scholarly journals Nonlinear Finite Element Analysis Formulation for Shear in Reinforced Concrete Beams

2019 ◽  
Vol 9 (17) ◽  
pp. 3503 ◽  
Author(s):  
Sang-Ho Kim ◽  
Sun-Jin Han ◽  
Kang Kim
Keyword(s):  
Shear Stress ◽  
Reinforced Concrete ◽  
Stress Function ◽  
Shear Stresses ◽  
Rc Beams ◽  
Test Results ◽  
Proposed Model ◽  
Load Displacement ◽  
Shear Stress Function ◽  
Column Element

This study suggests a novel beam-column element formulation that utilizes an equilibrium-driven shear stress function. The beam shear is obtained from the bi-axial states of micro-planes, through matrix condensation and zero vertical traction assumptions. This properly remedies the shear stiffening of a one-dimensional beam-column element, keeping its degrees of freedom to a minimum. For verification of the proposed method, a total of seven shear test results of reinforced concrete (RC) beams were collected from the literature, in which the key variables were the reinforcement ratio, the presence of shear reinforcement, and section shape. The advantages are clearly shown in the shear stresses distributions being accurately described and the global load-displacement relations being successfully obtained and matching well with various test results. The proposed model shows satisfactory descriptions of the monotonic load-displacement response of the RC beams failing in multiple modes that vary from diagonal-tension to flexural-compression. In addition, more accurate and reliable information of sectional responses including sectional shear deformation and stresses is collected, leading to better prediction of a potential shear failure mode. Finally, the advantages of the proposed model are demonstrated by comparing the analysis results of an RCT-beam by using the different shear assumptions that include the constant and parabolic shear strains, constant shear flow, and the proposed shear stress function.

Analysis of Premature Rip-Off Failure Mechanism of Reinforced Concrete Beams Strengthened with FRPs

2006 ◽  
Vol 324-325 ◽  
pp. 1325-1328
Author(s):  
Cheol Woo Park ◽  
Jong Sung Sim ◽  
Sung Jae Park
Keyword(s):  
Reinforced Concrete ◽  
Failure Mechanism ◽  
Failure Load ◽  
Reinforced Concrete Beams ◽  
Shear Stresses ◽  
Strengthening Effect ◽  
Rc Beams ◽  
Premature Failure ◽  
Cfrp Plate ◽  
Proposed Model

Various types and forms of FRP materials have been applied for structural strengthening of reinforced concrete (RC) beams. When CFRP plates are used, however, a premature failure used to occur before strengthening effect appears adequately. This is primarily due to the rip-off of CFRP plate attached on RC beams. Despite of numerous studies on the rip-off failure of externally strengthened RC beams, the failure mechanism is not clearly explained yet. Investigations from the literatures have shown that the rip-off failure is dependant on vertical and shear stresses at the level of main reinforcements in RC beams. This study suggests an analytical model to investigate the ripoff failure load based on the stresses at the level of main reinforcements. The proposed model is relatively simple and produces very comparable results to the test data. Therefore, it is anticipated that the proposed model can be successfully used to provide further information on the rip-off failure mechanisms and its prevention.

scholarly journals Seismic resistance of reinforced concrete-masonry shear walls with high steel percentages

1977 ◽  
Vol 10 (1) ◽  
pp. 1-16
Author(s):  
M. J. N. Priestley
Keyword(s):  
Shear Stress ◽  
Reinforced Concrete ◽  
Shear Failure ◽  
Hysteresis Loops ◽  
Shear Walls ◽  
Shear Stresses ◽  
Test Results ◽  
Displacement Ductility ◽  
Ultimate Shear Stress ◽  
Concrete Masonry

This paper summarizes test results of six heavily reinforced concrete masonry shear walls. The test programme was designed to investigate the necessity for the low ultimate shear stress specified by Masonry codes. Care was taken to accurately model good, but realistic design practice in detailing, and variables investigated in the series included steel percentage, influence of vertical load and confinement of potential crushing areas by mortar bed confining plates. Results are presented which clearly indicate that the maximum current code allowance for ultimate shear stress is unreasonably low. No wall suffered diagonal shear failure despite maximum shear stresses exceeding
four times the maximum code level. All walls displayed stable hysteresis loops at a displacement ductility factor of 2, and the less heavily reinforced walls (designed to approximately twice code levels) were satisfactory at
 DF = 4. Degradation was never catastrophic and occurred due to slip of the entire wall along the foundation beam. Methods for reducing the degradation are discussed. Confining plates did not significantly reduce the degradation of the hysteresis loops, but substantially reduced damage to the walls
 at high ductility factors. Values of required ductility for walls designed to the Loadings Code are investigated, and on the basis of these and the experimental results, recommendations are made for relaxation to the ultimate shear provisions of the masonry code.

scholarly journals A Monotonic Smeared Truss Model to Predict the Envelope Shear Stress—Shear Strain Curve for Reinforced Concrete Panel Elements under Cyclic Shear

2021 ◽  
Vol 2 (1) ◽  
pp. 174-194
Author(s):  
Luís Bernardo ◽  
Saffana Sadieh
Keyword(s):  
Shear Stress ◽  
Reinforced Concrete ◽  
Shear Strain ◽  
Peak Load ◽  
Strain Curve ◽  
Fiber Reinforced Polymers ◽  
Shear Stresses ◽  
Cyclic Shear ◽  
Concrete Panels ◽  
Truss Model

In previous studies, a smeared truss model based on a refinement of the rotating-angle softened truss model (RA-STM) was proposed to predict the full response of structural concrete panel elements under in-plane monotonic loading. This model, called the “efficient RA-STM procedure”, was validated against the experimental results of reinforced and prestressed concrete panels, steel fiber concrete panels, and reinforced concrete panels externally strengthened with fiber-reinforced polymers. The model incorporates equilibrium and compatibility equations, as well as appropriate smeared constitutive laws of the materials. Besides, it incorporates an efficient algorithm for the calculation procedure to compute the solution points without using the classical trial-and-error technique, providing high numerical efficiency and stability. In this study, the efficient RA-STM procedure is adapted and checked against some experimental data related to reinforced concrete (RC) panels tested under in-plane cyclic shear until failure and found in the literature. Being a monotonic model, the predictions from the model are compared with the experimental envelopes of the hysteretic shear stress–shear strain loops. It is shown that the predictions for the shape (at least until the peak load is reached) and for key shear stresses (namely, cracking, yielding, and maximum shear stresses) of the envelope shear stress–shear strain curves are in reasonably good agreement with the experimental ones. From the obtained results, the efficient RA-STM procedure can be considered as a reliable model to predict some important features of the response of RC panels under cyclic shear, at least for a precheck analysis or predesign.

scholarly journals BEHAVIOUR OF REINFORCED CONCRETE BEAMS WITHOUT STIRRUPS SUBJECTED TO STEEL REINFORCEMENT CORROSION

2016 ◽  
Vol 22 (2) ◽  
pp. 146-153 ◽  
Author(s):  
Rizwan AZAM ◽  
Ahmed K. EL-SAYED ◽  
Khaled SOUDKI
Keyword(s):  
Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Load Carrying Capacity ◽  
Longitudinal Reinforcement ◽  
Rc Beams ◽  
Test Results ◽  
Structural Behaviour ◽  
Three Point Bending ◽  
Load Carrying ◽  
Crack Widths

The effect of corrosion on the structural behaviour of reinforced concrete (RC) beams without stirrups was experimentally investigated. A total of seven medium-scale RC beams without stirrups were constructed. The beams measured 150 mm wide, 250 mm deep and 1700 mm long. The test variables included: three different longitudinal reinforcement ratios (0.91%, 1.21%, and 1.82%) and two different corrosion levels (3% and 10%). Four beams were subjected to artificial corrosion whereas three beams acted as control un-corroded. Following the corrosion phase, all beams were tested to failure in three point bending. Corrosion crack widths and cracking patterns were recorded at different stages of corrosion. The effect of different longitudinal reinforcement ratios on the rate of corrosion was observed. Test results revealed that the beams with higher reinforcement ratios experienced slower corrosion rate compared to beams with lower reinforcement ratios. All control beams failed in shear whereas corroded beams failed in bond. There was a significant reduction in the load carrying capacity of the corroded beams without stirrups compared to the control beams.

Test Analysis for RC Beams Strengthened with Externally Bonded Prestressed CFRP Laminates

2008 ◽  
Vol 385-387 ◽  
pp. 41-44 ◽  
Author(s):  
Shi Qi Cui ◽  
Jin Shan Wang ◽  
Zhao Zhen Pei ◽  
Zhi Liu
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Test Results ◽  
Test Analysis ◽  
Cfrp Laminates ◽  
Cfrp Sheet ◽  
Externally Bonded

Reinforced concrete beams strengthened with externally bonded CFRP sheet and prestressed CFRP are analyzed in this paper. Crack developments and displacements with curvatures for different beams are analyzed. Test results show that prestressed CFRP are able to control the development of macro cracks in concrete and prestressed CFRP is an effective method to improve the toughness of concrete, reduce strengthening cost and meanwhile enhance bearing capacity of concrete beams.

scholarly journals Alternative Strut and Tie Model for Reinforced Concrete Deep Beams

2018 ◽  
Vol 21 (1) ◽  
pp. 86
Author(s):  
Ahmed Faleh Al-Bayati
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Test Results ◽  
Deep Beams ◽  
Strut And Tie ◽  
Codes Of Practice ◽  
Proposed Model ◽  
Wide Range ◽  
The Mean ◽  
Strut And Tie Model

This paper presents a simple strut and tie model to calculate the shear strength of reinforced concrete deep beams. The proposed model assumes that the shear strength is the algebraic sum of three strength components: concrete diagonal strut, vertical stirrups, and horizontal web reinforcements. The contribution of each strength components was calibrated with the test results of 305 deep beams compiled from previous studies with wide range of geometrical and material properties. The predictions of the proposed model were compared with those of the current codes of practice (ACI-318-14 and ASHTOO 2014) and those of existing model in the literature. Comparisons revealed that the proposed model provided better predictions than other models. The mean of predicted strength to test of the proposed model, the ACI-318-14 model, the ASHTOO 2014 model were 0.98, 0.79, and 0.75, respectively. The corresponding standard deviations were 0.17, 0.28, and 0.49, respectively.

scholarly journals EMPIRICAL SHEAR BASED MODEL FOR PREDICTING PLATE END DEBONDING IN FRP STRENGTHENED RC BEAMS

2021 ◽  
Vol 27 (2) ◽  
pp. 117-138
Author(s):  
Ahmed K. El-Sayed ◽  
Mohammed A. Al-Saawani ◽  
Abdulaziz I. Al-Negheimish
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Failure Mode ◽  
Fiber Reinforced Polymers ◽  
Simplified Model ◽  
Rc Beams ◽  
Shear Cracks ◽  
Reinforced Polymers ◽  
Experimental Database ◽  
Proposed Model

This paper presents the development of a simplified model for predicting plate end (PE) debonding capacity of reinforced concrete (RC) beams flexurally strengthened using fiber reinforced polymers (FRP). The proposed model is based on the concrete shear strength of the beams considering main parameters known to affect the opening of the shear cracks and consequently affect PE debonding. The model considers also the effect of the location of the cut-off point of FRP plate along the span of the beam. The proposed model was verified against experimental database of 128 FRP-strengthened beams collected from previous studies that failed in PE debonding. In addition, the predictions of the proposed model were also compared with those of the existing PE debonding models. The predictions of the model were found to be comparable to the best predictions provided by the existing models, yet the proposed model is simpler. Furthermore, the proposed model was combined with the ACI 440 IC debonding equation to provide a procedure for predicting the governing debonding failure mode in FRP strengthened RC beams. The procedure was validated against 238 beam tests available in the literature, and shown to be a reliable approach.

scholarly journals Debonding Failure Analysis of Reinforced Concrete Beams Strengthened with CFRP Plates

2021 ◽  
Author(s):  
Rendy Thamrin ◽  
Zaidir Zaidir ◽  
Silvy Desharma
Keyword(s):  
Reinforced Concrete ◽  
Modulus Of Elasticity ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymers ◽  
Analytical Prediction ◽  
Rc Beams ◽  
Test Results ◽  
Fiber Element ◽  
Element Method

In this study, experimental work was carried out on reinforced concrete (RC) beams strengthened with carbon fiber reinforced polymers (CFRP) plates. This study aims to examine the effect of the reinforcement ratio on the flexural behavior of these beams and propose a new model for predicting the debonding moment. Six RC beams consisting of three control beams and three beams strengthened with CFRP plates were tested. The beams were simply supported and loaded with four-point bending. The test variable was the tensile reinforcement ratio (1%, 1.5%, and 2.5%). Analytical prediction using the fiber element method was also carried out to obtain the complete theoretical response of the beam due to flexural loads. The test results show that the reinforcement ratio affected the bending performance of RC beams with CFRP plates. Following this, the experimental data from 60 beam test results from published literature and this study were analyzed. From these data, it was found that the ratio of tensile reinforcement, the ratio of modulus of elasticity of concrete, the modulus of elasticity of the plate, and plate thickness all affect the value of debonding moment. A parametric study using fiber element and two-dimensional finite element method was also carried out to confirm the effect of these parameters on debonding failure. These parameters were then used to develop an equation to predict the debonding moment of RC beams strengthened with CFRP plates using simple statistical analysis. This analysis resulted in a simple model for predicting the debonding moment. Then the model is entered into a computer program, and the complete response of the cross-section due to debonding failure can be obtained.

The Experimental Study on Bearing Capacity of Reinforced Concrete Structure with Different Reinforce Methods

2014 ◽  
Vol 936 ◽  
pp. 1438-1441
Author(s):  
Qing Yi Liu ◽  
Xiao Mei Liu
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Steel Plate ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Test Results ◽  
Reinforced Concrete Structure ◽  
Fiber Sheet

Three reinforcement materials with steel plate, epoxies resin sheet, and glass fiber sheet adhering to failed reinforced concrete beams (RC beams) were used to improve the bearing capacity of Reinforced Concrete beams in the paper. The test results shows all the three materials were proved satisfied with bearing capacity increasing request. Strengthening effects with steel plate and epoxies resin sheet were more obvious.

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