Shear Strength Of Concrete Beams Research Articles

Shear strength of RC beam made with recycled brick aggregate

Shear strength of reinforced concrete (RC) beams made with recycled brick aggregate (RBA) was investigated. As control specimens, RC beams made with virgin brick aggregate (BA) were also investigated. For the investigation, 32 reinforced concrete beams of size 200 mm by 300 mm by 2100 mm and 200 mm by 300 mm by 2400 mm were made. The variables were steel ratio (0.82% and 1.23%), shear span to depth ratio (2.04 and 2.45), and compressive strength of concrete (24 MPa and 29 MPa). In the shear span of the beam specimens, shear reinforcements were not provided and the beams were designed to ensure shear failure according to ACI 318-14. Shear strength of the beams without shear reinforcement was evaluated by four-point loading test. Shear strength of concrete beams was also evaluated by using different codes and fracture mechanics approaches. These results were compared with the experimental results. The results obtained from this study were also compared with the shear database. It is revealed that the RC beams made with RBA show similar shear strength as of RC beams made with virgin BA. Existing code provisions, as well as fracture mechanics approach, can be used for predicting shear strength of concrete beams made with RBA.

A compression field based model to assess the shear strength of concrete beams reinforced with longitudinal FRP bars

The behaviour of FRP reinforced beams has not yet been fully understood. Therefore, current codes of practice in general tend to provide a high margin of safety when assessing the shear strength of FRP reinforced beams without web reinforcement. This may cause reinforcement congestion and increases the total cost of construction. To address this issue, a compression field based model to assess the shear strength of FRP reinforced concrete beams without web reinforcement is presented herein. The model aims to provide more accurate assessment than existing design provisions and formulas. The accuracy of the proposed model was assessed and compared with the most recent and relevant design provisions using a data base of 164 specimens from literature. The proposed model has yielded more accurate and consistent results in comparison with the models used in this study with a mean experimental to predicted value of 1.04 and a standard deviation of 0.21. Furthermore, a new hypothesis to explain the shear failure is also presented. Finally, the ability of the proposed model as well as the models used in this study to represent the parameters that control the shear strength was investigated using a parametric study.

Modeling the shear strength of concrete beams reinforced with CFRP bars under unsymmetrical loading

ABSTRACTThis study presents the development of a nonlinear finite element (FE) model that is capable of simulating the response and predicting the shear strength of concrete beams reinforced with carbon fiber-reinforced polymer (CFRP) bars. More specifically, this paper investigates the effect of unsymmetrical loading that creates two shear span-to-depth (a/d) ratios within the beam specimen and further complicates shear response. It is observed that the predicted FE results are in close agreement with the measured experimental results. Thus, it can be concluded that the developed models can be used to simulate the behavior of concrete beams reinforced with CFRP bars.

Laminated element analysis to predict the shear strength of concrete beams under distributed and concentrated loads

In the present study, an advanced analytical method was developed to evaluate the shear strength of slender concrete beams under distributed and concentrated transverse loads. The concrete shear capacity of the concrete beams is mainly provided by the compression zone of intact concrete since the tension zone of the concrete beams is severely damaged by flexural cracks before shear failure. The concrete shear capacity is evaluated based on concrete material failure criteria addressing combined compressive normal and shear stresses in the compression zone along the critical shear crack surface. For complete analysis, laminated elements are applied to take into account the stress variation in each location of the compression zone. The proposed analytical method can be used not only to predict the shear strength, but also the location and the angle of the critical shear crack. The shear strength is predicted using the proposed method, and the results are compared to those of an experiment, covering a wide range of design parameters. In addition, analytical studies were performed for analytical beam models subjected to distributed and concentrated loads. Based on the analysis results, the effect of various parameters including the loading type (distributed and concentrated transverse loads) on the shear strength and the critical shear crack was investigated.

Prediction of shear strength of reinforced concrete beams without shear reinforcement considering bond action of longitudinal reinforcements

The shear strength of concrete beams without shear reinforcement is determined by the shear strength of the concrete compressive zone, the shear force due to dowel action, and the shear force due to aggregate interlock. The existing models and formulas to predict shear strength of concrete beams based on geometric theories related to beam action and arch action that only consider shear resistance in relation to arch action while neglecting dowel action and aggregate interlock have been unable to accurately explain the shear resistance mechanism. This study proposes a more rational shear strength prediction formula that reflects the contribution of each component by linking the bond characteristics of longitudinal reinforcements based on the size effect and stress changes in longitudinal reinforcement to dowel action. The precision of the proposed formula was assessed by carrying out experiments with the shear-span-to-depth ratio ( a/ d = 2.0, 2.5, 3.0, and 4.0) as a variable. A ratio of shear bond failure distance to effective depth and the shear strength of concrete beams without shear reinforcement were compared to those obtained from the proposed prediction formula. As a result, it was confirmed that the proposed formula gives rational predictions for each shear contribution and exhibits a high accuracy compared to previous experimental results.

Comparison of main models for size effect on shear strength of reinforced and prestressed concrete beams

AbstractThis paper presents a critical comparison of the existing code provisions for the shear strength of concrete beams. The comparison is based on the computerized filtering‐out of the inevitable statistical bias from the available multivariate database on shear strength, on an examination of the predicted size effects on shear strength and their underlying hypotheses and on the results of recent high‐fidelity numerical simulations of shear failure. In addition to examining the existing models, the present comparison also provides several key considerations for testing the scientific soundness of any model of shear failure in concrete beams, which is necessary for future revisions to the design code provisions.

Parametric Study of Shear Strength of Concrete Beams Reinforced with FRP Bars

Fibre Reinforced Polymer (FRP) bars are being widely used as internal reinforcement in structural elements in the last decade. The corrosion resistance of FRP bars qualifies its use in severe and marine exposure conditions in structures. A total of eight concrete beams longitudinally reinforced with FRP bars were cast and tested over shear span to depth ratio of 0.5 and 1.75. The shear strength test data of 188 beams published in various literatures were also used. The model originally proposed by Indian Standard Code of practice for the prediction of shear strength of concrete beams reinforced with steel bars IS:456 (Plain and reinforced concrete, code of practice, fourth revision. Bureau of Indian Standards, New Delhi, 2000) is considered and a modification to account for the influence of the FRP bars is proposed based on regression analysis. Out of the 196 test data, 110 test data is used for the regression analysis and 86 test data is used for the validation of the model. In addition, the shear strength of 86 test data accounted for the validation is assessed using eleven models proposed by various researchers. The proposed model accounts for compressive strength of concrete (fck), modulus of elasticity of FRP rebar (Ef), longitudinal reinforcement ratio (ρf), shear span to depth ratio (a/d) and size effect of beams. The predicted shear strength of beams using the proposed model and 11 models proposed by other researchers is compared with the corresponding experimental results. The mean of predicted shear strength to the experimental shear strength for the 86 beams accounted for the validation of the proposed model is found to be 0.93. The result of the statistical analysis indicates that the prediction based on the proposed model corroborates with the corresponding experimental data.

Design for shear strength of concrete beams longitudinally reinforced with GFRP bars

In this paper, a model for the evaluation of shear strength of fibre reinforced polymer (FRP)-reinforced concrete beams is given. The survey of literature indicates that the FRP reinforced beams tested with shear span to depth ratio less than or equal to 1.0 is limited. In this study, eight concrete beams reinforced with GFRP rebars without stirrups are cast and tested over shear span to depth ratio of 0.5 and 1.75. The concrete compressive strength is varied from 40.6 to 65.3 MPa. The longitudinal reinforcement ratio is varied from 1.16 to 1.75. The experimental shear strength and load-deflection response of the beams are determined and reported in this paper. A model is proposed for the prediction of shear strength of beams reinforced with FRP bars. The proposed model accounts for compressive strength of concrete, modulus of FRP rebar, longitudinal reinforcement ratio, shear span to depth ratio and size effect of beams. The shear strength of FRP reinforced concrete beams predicted using the proposed model is found to be in better agreement with the corresponding test data when compared with the shear strength predicted using the eleven models published in the literature. Design example of FRP reinforced concrete beam is also given in the appendix.

Design for shear strength of concrete beams longitudinally reinforced with GFRP bars

In this paper, a model for the evaluation of shear strength of fibre reinforced polymer (FRP)-reinforced concrete beams is given. The survey of literature indicates that the FRP reinforced beams tested with shear span to depth ratio less than or equal to 1.0 is limited. In this study, eight concrete beams reinforced with GFRP rebars without stirrups are cast and tested over shear span to depth ratio of 0.5 and 1.75. The concrete compressive strength is varied from 40.6 to 65.3 MPa. The longitudinal reinforcement ratio is varied from 1.16 to 1.75. The experimental shear strength and load-deflection response of the beams are determined and reported in this paper. A model is proposed for the prediction of shear strength of beams reinforced with FRP bars. The proposed model accounts for compressive strength of concrete, modulus of FRP rebar, longitudinal reinforcement ratio, shear span to depth ratio and size effect of beams. The shear strength of FRP reinforced concrete beams predicted using the proposed model is found to be in better agreement with the corresponding test data when compared with the shear strength predicted using the eleven models published in the literature. Design example of FRP reinforced concrete beam is also given in the appendix.

Evaluation of Shear Strength of Concrete Beams with GFRP Reinforcement

This research presents an experimental study related to the shear behavior of simply supported reinforced concrete beams reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Four concrete beams reinforced with GFRP bars and four control concrete beams reinforced with steel bars were tested until failure. In order to realize the occurrence of shear failure, all tested beams were designed with longitudinal reinforcement only and without shear reinforcement. The test variables used in this study were the concrete strength, f'c, and longitudinal reinforcement ratio, ρ. The crack patterns, location of the diagonal crack and angle of the diagonal crack were also observed during the test. The shear design equations obtained from the codes and references were used to evaluate the data obtained from the test. Finally, based on the data obtained from experimental and theoretical analysis, comments and recommendation on the shear strength equations were suggested.

Prediction of Ultimate Shear Capacity of Reinforced Normal and High Strength Concrete Beams Without Stirrups Using Fuzzy Logic

The main objective of the present study is to predict the ultimate shear capacity of reinforced concrete beams no contains web reinforcement. Fuzzy inference system (FIS) was developed to predict the shear strength of these beams using Mamadani method. Fuzzy inference system (FIS) model has been proved to be very effective in predicting the ultimate shear strength of concrete beams without stirrups. The regression analysis between the output of the FIS model and the corresponding target, R2 = 0.9969 and 0.9509 for training and testing data, respectively. Based on FIS results, a parametric analysis was carried out to study the influence of each parameter affecting the shear strength of beams without stirrups and these results are compared with the provisions of ACI-code.

Effect of Fly Ash on the Shear Strength of Concrete Beams Without Shear Reinforcement

Abstract The following paper presents the results of an experimental investigation of the shear strength of full-scale reinforced concrete beams constructed with both high-volume fly ash concrete (HVFAC)—concrete with at least 50 % of the cement replaced with fly ash—and conventional concrete (CC). This study includes two HVFAC mixes and one CC mix. The two HVFAC mixes are identical except for the amount of Class C fly ash replacement of cement, with one mix replacing 50 % of the cement with fly ash and the other replacing 70 %. The test matrix included 18 beams—six for each concrete type—with three different longitudinal reinforcement ratios. The test results were compared to the shear provisions of both U.S. and international design codes, including the design provisions from Australia, Canada, Europe, and Japan. Furthermore, the shear strengths of the beams were evaluated based on fracture mechanics approaches, modified compression field theory (MCFT), and a shear database of CC specimens. Results of this study show that the HVFAC mixes possess comparable shear strength with the CC.

Shear strength model for fibre reinforced polymer shear reinforced concrete beams

In the present study, an integrated shear design method was developed to evaluate the shear strength of concrete beams with and without fibre reinforced polymer shear reinforcement. The contributions of fibre reinforced polymer steel re-bars, and concrete to shear strength were defined separately. The shear strength contribution of a concrete cross-section was defined by the strain-based shear strength model developed in the previous study. In the model, the shear strength of the concrete cross-section was evaluated based on the material failure criteria of the concrete subjected to the compressive normal stress and shear stress. In this study, the ratio of FRP effective strain to ultimate strain needed to evaluate the fibre reinforced polymer shear strength contribution was defined based on the existing test results. The proposed strength model was verified by comparing its prediction to prior test results. In the comparison, it was found that the proposed method accurately predicted the shear strengths of the test specimens for both FRP shear reinforced and unreinforced concrete beams.

Effect of High-Volume Fly Ash on Shear Strength of Concrete Beams

Every year concrete production exceeds 6.5 billion tons worldwide, nearly 1 ton for every man, woman, and child on the planet. In fact, concrete is used 10 times more than any other building material in the world, primarily because of its incredible versatility, availability, and relatively low cost. Unfortunately, the production of portland cement—the key ingredient in concrete—generates approximately a pound of carbon dioxide for every pound of cement produced. One method of reducing concrete's carbon footprint is to replace a significant amount of the cement with fly ash, a by-product of coal-burning thermal power stations. This paper presents the results of an investigation of the shear strength of full-scale reinforced concrete beams constructed with both high-volume fly ash concrete (concrete with at least 50% of the cement replaced with fly ash) and conventional concrete. A test matrix of 16 beams included 12 beams without shear reinforcing and four with shear reinforcing in the form of stirrups; eight beams were constructed from each concrete type. Evaluation of the test results included a comparison with U.S. and international design codes, an examination based on AASHTO load and resistance factor design provisions of the longitudinal strains and angle of the critical flexure-shear crack, a comparison with an extensive database of shear tests on conventional concrete, and a detailed statistical study. The results revealed that the high-volume fly ash concrete beams had higher shear strengths than the conventional concrete beams tested in this investigation.

Shear strength of concrete beams cast with self-compacting concrete containing different fillers and coarse aggregates

An experimental investigation was conducted to evaluate the shear strength provided by different self-compacting concrete mixes proportioned using different fillers and coarse aggregates. A total of 28 simple beams without shear reinforcement were tested in flexure. The test parameters included the use of gravel versus crushed dolomite as coarse aggregates, the amount of longitudinal reinforcement, and the composition and percentage of fillers. Dolomite stone powder with either silica fume or fly ash was used as fillers replacing cement aiming at reducing the cost of the mix and obtaining better performance. The test results indicated that the overall structural performance in terms of cracking pattern and shear strength was comparable in all mixes. While the dolomite beams sustained higher ultimate shear loads, the normalized shear strength of most of the gravel beams were higher compared to their dolomite counterparts due to the capability of gravel beams to develop interlocking mechanisms and post-cracking shear resistance compensating the influence of the lower compressive strength.

Optimization of existing equations using a new Genetic Programming algorithm: Application to the shear strength of reinforced concrete beams

A method based on Genetic Programming (GP) to improve previously known empirical equations is presented. From a set of experimental data, the GP may improve the adjustment of such formulas through the symbolic regression technique. Through a set of restrictions, and the indication of the terms of the expression to be improved, GP creates new individuals. The methodology allows us to study the need of including new variables in the expression. The proposed method is applied to the shear strength of concrete beams. The results show a marked improvement using this methodology in relation to the classic GP and international code procedures.

Predicting the Shear Strength of Concrete Beams Reinforced with Fiber Reinforced Polymer Bars Using Adaptive Neuro-Fuzzy Inference System

Predicting the Shear Strength of Concrete Beams Reinforced with Fiber Reinforced Polymer Bars Using Adaptive Neuro-Fuzzy Inference System

Prediction of the Shear Strength of Concrete Beams Reinforced with Fiber Reinforced Polymer Bars Using Artificial Neural Networks Model

Prediction of the Shear Strength of Concrete Beams Reinforced with Fiber Reinforced Polymer Bars Using Artificial Neural Networks Model

콘크리트 도로교 설계를 위한 저항계수 체계별 신뢰도 분석

As a background study to apply the reliability-based resistance factors to the domestic concrete bridge design code, a comparative study is conducted for the design results and the reliability indexes obtained by adopting different resistance factor formats to yield the design strength of concrete structures. The design results which are calculated by applying the section resistance factors of the current domestic design code and the material resistance factors of Eurocode are compared for the concrete beam bridge. The reliability index is calculated by considering the uncertainties involved in material, dimension and strength equation during the design procedure to get the strength of concrete structure. Also, the sensitivity analysis is performed to figure out which design variables have great impact on the reliability index. The resistance factors of the current domestic bridge design code, AASHTO LRFD and Eurocode are applied to the bridge design for flexure and shear strength and the results show that the resistance factors of the domestic code give the largest reliability indexes. It is observed that the probabilistic distribution of the live load makes difference for the reliability index and the yield strength of reinforcing steel and the live load have great impact on the reliability of both flexural and shear strength of concrete beam through the sensitivity analysis.

FRP 전단 보강 콘크리트 보의 전단강도 모델

이 연구에서는 FRP 전단보강 및 무보강 콘크리트 보의 전단강도를 정확하게 평가하기 위하여 통합전단설계방법을 개발하였다. 이를 위하여, FRP의 전단강도 기여분과 콘크리트의 전단강도 기여분을 각각 정의하였다. 기존의 FRP 전단강도 평가모델과 실험 결과를 비교 분석한 결과, Triantafillou의 FRP 전단강도 평가모델이 FRP의 유효변형률과 전단강도의 추정이 우수하므로 Triantafillou의 모델을 이용하여 FRP의 전단강도 기여분을 정의하였다. 콘크리트 전단강도 기여분은 선행 연구에서 제안된 변형도 기반 전단강도모델을 이용하여 정의하였다. 콘크리트 단면의 압축대에 작용하는 압축응력과 전단응력의 상관관계를 고려하기 위하여 콘크리트 재료파괴기준을 이용하여 콘크리트 전단강도 기여분을 산정하였다. 제안한 설계방법은 기존 실험 연구 결과와 비교하여 유효성을 검증하였다. 비교 결과 제안한 설계방법은 다양한 설계변수 범위에서 FRP 전단보강 및 무보강 콘크리트 보의 전단강도를 정확하게 평가하는 것으로 나타났다.