Horizontal Shear Reinforcement Research Articles

Evaluation of shear behavior of short-span reinforced concrete deep beams strengthened with fiber reinforced polymer strips

The application of externally bonded fiber-reinforced polymers (EB-FRP) is known to improve the shear behavior of reinforced concrete beams. Nevertheless, the studies available in the literature are not sufficient to explain the shear behavior of the beams that have low shear span to effective depth ratios (av/d) and are strengthened with FRP and the interaction between the horizontal steel shear reinforcement and FRP strips. To fill these gaps in the literature, an experimental study involving twenty-two tests of deep beams with a low av/d and with different amounts of vertical and horizontal steel shear reinforcement was carried out. Both unstrengthened and strengthened with fully wrapped FRP strips beams were tested where the number of FRP layers, the spacing between them and the type of FRP material were varied. The experimental results showed that the FRP strips improved the shear and ductility capacities of beams with low av/d. In addition, as the vertical shear steel reinforcement ratio in the beams strengthened with FRP strips increased, the percentage increases in the shear and deflection capacities decreased. Also, as the horizontal shear steel reinforcement ratio in the strengthened beams increased, the percentage increase in the shear capacity increased. Finally, a new equation was proposed to estimate the FRP contribution to the shear capacity. To prove the reliability of the proposed equation, a comparative study was conducted using twenty existing equations.

Shear Behavior of Reinforced Concrete Inverted-T Deep Beam

Contrary to top-loaded deep beams, Inverted-T (IT) deep beams are loaded on ledges at the beam’s bottom chord. The presence of the load near the bottom of the beams creates a tension field in the web at the loading points. An experimental investigation was carried out in which 8 specimens of reinforced concrete IT deep beams were tested and the effect of the following variables was studied: changing the hanger diameter, hanger arrangement in terms of spacing and distribution distance, hanger reinforcement ratio, vertical and horizontal web shear reinforcement diameter, and spacing. In addition, all the tested beams had long ledges extending to the end of the beam. It was concluded that hanger reinforcement diameter and horizontal web shear reinforcement have an insignificant effect on the IT deep beam capacity. While the change in hanger arrangement, vertical web reinforcement, and ledge length has a significant effect on IT deep beam capacity. The maximum spacing of the hanger reinforcement and the minimum hanger reinforcement ratio passing through the load plate length will be studied in the following publication. A finite element model (FEM) was presented to predict the behavior of IT deep beams. The simulation was carried out using the ABAQUS 2017 software program. The results of the numerical model showed good agreement with the experimental program. Analysis using design codes was checked against the experimental data, where the computed beam capacities were compared to those obtained from the test results. The comparison showed a remarkable difference between the predictions using the design codes and the test results. Computation using design codes significantly underestimated the capacities of the beams. Doi: 10.28991/CEJ-2023-09-05-04 Full Text: PDF

The Behavior of Interior Beam-Column Joint Models Using Self-Compacting Concrete with Variations of Shear Reinforcement Subjected to Cyclic Lateral Loads

The joint of a beam-column is crucial due to the distribution of cyclic lateral loads. Therefore, the joint detail must meet the design requirements of earthquake-resistant structures. Casting work in joint zones where the steel reinforcement spaces are close requires concrete materials that are easy to flow. An alternative to overcome the difficulty is using Self-Compacting Concrete (SCC) material. However, the properties of SCC for beam-column joint structures under earthquake loads still need to be studied further. This study aimed to analyze the behavior of the Interior Beam-Column (IBC) joint using SCC with variations of shear reinforcement subjected to cyclic lateral loads. Three types of shear reinforcement were modeled using numerical analysis. Variations of horizontal and diagonal shear reinforcements were compared to determine the best performance. The SCC-S3 IBC joint model with horizontal and diagonal shear reinforcements achieved the highest lateral forces and resisted compressive and tensile stresses in the largest stress contour and better stiffness degradation than other models of SCC IBC joints. The results showed that the SCC-S3 IBC joint with a combination of horizontal and diagonal shear reinforcements showed the best performance.

Structural behavior of high-strength concrete corbels involving steel fibers or closed stirrups

A comprehensive experimental evaluation of the shear behavior of corbels made by high-strength concrete (HSC) with steel fiber or with stirrups was investigated. Thirteen samples were prepared and tested, the main variables in this research were steel fiber type, steel fiber content (Vf %), and amount of horizontal closed stirrups (Ah). The constants in this investigation were the area of the main steel reinforcement (As), ratio of shear span to depth (a/d) and cube concrete strength (fcu). The obtained results clearly showed that, the presence of fibers or closed stirrups enhanced the strength and decreased the deformation of the explored specimens. It was concluded that the horizontal shear reinforcement can be substituted by supplementation of steel fibers to RHSC corbels. A comparison was performed between the test results and estimated shear capacity by ACI code and other adopted equations. Very conservative shear strength values were obtained from ACI 318–19 for corbels prepared with high-strength concrete because the strut and tie method were influenced by concrete strength and did not take the contribution of closed stirrups into account. However, the shear friction method depends only on the quantity of the main steel reinforcement and closed stirrups. Russo [2] proposed a model that adequately predicted the ultimate force of high-strength RC corbels incorporating closed stirrups, but this model did not take the effect of steel fibers into account. Campione [3] added the effect of steel fibers by means of the residual tensile strength expression.

The behavior of self compacting concrete exterior beam-column joints with a variation of shear reinforcement against cyclic lateral loads

The beam-column joints are designed to have sufficient capacity under earthquake loads. This requirement needs design details of reinforcement that fulfill the seismic criteria and adequate compaction of concrete. Using Self Compacting Concrete (SCC) material can solve the difficulty of compacting conventional concrete due to the close reinforcement distance. This study aimed to analyze the behavior of the Exterior Beam-column Joints (EBJ) using SCC as materials with a variation of shear reinforcements to withstand cyclic lateral loads. The analysis was carried out using the ANSYS software and the Finite Element Method. The analysis included hysteresis curves, stress contours, ductility, stiffness, and structural strength. The performance of an EBJ without shear reinforcement (EBJ-S1 model) was compared to other EBJs using horizontal (EBJ-S2 model) and diagonal (EBJ-S3 model) shear reinforcements in the joint zones. The results showed that horizontal and diagonal shear reinforcement in the joint zones affected the performance of the EBJs in resisting cyclic lateral loads as the representative of earthquake loads. The EBJ without shear reinforcement could withstand compressive stresses of 3.33 to 17.22 MPa, while both EBJs using horizontal and diagonal shear reinforcement achieved the same compressive stresses range of 3.33 to 20 MPa. The EBJ with diagonal reinforcement performed a wider compressive area of stress contour than the EBJ of horizontal reinforcement. The EBJ-S3 model achieved the highest ductility value of 4.733 with diagonal shear reinforcements because it achieved the highest ultimate displacement of the other EBJ models.

Strengths of Struts and Nodal Zones for Strut-and-Tie Model Design of Reinforced Concrete Corbels

The strut-and-tie model (STM) method is useful for the limit state design of reinforced concrete (RC) corbels. However, for the rational design of RC corbels, designers must accurately determine the strengths of concrete struts and nodal zones to check the strength conditions of a selected STM and the anchorage of reinforcing bars in nodal zones. In this study, the authors suggested a numerical process for determining the strengths of concrete struts and nodal zones in RC corbel STMs. The technique incorporates the state of two-dimensional (2-D) stresses at the strut and nodal zone locations, 2-D failure envelope of concrete, deviation angle between the strut orientation and compressive principal stress trajectory, and the effect of concrete confinement by reinforcing bars. The authors also proposed the strength equations of struts and nodal zones that apply to the typical determinate and indeterminate STMs of RC corbels. The authors considered the effects of the shear span-to-effective depth ratio, the horizontal-to-vertical load ratio, and the primary tensile and horizontal shear reinforcement ratios in developing the strength equations. The authors predicted the failure strengths of 391 RC corbels tested to examine the appropriateness of the proposed numerical process and strength equations. The predicted failure strength compares very well with experimental results, proving that the rational analysis and design of RC corbels are possible by using the present study's strut and nodal zone strengths. Doi: 10.28991/cej-2021-03091725 Full Text: PDF

Experimental Study on Shear Behavior of Reinforced Concrete Sandwich Deep Beam

In present making of construction industry at a high pace. The tendency of world influenced the high raised buildings. In modern days one of the most common element is deep beam, constructed a small span to depth ratio. The transfer girders most of used in deep beams. In an experimental program consists of 12 deep beam specimens are carried out for shear strength behavior investigation of Reinforced Concrete sandwich deep beam concealed with insulation pad in various depths 200mm and 300mm and 400mm. in the experimental program effective length, depth, the width of the specimens, width of bearing plates, longitudinal reinforcement as 1% to maintain constantly and horizontal reinforcement as varies as 0.15% and 0.25% and 0.35%. We are considered shear span to depth ratio of deep beam is 0.95. The main aim of the experimental study the influence of longitudinal shear reinforcement along with vertical and horizontal shear reinforcement on the shear strength, shear ductility of RC sandwich deep beams of insulation pads placed at different depths.

Evaluation of Cracking and Serviceability Performance of Lightweight Aggregate Concrete Deep Beams

This paper investigated the diagonal crack propagation and serviceability performance of fifteen deep beams fabricated using lightweight aggregate concrete (LWAC). Experimental variables included the shear span-depth ratio, beam section depth, and bearing plate width. The test results were reported in terms of crack propagation, diagonal crack width, diagonal cracking load, and size effect on the serviceability of deep beams; they were also employed to establish a relationship between residual shear bearing capacity and maximum diagonal crack width for such components. In addition, the crack width limits in current code provisions were utilized to further evaluate the serviceability of LWAC deep beams. The test results revealed that the diagonal crack propagation is almost independent of the variation of beam depth, while the diagonal crack width exhibited an obvious increasing trend as shear span-depth ratio or bearing plate width increased. At service load level, the crack width limit of 0.4 mm stipulated in ACI 224-R-01 can be satisfied by LWAC deep beams with horizontal and vertical shear reinforcement ratios more than 0.3%.

Structural behavior of SCC continuous deep beam strengthening and retrofitting with carbon fiber reinforced polymer strips

This study presents an experimental work to investigate the structural behavior of continuous self-compacting concrete (SCC) deep beams strengthened and retrofitted with woven carbon fiber reinforced polymer (CFRP) strips and evaluate their shear capacity. The work includes casting and testing fourteen beams specimens. All tested beams have the same dimensions, the same flexural reinforcement and concrete compressive strength with two continuous span and have been subjected to two-point loads. The test specimens were divided into three groups. The first group including eight beams with minimum ratio of shear reinforcement (ρv= ρh=0.25%) and two parameters considered, shear span to overall depth ratio (a/h) and three different schemes of CFRP strip. The second group including four beams without interior vertical and horizontal shear reinforcement (ρv=ρh=0%) with three different schemes of CFRP strip and control beam. The third group consists of two beams with minimum ratio (ρv= ρh=0.25%) were firstly loaded to 65% of the ultimate load of control beams, after that the loads were released and then retrofitted by CFRP strip by two different schemes. The experimental results show that the specimens with vertical CFRP strips an increase in ultimate strength load by 32.6% and 20% compared to the control beams.

Enhancement of shear strength of deep beams using hybrid fibres and suggesting an alternative for strut and tie model

This paper investigates the behaviour of 4 deep beams prepared by varying the percentages of horizontal and vertical shear reinforcement. First, two specimens are prepared in a regular way of placing shear reinforcement, the third specimen is made by introducing fibres and for the fourth beam, since Indian Standards does not have any provisions for strut and tie model (STM), the shear reinforcement is placed as an alternate in place of STM by meeting the design standards of Indian codes. Different parameters like percentage of horizontal shear reinforcement, vertical shear reinforcement, and shear span depth ratio, web reinforcement was studied and validated analytically through ABAQUS software.

Design of Reinforced Concrete Deep Beams using Particle Swarm Optimization Technique

Researches available in literature interrelating neural networks to civil engineering design problems, especially for beep beams, are very rare. Therefore, an optimization algorithm is developed and verified in this study and coded using MATLAB functions to determine the optimum cost design of reinforced concrete deep beams. ACI 318-14 code method is used benefiting from iterative particle swarm optimization technique due to its efficiency and reliability. Minimizing total cost is used as the objective function in terms of four decision variables. Self-adaptive penalty function technique is used to handle constraints for each of the 300 randomly selected particles, and in each of the 50 total iterations followed for each one of four suggested deep beam design case studies. Performing all iterations is used as a stopping criteria for the developed algorithm. Comparative studies are made to show the effect of concrete compressive strength, live load scheme, and length of deep beam, on the optimum total cost and the corresponding decision variables. Results presented in the form of graphs and tables show that the loading condition has a significant effect on the total cost of deep beams. The cost increase is accompanied by deep beam length increase, height increase, longitudinal reinforcement area increase and vertical shear reinforcement area decrease. The calculated optimum cost is noticed for beam DB1, which is 1255 US$, with 1.29 m beam height, 0.01445 m2 vertical shear reinforcement, 0.00914 m2 horizontal shear reinforcement and 0.00238 m2 main longitudinal reinforcement. The results show a relatively less difference in total cost between all the four beams at 4 m length compared to 8 m length. Also, a relatively mild increase in total cost is happened for beams DB3 and DB4 as the height increases, especially above 1.7 m height. As the main longitudinal reinforcement increases, cost of DB4 is affected more significantly than others, and as the vertical shear reinforcement increases, DB4 curve shows a relatively low degradation in cost.

Shear Strength and Behavior of Reinforced Concrete Corbels Containing either Carbon Fibers or Stirrups

In the present paper, an experimental research is presented regarding the shear strength and behavior of concrete corbels with carbon fiber or stirrups as shear reinforcement. Tests were carried out on ten120 x 250 x 250 mm corbels subjected to vertical loading. The influence of concrete grade type (normal and moderately high strength concretes), carbon fiber percentage and of the percentage of the horizontal shear reinforcement on the shear strength of the corbels were considered. The test results in term of load-deflection curves and crack patterns show that the shear strength and deformation capacity was improved with the increase in the percentage of carbon fibers in reinforced concrete corbels. These clearly demonstrate the benefits of using carbon fiber as shear reinforcement in combination (fibers and stirrups) or as replacement for stirrups. An equation was proposed for predicting the shear strength of the reinforced concrete corbels subjected to vertical load. The equation was compared with equations given by ACI 318-14. The ACI equations were more conservative for predicting the ultimate shear strength of all corbels.

Analysis of the punching behavior of RC flat slabs with horizontal and vertical shear reinforcement

Punching failure is one of the major drawbacks of using flat slabs in the design of reinforced concrete structures. Punching shear analysis is very complicated which appears clearly in the large variation of the equations used by the different codes in calculating the punching shear capacity. There are many factors that affect the punching shear capacity of an element. This current research aims to investigate the contribution of two of these factors which are the horizontal flexural reinforcement, and the vertical shear reinforcement in the form of stirrups. Following the experimental program conducted at the reinforced concrete laboratory of the Faculty of Engineering at Cairo University, Egypt and verification using the finite non-linear analysis software (ANSYS 15), good correlation was observed between the analytical models and their corresponding experimental data. This proves that ANSYS 15 allows for studying the punching behavior of the flat slab in more details which could not be monitored in the laboratory. As a result, a detailed parametric study as well as comparison with some design codes was conducted using thirteen full scale flat slab specimens in order to simulate real life problems. The specimens had a loaded span of 2000 mm and a total thickness of 250 mm. The variables under study were the flexural reinforcement ratio and stirrups spacing and diameter in order to further enhance the understanding of the behavior of flat slabs in punching.

80 MPa급 콘크리트를 활용한 이중합성 거더의 수평접합면 구조거동에 관한 실험적 연구

Abstract The horizontal shear capacity when the flange of a steel girder is replaced with 80 MPa concrete is important for its structural safety. In this study, 6 specimens with different interface conditions were designed andfabricated based on the Limit State Design Code on Korean Highway Bridges and static tests were performed to measure the horizontal shear capacity. Not only the resistance factors of the stud shear connector, concrete and reinforcement, but also the surface conditions of the casing concrete and spacing of the horizontal shear reinforcements were used as the experimental variables. The experiments showed that the interfaces between the steelgirder and the concrete flange have stronger joint performance than those between the concrete flange and deck slab. To ensure the composite action in the plastic zone, the conservative horizontal shear reinforcement is more importantthan the roughness in the concrete face. Keywords : Composite action, Concrete flange, Horizontal shear, Interface condition, Static test

Influence Factors for the Shear Strength of Exterior and Interior Reinforced Concrete Beam-column Joints

This paper investigates the key influence factors for the shear strength of both exterior and interior reinforced concrete (RC) beam-column joints. A database of totally 172 experimental RC beam-column connections constructed using the published literature was used in the analysis. Based on the database, the correlation coefficient (CC) between the considered parameters and the tested joint shear strength was computed, and the important level of these parameters was quantified. Results of the analysis showed that five key parameters for the joint shear strength included (1) the concrete compressive strength, (2) the vertical joint shear reinforcement, (3) the beam bars detail index, (4) the horizontal joint shear reinforcement and (5) the column axial stress. Among the influence factors, the concrete compressive strength had the most significant correlation to the joint shear strength and interestingly its correlation was higher for the interior connections with CC = 0.8 compared to CC = 0.69 for the exterior connections. For the remaining factors, the analysis conversely showed that their correlations to the joint shear strength of exterior joint were stronger than that of the interior joint.

강섬유보강 콘크리트와 일반 콘크리트 합성보의 전단강도

Composite construction of precast concrete and cast-in-place concrete is currently used for the modular construction. In this case, the use of steel fiber reinforced concrete (SFRC) could be beneficial for precast concrete. However, the shear strength of such composite members (SFRC and cast-in-place concrete) is not clearly defined in current design codes. In the present study, steel fiber composite beam tests were conducted to evaluate the effect of steel fibers on the composite members. The test variables are the area ratio of SFRC and shear reinforcement ratio. The test results showed that when minimum horizontal shear reinforcement was used, the shear strength of composite beams increased in proportion to the area ratio of steel fiber reinforced concrete. However, because of the steel fiber, the composite beams were susceptible to horizontal shear failure. Thus, minimum horizontal shear reinforcement is required for SFRC composite beams.

Shear Behavior of Joint The Partial Prestressed Concrete Beam-Column Reinforced Concrete of Ductile Frame Structure Building In a Scure Residents and for Settlement Environment

Concentration of this study is to create a Specimens model of Joint Interior Beam - Column using Partial Prestressed Concrete Beams elements connected with Reinforced Concrete Column. Design capacity of Beam- Column Joint Shear is the horizontal shear reinforcement in the form of stirrups AE 10-50 mm to fill the empty space bj = 288 mm . The capacity Shear that can be deployed by the cross bar = 103.62 kN. Total shear force that is capable of detained by the beam-column joint structures are Vjh = 409 kN. This study is a continuation of research SRPMK models shaped beam - column joint with beam section 250/400 mm , and the column section 400/400 mm , the source of funds from Research Ditlitabmas Decentralization Program of Higher Education , through ITS Featured Research Grant in 2013 . Experimental studies have been conducted with Cyclic loading ( pseudo dynamic ) lateral , static axial load on the column as a stabilizer . Specimens ability to withstand Ultimate Lateral Cyclic Load : conditions Load push (press) = 470.90 kN and Load Pull = 465.80 kN. Everything is > 409 kN. Ductility structure also qualified in 3.50% Drift Ratio: Conditions Press m = 1.27 > 1.20, Pull Conditions m = 1.29 > 1.20. In general, behavioral modeling structure has qualified as a reliable protection occupancy when the building was hit by an earthquake.

Interstory Drifts from Shear Strains at Base of High-Rise Concrete Shear Walls

Shear strains may have negligible influence on maximum displacements at the top of slender shear walls, but may significantly increase interstory drift ratios at lower levels where gravity-load columns are often less flexible. A nonlinear finite-element (FE) model calibrated with experimental results confirmed that large shear strains occur in flexural tension regions of concrete walls due to vertical tension strains in the presence of diagonal cracks and in the absence of demand on the horizontal shear reinforcement. A fan of diagonal cracks will form at the base of flexurally hinging walls independent of the shear stress level. A parametric study confirmed that a principal strain angle of 75° can be used to estimate shear strains from vertical tension strains. Thus interstory drift ratios due to shear strains can be estimated from the easily calculated flexural demands. A simple and safe estimate of interstory drift ratio due to shear strains is 60% of the global drift ratio. Interstory drift ratios from shear strains up to 0.8% have been measured in slender wall tests.

Shear performance of plain concrete cross-section based on permanent Uni-wall system

For the permanent Uni-wall system method, horizontal shear reinforcements are not placed in the joints between the circular casing pile and special casing pile. The joints of piles consequently have a plain concrete section. This study aims to evaluate the shear performance of the plain concrete cross-section found in the permanent Uni-wall system method. This paper analysed the existing design code for a plain concrete cross-section, examined the shear performance of joints through shear experiments, and then compared the results with those from a structural analysis. From the test results, it was found that the minimum shear strength of all specimens had 2·98 times greater bearing capacity than the nominal shear strength.

Adaptive Neural Fuzzy Inference System Models for Predicting the Shear Strength of Reinforced Concrete Deep Beams

A reinforced concrete member in which the total span or shear span is especially small in relation to its depth is called a deep beam. In this study, a new approach based on the Adaptive Neural Fuzzy Inference System (ANFIS) is used to predict the shear strength of reinforced concrete (RC) deep beams. A constitutive relationship was obtained correlating the ultimate load with seven mechanical and geometrical parameters. These parameters contain Web width, Effective depth, Shear span to depth ratio, Concrete compressive strength, Main reinforcement ratio, Horizontal shear reinforcement ratio and Vertical shear reinforcement ratio.The ANFIS model is developed based on 214 experimental database obtained from the literature. The data used in the present study, out of the total data, 80% was used for training the model and 20% for checking to validate the model. The results indicated that ANFIS is an effective method for predicting the shear strength of reinforced concrete (RC) deep beams and has better accuracy and simplicity compared to the empirical methods.