through mercury intrusion porosimetry (MIP). Data so obtained on the measured initial surface absorption rate of water by concrete and characteristics of pore system of concrete estimated from porosimetry results were used to develop correlations between them. Through these correlations, potential of MIP in assessing the durability quality of concrete in actual structure is demonstrated

Mechanical Properties and Durability of "Waterless Concrete"

Science.gov (United States)

Toutanji, Houssam; Grugel, Richard N.

2008-01-01

Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and by oxidation soil iron and sulfur can be produced. Iron can be used to reinforce the sulfur concrete. Sulfur concrete specimens were cycled between liquid nitrogen (approximately 191 C) and room temperature (approximately 21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (approximately 21 C) and approximately 101 C. Test results showed that due to temperature cycling, compressive strength of cycled specimens was 20% of those non-cycled. Microscopic examination of the fracture surfaces from the cycled samples showed clear de-bonding of the sulfur from the aggregate material whereas it was seen well bonded in those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibers. The glass fibers from lunar regolith simulant was melted in a 25 cc Pt-Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to 1 hour. Glass fibers were cast from the melt into graphite crucibles and were annealed for a couple of hours at 600 C. Glass fibers and small rods were pulled from the melt. 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 glass fibers were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Prisms beams strengthened with glass fibers were tested in 4-point bending test. Beams strengthened with glass fiber showed to

Ductility Analysis of RC Beams Considering the Concrete Confinement Effect Produced by the Shear Reinforcement: a Numerical Approach

Directory of Open Access Journals (Sweden)

Caio Gorla Nogueira

Full Text Available Abstract In this paper, a simplified numerical approach to study the influence of the confinement effect provided by transversal reinforcement on the ductility behavior of RC beams in bending is proposed. A unidimensional FEM mechanical model coupled to the Mazars’ damage model to simulate concrete behavior was adopted to assess ductility curvatures at the ultimate limit state. The confinement effect was incorporated to the numerical model through a calibration process of the damage internal parameters, based on the Least Square Method and an analytical law proposed by Kent and Park (1971. Several numerical analyses were carried out considering different designs of RC beams according to a parametric study varying the neutral axis position, concrete compressive strength and the volumetric transversal reinforcement ratio. The obtained results showed the importance of the amount of transversal reinforcement on the ductility behavior, increasing the ductility factor even for the cases with inappropriate neutral axis position.

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.

Design Oriented Model for the Assessment of T-Shaped Beam-Column Joints in Reinforced Concrete Frames

Directory of Open Access Journals (Sweden)

Antonio Bossio

2017-12-01

Full Text Available Beam-column joints represent very important elements of reinforced concrete (RC structures. In fact, beams and columns, at the boundary, generate internal forces acting on concrete core and on reinforcement bars with a very high gradient. To fully understand the seismic performances and the failure modes of T-shaped beam-column joints (external corner-positioned in RC structures, a simplified analytical model of joint behaviour is proposed and theoretical simulations have been performed. The model is based on the solution of a system of equilibrium equations of cracked joint portions designed to evaluate internal stresses at different values of column shear forces. The main aim of the proposed model is to identify the strength hierarchy. Limit values of different internal stresses allow us to detect the occurrence of different failure modes (namely the failure of the cracked joint, the bond failure of passing through bars, and the flexural/shear failures of columns or beams associated with column shear forces; the smaller one represents the capacity of the joint. The present work, focusing on T-shaped joints, could represent a useful tool for designers to quantify the performance of new structures or of existing ones. In fact, such a tool allows us to push an initial undesired failure mode to a more appropriate one to be evaluated. Finally, some experimental results of tests available in literature are reported, analysed, and compared to the predictions of the proposed model (by means of a worked example and of some international codes. The outcomes confirm that failure modes and corresponding joint capacities require an analytical model, like the proposed one, to be accurately predicted.

Final Report: Self Consolidating Concrete Construction for Modular Units

Energy Technology Data Exchange (ETDEWEB)

Gentry, Russell [Georgia Inst. of Technology, Atlanta, GA (United States); Kahn, Lawrence [Georgia Inst. of Technology, Atlanta, GA (United States); Kurtis, Kimberly [Georgia Inst. of Technology, Atlanta, GA (United States); Petrovic, Bojan [Georgia Inst. of Technology, Atlanta, GA (United States); Loreto, Giovanni [Georgia Inst. of Technology, Atlanta, GA (United States); Van Wyk, Jurie [Westinghouse Electric Company, Cranberry Township, PA (United States); Canterero-Leal, Carlos [Westinghouse Electric Company, Cranberry Township, PA (United States)

2016-07-29

This report outlines the development of a self-consolidating concrete (also termed “self-compacting concrete” or SCC) so that concrete placement can be made into steel plate composite (SC) modular structures without the need for continuous concrete placement. As part of the research, SCC mixtures were developed and validated to ensure sufficient shear capacity across cold-joints, while minimizing shrinkage and temperature increase during curing to enhance concrete bonding with the steel plate construction found in modular units. The self-roughening concrete produced as part of this research was assessed in SC structures at three scales: small-scale shear-friction specimens, mid-scale beams tested in in-plane and out-of-plane bending, and a full-scale validation test using an SC module produced by Westinghouse as part of the Plant Vogtle expansion. The experiments show that the self-roughening concrete can produce a cold-joint surface of 0.25 inches (6 mm) without external vibration during concrete placement. The experiments and subsequent analysis show that the shear friction provisions of ACI 318-14, Section 22.9 can be used to assess the shear capacity of the cold-joints in SC modular construction, and that friction coefficient of 1.35 is appropriate for use with these provisions.

Calculation of the residual bearing capacity of reinforced concrete beams by the rigidity (deflection) criterion

OpenAIRE

V.S. Utkin; S.A. Solovyov

2015-01-01

The article proposes the method of calculating the bearing capacity of reinforced concrete beams at the operational stage by the rigidity (deflection) criterion. The methods, which were used in the article, are integral test and probabilistic methods for describing random variables. The author offers a new technique of calculating a deflection limit by a criterion of residual deformations. The article exemplifies the usage of the evidence theory for statistical information processing in the f...

The Hysteretic Behavior of Partially Pre-Stressed Beam-Column Joint Sub-assemblages Made of Reactive Powder Concrete

Directory of Open Access Journals (Sweden)

Siti Aisyah Nurjannah

2016-11-01

Full Text Available Reactive powder concrete (RPC is an alternative to normal concrete (NC allowing for significantly higher strength of partially pre-stressed concrete structures. In the Indonesian national standard SNI 03-2847-2013 (2013 and the American standard ACI 318-14 (2014, the partial pre-stressed ratio (PPR is limited to a maximum of 25.0 percent to ensure that pre-stressed concrete structures remain ductile and capable to dissipate seismic energy sufficiently. The objective of this experimental study was to investigate the hysteretic performance of partially pre-stressed-RPC (PP-RPC for both interior and exterior beam-column joint sub-assemblages. Four specimens with different levels of PPR were tested with a combination of constant axial compression and cyclic lateral loads. The PPR used for the first and the second two specimens were 22.8% and 33.8%, respectively. The strength of the RPC was 101.60 MPa for all specimens. The results showed that increasing the PPR of PP-RPC improves its hysteretic performance. The best performing specimen, with a PPR of 33.8%, had a ductility that was 1.97 times that of the specimen with a PPR of 22.8%.

Evaluation of aged concrete structures for continued service in nuclear power plants

International Nuclear Information System (INIS)

Naus, D.J.; Marchbanks, M.F.; Arndt, E.G.

1988-01-01

Results are summarized of a study on concrete component aging and its significance relative to continued service of nuclear power plants (NPPs) beyond the initial period for which they were granted operating licenses. Progress is presented of a second study being conducted to identify and provide acceptance criteria for structural safety issues which the USNRC staff will need to address when applications are submitted for continued service of NPPs. Major activities under this program include: development of a materials property data base, establishment of structural component assessment and repair procedures, and development of a methodology for determination of structural reliability

Heavy vehicle simulator (HVS) evaluation of load transfer efficiency and continuously reinforced concrete inlays on the N3 near Pietermartizburg

CSIR Research Space (South Africa)

Du Plessis, L

2006-07-01

Full Text Available The paper addresses two different heavy Vehicle Simulator (HVS) studies conducted on concrete: Load transfer through aggregate interlock and the use of dowels and the evaluation of the performance of an in-service continuously reinforced concrete...

CEBAF [Continuous Electron Beam Accelerator Facility] design overview and project status

International Nuclear Information System (INIS)

Leemann, C.

1988-01-01

This paper discusses the design and specifications of the Continuous Electron Beam Accelerator Facility. Beam performance objectives are discussed, as well as the recirculating linac concept, the injector, cavities, cryogenic system, beam transport and optics, rf system and construction progress. 19 refs., 10 figs

Strengthening of Reinforced Concrete Beam in Shear Zone by Compensation the Stirrups with Equivalent External Steel Plates

Directory of Open Access Journals (Sweden)

Khamail Abdul-Mahdi Mosheer

2016-09-01

Full Text Available An experimental study on reinforced concrete beams strengthened with external steel plates instead of shear stirrups has been held in this paper. Eight samples of the same dimensions and properties were used. Two of them were tested up to failure and specified as references beams; one with shear reinforcement and the other without shear reinforcement. Another samples without shear reinforcement were tested until the first shear crack occurs, then the samples strengthened on both sides with external steel plates as equivalent area of removed stirrups. The strengthened beams were divided into three groups according to the thickness of plates (1, 1.5, 2 mm, each group involved two beams; one bonded using epoxy and the other bonded using epoxy with anchored bolts. Finally, the strengthened beams tested when using anchored bolts with epoxy glue to bond plates. Where the increasing in maximum load is higher than that in reference beam with no internal stirrups reach to (75.46 –106.13% and has a good agreement with the control beam with shear reinforcement reach to (76.06 – 89.36% of ultimate load.

Generalization of a global model for reinforced concrete beams under combined axial force and bending moments

International Nuclear Information System (INIS)

Bairrao, R.; Millard, A.; Barbe, B.

1991-01-01

A large set of numerical data was obtained using a program recently developed. From the various results achieved, new analytical expressions for the definition of damage and plasticity criteria are being derived. The importance of taking into account the presence of general bending was highlighted. The extension to 3D bending, of the previous global models for reinforced concrete beams under combined axial force and bending, is under development. (author)

Strength and behavior in shear of reinforced concrete deep beams under dynamic loading conditions

Energy Technology Data Exchange (ETDEWEB)

Adhikary, Satadru Das [School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore); Li, Bing, E-mail: cbli@ntu.edu.sg [School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore); Fujikake, Kazunori [Department of Civil and Environmental Engineering, National Defense Academy, Yokosuka 239 8686 (Japan)

2013-06-15

Highlights: ► Effects of wider range of loading rates on dynamic shear behavior of RC deep beams. ► Experimental investigation of RC deep beam with and without shear reinforcements. ► Verification of experimental results with truss model and FE simulation results. ► Empirical equations are proposed to predict the dynamic increase factor of maximum resistance. -- Abstract: Research on reinforced concrete (RC) deep beams has seen considerable headway over the past three decades; however, information on the dynamic shear strength and behavior of RC deep beams under varying rates of loads remains limited. This paper describes the experimental results of 24 RC deep beams with and without shear reinforcements under varying rates of concentrated loading. Results obtained serve as useful data on shear resistance, failure patterns and strain rates corresponding to varying loading rates. An analytical truss model approach proves its efficacy in predicting the dynamic shear resistance under varying loading rates. Furthermore, three-dimensional nonlinear finite element (FE) model is described and the simulation results are verified with the experimental results. A parametric study is then conducted to investigate the influence of longitudinal reinforcement ratio, transverse reinforcement ratio and shear span to effective depth ratio on shear behavior. Subsequently, two empirical equations were proposed by integrating the various parameters to assess the dynamic increase factor (DIF) of maximum resistance under varying rates of concentrated loading.

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

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....

Effects of Continuous and Pulsating Water Jet on CNT/Concrete Composite

Czech Academy of Sciences Publication Activity Database

Foldyna, Vladimír; Foldyna, Josef; Klichová, Dagmar; Klich, Jiří; Hlaváček, Petr; Bodnárová, L.; Jarolím, T.; Mamulová Kutláková, K.

2017-01-01

Roč. 63, č. 10 (2017), s. 583-589 ISSN 0039-2480 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082; GA ČR GA15-23219S Institutional support: RVO:68145535 Keywords : pulsating and continuous water jet * CNT/concrete composite * material removal Subject RIV: JQ - Machines ; Tools OBOR OECD: Civil engineering Impact factor: 0.914, year: 2016 http://ojs.sv-jme.eu/index.php/sv-jme/ article /view/sv-jme.2017.4357

Evaluation of concrete inlay for continuously reinforced concrete pavement rehabilitation.

Science.gov (United States)

2010-06-01

In 1996, WisDOT constructed a concrete inlay test section on I43 in Manitowoc County. The existing pavement was CRCP constructed in 1978 and was badly deteriorated with punchouts. In the area of the 2777foot test section, the existing paveme...

Prestressed CFRP Fabrics for Flexural Strengthening of Concrete Beams with an Easy Prestressing Technique

Science.gov (United States)

Şakar, G.; Tanarslan, H. M.

2014-09-01

It is proposed to use prestressed CFRP plates for strengthening in order to prevent their debonding and thus to increase their strengthening efficiency. For this purpose, and easy-to-use piece of equipment was created. To determine the effectiveness of this method, an experimental program was carried out, and the effect of prestressed CFRP on the behavior and ultimate strength of reinforced concrete beams was examined in threepoint bending tests. A remarkable increase in their strength with debonding was seen for every specimen to which a prestressed CFRP plate had been applied.

Development of a device for continuous automatic monitoring of consolidation of fresh concrete. Final report

International Nuclear Information System (INIS)

Lee, P.L.; Eggert, G.J.

1978-01-01

Quality of portland cement concrete can be increased if water/cement ratios are reduced; however, this increase is only achieved if concrete is adequately consolidated. This study was conducted to develop a device to permit continuous automatic monitoring of the degree of consolidation during pavement construction. A literature search identified several candidate techniques, the most feasible being a nuclear backscatter technique to measure concrete density. A prototype instrument was developed with a 500mCi source of Cesium (137) and a sodium iodide/photomultiplier sensing unit. The sensor head is located 1 inch (25.4 mm) above the concrete. It is moved back and forth across the width of the pavement by a traversing mechanism mounted to the back of a slip-form paver. Density is recorded on chart paper. The CMD (Consolidation Monitoring Device) is capable of sensing and displaying changes in density while traversing over the pavement surface at 17 fpm (0.086 m/s). It can duplicate core density measurements within a + or -2-1 pcf (+ or -36 kg cu m) confidence range

Measurement of neutron diffusion length in heavy concrete

International Nuclear Information System (INIS)

Krejci, D.

2007-04-01

Using an aluminium sampler filled with heavy concrete the neutron diffusion length was determined, measuring thermal and fast neutrons over the whole beam hole with various threshold detectors using gold samples. These calculations should describe the neutron distribution in the whole concrete shield of the reactor and contribute to the investigation of the activation of the concrete shield using reactor parameters like operating time, power and neutron flux. Instrumentation, activation and positioning of the samples in the beam hole of the TRIGA Mark II reactor are described. (nevyjel)

Computer simulations for intense continuous beam transport in electrostatic lens systems

International Nuclear Information System (INIS)

Zhao Xiaosong; Lv Jianqin

2008-01-01

A code LEADS based on the Lie algebraic analysis for the continuous beam dynamics with space charge effect in beam transport has been developed. The program is used for the simulations of axial-symmetric and unsymmetrical intense continuous beam in the channels including drift spaces, electrostatic lenses and DC electrostatic accelerating tubes. In order to get the accuracy required, all elements are divided into many small segments, and the electric field in the segments is regarded as uniform field, and the dividing points are treated as thin lenses. Iteration procedures are adopted in the program to obtain self-consistent solutions. The code can be used in the designs of low energy beam transport systems, electrostatic accelerators and ion implantation machines. (authors)

Evaluation of aged concrete structures for continued service in nuclear power plants

International Nuclear Information System (INIS)

Naus, D.J.; Marchbanks, M.F.; Arndt, E.G.

1988-01-01

Results are summarized of a study on concrete component aging and its significance relative to continued service of nuclear power plants (NPPs) beyond the initial period for which they were granted operating licenses. Progress is presented of a second study being conducted to identify and provide acceptance criteria for structural safety issues which the USNRC staff will need to address when applications are submitted for continued service of NPPs. Major activities under this program include: development of a materials property data base, establishment of structural component assessment and repair procedures, and development of a methodology for determination of structural reliability. 19 refs., 5 figs., 3 tabs

Study on Effects of Different Replacement Rate on Bending Behavior of Big Recycled Aggregate Self Compacting Concrete

Science.gov (United States)

Li, Jing; Guo, Tiantian; Gao, Shuai; Jiang, Lin; Zhao, Zhijun; Wang, Yalin

2018-03-01

Big recycled aggregate self compacting concrete is a new type of recycled concrete, which has the advantages of low hydration heat and green environmental protection, but its bending behavior can be affected by different replacement rate. Therefor, in this paper, the research status of big Recycled aggregate self compacting concrete was systematically introduced, and the effect of different replacement rate of big recycled aggregate on failure mode, crack distribution and bending strength of the beam were studied through the bending behavior test of 4 big recycled aggregate self compacting concrete beams. The results show that: The crack distribution of the beam can be affected by the replacement rate; The failure modes of big recycled aggregate beams are the same as those of ordinary concrete; The plane section assumption is applicable to the big recycled aggregate self compacting concrete beam; The higher the replacement rate, the lower the bending strength of big recycled aggregate self compacting concrete beams.

Self-Compacting Concrete in Precast Elements Industry

Directory of Open Access Journals (Sweden)

Corneliu Bob

2005-01-01

Full Text Available In this paper the authors present information about the Self-Compacting Concrete and experimental results regarding the use of them into precast element industry. This type of concrete does not require vibration for placing and compaction; it is able to flow under its own weight, completely filling formwork and achieving full compaction, even in the presence of congested reinforcement. The experimental programme has take into account two prestressed beams which were prefabricated and tested on a special stands. The beams of Self-Compacting Concrete with the length of 24 m were prepared at „Beton-Star” Kft, Kecsekenet, Hungary, and used at the CASCO, Satu-Mare.

Performance polymeric concrete with synthetic fiber reinforcement against reflective cracking in rigid pavement overlay

International Nuclear Information System (INIS)

Khan, N.U.; Khan, B.

2012-01-01

Cement concrete pavements are used for heavy traffic loads throughout the world owing to its better and economical performance. Placing of a concrete overlay on the existing pavement is the most prevalent rehabilitating method for such pavements, however, the problem associated with the newly placed overlay is the occurrence of reflective cracking. This paper presents an assessment of the performance of polymeric concrete with synthetic fiber reinforcement against reflective cracking in an overlay system. The performance of polymeric concrete with synthetic fibers as an overlay material is measured in terms of the load-deflection, strain-deflection and load-strain behavior of beams of the polymeric concrete. For this purpose, five types of beams having different number of fiber wires and position are tested for flexure strength. Deflection/strains for each increment of load are recorded. In addition, cubes of plain concrete and of concrete with synthetic fiber needles were tested after 7 and 28 days for compressive strengths. Finite element models in ANSYS software for the beams have also been developed. Beams with greater number of longitudinal fiber wires displayed relatively better performance against deflection whilst beams with synthetic fiber needles showed better performance against strains. Thus, polymeric concrete overlay with fiber reinforcement will serve relatively better against occurrence of reflective cracking. (author)

Hybrid structure in civil engineering construction. Composite types of steel and concrete; Doboku bun`ya ni okeru fukugo kozo. Kozai to concrete no ittai keishiki

Energy Technology Data Exchange (ETDEWEB)

Sato, T. [JR Railway Technical Research Inst. Tokyo (Japan)

1995-03-30

In connection with hybrid structures in civil engineering construction, classification and application of composite types of steel and concrete are discussed. H steel embedded beam is a composite beam in which the H shape steel of the main beam is connected to rolled or welded H shape steel using cross beams. Composite structure columns are grouped into the composite column and the steel pipe concrete column. SRC piers are often adopted from the viewpoints of constraints for execution of works and vibration proof. Steel and concrete hybrid structure is a kind of structural system in which various kinds of materials such as steel, RC, or PC members are connected. The cable stayed bridge utilizes characteristics of steel and concrete effectively. For the piers of municipal expressway viaducts, there are executed cases of mixed structures which have RC, SRC columns for T shape piers and S structure for the bridges. SRC structure and composite columns are adopted often for structures of subway stations. 7 refs., 7 figs.

NANOMODIFIED CONCRETE

Directory of Open Access Journals (Sweden)

B. M. Khroustalev

2015-01-01

Full Text Available One of the main directions in construction material science is the development of  next generation concrete that is ultra-dense, high-strength, ultra-porous, high heat efficient, extra corrosion-resistant. Selection of such direction is caused by extreme operational impacts on the concrete, namely: continuously increasing load on the concrete and various dynamics of such loads; the necessity in operation of concrete products in a wide temperature range and their exposure to various chemical and physical effects.The next generation concrete represents high-tech concrete mixtures with additives that takes on and retain the required properties when hardening and being used under any operational conditions. A differential characteristic of the next generation concrete is its complexity that presumes usage of various mineral dispersed components, two- and three fractional fine and coarse aggregates, complex chemical additives, combinations of polymer and iron reinforcement.Design strength and performance properties level of the next generation concrete is achieved by high-quality selection of the composition, proper selection of manufacturing techniques, concrete curing, bringing the quality of concrete items to the required level of technical condition during the operational phase. However, directed formation of its structure is necessary in order to obtain high-tech concrete.Along with the traditional methods for regulation of the next generation concrete structure, modification of concrete while using silica nanoparticles is also considered as a perspective one because the concrete patterning occurs due to introduction of a binder in a mineral matrix. Due to this it is possible to obtain nano-modified materials with completely new properties.The main problem with the creation of nano-modified concrete is a uniform distribution of nano-materials in the volume of the cement matrix which is particularly important in the cases of adding a modifier in

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

Science.gov (United States)

2004-03-01

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

Fast neutron fluxes distribution in Egyptian ilmenite concrete

International Nuclear Information System (INIS)

Megahed, R.M.; Abou El-Nasr, T.Z.; Bashter, I.I.

1978-01-01

This work is concerned with the study of the distribution of fast neutron fluxes in a new type of heavy concrete made from Egyptian ilmenite ores. The neutron source used was a collimated beam of reactor neutrons emitted from one of the horizontal channels of the ET-RR-1 reactor. Measurements were carried-out using phosphorous activation detectors. Iso-flux curves were represented which give directly the shape and thickness required to attenuate the emitted fast neutron flux to a certain value. The relaxation lengths were also evaluated from the measured data for both disc monodirectional source and infinite plane monodirectional source. The obtained values were compared with that calculated using the derived values of relative number densities and microscopic removal cross-sections of the different constituents. The obtained data show that ilmenite concrete attenuates fast neutron flux more strongly than ordinary concrete. A semiemperical formula was derived to calculate the fast neutron flux at different thicknesses along the beam axis. Another semiemperical formula was also derived to calculate the fast neutron flux in ordinary concrete along the beam axis using the corresponding value in ilmenite concrete

Prediction of reinforcement corrosion using corrosion induced cracks width in corroded reinforced concrete beams

International Nuclear Information System (INIS)

Khan, Inamullah; François, Raoul; Castel, Arnaud

2014-01-01

This paper studies the evolution of reinforcement corrosion in comparison to corrosion crack width in a highly corroded reinforced concrete beam. Cracking and corrosion maps of the beam were drawn and steel reinforcement was recovered from the beam to observe the corrosion pattern and to measure the loss of mass of steel reinforcement. Maximum steel cross-section loss of the main reinforcement and average steel cross-section loss between stirrups were plotted against the crack width. The experimental results were compared with existing models proposed by Rodriguez et al., Vidal et al. and Zhang et al. Time prediction models for a given opening threshold are also compared to experimental results. Steel cross-section loss for stirrups was also measured and was plotted against the crack width. It was observed that steel cross-section loss in the stirrups had no relationship with the crack width of longitudinal corrosion cracks. -- Highlights: •Relationship between crack and corrosion of reinforcement was investigated. •Corrosion results of natural process and then corresponds to in-situ conditions. •Comparison with time predicting model is provided. •Prediction of load-bearing capacity from crack pattern was studied

77 FR 54652 - Draft Program Comment for Common Post-1945 Concrete and Steel Bridges

Science.gov (United States)

2012-09-05

... constructed by State transportation agencies after 1945, using reinforced concrete or steel beams and designs... proposed Program Comment: Program Comment for Common Post-1945 Concrete and Steel Bridges I. Introduction... reinforced concrete or steel beams and designs that quickly became standardized. These common bridge types...

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.

The Shrinkage Cracking Behavior in Reinforced Reactive Powder Concrete Walls

Directory of Open Access Journals (Sweden)

Samir A. Al-Mashhadi

2017-07-01

Full Text Available In this study, the reduced scale wall models were used (they are believed to resemble as much as possible the field conditions to study the shrinkage behavior of reactive powder concrete (RPC base restrained walls. Six base restrained RPC walls were casted in different length/height ratios of two ratios of steel fiber by volume in Summer. These walls were restrained by reinforced concrete bases to provide the continuous base restraint to the walls. The mechanical properties of reactive powder concrete investigated were; compressive strength between (75.3 – 140.1 MPa, splitting tensile strength between (5.7 – 13.9 MPa, flexural tensile strength (7.7 – 24.5 MPa, and static modulus of elasticity (32.7 – 47.1GPa. Based on the observations of this work, it was found that the cracks did not develop in the reduced scale of the reactive powder concrete (RPC walls restrained from movement at their bases for different L/H ratios (2, 5, and 10 and for two ratio of steel fiber (1% & 2% during 90 days period of drying conditions. Moreover, the shrinkage values increase toward the edges. Based on the results of this work, the increase in the maximum shrinkage values of walls with 1% steel fiber were (29%, 28%, 28% of the maximum shrinkage values of walls with 2% steel fiber of length/height ratios of (2, 5, and 10 respectively. The experimental observation in beam specimens showed that the free shrinkage, tensile strain capacity and elastic tensile strain capacity (at date of cracking of beams with 1% steel fiber were higher than the beams with 2% steel fiber by about (24%, (45% and (42% respectively

Application of numerical simulation to study the behavior of deep beams of reinforced concrete; Aplicacion de la simulacion numerica al estudio del comportamiento de vigas de gran peralto de hormigon armado

Energy Technology Data Exchange (ETDEWEB)

Rodriguez Plasencia, G.; Douglas Bonilla Rocha, J.; Hernandez Santana, J. J.

2012-07-01

In this investigation a preliminary study is carried out of the behaviour of deep beams of reinforced concrete under static loads with the prevalence of the shear force, starting from the numerical simulation of the experimental studies. A bilinear model is considered for steel and the Drucker-Prager model is considered for concrete. ABAQUS (2008) is utilized to model the deep beams test. the numerical results obtained have goad correspondence with the experimental values; this fact demonstrates the validity and effectiveness of the Finite element Method for the study of the behaviour of deep beams of reinforced concrete. Moreover, taking advantage of the benefits of numerical simulation, the stress states are analysed through the stress iso lines and iso zones obtained. Also parameters that are decisive in the tension-deformational behaviour of these types of structures are numerically analysed. (Author) 19 refs.

Practical assessment of magnetic methods for corrosion detection in an adjacent precast, prestressed concrete box-beam bridge

Science.gov (United States)

Fernandes, Bertrand; Titus, Michael; Nims, Douglas Karl; Ghorbanpoor, Al; Devabhaktuni, Vijay Kumar

2013-06-01

Magnetic methods are progressing in the detection of corrosion in prestressing strands in adjacent precast, prestressed concrete box-beam bridges. This study is the first field trial of magnetic strand defect detection systems on an adjacent box-beam bridge. A bridge in Fayette County, Ohio, which was scheduled for demolition, was inspected. Damage to prestressed box-beams is often due to corrosion of the prestressing strands. The corroded strands show discontinuities and a reduced cross-sectional area. These changes, due to corrosion, are reflected in the magnetic signatures of the prestressing steel. Corrosion in the prestressing steel was detected using two magnetic methods, namely the 'magnetic flux leakage' (MFL) and the 'induced magnetic field'. The purpose of these tests was to demonstrate the ability of the magnetic methods to detect hidden corrosion in box-beams in the field and tackle the logistic problem of inspecting box-beams from the bottom. The inspections were validated by dissecting the bottom of the box-beams after the inspections. The results showed that the MFL method can detect hidden corrosion and strand breaks. Both magnetic field methods were also able to estimate corrosion by detecting the effective cross-sectional area of the strand in sections of the beams. Thus, it was shown that the magnetic methods can be used to predict hidden corrosion in prestressing strands of box-beams.

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...

Inspection Strategies for Concrete Bridges

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard; Thoft-Christensen, Palle

1989-01-01

In this paper an optimal inspection strategy for concrete bridges based on periodic routine and detailed inspections is presented. The failure mode considered is corrosion of the reinforcement due to chlorides. A simple modelling of the corrosion and of the inspection strategy is presented....... The optimal inspection strategy is determined from an optimization problem, where the design variables are time intervals between detailed inspections and the concrete cover. The strategy is illustrated on a simple structure, namely a reinforced concrete beam....

Implementation of Highly-Flowable Strain Hardening Fiber Reinforced Concrete in New RC Beam-Column Joints

Directory of Open Access Journals (Sweden)

Liao Wen-Cheng

2018-01-01

Full Text Available The purpose of New RC project was aimed to reduce the member sections and increase the available space of high rise buildings by using high strength concrete (f’c > 70 MPa and high strength rebars (fy > 685 MPa. Material consumptions and member section sizes can be further reduced owing to the upgrade of strength. However, the nature of brittleness of high strength may also cause early cover spalling and other ductility issues. Addition of steel fibers is an alternative as transverse reinforcement. Highly flowable strain hardening fiber reinforced concrete (HF-SHFRC has excellent workability in the fresh state and exhibits the strain-hardening and multiple cracking characteristics of high performance fiber reinforced cementitious composites (HPFRCC in their hardened state. The objective of this study is to investigate the feasibility of implementing HF-SHFRC in New RC building systems, particularly for beam-column joints as an alternative of transverse reinforcements. Four full-scale exterior beam-column joints, including two specimens with intensive transverse reinforcements and two specimens made of HF-SHFRC without any stirrup, are tested. Test results show that the HF-SHFRC specimens perform as well as specimens with intensive transverse reinforcements regarding failure mode, ductility, energy dissipation and crack width control. Integration of New RC building systems and HF-SHFRC can assuring construction qualities and further diminish labor work and give infrastructure longer service life, and eventually lower the life-cycle cost.

Surface modification of the metal plates using continuous electron beam process (CEBP)

International Nuclear Information System (INIS)

Kim, Jisoo; Kim, Jin-Seok; Kang, Eun-Goo; Park, Hyung Wook

2014-01-01

Highlights: • We performed surface modification of SM20C, SUS303, and Al6061 using CEBP. • We analyzed surface properties and microstructure after electron-beam irradiation. • The surface quality was improved after electron-beam irradiation. • The surface hardness for SM20C was increased by ∼50% after CEBP irradiation. - Abstract: The finishing process is an important component of the quality-control procedure for final products in manufacturing applications. In this study, we evaluated the performance of continuous electron-beam process as the final process for finishing SM20C (steel alloy), SUS303 (stainless steel alloy), and Al6061 (aluminum alloy) surfaces both on the initially smooth and rough surfaces. Surface modification of the metals was carried out by varying the feed and frequency of the continuous electron-beam irradiation procedure. The resulting surface roughness was examined with respect to the initial surface roughness of the metals. SM20C and SUS303 experienced an improvement in surface roughness, particularly for initially rough surfaces. Continuous electron-beam process produced craters during the process and the effect of this phenomenon on the resulting surface roughness was relatively large with the initially smooth SM20C and SUS303 alloy surfaces. For Al6061, the continuous electron-beam process was effective at improving its surface roughness even with the initially smooth surface under the optimized conditions of process; this was attributed to its low melting point. Scanning electron microscopy was used to identify metallurgical variation within the thin melted and re-solidification layers of the tested alloys. Changes in the surface contact angle and hardness before and after electron-beam irradiation were also examined

Surface modification of the metal plates using continuous electron beam process (CEBP)

Energy Technology Data Exchange (ETDEWEB)

Kim, Jisoo, E-mail: kimjisu16@unist.ac.kr [School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology, UNIST-gil 50, Eonyang-eup, Ulju-gun, Ulsan Metropolitan City 689-798 (Korea, Republic of); Kim, Jin-Seok, E-mail: totoro22@kitech.re.kr [Korea Institute of Industrial Technology (KITECH), KITECH Cheonan Headquarters 35-3 Hongcheon-ri, Ipjang-myeon, Cheonan-si, Chungcheongnam-do 330-825 (Korea, Republic of); Kang, Eun-Goo, E-mail: egkang@kitech.re.kr [Korea Institute of Industrial Technology (KITECH), KITECH Cheonan Headquarters 35-3 Hongcheon-ri, Ipjang-myeon, Cheonan-si, Chungcheongnam-do 330-825 (Korea, Republic of); Park, Hyung Wook, E-mail: hwpark@unist.ac.kr [School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology, UNIST-gil 50, Eonyang-eup, Ulju-gun, Ulsan Metropolitan City 689-798 (Korea, Republic of)

2014-08-30

Highlights: • We performed surface modification of SM20C, SUS303, and Al6061 using CEBP. • We analyzed surface properties and microstructure after electron-beam irradiation. • The surface quality was improved after electron-beam irradiation. • The surface hardness for SM20C was increased by ∼50% after CEBP irradiation. - Abstract: The finishing process is an important component of the quality-control procedure for final products in manufacturing applications. In this study, we evaluated the performance of continuous electron-beam process as the final process for finishing SM20C (steel alloy), SUS303 (stainless steel alloy), and Al6061 (aluminum alloy) surfaces both on the initially smooth and rough surfaces. Surface modification of the metals was carried out by varying the feed and frequency of the continuous electron-beam irradiation procedure. The resulting surface roughness was examined with respect to the initial surface roughness of the metals. SM20C and SUS303 experienced an improvement in surface roughness, particularly for initially rough surfaces. Continuous electron-beam process produced craters during the process and the effect of this phenomenon on the resulting surface roughness was relatively large with the initially smooth SM20C and SUS303 alloy surfaces. For Al6061, the continuous electron-beam process was effective at improving its surface roughness even with the initially smooth surface under the optimized conditions of process; this was attributed to its low melting point. Scanning electron microscopy was used to identify metallurgical variation within the thin melted and re-solidification layers of the tested alloys. Changes in the surface contact angle and hardness before and after electron-beam irradiation were also examined.

Rotation capacity of self-compacting steel fibre reinforced concrete beams

NARCIS (Netherlands)

Schumacher, P.; Walraven, J.C.; Den Uijl, J.A.; Bigaj-van Vliet, A.

2009-01-01

Steel fibres are known to enhance the toughness of concrete in compression and in tension. Steel fibres also improve the bond properties between concrete matrix and reinforcing steel bars. In order to investigate the effect of steel fibres on the rotation capacity of reinforced concrete members,

Experimental Investigations on Effect of Damage on Vibration Characteristics of a Reinforced Concrete Beam

Science.gov (United States)

Srinivas, V.; Jeyasehar, C. Antony; Ramanjaneyulu, K.; Sasmal, Saptarshi

2012-02-01

Need for developing efficient non-destructive damage assessment procedures for civil engineering structures is growing rapidly towards structural health assessment and management of existing structures. Damage assessment of structures by monitoring changes in the dynamic properties or response of the structure has received considerable attention in recent years. In the present study, damage assessment studies have been carried out on a reinforced concrete beam by evaluating the changes in vibration characteristics with the changes in damage levels. Structural damage is introduced by static load applied through a hydraulic jack. After each stage of damage, vibration testing is performed and system parameters were evaluated from the measured acceleration and displacement responses. Reduction in fundamental frequencies in first three modes is observed for different levels of damage. It is found that a consistent decrease in fundamental frequency with increase in damage magnitude is noted. The beam is numerically simulated and found that the vibration characteristics obtained from the measured data are in close agreement with the numerical data.

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.

Mechanical characterization and structural analysis of recycled fiber-reinforced-polymer resin-transfer-molded beams

Science.gov (United States)

Tan, Eugene Wie Loon

1999-09-01

The present investigation was focussed on the mechanical characterization and structural analysis of resin-transfer-molded beams containing recycled fiber-reinforced polymers. The beams were structurally reinforced with continuous unidirectional glass fibers. The reinforcing filler materials consisted entirely of recycled fiber-reinforced polymer wastes (trim and overspray). The principal resin was a 100-percent dicyclo-pentadiene unsaturated polyester specially formulated with very low viscosity for resin transfer molding. Variations of the resin transfer molding technique were employed to produce specimens for material characterization. The basic materials that constituted the structural beams, continuous-glass-fiber-reinforced, recycled-trim-filled and recycled-overspray-filled unsaturated polyesters, were fully characterized in axial and transverse compression and tension, and inplane and interlaminar shear, to ascertain their strengths, ultimate strains, elastic moduli and Poisson's ratios. Experimentally determined mechanical properties of the recycled-trim-filled and recycled-overspray-filled materials from the present investigation were superior to those of unsaturated polyester polymer concretes and Portland cement concretes. Mechanical testing and finite element analyses of flexure (1 x 1 x 20 in) and beam (2 x 4 x 40 in) specimens were conducted. These structurally-reinforced specimens were tested and analyzed in four-point, third-point flexure to determine their ultimate loads, maximum fiber stresses and mid-span deflections. The experimentally determined load capacities of these specimens were compared to those of equivalent steel-reinforced Portland cement concrete beams computed using reinforced concrete theory. Mechanics of materials beam theory was utilized to predict the ultimate loads and mid-span deflections of the flexure and beam specimens. However, these predictions proved to be severely inadequate. Finite element (fracture propagation

Lightweight HPC beam OMEGA

Science.gov (United States)

Sýkora, Michal; Jedlinský, Petr; Komanec, Jan

2017-09-01

In the design and construction of precast bridge structures, a general goal is to achieve the maximum possible span length. Often, the weight of individual beams makes them difficult to handle, which may be a limiting factor in achieving the desired span. The design of the OMEGA beam aims to solve a part of these problems. It is a thin-walled shell made of prestressed high-performance concrete (HPC) in the shape of inverted Ω character. The concrete shell with prestressed strands is fitted with a non-stressed tendon already in the casting yard and is more easily transported and installed on the site. The shells are subsequently completed with mild steel reinforcement and cores are cast in situ together with the deck. The OMEGA beams can also be used as an alternative to steel - concrete composite bridges. Due to the higher production complexity, OMEGA beam can hardly substitute conventional prestressed beams like T or PETRA completely, but it can be a useful alternative for specific construction needs.

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...

Beam characterization of a new continuous wave radio frequency quadrupole accelerator

Energy Technology Data Exchange (ETDEWEB)

Perry, A., E-mail: aperry4@hawk.iit.edu [Argonne National Laboratory, Argonne, IL 60439 (United States); Illinois Institute of Technology, Chicago, IL 60616 (United States); Dickerson, C.; Ostroumov, P.N.; Zinkann, G. [Argonne National Laboratory, Argonne, IL 60439 (United States)

2014-01-21

A new Continuous Wave (CW) Radio Frequency Quadrupole (RFQ) for the ATLAS (Argonne Tandem Linac Accelerator System) Intensity Upgrade was developed, built and tested at Argonne National Laboratory. We present here a characterization of the RFQ output beam in the longitudinal phase space, as well as a measurement of the transverse beam halo. Measurement results are compared to simulations performed using the beam dynamics code TRACK. -- Highlights: • Beam commissioning of a new CW RFQ has been performed at Argonne National Laboratory. • Energy spread and bunch shape measurements were conducted. • The formation of a beam halo in the transverse phase space was studied.

Combined Effect of Initial Curing Temperature and Crack Width on Chloride Penetration in Reinforced Concrete Beams

Directory of Open Access Journals (Sweden)

Elkedrouci Lotfi

2018-01-01

Full Text Available Reinforced concrete (RC structures are gradually being degraded all over the world, largely due to corrosion of the embedded steel bars caused by an attack of chloride penetration. Initial curing would be regarded as one factor influencing chloride diffusion in concrete in combination with cover cracking that is also of great attention for reinforced structures. In this study, a non-steady state diffusion test of chloride ion involving RC beam specimens with a water-to-cement ratio of 0.5, initial curing temperatures of 5°C or 20°C and three types of crack widths ranging from 0 to 0.2mm was performed. Chloride content at 5°C or was determined. The results show that the higher chloride content was obtained in condition of crack width large than 0.1mm with low initial curing temperature and there are no obvious differences in chloride content when the crack width was not larger than 0.1mm.

Preparation and characterization of glass fibers – polymers (epoxy bars (GFRP reinforced concrete for structural applications

Directory of Open Access Journals (Sweden)

Alkjk Saeed

2016-06-01

Full Text Available The paper presents some of the results from a large experimental program undertaken at the Department of Civil Engineering of Damascus University. The project aims to study the ability to reinforce and strengthen the concrete by bars from Epoxy polymer reinforced with glass fibers (GFRP and compared with reinforce concrete by steel bars in terms of mechanical properties. Five diameters of GFRP bars, and steel bars (4mm, 6mm, 8mm, 10mm, 12mm tested on tensile strength tests. The test shown that GFRP bars need tensile strength more than steel bars. The concrete beams measuring (15cm wide × 15cm deep × and 70cm long reinforced by GFRP with 0.5 vol.% ratio, then the concrete beams reinforced by steel with 0.89 vol.% ratio. The concrete beams tested on deflection test. The test shown that beams which reinforced by GFRP has higher deflection resistance, than beams which reinforced by steel. Which give more advantage to reinforced concrete by GFRP.

Comparison between continuous and localized methods to evaluate the flow rate through containment concrete structures

Energy Technology Data Exchange (ETDEWEB)

Jason, L., E-mail: ludovic.jason@cea.fr [Atomic Energy Commission (CEA), DEN, DANS, DM2S, SEMT, Mechanics and System Simulation Laboratory (LM2S), F-91191 Gif sur Yvette (France); LaMSID, UMR CNRS-EDF-CEA 8193, F-92141 Clamart (France); Masson, B. [Electricité de France (EDF), SEPTEN, F-69628 Villeurbanne (France)

2014-10-01

Highlights: • The contribution focuses on the gas transfer through reinforced concrete structures. • A continuous approach with a damage–permeability law is investigated. • It is significant, for this case, only when the damage variable crosses the section. • In this case, two localized approaches are compared. • It helps at evaluating a “reference” crack opening for engineering laws. - Abstract: In this contribution, different techniques are compared to evaluate the gas flow rate through a representative section of a reinforced and prestressed concrete containment structure. A continuous approach is first applied which is based on the evaluation of the gas permeability as a function of the damage variable. The calculations show that the flow rate becomes significant only when the damage variable crosses the section. But in this situation, the continuous approach is no longer fully valid. That is why localized approaches, based on a fine description of the crack openings, are then investigated. A comparison between classical simplified laws (Poiseuille flow) and a more refined model which takes into account the evolution of the crack opening in the depth of the section enables to define the validity domain of the simplified laws and especially the definition of the associated “reference opening”.

Shear strength of reinforced concrete beams strengthened by P.B.O. fiber mesh under loading

Directory of Open Access Journals (Sweden)

Blikharskyy Zinoviy

2017-01-01

Full Text Available This article presents experimental study of sheer strength of reinforced concrete beams without transverse steel reinforcement, which strengthened by composite materials. The feature of tests is that the beams’ strengthening is made under simultaneous action of loading. The research program involves a series of test beams with size 2100 × 200 × 100 mm and which contains control sample and three reinforced samples by reinforcing FRCM system. FRCM system consisting of two components: mineral mortar based on modified cement Ruredil X Mesh M750 and reinforcing P.B.O. fiber mesh Ruredil X Mesh Gold (Italy. The strength research of test samples was carried out with the shear distance to effective depth ratio a/d = 2. The strengthening loading levels were selected at 0.0, 0.3, 0.5 from shear strength of non strengthened control sample. As a result of experimental studies we found that during strengthening design the inclined cross section of beams we should take into account the existing level of loading. Using the strengthening system Ruredil X Mesh Gold the strengthening effect is reduced at 2.8 to 2.9 times while the existing level of loading increase from 0 to 50%.

Thermo-mechanical simulation and parameters optimization for beam blank continuous casting

International Nuclear Information System (INIS)

Chen, W.; Zhang, Y.Z.; Zhang, C.J.; Zhu, L.G.; Lu, W.G.; Wang, B.X.; Ma, J.H.

2009-01-01

The objective of this work is to optimize the process parameters of beam blank continuous casting in order to ensure high quality and productivity. A transient thermo-mechanical finite element model is developed to compute the temperature and stress profile in beam blank continuous casting. By comparing the calculated data with the metallurgical constraints, the key factors causing defects of beam blank can be found out. Then based on the subproblem approximation method, an optimization program is developed to search out the optimum cooling parameters. Those optimum parameters can make it possible to run the caster at its maximum productivity, minimum cost and to reduce the defects. Now, online verifying of this optimization project has been put in practice, which can prove that it is very useful to control the actual production

Optimization of the bending stiffness of beam-to-column and column-to-foundation connections in precast concrete structures

Directory of Open Access Journals (Sweden)

R. R. R. COSTA

Full Text Available Abstract This work involved the structural optimization of precast concrete rigid frames with semi-rigid beam-to-column connections. To this end, several frames were simulated numerically using the Finite Element Method. Beams and columns were modeled using bar elements and their connections were modeled using spring elements, with variable bending stiffness. The objective function was based on the search of the least stiff connection able to ensure the global stability of the building. Lastly, a connection model with optimal stiffness was adopted to design the frame. Semi-rigid beam-to-column connections with a constraint factors of 0.33 sufficed to ensure the maximum allowable horizontal displacement and bending moment of the connection, with a global stability parameter of 1.12. This confirms that even connections with low constraints generate significant gains from the structural standpoint, without affecting construction and assembly-related aspects.

Assessment of Structural Behavior of Non-corroded and Corroded RCC Beams Using Finite Element Method

Directory of Open Access Journals (Sweden)

Anand Parande

2008-09-01

Full Text Available A three dimensional finite element model is developed to examine the structural behaviour of corroded reinforced concrete beam and non corroded reinforced concrete beam. Non linear finite element analysis is performed using the ANSYS program. SOLID 65, LINK 8 element represent concrete and discrete reinforcing steel bars, based on each component actual characteristics, non linear material properties are defined for both elements. The effect of corrosion in reinforced concrete is studied by finite element analysis; an approach is developed to model the corrosion product expansion causing concrete cover cracking for this, beam has been modeled using ANSYS and using this data the beam has been casted with M20 concrete after 28 days the beam will be tested for flexural strength. The comparison between ANSYS prediction and field data are made in terms of deflection, stress, strain, bond strength and crack pattern of concrete beam.

Fatigue Performance of Fiber Reinforced Concrete

DEFF Research Database (Denmark)

Jun, Zhang; Stang, Henrik

1996-01-01

The objective of the present study is to obtain basic data of fibre reinforced concrete under fatigue load and to set up a theoretical model based on micromechanics. In this study, the bridging stress in fiber reinforced concrete under cyclic tensile load was investigted in details. The damage...... mechanism of the interface between fiber and matrix was proposed and a rational model given. Finally, the response of a steel fiber reinforced concrete beam under fatigue loading was predicted based on this model and compared with experimental results....

Achieving Mixtures of Ultra-High Performance Concrete

Directory of Open Access Journals (Sweden)

Mircea POPA

2013-07-01

Full Text Available Ultra-High Performance Concrete (UHPC is a relatively new concrete. According to [11] UHPC is that concrete which features compressive strength over C100/115 class. Up to this point standards for this type of concrete were not adopted, although its characteristic strength exceeds those specified in [33]. Its main property is high compressive strength. This provides the possibility of reducing the section of elements (beams or columns made of this type of concrete, while the load capacity remains high. The study consists in blending mixtures of UHPC made of varying proportions of materials. The authors have obtained strengths of up to 160 MPa. The materials used are: Portland cement, silica fume, quartz powder, steel fibers, superplasticiser, sand and crushed aggregate for concrete - andesite.

Performance of Hybrid Reinforced Concrete Beam Column Joint: A Critical Review

Directory of Open Access Journals (Sweden)

Md Rashedul Kabir

2016-04-01

Full Text Available Large residual strain in reinforced concrete structures after a seismic event is a major concern for structural safety and serviceability. Alternative reinforcement materials like fiber-reinforced polymer (FRP have been widely used to mitigate corrosion problems associated with steel. Low modulus of elasticity and brittle behavior compared to steel has made the use of FRP unsuitable in seismic resistant strictures. A combination of steel-FRP reinforcement configuration can address the problem of corrosion. Therefore, introducing a material that shows strong post elastic behavior without any decay due to corrosion is in demand. Shape memory alloy (SMA, a novel material, is highly corrosion resistive and shows super elastic property. Coupling SMA with FRP or steel in the plastic hinge region allows the structure to undergo large deformations, but regains its original shape upon unloading. In this study, the performance characteristics of four previously tested beam-column joints reinforced with different configurations (steel, SMA/steel, glass fiber reinforced polymer (GFRP and SMA/FRP are compared to assess their capacity to endure extreme loading. Experimental results are scrutinized to compare the behavior of these specimens in terms of load-story drift and energy dissipation capacity. SMA/FRP and SMA/Steel couples have been found to be an acceptable approach to reduce residual deformation in beam-column joints with adequate energy dissipation capacity. However, SMA/FRP is superior to SMA/Steel concerning to the corrosion issue in steel.

Environmental assessment: Continuous Electron Beam Accelerator Facility, Newport News, Virginia

International Nuclear Information System (INIS)

1987-01-01

This Environmental Assessment has been prepared by the US Department of Energy (DOE) to fulfill its obligations pursuant to Sect. 102 of the National Environmental Policy Act (NEPA) of 1969 (Public Law 91-190). The proposed federal action addressed in this document is DOE's funding of a Continuous Electron Beam Accelerator Facility (CEBAF) at Newport News, Virginia. DOE intends to contract with the Southeastern Universities Research Association (SURA) for operation of CEBAF, a continuous wave (CW) linear accelerator system (linac) capable of providing high-duty-factor beams throughout the energy range from 0.5 to 4.0 GeV. CEBAF will be the first of its kind worldwide and will offer a multi-GeV energy, high-intensity, high-duty-factor electron beam for use by the US nuclear physics community in research on the states of nuclear matter and the short-distance behavior of nuclei. The CEBAF project is largely in the conceptual design stage, with some components in the preliminary design stage. Construction is anticipated to begin in 1987 and be completed by 1992

Evaluation of nuclear power plant concrete to maintain continued service

International Nuclear Information System (INIS)

McColm, E.J.; Mukherjee, P.K.; Sato, J.A.

1997-01-01

Nuclear power plant concrete structures in addition to satisfying structural requirements are a major part of the safety and containment systems. As a result, the structures are required to operate satisfactorily for the life of the plant and until well after decommissioning. Successful life management requires an understanding of potential degradation mechanisms that can impact on the performance of these structures, regular well planned inspection programs and the use of specialized repair and maintenance programs. These aspects of nuclear life management are discussed with an example of inspection and repair conducted at one of Ontario Hydro's nuclear generating stations. The example is discussed in terms of the performance requirements of the containment concrete. The plant referred to has been in operation for over 20 years, making it currently the oldest operating commercial nuclear power plant in Ontario, Canada. The information on the concrete containment structures included baseline construction data on the concrete material properties and the results of periodic scheduled and other interim specialized inspections. Also available were the results of laboratory testing of concrete cores obtained from the structures. The data from these inspections and laboratory testing were used to monitor the aging characteristics of the structures and to plan appropriate repair activities. (author)

Cracking in autoclaved aerated concrete: Experimental investigation and XFEM modeling

International Nuclear Information System (INIS)

Ferretti, D.; Michelini, E.; Rosati, G.

2015-01-01

The paper aims to investigate and model cracking development in beams and deep-beams made of autoclaved aerated concrete (AAC). Fracture mechanics of AAC has been first studied by performing three-point bending tests on beams, similar to those commonly used for ordinary concrete elements. In some of these tests, crack growth has been also monitored by using ESPI laser technique. In this way, it has been possible to calibrate the main parameters of a proper cohesive law by means of extended finite element inverse analysis. Subsequently, cracking tests have been also performed on deep-beams, whose behavior is more representative of full scale walls. To validate the proposed cohesive law, deep-beam experimental behavior has been finally simulated through XFEM

Cracking in autoclaved aerated concrete: Experimental investigation and XFEM modeling

Energy Technology Data Exchange (ETDEWEB)

Ferretti, D., E-mail: daniele.ferretti@unipr.it [Department of Civil, Environmental, Land Management Engineering and Architecture, University of Parma, P.co Area delle Scienze 181/A, 43124 Parma (Italy); Michelini, E. [Department of Civil, Environmental, Land Management Engineering and Architecture, University of Parma, P.co Area delle Scienze 181/A, 43124 Parma (Italy); Rosati, G. [Department of Civil and Environmental Engineering, Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano (Italy)

2015-01-15

The paper aims to investigate and model cracking development in beams and deep-beams made of autoclaved aerated concrete (AAC). Fracture mechanics of AAC has been first studied by performing three-point bending tests on beams, similar to those commonly used for ordinary concrete elements. In some of these tests, crack growth has been also monitored by using ESPI laser technique. In this way, it has been possible to calibrate the main parameters of a proper cohesive law by means of extended finite element inverse analysis. Subsequently, cracking tests have been also performed on deep-beams, whose behavior is more representative of full scale walls. To validate the proposed cohesive law, deep-beam experimental behavior has been finally simulated through XFEM.

The effect of recycled concrete aggregate properties on the bond strength between RCA concrete and steel reinforcement

International Nuclear Information System (INIS)

Butler, L.; West, J.S.; Tighe, S.L.

2011-01-01

The purpose of this study was to investigate the influence that replacing natural coarse aggregate with recycled concrete aggregate (RCA) has on concrete bond strength with reinforcing steel. Two sources of RCA were used along with one natural aggregate source. Numerous aggregate properties were measured for all aggregate sources. Two types of concrete mixture proportions were developed replacing 100% of the natural aggregate with RCA. The first type maintained the same water-cement ratios while the second type was designed to achieve the same compressive strengths. Beam-end specimens were tested to determine the relative bond strength of RCA and natural aggregate concrete. On average, natural aggregate concrete specimens had bond strengths that were 9 to 19% higher than the equivalent RCA specimens. Bond strength and the aggregate crushing value seemed to correlate well for all concrete types.

flexural improvement of plain concrete beams strengthened

African Journals Online (AJOL)

Muhammad Nura Isa

Results show significant improvement in both stiffness and load bearing capacity of plain concrete ... Various methods have been developed to increase their strength capacity by using .... obtained by carrying out uniaxial direct tensile strength.

FINITE ELEMENT ANALYSIS OF DEEP BEAM UNDER DIRECT AND INDIRECT LOAD

Directory of Open Access Journals (Sweden)

Haleem K. Hussain

2018-05-01

Full Text Available This research study the effect of exist of opening in web of deep beam loaded directly and indirectly and the behavior of reinforced concrete deep beams without with and without web reinforcement, the opening size and shear span ratio (a/d was constant. Nonlinear analysis using the finite element method with ANSYS software release 12.0 program was used to predict the ultimate load capacity and crack propagation for reinforced concrete deep beams with openings. The adopted beam models depend on experimental test program of reinforced concrete deep beam with and without openings and the finite element analysis result showed a good agreement with small amount of deference in ultimate beam capacity with (ANSYS analysis and it was completely efficient to simulate the behavior of reinforced concrete deep beams. The mid-span deflection at ultimate applied load and inclined cracked were highly compatible with experimental results. The model with opening in the shear span shows a reduction in the load-carrying capacity of beam and adding the vertical stirrup has improve the capacity of ultimate beam load.

Flexural fatigue behavior of steel fiber reinforced concrete structures

International Nuclear Information System (INIS)

Chang, G.I.; Chai, W.K.; Park, C.W.; Min, I.K.

1993-01-01

In this thesis, the fatigue tests are performed on a series of SFRC (steel fiber reinforced concrete) to investigate the fatigue behavior of SFRC varing with the steel fiber contents and the steel fiber aspect ratios. Thirty SFRC beams are used in this test. The relationships between repeated loading cycle and mid-span deflection of the beams are observed under the three-point loading system. From the test results, the effects of the fiber content and the fiber aspect ratio on the concrete fatigue behavior were studied. According to the regression technique, some empirical formulae for predicting the fatigue strength of SFRC beams are also suggested. (author)

A Multiple-room, Continuous Beam Delivery, Hadron-therapy Installation

Science.gov (United States)

Méot, F.

A proton-therapy hospital installation, based on multiple beam extraction systems from a fixed-field synchrotron, is presented and commented. Potential interest as hospital operation efficiency, as well as estimates of the impact of continuous, multiple-port extraction, on the cost of a session, are discussed.

Analysis of the influence of dynamic phenomena on the fracture of a reinforced concrete beam under quasistatic loading (computations and experiment)

Science.gov (United States)

Bykov, A. A.; Matveenko, V. P.; Serovaev, G. S.; Shardakov, I. N.; Shestakov, A. P.

2015-07-01

Construction of numerical models which reliably describe the processes of crack formation and development in reinforced concrete permit estimating the bearing capacity and structural strength of any structural element without using expensive full-scale experiments. In the present paper, an example of four-point bending of a rectangular beam is used to consider a finite-element model of concrete fracture. The results obtained by quasistatic calculations and by solving the problem with inertia forces taken into account are compared. The kinetic energy contribution to the total mechanical energy of the system at the crack origination moment, which is greater than 30%, is estimated to justify the expediency of taking the inertia forces into account. The crack distribution characters obtained numerically and observed experimentally are compared. It is shown that the leading role in the evolution of the crack formation process is played by the mechanism of fracture of bonds between the reinforcing elements and the concrete.

Design and testing of tubular polymeric capsules for self-healing of concrete

Science.gov (United States)

Araújo, M.; Van Tittelboom, K.; Feiteira, J.; Gruyaert, E.; Chatrabhuti, S.; Raquez, J.-M.; Šavija, B.; Alderete, N.; Schlangen, E.; De Belie, N.

2017-10-01

Polymeric healing agents have proven their efficiency to heal cracks in concrete in an autonomous way. However, the bottleneck for valorisation of self-healing concrete with polymeric healing agents is their encapsulation. In the present work, the suitability of polymeric materials such as poly(methyl methacrylate) (PMMA), polystyrene (PS) and poly(lactic acid) (PLA) as carriers for healing agents in self-healing concrete has been evaluated. The durability of the polymeric capsules in different environments (demineralized water, salt water and simulated concrete pore solution) and their compatibility with various healing agents have been assessed. Next, a numerical model was used to simulate capsule rupture when intersected by a crack in concrete and validated experimentally. Finally, two real-scale self-healing concrete beams were made, containing the selected polymeric capsules (with the best properties regarding resistance to concrete mixing and breakage upon crack formation) or glass capsules and a reference beam without capsules. The self-healing efficiency was determined after crack creation by 3-point-bending tests.

Self-sensing concrete with nanomaterials

OpenAIRE

Chen, Z.; Ding, Y.; Torgal, Fernando Pacheco; Zhang, Y.

2013-01-01

Conductive concrete containing nano carbon black (NCB) and carbon fibre (CF) to enable the self-diagnosis of strain and damage was studied. The effect of NCB and CF on workability, mechanical properties and fractional change in resistance (FCR) in fresh and hardened concrete was analysed. The relationship between the FCR, the strain of initial geometrical neutral axis (IGNA) and the degree of beam damage was established. The results showed that the relationship between the FCR and the IGNA st...

Cracking and Strain Analysis of Beams Reinforced with Composite Bars

Directory of Open Access Journals (Sweden)

Edgaras Timinskas

2012-11-01

Full Text Available The paper discusses the results of experimental and numerical modelling using two beams reinforced with GFRP bars. One beam was made of plain concrete while the other contained short steel fibres. The influence of steel fibres on deflection and cracking behaviour was studied. A comparative analysis of experimental results has shown that steel fibres significantly reduce deflections and average crack width of the beam. Moreover, an addition of steel fibres to the concrete mix led to a more ductile failure mode of the beam. Numerical analysis employing nonlinear finite element software ATENA has revealed that a good agreement between calculated and experimental results regarding an ordinary concrete GFRP reinforced beam can be obtained.

Flexural fracture and fatigue behavior of steel-fiber-reinforced concrete structures

International Nuclear Information System (INIS)

Chang, D.I.

1995-01-01

Fracture and fatigue tests were performed in order to investigate the fracture and fatigue behavior of steel-fibre-reinforced concrete (SFRC) structures. 33 SFRC beams were used in the fracture and fatigue tests. The relationship between loading, strain and midspan deflection of the beams was observed under the three-point loading system.From the test results, the effects of the fiber content, fiber aspect ratio and notch-to-depth ratio on the concrete fracture and fatigue behavior were studied, and the fatigue strengths of SFRC beams were calculated. According to the regression technique, some empirical formulae for predicting the fatigue strength of SFRC beams were also suggested. (orig.)

Application of super workable concrete to main tower of cable-stayed prestressed concrete bridge. ; Kiba park grand bridge. PC shachokyo no shuto eno tekiyo. ; Kiba koen ohashi

Energy Technology Data Exchange (ETDEWEB)

Matsuoka, Y.; Shindo, T.; Sakamoto, A. (Taisei Corp., Tokyo (Japan))

1993-08-01

The Kiba Park Grand Bridge is a cable-stayed prestressed concrete (PC) bridge with a length of 186m. The main tower of this PC cable-stayed bridge consists of a pair of vertical columns with height of 60m and a beam connecting the columns. For the purpose of the advanced efficiency of construction without formwork and removal work and the improvement of durability, the precast buried formwork made of polymer impregnated concrete formwork was adopted. Approximate 650 cubic meter of super workable concrete was placed for the upper part ranging from 7th to 17th blocks of vertical columns and the beam. Blast furnace cement B and fly ash were used as binder. Naphthalenesulfonic acid type high performance water reducing agent and lignosulfonic acid type AE (air-entraining) water reducing agent were used as admixtures. Super workable concrete was mixed using forced double-axle mixers in the ready-mixed concrete plant. Satisfactory quality of the fresh concrete and strength of the hardened concrete were obtained. 2 refs., 11 figs., 3 tabs.

Effect of acid corrosion on crack propagation of concrete beams

Indian Academy of Sciences (India)

HU SHAOWEI

2018-03-10

Mar 10, 2018 ... sive strength, low price, convenient construction modelling and workability, as well as corrosion ... These test results showed that the elastic modulus and fracture parameters of concrete structures reduced ... due to nonlinear characteristics of concrete materials, the classical linear elastic fracture mechanics.

Spread prestressed concrete slab beam bridges.

Science.gov (United States)

2015-04-01

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

End region detailing of pretensioned concrete bridge girders : [summary].

Science.gov (United States)

2013-03-01

Introduction of the Florida-I Beam (FIB) in 2009 renewed interest in prestressed concrete beam design, especially end region details. In this study, University of Florida researchers examined construction detailing at the FIB end region.

Fracture Behavior and Properties of Functionally Graded Fiber-Reinforced Concrete

International Nuclear Information System (INIS)

Roesler, Jeffery; Bordelon, Amanda; Gaedicke, Cristian; Park, Kyoungsoo; Paulino, Glaucio

2008-01-01

In concrete pavements, a single concrete mixture design is selected to resist mechanical loading without attempting to adversely affect the concrete pavement shrinkage, ride quality, or noise attenuation. An alternative approach is to design distinct layers within the concrete pavement surface which have specific functions thus achieving higher performance at a lower cost. The objective of this research was to address the structural benefits of functionally graded concrete materials (FGCM) for rigid pavements by testing and modeling the fracture behavior of different combinations of layered plain and synthetic fiber-reinforced concrete materials. Fracture parameters and the post-peak softening behavior were obtained for each FGCM beam configuration by the three point bending beam test. The peak loads and initial fracture energy between the plain, fiber-reinforced, and FGCM signified similar crack initiation. The total fracture energy indicated improvements in fracture behavior of FGCM relative to full-depth plain concrete. The fracture behavior of FGCM depended on the position of the fiber-reinforced layer relative to the starter notch. The fracture parameters of both fiber-reinforced and plain concrete were embedded into a finite element-based cohesive zone model. The model successfully captured the experimental behavior of the FGCMs and predicted the fracture behavior of proposed FGCM configurations and structures. This integrated approach (testing and modeling) demonstrates the viability of FGCM for designing layered concrete pavements system

Structural Aging Program to evaluate continued performance of safety-related concrete structures in nuclear power plants

International Nuclear Information System (INIS)

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

1994-01-01

This report discusses the Structural Aging (SAG) Program which is being conducted at the Oak Ridge National Laboratory (ORNL) for the United States Nuclear Regulatory commission (USNRC). The 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. The program is organized into three technical tasks: Materials Property Data Base, Structural Component Assessment/Repair Technologies, and Quantitative Methodology for continued Service Determinations. Objectives and a summary of recent accomplishments under each of these tasks are presented

Development of chloride-induced corrosion in pre-cracked RC beams under sustained loading: Effect of load-induced cracks, concrete cover, and exposure conditions

Energy Technology Data Exchange (ETDEWEB)

Yu, Linwen [Université de Toulouse, UPS, INSA, LMDC, Toulouse (France); Université de Sherbrooke, Quebec (Canada); François, Raoul, E-mail: raoul.francois@insa-toulouse.fr [Université de Toulouse, UPS, INSA, LMDC, Toulouse (France); Dang, Vu Hiep [Hanoi Architectural University, Faculty of Civil Engineering, Hanoi (Viet Nam); L' Hostis, Valérie [CEA Saclay, CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, Gif-sur-Yvette (France); Gagné, Richard [Université de Sherbrooke, Quebec (Canada)

2015-01-15

This paper deals with corrosion initiation and propagation in pre-cracked reinforced concrete beams under sustained loading during exposure to a chloride environment. Specimen beams that were cast in 2010 were compared to specimens cast in 1984. The only differences between the two sets of beams were the casting direction in relation to tensile reinforcement and the exposure conditions in the salt-fog chamber. The cracking maps, corrosion maps, chloride profiles, and cross-sectional loss of one group of two beams cast in 2010 were studied and their calculated corrosion rates were compared to that of beams cast in 1984 in order to investigate the factors influencing the natural corrosion process. Experimental results show that, after rapid initiation of corrosion at the crack tip, the corrosion process practically halted and the time elapsing before corrosion resumed depended on the exposure conditions and cover depth.

CEBAF [Continuous Electron Beam Accelerator Facility] scientific program

International Nuclear Information System (INIS)

Gross, F.

1986-01-01

The principal scientific mission of the Continuous Electron Beam Facility (CEBAF) is to study collective phenomena in cold (or normal) nucler matter in order to understand the structure and behavior of macroscopic systems constructed from nuclei. This document discusses in broad popular terms those issues which the CEBAF experimental and theoretical program are designed to address. Specific experimental programs currently planned for CEBAF are also reivewed. 35 refs., 19 figs

Study on the causes and methods of influencing concrete deflection

Science.gov (United States)

Zhou, Ying; Zhou, Xiang; Tang, Jinyu

2017-09-01

Under the long-term effect of static load on reinforced concrete beam, the stiffness decreases and the deformation increases with time. Therefore, the calculation of deflection is more complicated. According to the domestic and foreign research results by experiment the flexural deflection of reinforced concrete, creep, age, the thickness of the protective layer, the relative slip, the combination of steel yielding factors of reinforced concrete deflection are summarized, analyzed the advantages and disadvantages of the traditional direct measurement of deflection, that by increasing the beam height, increasing the moment of inertia, ncrease prestressed reinforcement ratio, arching, reduce the load, and other measures to reduce the deflection of prestressed construction, improve the reliability of structure.

Effect of Salt Water in the Production of Concrete | Mbadike ...

African Journals Online (AJOL)

In this research work, the effect of salt water in the production of concrete was investigated. A total of ninety (90) concrete cubes were cast for compression strength test i.e. forty five cubes were cast using fresh water and the other forty five cubes were also cast using salt water. Similarly, a total of ninety (90) concrete beams ...

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....

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...

Induced radioactivity in Bevatron concrete radiation shielding blocks

International Nuclear Information System (INIS)

Moeller, G.C.; Donahue, R.J.

1994-07-01

The Bevatron accelerated protons up to 6.2 GeV and heavy ions up to 2.1 GeV/amu. It operated from 1954 to 1993. Radioactivity was induced in some concrete radiation shielding blocks by prompt radiation. Prompt radiation is primarily neutrons and protons that were generated by the Bevatron's primary beam interactions with targets and other materials. The goal was to identify the gamma-ray emitting nuclides (t 1/2 > 0.5 yr) that could be present in the concrete blocks and estimate the depth at which the maximum radioactivity presently occurs. It is shown that the majority of radioactivity was produced via thermal neutron capture by trace elements present in concrete. The depth of maximum thermal neutron flux, in theory, corresponds with the depth of maximum induced activity. To estimate the depth at which maximum activity occurs in the concrete blocks, the LAHET Code System was used to calculate the depth of maximum thermal neutron flux. The primary beam interactions that generate the neutrons are also modeled by the LAHET Code System

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

Directory of Open Access Journals (Sweden)

Hanbing Liu

2016-01-01

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

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)

Calibrating and validating a FE model for long-term behavior of RC beams

Directory of Open Access Journals (Sweden)

Tošić Nikola D.

2014-01-01

Full Text Available This study presents the research carried out in finding an optimal finite element (FE model for calculating the long-term behavior of reinforced concrete (RC beams. A multi-purpose finite element software DIANA was used. A benchmark test in the form of a simply supported beam loaded in four point bending was selected for model calibration. The result was the choice of 3-node beam elements, a multi-directional fixed crack model with constant stress cut-off, nonlinear tension softening and constant shear retention and a creep and shrinkage model according to CEB-FIP Model Code 1990. The model was then validated on 14 simply supported beams and 6 continuous beams. Good agreement was found with experimental results (within ±15%.

SU-E-T-90: Concrete Forward-Scatter Fractions for Radiotherapy Shielding Applications

International Nuclear Information System (INIS)

Tanny, S; Parsai, E

2014-01-01

Purpose: There is little instruction within the primary shielding guidance document NCRP 151 for vault designs where the primary beam intercepts the maze. We have conducted a Monte-Carlo study to characterize forward-scattered radiation from concrete barriers with the intent of quantifying what amount of additional shielding outside the primary beam is needed in this situation. Methods: We reproduced our vault in MCNP 5 and simulated spectra obtained from the literature and from our treatment planning system for 10 and 18 MV beams. Neutron and gamma-capture contributions were not simulated. Energy deposited was scored at isocenter in a water phantom, within various cells that comprised the maze, and within cells that comprised the vault door. Tracks were flagged that scattered from within the maze to the door and their contributions were tallied separately. Three different concrete mixtures found in the literature were simulated. An empirically derived analytic equation was used for comparison, utilizing patient scatter fractions to approximate the scatter from concrete. Results: Our simulated data confirms that maze-scattered radiation is a significant contribution to total photon dose at the door. It contributes between 20-35% of the photon shielding workload. Forward-scatter fractions for concrete were somewhat dependent on concrete composition and the relative abundance of higher-Z elements. Scatter fractions were relatively insensitive to changes in the primary photon spectrum. Analytic results were of the same magnitude as simulated results. Conclusions: Forward-scattered radiation from the maze barrier needs to be included in the photon workload for shielding calculations in non-standard vault designs. Scatter fractions will vary with concrete composition, but should be insensitive to spectral changes between machine manufacturers. Further plans for investigation include refined scatter fractions for various concrete compositions, scatter fraction

SU-E-T-90: Concrete Forward-Scatter Fractions for Radiotherapy Shielding Applications

Energy Technology Data Exchange (ETDEWEB)

Tanny, S; Parsai, E [University of Toledo Medical Center, Toledo, OH (United States)

2014-06-01

Purpose: There is little instruction within the primary shielding guidance document NCRP 151 for vault designs where the primary beam intercepts the maze. We have conducted a Monte-Carlo study to characterize forward-scattered radiation from concrete barriers with the intent of quantifying what amount of additional shielding outside the primary beam is needed in this situation. Methods: We reproduced our vault in MCNP 5 and simulated spectra obtained from the literature and from our treatment planning system for 10 and 18 MV beams. Neutron and gamma-capture contributions were not simulated. Energy deposited was scored at isocenter in a water phantom, within various cells that comprised the maze, and within cells that comprised the vault door. Tracks were flagged that scattered from within the maze to the door and their contributions were tallied separately. Three different concrete mixtures found in the literature were simulated. An empirically derived analytic equation was used for comparison, utilizing patient scatter fractions to approximate the scatter from concrete. Results: Our simulated data confirms that maze-scattered radiation is a significant contribution to total photon dose at the door. It contributes between 20-35% of the photon shielding workload. Forward-scatter fractions for concrete were somewhat dependent on concrete composition and the relative abundance of higher-Z elements. Scatter fractions were relatively insensitive to changes in the primary photon spectrum. Analytic results were of the same magnitude as simulated results. Conclusions: Forward-scattered radiation from the maze barrier needs to be included in the photon workload for shielding calculations in non-standard vault designs. Scatter fractions will vary with concrete composition, but should be insensitive to spectral changes between machine manufacturers. Further plans for investigation include refined scatter fractions for various concrete compositions, scatter fraction

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.)

Statistical Analysis of 3-Point Bending Properties of Polymer Concretes Made From Marble Powder Waste, Sand Grains, and Polyester Resin

Science.gov (United States)

Benzannache, N.; Bezazi, A.; Bouchelaghem, H.; Boumaaza, M.; Amziane, S.; Scarpa, F.

2018-01-01

The mechanical performance of concrete polymer beams subjected to 3-point bending was investigated. The polymer concrete incorporates marble powder waste and quarry sand. The results obtained showed that the type of sand, and amount of marble powder and sand aggregate affected the resistance of the polymer concrete beams significantly. The marble waste increased their bending strength by reducing the porosity of polymer concrete.

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.

The Recent Research on Bamboo Reinforced Concrete

Directory of Open Access Journals (Sweden)

Dewi Sri Murni

2017-01-01

Full Text Available The paper presents the last research on bamboo reinforced concrete in Brawijaya University Indonesia. Three kinds of structures studied in recent year, the mounting of pegs on reinforcement, the use of lightweight brick to reduce the weight of the beams, and the use the light weight aggregate for bamboo concrete composite frame. All that experiments overcome some problems exist in using bamboo as environmental acceptance structures.

Producing Durable Continuously Reinforced Concrete Pavement using Glass-ceramic Coated Reinforcing Steel

Science.gov (United States)

2010-02-01

reinforcement if the enamel is broken  Embedded cement grains hydrate if enamel is cracked to self-heal with the formation of calcium silicate hydrate Goal...Reinforced Concrete Pavement The 600% volume change in the iron to iron oxide formation put the concrete in tension and it cracks an spalls BUILDING...corrodes prematurely and delaminates the pavement  Moisture and chlorides can move through the natural porosity of concrete and the cracks in the

Effect of discrete glass fibers on the behavior of R.C. Beams exposed to fire

Directory of Open Access Journals (Sweden)

Magdy Riad

2017-08-01

Full Text Available The main objective of this paper is to investigate the effect of adding discrete glass fibers on the behavior of reinforced concrete (RC beams under different fire and cooling conditions. Eighteen beams with different concrete compressive strengths were tested to study the behavior of reinforced concrete (RC beams containing discrete glass fibers when exposed to different fire and cooling conditions. Nine beams were prepared from normal strength concrete (NSC with compressive strength equal to 35 MPa while the other beams were prepared from high strength concrete (HSC with compressive strength equal to 60 MPa. The beams contained different contents of discrete glass fibers. The modes of failure of tested specimens show that the crack patterns change according to fire condition and fiber content. Analysis of test results show that adding discrete glass fibers to NSC increased the residual stiffness of the tested specimens after firing and decreased the rate of the deflection gain during firing. Also adding fibers to concrete has a limited positive effect on the ultimate strength of the specimens compared to the control specimens. Its effect on deflection due to fire is more pronounced. Finally, the recommended optimum ratio of discrete glass fibers is not more than 0.5% of the total concrete weight.

Short and long term behaviour of externally bonded fibre reinforced polymer laminates with bio-based resins for flexural strengthening of concrete beams

Science.gov (United States)

McSwiggan, Ciaran

The use of bio-based resins in composites for construction is emerging as a way to reduce of embodied energy produced by a structural system. In this study, two types of bio-based resins were explored: an epoxidized pine oil resin blend (EP) and a furfuryl alcohol resin (FA) derived from corn cobs and sugar cane. Nine large-scale reinforced concrete beams strengthened using externally bonded carbon and glass fibre reinforced bio-based polymer (CFRP and GFRP) sheets were tested. The EP resin resulted in a comparable bond strength to conventional epoxy (E) when used in wet layup, with a 7% higher strength for CFRP. The FA resin, on the other hand, resulted in a very weak bond, likely due to concrete alkalinity affecting curing. However, when FA resin was used to produce prefabricated cured CFRP plates which were then bonded to concrete using conventional epoxy paste, it showed an excellent bond strength. The beams achieved an increase in peak load ranging from 18-54% and a 9-46% increase in yielding load, depending on the number of FRP layers and type of fibres and resin. Additionally, 137 concrete prisms with a mid-span half-depth saw cut were used to test CFRP bond durability, and 195 CFRP coupons were used to examine tensile strength durability. Specimens were conditioned in a 3.5% saline solution at 23, 40 or 50°C, for up to 240 days. Reductions in bond strength did not exceed 15%. Bond failure of EP was adhesive with traces of cement paste on CFRP, whereas that of FA was cohesive with a thicker layer of concrete on CFRP, suggesting that the bond between FA and epoxy paste is excellent. EP tension coupons had similar strength and modulus to E resin, whereas FA coupons had a 9% lower strength and 14% higher modulus. After 240 days of exposure, maximum reductions in tensile strength were 8, 19 and 10% for EP, FA and E resins, respectively. Analysis of Variance (ANOVA) was also performed to assess the significance of the reductions observed. High degrees of

Mechanical properties of polymer-modified porous concrete

Science.gov (United States)

Ariffin, N. F.; Jaafar, M. F. Md.; Shukor Lim, N. H. Abdul; Bhutta, M. A. R.; Hussin, M. W.

2018-04-01

In this research work, polymer-modified porous concretes (permeable concretes) using polymer latex and redispersible polymer powder with water-cement ratio of 30 %, polymer-cement ratios of 0 to 10 % and cement content of 300 kg/m3 are prepared. The porous concrete was tested for compressive strength, flexural strength, water permeability and void ratio. The cubes size of specimen is 100 mm ×100 mm × 100 mm and 150 mm × 150 mm × 150 mm while the beam size is 100 mm × 100 mm × 500 mm was prepared for particular tests. The tests results show that the addition of polymer as a binder to porous concrete gives an improvement on the strength properties and coefficient of water permeability of polymer-modified porous concrete. It is concluded from the test results that increase in compressive and flexural strengths and decrease in the coefficient of water permeability of the polymer-modified porous concrete are clearly observed with increasing of polymer-cement ratio.

Performance of "Waterless Concrete"

Science.gov (United States)

Toutanji, H. A.; Grugel, R. N.

2009-01-01

Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in a lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and, by oxidation of the soil, iron and sulfur can be produced. Sulfur concrete specimens were cycled between liquid nitrogen (approx.]91 C) and room temperature (^21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (^21 C) and ^-101 C. Test results showed that due to temperature cycling, the compressive strength of cycled specimens was 20% of those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibres. The lunar regolith simulant was melted in a 25 cc Pt- Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to i hour. Glass fibres and small rods were pulled from the melt. The glass fibres were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Beams strengthened with glass fibres showed to exhibit an increase in the flexural strength by as much as 45%.

The design of an instrumented rebar for assessment of corrosion in cracked reinforced concrete

DEFF Research Database (Denmark)

Pease, Bradley Justin; Geiker, Mette Rica; Stang, Henrik

2011-01-01

rebar with 17 electronically isolated corrosion sensors. Instrumented and standard rebars were cast into concrete beams and bending cracks were induced and held open using steel frames. Epoxy impregnation was used to assess and compare cracks in the concrete around the instrumented and standard rebar...... between the steel and concrete. Cracked beams with cast-in instrumented and standard rebars were ponded with a 10\\% chloride solution and the open circuit corrosion potential (OCP) of the 17 sensors was measured for up to 62 days. Measurements from the individual sensors indicate when and where active...

Strengthening of non-seismically detailed reinforced concrete beam ...

Indian Academy of Sciences (India)

work and in order to carry the anchorages sufficiently away from the column face ..... Owing to the strengthening application, joint shear stress–strain behaviour was ..... structures (ACI 352R-02), MI: American Concrete Institute, Farmington Hills.

Finite element analysis of FRP-strengthened RC beams

Directory of Open Access Journals (Sweden)

Teeraphot Supaviriyakit

2004-05-01

Full Text Available This paper presents a non-linear finite element analysis of reinforced concrete beam strengthened with externally bonded FRP plates. The finite element modeling of FRP-strengthened beams is demonstrated. Concrete and reinforcing bars are modeled together as 8-node isoparametric 2D RC element. The FRP plate is modeled as 8-node isoparametric 2D elastic element. The glue is modeled as perfect compatibility by directly connecting the nodes of FRP with those of concrete since there is no failure at the glue layer. The key to the analysis is the correct material models of concrete, steel and FRP. Cracks and steel bars are modeled as smeared over the entire element. Stress-strain properties of cracked concrete consist of tensile stress model normal to crack, compressive stress model parallel to crack and shear stress model tangential to crack. Stressstrain property of reinforcement is assumed to be elastic-hardening to account for the bond between concrete and steel bars. FRP is modeled as elastic-brittle material. From the analysis, it is found that FEM can predict the load-displacement relation, ultimate load and failure mode of the beam correctly. It can also capture the cracking process for both shear-flexural peeling and end peeling modes similar to the experiment.

High-performance heavy concrete as a multi-purpose shield

International Nuclear Information System (INIS)

Mortazavi, S. M. J.; Mosleh-Shirazi, M. A.; Roshan-Shomal, P.; Raadpey, N.; Baradaran-Ghahfarokhi, M.

2010-01-01

Concrete has long been used as a shield against high-energy photons and neutrons. In this study, colemanite and galena minerals (CoGa) were used for the production of an economical high-performance heavy concrete. To measure the gamma radiation attenuation of the CoGa concrete samples, they were exposed to a narrow beam of gamma rays emitted from a 60 Co radiotherapy unit. An Am-Be neutron source was used for assessing the shielding properties of the samples against neutrons. The compression strengths of both types of concrete mixes (CoGa and reference concrete) were investigated. The range of the densities of the heavy concrete samples was 4100-4650 kg m -3 , whereas it was 2300-2600 kg m -3 in the ordinary concrete reference samples. The half-value layer of the CoGa concrete samples for 60 Co gamma rays was 2.49 cm; much less than that of ordinary concrete (6.0 cm). Moreover, CoGa concrete samples had a 10% greater neutron absorption compared with reference concrete. (authors)

Concrete Crack Measurement and Analysis Based on Terrestrial Laser Scanning Technology

Directory of Open Access Journals (Sweden)

Xiangyang Xu

2015-03-01

Full Text Available Terrestrial laser scanning (TLS has become one of the potential technologies for an object three-dimensional (3D information acquisition. The using vibration analysis for early detection of cracks has gained popularity over the years and in the last decade substantial progress has been made in that direction. However, the crack detection using TLS is also a good method. In the experimental part of this study, the effect of crack width and location on modal properties of the beam was investigated. The recent paper provides a method for automatic concrete cracks detection from the data that was obtained by TLS. The method of cracks detection is achieved by six steps. The objective of this study is to analyze the crack of concrete beams both experimentally and using MATLAB analysis. Besides this, information about the width, location and percentage of cracks in cracked concrete beams can be obtained using this technique.

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.

Improvements of PKU PMECRIS for continuous hundred hours CW proton beam operation

International Nuclear Information System (INIS)

Peng, S. X.; Ren, H. T.; Zhang, T.; Zhang, J. F.; Xu, Y.; Guo, Z. Y.; Zhang, A. L.; Chen, J. E.

2016-01-01

In order to improve the source stability, a long term continuous wave (CW) proton beam experiment has been carried out with Peking University compact permanent magnet 2.45 GHz ECR ion source (PKU PMECRIS). Before such an experiment a lot of improvements and modifications were completed on the source body, the Faraday cup and the PKU ion source test bench. At the beginning of 2015, a continuous operation of PKU PMECRIS for 306 h with more than 50 mA CW beam was carried out after success of many short term tests. No plasma generator failure or high voltage breakdown was observed during that running period and the proton source reliability is near 100%. Total beam availability, which is defined as 35-keV beam-on time divided by elapsed time, was higher than 99% [S. X. Peng et al., Chin. Phys. B 24(7), 075203 (2015)]. A re-inspection was performed after another additional 100 h operation (counting time) and no obvious sign of component failure was observed. Counting the previous source testing time together, this PMECRs longevity is now demonstrated to be greater than 460 h. This paper is mainly concentrated on the improvements for this long term experiment

Improvements of PKU PMECRIS for continuous hundred hours CW proton beam operation

Science.gov (United States)

Peng, S. X.; Zhang, A. L.; Ren, H. T.; Zhang, T.; Zhang, J. F.; Xu, Y.; Guo, Z. Y.; Chen, J. E.

2016-02-01

In order to improve the source stability, a long term continuous wave (CW) proton beam experiment has been carried out with Peking University compact permanent magnet 2.45 GHz ECR ion source (PKU PMECRIS). Before such an experiment a lot of improvements and modifications were completed on the source body, the Faraday cup and the PKU ion source test bench. At the beginning of 2015, a continuous operation of PKU PMECRIS for 306 h with more than 50 mA CW beam was carried out after success of many short term tests. No plasma generator failure or high voltage breakdown was observed during that running period and the proton source reliability is near 100%. Total beam availability, which is defined as 35-keV beam-on time divided by elapsed time, was higher than 99% [S. X. Peng et al., Chin. Phys. B 24(7), 075203 (2015)]. A re-inspection was performed after another additional 100 h operation (counting time) and no obvious sign of component failure was observed. Counting the previous source testing time together, this PMECRs longevity is now demonstrated to be greater than 460 h. This paper is mainly concentrated on the improvements for this long term experiment.

Improvements of PKU PMECRIS for continuous hundred hours CW proton beam operation

Energy Technology Data Exchange (ETDEWEB)

Peng, S. X., E-mail: sxpeng@pku.edu.cn; Ren, H. T.; Zhang, T.; Zhang, J. F.; Xu, Y.; Guo, Z. Y. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Zhang, A. L.; Chen, J. E. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

2016-02-15

In order to improve the source stability, a long term continuous wave (CW) proton beam experiment has been carried out with Peking University compact permanent magnet 2.45 GHz ECR ion source (PKU PMECRIS). Before such an experiment a lot of improvements and modifications were completed on the source body, the Faraday cup and the PKU ion source test bench. At the beginning of 2015, a continuous operation of PKU PMECRIS for 306 h with more than 50 mA CW beam was carried out after success of many short term tests. No plasma generator failure or high voltage breakdown was observed during that running period and the proton source reliability is near 100%. Total beam availability, which is defined as 35-keV beam-on time divided by elapsed time, was higher than 99% [S. X. Peng et al., Chin. Phys. B 24(7), 075203 (2015)]. A re-inspection was performed after another additional 100 h operation (counting time) and no obvious sign of component failure was observed. Counting the previous source testing time together, this PMECRs longevity is now demonstrated to be greater than 460 h. This paper is mainly concentrated on the improvements for this long term experiment.

29 CFR 1926.704 - Requirements for precast concrete.

Science.gov (United States)

2010-07-01

... 29 Labor 8 2010-07-01 2010-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural framing...

Concrete durability

OpenAIRE

Gaspar Tébar, Demetrio

1991-01-01

The evidence that the concrete is not a material for ever was noticed from the beginning of its industrial use. In the present work, the author describes the studies carried out during the last century and the early ages of the present one, mainly devoted to the study of the durability in sea water. At the present days, and in spite of the numerous papers published from then, the study of the concrete durability continues focusing the research priorities and economical resources of rese...

Experimental investigation of the relation between damage at the concrete-steel interface and initiation of reinforcement corrosion in plain and fibre reinforced concrete

International Nuclear Information System (INIS)

Michel, A.; Solgaard, A.O.S.; Pease, B.J.; Geiker, M.R.; Stang, H.; Olesen, J.F.

2013-01-01

Highlights: •Cracked plain and steel fibre reinforced concrete flexural beams were investigated. •“Instrumented rebars” provided location- and time-dependent corrosion measurements. •Interfacial condition can be used as a reliable indicator to quantify the risk of corrosion. •Simulated interfacial conditions are in very good agreement with all experimental observations. -- Abstract: Cracks in covering concrete are known to hasten initiation of steel corrosion in reinforced concrete structures. To minimise the impact of cracks on the deterioration of reinforced concrete structures, current approaches in (inter)national design codes often limit the concrete surface crack width. Recent investigations however, indicate that the concrete-reinforcement interfacial condition is a more fundamental criterion related to reinforcement corrosion. This work investigates the relation between macroscopic damage at the concrete-steel interface and corrosion initiation of reinforcement embedded in plain and fibre reinforced concrete. Comparisons of experimental and numerical results indicate a strong correlation between corrosion initiation and interfacial condition

Shielding properties of the ordinary concrete loaded with micro- and nano-particles against neutron and gamma radiations.

Science.gov (United States)

Mesbahi, Asghar; Ghiasi, Hosein

2018-06-01

The shielding properties of ordinary concrete doped with some micro and nano scaled materials were studied in the current study. Narrow beam geometry was simulated using MCNPX Monte Carlo code and the mass attenuation coefficient of ordinary concrete doped with PbO 2 , Fe 2 O 3 , WO 3 and H 4 B (Boronium) in both nano and micro scales was calculated for photon and neutron beams. Mono-energetic beams of neutrons (100-3000 keV) and photons (142-1250 keV) were used for calculations. The concrete doped with nano-sized particles showed higher neutron removal cross section (7%) and photon attenuation coefficient (8%) relative to micro-particles. Application of nano-sized material in the composition of new concretes for dual protection against neutrons and photons are recommended. For further studies, the calculation of attenuation coefficients of these nano-concretes against higher energies of neutrons and photons and different particles are suggested. Copyright © 2018 Elsevier Ltd. All rights reserved.

Study of measurement method of tritium induced in concrete of high-energy proton accelerator facilities

International Nuclear Information System (INIS)

Ohtsuka, N.; Ishihama, S.; Kunifuda, T.; Hayasaka, N.; Miura, T.

2001-01-01

Various long-loved radionuclides, 3 H, 7 Be, 22 Na, 51 Cr, 54 Mn, 56 Co, 57 Co, 60 Co, 134 Cs, 152 Eu and 154 Eu, have been produced in the shielding concrete of high energy proton accelerator facility through both nuclear spallation reactions and thermal neutron capture reactions of concrete elements, during machine operation. Tritium is the most important nuclide from the radiation protection. There were, however, few measurements of tritium concentration induced in the shielding concrete. In this study, the conditions of measurement method of tritium concentration induced in shielding concrete have been investigated using the activated shielding concrete of the 12 GeV proton beam-line tunnel at KEK and the standard rock (JG-1) irradiated of thermal neutron at the reactor. And the depth profiles of tritium induced in the shielding concrete of slow extracted proton beam line at KEK were determined using this method. (author)

Flexural Behavior of RC Members Using Externally Bonded Aluminum-Glass Fiber Composite Beams

Directory of Open Access Journals (Sweden)

Ki-Nam Hong

2014-03-01

Full Text Available This study concerns improvement of flexural stiffness/strength of concrete members reinforced with externally bonded, aluminum-glass fiber composite (AGC beams. An experimental program, consisting of seven reinforced concrete slabs and seven reinforced concrete beams strengthened in flexure with AGC beams, was initiated under four-point bending in order to evaluate three parameters: the cross-sectional shape of the AGC beam, the glass fiber fabric array, and the installation of fasteners. The load-deflection response, strain distribution along the longitudinal axis of the beam, and associated failure modes of the tested specimens were recorded. It was observed that the AGC beam led to an increase of the initial cracking load, yielding load of the tension steels and peak load. On the other hand, the ductility of some specimens strengthened was reduced by more than 50%. The A-type AGC beam was more efficient in slab specimens than in beam specimens and the B-type was more suitable for beam specimens than for slabs.

Properties of Concrete partially replaced with Coconut Shell as Coarse aggregate and Steel fibres in addition to its Concrete volume

Science.gov (United States)

Kalyana Chakravarthy, P. R.; Janani, R.; Ilango, T.; Dharani, K.

2017-03-01

Cement is a binder material with various composition of Concrete but instantly it posses low tensile strength. The study deals with mechanical properties of that optimized fiber in comparison with conventional and coconut shell concrete. The accumulation of fibers arbitrarily dispersed in the composition increases the resistance to cracking, deflection and other serviceability conditions substantially. The steel fiber in extra is one of the revision in coconut shell concrete and the outcome of steel fiber in coconut shell concrete was to investigate and compare with the conventional concrete. For the given range of steel fibe from 0.5 to 2.0%, 12 beams and 36 cylindrical specimens were cast and tested to find the mechanical properties like flexural strength, split tensile, impact resistance and the modulus of elasticity of both conventional and coconut shell concrete has been studied and the test consequences are compared with the control concrete and coconut shell concrete for M25 Grade. It is fulfilled that, the steel fibers used in this venture has shown significant development in all the properties of conventional and coconut shell concrete while compared to controlled conventional and coconut shell concrete like, Flexural strength by 6.67 % for 1.0 % of steel fiber in conventional concrete and by 5.87 % for 1.5 % of steel fiber in coconut shell concrete.