Behavior Of Concrete Deep Beams Research Articles

Effects of the Concrete Strength and FRP Reinforcement Type on the Non-Linear Behavior of Concrete Deep Beams

To provide sustainable reinforced concrete deep beams, the replacement of steel rebars by FRP rebars with high-chemical resistance is proposed by researchers. However, the effects of the concrete strength, top and web longitudinal reinforcements, and types of FRP flexural rebars on the non-linear performance of concrete deep beams have rarely been evaluated. This study numerically assessed the effects of the top and web longitudinal reinforcements and concrete strength on the non-linear behaviour of GFRP- and CFRP-strengthened concrete deep beams with various shear span-to-overall depth (a/h) ratios. As per the results, the highest tensile stress was obtained for the steel reinforcement, and the tensile stress in the CFRP reinforcement was more than that of the GFRP reinforcement under the failure load. Meanwhile, the results of high- and normal-strength concrete deep beams with the web reinforcement (16.4%) were lower than those without the web reinforcement (22.3%). Therefore, the web reinforcement moderately compensated for the low strength of normal concrete and the absence of the top longitudinal rebar to reinforce concrete deep beams in carrying the ultimate load. Furthermore, the participation of the GFRP reinforcement with the high-strength concrete was more than that with the normal-strength concrete in carrying a higher amount of loading.

Numerical investigation of RC deep beams containing recycled aggregates

In this study, the behavior of reinforced concrete deep beams containing natural coarse aggregates (NCA), recycled concrete aggregates (RCA), and recycled asphalt pavement aggregates (RAP) was numerically investigated. The required parameters for use in the nonlinear finite element analysis were discussed in detail. To examine the accuracy of the nonlinear analysis, the numerical analysis results for deep beams containing NCA, RCA, and RAP were validated with experimental results. The most important parameters that could affect the behavior of concrete deep beams were proposed. The numerical analysis results for 63 concrete deep beam specimens indicated that the deep beams containing NCA and RCA exhibited nearly similar behavior for any a/h and L/h ratios, whereas RAP deep beams behaved differently from the two corresponding specimens. The deep beams made with RCA and NCA had brittle behavior for any value of the a/h and L/h ratios, while those containing RAP showed more ductility. The energy absorption was far greater for RAP deep beams compared with the NCA and RCA specimens. The absorbed energy in NCA and RCA deep beams was nearly the same. The size effect phenomenon was almost similar in the deep beams made with NCA and RCA, whereas in the RAP deep beams, the intensity of this effect was less severe.

Nonlinear Finite Element Analysis for Concrete Deep Beam Reinforced with GFRP Bars

This work investigates the behavior of concrete deep beams reinforced with GFRP bars by conducting an experimental test on a half-scale GFRP deep beam and evaluating the findings by ANSYS software. Also, ANSYS was used to perform nonlinear finite element analysis NLFEA on five specimens with different reinforcement ratios of GFRP bars (0.15%, 0.41%, 0.53%, 0.67%, and 0.79%) to examine the influence of the GFRP reinforcement ratio on the behavior of deep beams. The outcomes of the experiment were sufficiently reflected in the analysis. The program's viability was confirmed by comparing it to accessible experimental data, and the agreement was found to be acceptable. Throughout the loading stages, the NLFEA produced a reasonable estimate of the center deflection for the test specimen. It was established that raising the specimen's reinforcement ratio led to an increase in beam capacity by (10 %, 18%, 31% and 47%) for reinforcement ratios (0.41%, 0.53%, 0.67% and 0.79%) and also the ultimate stiffness increased by (6%, 7%, 29%, and 44%) compared to specimen B1. Also found that the energy absorption enhanced by (23 %, 38 %, 106 %, and 152 %), on the opposite, this increase causes the specimen's deflection to decrease by (11 %, 17%, 52%, and 66%) by comparing to specimen B1. From the outputs results, it was found that the code provision was more conservative than the analytical model. For future work, Significant and cost-effective improvements to the manufacture of GFRP bars from locally sourced raw materials. Also, Extensive experimental work to investigate the long-term behavior of GFRP-reinforced concrete beams in harsh situations. The performance of GFRP reinforced specimens subjected to shear, fatigue, and cyclic stresses in service must be evaluated.

Shear Behavior of Steel-Fiber-Reinforced Recycled Aggregate Concrete Deep Beams

Results of an experimental investigation aimed at studying the effect of steel fibers on the shear behavior of concrete deep beams made with a 100% recycled concrete aggregate (RCA) are presented in this paper. The study comprised testing of seven concrete deep beam specimens with a shear span-to-depth ratio (a/h) of 1.6. Two beams were made of natural aggregates (NAs) without steel fibers, two beams were made of a 100% RCA without steel fibers, and three beams were made of RCA-based concrete with steel fibers at volume fractions (vf) of 1, 2, and 3%. Two of the beams without steel fibers included a minimum shear reinforcement. Test results showed that the beam with a 100% RCA without steel fibers exhibited a lower post-cracking stiffness, reduced shear cracking load, and lower shear capacity than those of the NA-based control beam. The detrimental effect of the RCA on the shear response was less pronounced in the presence of the minimum shear reinforcement. The addition of steel fibers significantly improved the shear response of the RCA-based beams. The post-cracking stiffness of the RCA-based concrete beams with steel fibers coincided with that of a similar beam without fibers containing the minimum shear reinforcement. The use of steel fibers in RCA beams at vf of 1 and 2% restored 80 and 90% of the shear capacity, respectively, of a similar beam with the minimum shear reinforcement. The response of the RCA specimen with vf of 3% outperformed that of the NA-based control beam with the minimum shear reinforcement, indicating that steel fibers can be used in RCA deep beams as a substitution to the minimum shear reinforcement. The shear capacities obtained from the tests were compared with predictions of published analytical models.

Structural Behavior of Concrete Deep Beams Reinforced with Steel Ducts

The aim of the research is to investigate the structural behavior of deep beams with a longitudinal opening reinforced by steel pipes. The experimental program included a test of (10) specimens with dimensions of (1500mm) length, (500mm) overall height and (250mm) width. One of these specimens was casted with solid section (without longitudinal opening) to keep it as a reference specimen for comparison purposes. The variables considered in this research were, the shape of the openings (circular, square, and rectangular) was adopted, opening size (three variable sizes of circular openings 4in,3in, and 2in) were used, in addition to the void’s ratio. The Load-deflection curves and crack patterns for the tested beams were discussed. The experimental results showed that the structural behavior of specimens with circular openings was approximately equal to the reference beam, where it gave efficiency about (103%) with respect to the reference beam. The specimens with square and rectangular openings gave an average load carrying capacity about (81%-35%) respectively with respect to the reference beam. Also, its noticed that the specimens containing rectangular openings were inefficient and caused early collapse. Using of steel pipes to reinforce the longitudinal opening was observed to be efficient for improving the load carrying capacity and stiffness of deep beams, the results showed that the ultimate load was increased by 22.6% compared to the beam with unreinforced opening.

Behaviour of Rectangular Concrete Deep Beams with Hybrid Fibre Reinforced Polymer Reinforcements Considering Web Openings

The use of non-corrosive reinforcements in the place of steel reinforcements has therefore been focused as an alternative to improve the life span of the concrete structures. Fibre Reinforced Polymer (FRP) reinforcements offer many advantages over steel reinforcements including resistance to electrochemical corrosion, high strength to weight ratio and easy in fabrication and electromagnetic insulating properties. Further, the use of hybrid FRP reinforcements, in lieu of conventional steel reinforcements requires better understanding under different parametric conditions. Therefore the present study deals mainly with the behaviour of Concrete Deep beams with and without openings reinforced internally with hybrid type Fibre Reinforced Polymer (FRP) reinforcements under static loading conditions. In structural applications, deep beams are commonly used as large span structures such as transfer girders in buildings, bridges, foundation walls, shear walls and offshore structures. In this study,high strength concrete deep beams are investigated. Among the eight beams, four beams are reinforced internally using conventional reinforcements with and without web opening, four beams are reinforced internally using hybrid FRP reinforcements with and without web openings. Different parameters like, high strength concrete, web opening positions (Top, Middle and Bottom), span sprinkled FRP hybrid reinforcements are considered. Based on this study, static load carrying capacities and their modes of failures of deep beams reinforced internally with FRP hybrid type reinforcements for various web openings positions are compared by finite element modelling using ANSYS software with the existing theories for better under standings. Based on the modelling and theoretical work, final conclusions of the present study are derived.

A REVIEW OF BEHAVIOR OF REINFORCED CONCRETE DEEP BEAMS

Reinforced concrete deep beams are structural members having depth much greater than normal in relation to their span, while the thickness in the perpendicular direction is much smaller than either span or depth. The strength of deep beams is usually controlled by shear, rather than flexure. In this study, the previous researches related to reinforced concrete deep beams will be reviewed. These researches approximately started in the second half of the past century. Large numbers of researchers studied the behavior of concrete deep beams and the determination of their capacity. Some of these researches are experimental investigations carried out by testing a number of deep beams with variation in some parameters, while the others are theoretical to estimate deep beam capacity by developing some theories and suggestion of equations for calculating its capacity and comparisons were made with those adopted by some codes. Because of the large number of these researches, their review requires large part of this study, and because the prior studies elaborately reviewed the pioneer researches, only the researches made since year 2000 will be reviewed in this study.

Modeling of shear mechanisms and strength of concrete deep beams reinforced with FRP bars

With the growing application of concrete structures reinforced with fiber reinforced polymer (FRP) composite materials, it is necessary to develop more rational mechanical models for their load-carrying capacity evaluation. Firstly, this study numerically analyzed the influences of differences in bond behavior and axial stiffness between FRP and steel bars on the shear behavior of concrete deep beams. It was identified the reinforcement stiffness is the main influencing factor, and an explanation on how the reinforcement stiffness influences the shear performance of deep beams at the mechanism-level was also provided. On this basis, a mechanical cracking strut-and-tie model (CSTM), which theoretically considered the effect of the critical shear crack on the diagonal strut capacity, was proposed to predict shear mechanisms and strength of concrete deep beams reinforced with FRP bars. The proposed CSTM was verified by a shear database of 52 existing tests and compared with predictions of other models. In addition, for purpose of practical design, a simplified CSTM was proposed and verified to be superior to the shear models of CSA S086-12 and ACI 440.1R-15 in terms of safety margin and accuracy.

Nonlinear Finite Element Modeling of Shear Behavior of Concrete Deep Beams Reinforced with Internal Glass Fiber-Reinforced Polymer Bars by ANSYS

The purpose of this paper is to numerically trace the behavior of concrete deep beams reinforced with internal Glass Fiber-Reinforced Polymer (GFRP) bars and containing no web reinforcement by using ANSYS program. For this purpose, a finite element model is used for concrete deep beams that previously examined in an experimental study and its predicted failure loads were compared with the actual failure loads. The results of the finite element model were in a good agreement with observations from the experimental study. The comparisons showed that the used model has the ability to capture the shear behavior, as well as load-deflection response and crack patterns of deep beams reinforced with internal GFRP bars in the entire range of loading. The paper is also covered a parametric study on shear span-to-depth (a/d) ratio, GFRP reinforcement ratio and concrete compressive strength which they usually have high impacts on the behavior of fiber-reinforced concrete beams. The results of the parametric study showed that the ultimate failure load of beams reinforced with GFRP bars was higher than that of steel-reinforced concrete beams. The maximum failure load was observed to decrease by decreasing the a/d ratio. The stiffness and ductility of the beams were increasing by increasing the reinforcement ratio.

Effect of Development and Geometry on Behavior of Concrete Deep Beams

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Behavior of Concrete Deep Beams Reinforced with Internal Fiber-Reinforced Polymer—Experimental Study

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Behaviour of concrete deep beams with openings and low shear span-to-depth ratio

The goal of this study is to experimentally and analytically evaluate the influence of circular openings in reinforced concrete deep beams with low shear span-to-depth ratio.Twenty reinforced concrete small-scale deep beams with or without openings were tested in flexure under four-point loading. The beams had a small shear span-to-depth ratio in order to stress the shear behavior. The specimens had different reinforcement arrangements and opening positions. The load was transmitted to the specimen with bearing plates having the same side length as the beam. Two LVDT’s were arranged to record the transverse and axial strain of the theoretical struts forming in the beam. Additionally another device was mounted to measure the middle deflection of the beam.Comparative analysis of the experimental results shows that: the effect of the hole depends on its position in the beam; the benefit of the presence of reinforcement depends on its arrangement.An analytical model is proposed to predict the shear strength and corresponding deflection of deep beams with openings and the results are also compared with a non-linear finite element analysis showing good agreement.

Shear strength of fibre-reinforced polymer reinforced concrete deep beams without web reinforcement

This paper describes an experimental investigation to evaluate the shear strength and behavior of concrete deep beams reinforced with fibre-reinforced polymer (FRP) bars. A total of ten full-scale ...

SHEAR STRENGTH OF REINFORCED AND PRESTRESSED CONCRETE DEEP BEAMS. PART II: THE SUPPORTING EVIDENCE.

Keywords NANYANG TECHNOLOGICAL UNIVERSITY, SINGAPORE, NEWCASTLE UNIVERSITY AUTOWAYS CONSTRUCTION, KUALA LUMPUR CONCRETE, BEAMS, DEEP, REINFORCED, PRESTRESSED, STRENGTH, SHEAR, TENDONS, PROFILES, PRESTRESSING, TESTS, SERVICEABILITY, PROPERTIES, WEBS, ORTHOGONAL, REINFORCEMENT, DEFORMATION, BEHAVIOUR, ULTIMATE, LOADS, CRACKING, FAILURES, MODES, STEEL, TENSION, STRAIN, RATIOS, SPAN TO DEPTH, EQUATIONS, CRACKS, SPLITTING, DIAGONAL, LIMIT STATE... Show All