Vertical Shear Reinforcement Research Articles

Impact of Vertical and Diagonal Shear Reinforcement on the Structural Integrity of a Deep Beam

This research investigates the shear strength behaviour of deep beams with different angles of inclinations of the transverse reinforcements with the longitudinal reinforcements. A mix ratio of 1:1½:3 of concrete was used in this investigation with a total number of three (3) deep beam models of 150×300×750 mm and the characteristic compressive strength of concrete used for the production of the beams was determined to be 14.5 N/mm2. The study concludes that the ultimate resisting load of the beam depends on the angle of inclination of the shear links and maximum with 90o inclination angle of the shear links which decreases with a decrease in the angle of inclination. Hence, all shear reinforcement must not be inclined at an angle other than 90o to the longitudinal reinforcement to avoid shear-compression failure along the shear diagonal.

Optimum Design of Reinforced Concrete Beams with Large Opening Using Neural Network Algorithm

It is quite rare to find researches in the literature connecting neural networks to design challenges in civil engineering, particularly with regard to beam with large openings. Therefore, to ascertain the best cost design for such a beam, an optimization technique is developed, written using MATLAB functions, and verified in this study. Because of the efficiency and dependability of the iterative Particle Swarm Optimization (PSO) process, the ACI 318-19 code method is adopted via this algorithm. Using four beam design (decision) variables, which are: beam width b, longitudinal tension reinforcement area As, longitudinal compression reinforcement area A’s, and vertical shear reinforcement area Av; the objective is to minimize the overall beam cost function. The constraints for each of the 60 randomly chosen particles are handled using the self-adaptive penalty function technique, which is applied in all the 100 iterations for each of the four proposed beam design case studies with identical openings. For the developed method, completing all iterations serves as a stopping criterion. Comparative studies are conducted to demonstrate how the compressive strength of concrete and the live load scheme affect the optimal overall beam cost and the associated design variables. The relations between cost of beams and the four design variables, which are presented through graphs and tables, indicate that the beam’s cost is significantly impacted by the loading condition. This is shown by increasing the cost of beam B1, with no sustained live loads, from 722 US dollars to 984 US dollars for beam B4, which has concentrated and distributed sustained live loads. Future research is advised to include modern strengthening techniques for beams with openings, and apply this research to a PSO algorithm with several objectives.

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.

Parametric studies on prefabricated cage-reinforced deep beams

The research article is focused on investigating the shear capacity performance for twenty-four simply supported deep beams reinforced with a Prefabricated Cage under a two-point load to enable a better understanding of the effects of effective length-to-overall depth ratio, depth-to-thickness ratio, effective length to thickness ratio, spacing of vertical web shear reinforcement, yield strength and thickness of cold-formed steel sheet. The shear behaviour of Prefabricated Cage Reinforced deep beams is compared with rebar-reinforced deep beams by using the computational platform, ABAQUS. The ultimate failure load, displacement, and shear ductility were obtained from the analytical results. The ultimate load-carrying capacity of Prefabricated Cage Reinforced deep beams is higher than conventionally reinforced deep beams. It was observed that Prefabricated Cage Reinforced deep beams exhibited better shear resistance than Conventional Deep beams. Therefore, Prefabricated Cage reinforcement is suggested as an efficient method of reinforcement in deep beams compared to conventional reinforcement and it is found to be economical when utilized in large-scale construction works.

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

Strengthening of beam against shear failure by means of vertical prestressed shear reinforcement

Strengthening of concrete beams, limited by shear resistance, is one possibility how to extend life span of a structure. Application of a vertical prestressed shear reinforcement is an efficient way how to increase the shear resistance of concrete beam. Unfortunately, current codes lack the information how to design optimal amount of the vertical prestressed shear reinforcement and how to assess retrofitted structure. In this paper, applicability of various codes of practise is assessed as option for design of vertical prestresses shear reinforcement. The presented models are compared with test data available in literature. The results of this paper show that presented models provide un-conservative approach for assessment of reinforced concrete structure strengthened by vertical prestressed shear reinforcement with the space for improvement.

Investigations on Interface Shear Fatigue of Semi-Precast Slabs with Lattice Girders

Due to their high cost efficiency and flexibility, semi-precast concrete slabs with lattice girders are widely used in constructions all over the world. Prefabricated concrete slabs, combined with in situ concrete topping, exhibit a quasi-monolithic structural behavior in which lattice girders serve as vertical shear reinforcement and ensure the transfer of longitudinal shear within the interface, acting in combination with concrete-to-concrete bonding mechanisms. To be applicable in industrial and bridge construction, semi-precast slabs need to have sufficient resistance against fatigue failure. To improve and expand the limits of application, theoretical and experimental investigations are conducted at the Institute of Structural Concrete (IMB), RWTH Aachen University. To investigate the fatigue behavior of lattice girders, small size tests with lattice girder diagonals were carried out. These test results have been used to derive an S–N curve (S: stress, N: number of load cycles) for lattice girders for a more refined fatigue design. Subsequently, the fatigue behavior of semi-precast slabs with lattice girders was investigated by fatigue tests on single-span slab segments. The fatigue design regulations of lattice girders according to technical approvals can generally be confirmed by this test program; however, they tend to be conservative. The use of the derived S–N curve leads to significantly improved agreement of fatigue behavior observed in tests and design expressions.

Analysis on the Influence of Topography on a Short-Time Local Heavy Rainfall Forecast in Western Xinjiang

Based on the prediction results of RmAPs-CAV1.0, a short time heavy rainfall in western Xinjiang was simulated and analyzed. By comparing the forecast results with the actual precipitation, it is found that RMAPS-CAV1.0 can accurately reflect the important forecast parameters of the short-time heavy precipitation system, such as precipitation level and starting time. Contrast observation and prediction results found that the terrain has forced effect to the surface wind field, the precipitation process in Yili valley special opening of the west mountain terrain, the center is located in Kazakhstan in central Asia low vortex cause lower for the westerly Yili river valley, the center is located in the Tarim Basin of central Asia for Piandongfeng middle low vortex makes the Yili river valley, cause the Yili river valley and the lower levels of vertical wind shear reinforcement; In the Yili River Valley, the combination of topography and the central Asian vortex circulation in Kazakhstan forms a low-altitude convergence line. The low-level westerly winds transport water vapor into the valley, and the northerly airflow in the valley and the northern margin of the Taklamakan Desert converge near the windward slope, and the enhanced upward movement results in the uplift of the water vapor accumulated in the valley. The result analysis of RMAPS-CAV1.0 shows that the warm and cold airflow and water vapor under the action of topography have important contributions to the generation of this precipitation.

Investigating the Mechanical Properties and Fracture Behavior of Welded-Wire Reinforcement

AbstractWelded-wire reinforcement (WWR) is widely used as the main reinforcement in bridge decks and vertical shear reinforcement in concrete bridge girders. Previous studies on concrete members re...

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.

Finite element analysis of RC deep beams strengthened with I-section and truss reinforcement

Shear failure is a major criterion in Reinforced Concrete (RC) Deep Beams, and several investigations were made in the past but only a few succeeded. Alignment of shear reinforcement plays a crucial role in the shear failure and it helps to study its behaviour during critical cracking. This paper investigates the behaviour of 4 deep beams designed by varying the vertical shear reinforcement (in %) and horizontal reinforcement (in %). 2 specimens were cast in conventional way of placing of shear reinforcement and third specimen consists of shear reinforcement in form of truss since deep beams were more effective with strut and tie combinations. A Rolled I section is introduced in the fourth specimen to know the composite behaviour of deep beams. Various parameters like percentage of shear reinforcement, load vs deflection and shear stresses were studied using 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.

Flexural Performance of Laced Reinforced Concrete Beams under Static and Fatigue Loads

This paper introduces experimental results of eighteen simply supported reinforced concrete beams of cross sections ( ) and length 3000 mm to study the effect of lacing reinforcement on the performance of such beams under static and fatigue loads. Twelve reinforced concrete beams (two of them are casted with vertical shear reinforcement used as control beams) are tested under four points bending loading with displacement control technique and six laced reinforced concrete beams were exposed to high frequency (10 Hz) by fixing the fatigue load in each cycle. Three parameters are used in the designed beams, which are: lacing bar diameter (4mm, 6mm, and 8mm), lacing bar inclination angle to horizontal , and lacing steel ratio depending on number of lacing bar in each longitudinal face of beam and lacing bar diameter. The comparison results of experimental tests revealed that the ultimate loads of laced reinforced concrete beams are higher than the conventional reinforced concrete beams due to increasing lacing bar diameter, angle of inclination lacing bar, and lacing steel ratio, while the deflection is reduced. Also, the laced reinforced concrete beams can safely withstand the fatigue loading.

Evaluation of TS500-2000 Shear Strength Provisions for Deep Beams

In order to account for the strut action in point loaded deep beams, TS500-2000 allows use of simple shear strength equations instead of more refined models. According to TS500, when the clear span-to-depth ratio, ln/d is less than 5, the shear strength of deep beams containing both vertical and horizontal shear reinforcement can be calculated by a simple expression which accounts for the effect of web reinforcements along with the clear span-to-depth ratio, ln/d. In this study, the accuracy and conservativeness of the shear strength equations for deep beams in the TS500-2000 are evaluated. ACI-DAfStb evaluation database of shear tests on point loaded simply supported reinforced concrete members with vertical and horizontal shear reinforcement, is used for this purpose. Based on the results obtained, recommendations are made to improve the accuracy of TS500-2000 sectional shear design equations.

Shear Behavior of High Strength Self Compacting Concrete Beams

This research presents an experimental study to investigate the shear behavior of high strength self-compacting concrete slender beams. The experimental program includes testing seven beams with constant size of (150mm height ×125mm width×1000mm length) to study the effect of shear span to effective depth ratio (a/d), longitudinal reinforcement ratio (ρw) and shear reinforcement ratio (ρv) on shear behavior for these beams. The experimental results showed that, increase shear span to effective depth ratio (a/d) has pronounced effect on decreasing diagonal cracking load and ultimate shear strength and increasing the ductility ratio, as (a/d) increase from 2.5 to 3.0, the decreases in diagonal cracking load and ultimate shear strength are with percentages of 17.8% , 21.6% respectively, while the ductility ratio increase with percentage of 16.7%. Also the results showed that the longitudinal reinforcement ratio (ρw) has significant effect on the gain in shear bearing capacity and ductility ratio, as increasing of longitudinal reinforcement ratio from 3.191% to 6.383% the increases in diagonal cracking load, ultimate shear strength and ductility ratio are with percentages of 43.8%, 46.6% and 37.0% respectively. Furthermore the results revealed that the vertical shear reinforcement has the major effect in improvement the shear behavior of these beams, however, using shear reinforcement (ρv) with percentage of 0.502% results in increase diagonal cracking load, ultimate shear strength and ductility ratio with percentages 50.7%, 63.6% and 48.1% respectively as compared with beam without shear reinforcement. Also presence of vertical shear reinforcement changed the mode of failure from the brittle to ductile.

Effect of flexural and shear reinforcement on the punching behavior of reinforced concrete flat slabs

Punching is one of the most important phenomena to be considered during the design of reinforced concrete flat slabs. Three main factors affect the punching behavior. These factors are concrete compressive strength, horizontal flexural reinforcement, and vertical shear reinforcement in the form of stirrups, studs or other forms. This paper is part of an ongoing research program conducted at the concrete laboratory of the Faulty of Engineering, Cairo University to assess the contribution of horizontal flexural reinforcement and vertical shear reinforcement on the punching behavior of reinforced concrete flat slabs. In the current research, seven half scale specimens are cast and tested. The specimens had dimensions of 1050×1050mm and a total thickness of 100mm. All specimens were connected to a square column of dimensions 150×150mm and loaded at the four corners with a span 950mm. The parameters considered in this research included spacing between vertical stirrups, width of the stirrups, number of stirrups branches and the ratio of the horizontal flexural reinforcement. During testing, ultimate capacity, steel strain, cracking pattern and deformation were recorded. The experimental results were analyzed and compared against values estimated from different international design codes.

Shear strength of reinforced concrete beam-column joints with crossed inclined bars

A new analytical approach for the evaluation of the shear strength of reinforced concrete beam-column joints with crossed inclined reinforcement is developed. The proposed model considers that a joint member resists to the applied shear via three mechanisms, the concrete diagonal strut, the steel conventional shear reinforcement truss and the X-bars truss. Failure criteria are adopted in order to quantify the contribution of the crossed inclined bars to the shear capacity of the joint. The joint shear strength is calculated using a simple expression as a function of the shear resistance of the joint without X-bars. The developed procedure is applicable to beam-column joint elements with crossed inclined reinforcement as the only shear reinforcement in the joint region or with the combination of X-bars and conventional horizontal or/and vertical shear reinforcement. The proposed approach is verified by comparisons between analytically predicted shear strength values and experimentally obtained ones derived from the literature. The parameters that influence the shear capacity of joints with X-bars have been investigated and special design graphs have been plotted for designing the crossed inclined reinforcement in the joint area. The application of the proposed approach has been illustrated by three numerical examples.