Effect Of Transverse Reinforcement Research Articles

Investigação da contribuição do engrenamento dos agregados em vigas de concreto armado e concreto reforçado com fibras de aço

Abstract Shear strength in reinforced concrete (RC) beams, especially in steel fiber reinforced concrete (SFRC) beams is a subject of great interest in structural engineering. In the case of beams without transverse reinforcement, the failure is explained based on a predefined crack pattern and kinematics, and the transfer of shear force accomplished through different mechanisms. Among these mechanisms, the aggregate interlock is present in most of the existing shear strength mechanical models in the literature, with divergences regarding its performance and preponderance. Thus, this paper focuses on evaluating the contribution of aggregate interlock throughout the critical crack formation process up to the ultimate load by performing bending tests on small-scale rectangular RC and SFRC beams without considering the effect of transverse reinforcement. The Digital Image Correlation (DIC) technique is used to track the patterns of shear cracks and their associated kinematics by measuring the relative displacements of opening (w) and sliding (δ). A detailed description of the shear behavior of these beams is provided by quantifying the aggregate interlock using the simplified Walraven model. The results help to understand the level of contribution of the aggregate interlock, and the main differences between structural elements of concrete with and without steel fibers in the scope of the shear strength.

Effect of Transverse Reinforcement on Shear Response of Fiber-Reinforced Polymer Post-Tensioned Concrete Beams

Effect of Transverse Reinforcement on Shear Response of Fiber-Reinforced Polymer Post-Tensioned Concrete Beams

Analytical and Numerical Investigation of the Behavior of Engineered Cementitious Composite Members under Shear Loads.

This research discusses the performance of engineered cementitious composite (ECC) beams with and without transverse reinforcements using thorough analytical and finite element (FE) approaches under shear. The overall goal of this investigation was to assess the impact of various design characteristics, such as (i) shear span-to-effective depth ratio, (ii) transverse reinforcement ratio, etc., on the shear behavior of ECC beams. Nonlinear three-dimensional (3-D) FE analysis was performed with the commercial software ABAQUS to simulate the shear performance of ECC beams by employing the material properties obtained from the damage plasticity model. The correctness of the proposed FE model was validated with the benchmark experiments available in the literature. The developed FE model accurately computed the ECC beam’s overall load–deflection behavior and failure modes. In addition, the provision available in the Architectural Institute of Japan (AIJ) A-method was successfully employed to assess the shear load-carrying capacity of ECC beams. Furthermore, the effects of transverse reinforcement (pw) and shear span-to-depth ratio (a/d) on the behavior of ECC beams were also investigated. From a detailed parametric study, it was understood that a decreased a/d ratio exhibits enhanced load-carrying capacity for beams with and without stirrups for a particular cross-section. It was also observed that for the entire a/d ratio, the amount of stirrups had no substantial effect on the load-carrying capability of ECC beams.

Experimental and numerical evaluation of steel fibres RC patterns influence on the seismic behaviour of the exterior concrete beam-column connections

Exterior concrete beam-column connections are one of the important parts of the concrete structural frames that play an important role in controlling the seismic behaviour of structures during an earthquake. Providing sufficient ductility for beam-column connections helps to dissipate more energy during a cyclic load and improves the performance of structures. In this study, the cyclic behaviour of exterior concrete beam-column connection was studied experimentally and numerically. To improve the cyclic performance of the connections, steel fibres (SF) were used. A total of 20 exterior concrete beam-column connections were produced and tested under a cyclic load. SF were added at 1% in terms of volume. SF-reinforced concrete was used in four different patterns. In addition, the influence of bent angles for longitudinal reinforcement bar in the connection region was studied: 90° and 135°. Furthermore, the effect of transverse reinforcement on the cyclic behaviour of the connection was studied by providing different spacings in the column: 150 mm and 100 mm. Formerly, a finite element method software, ABAQUS, was used to study the effect of compressive strength of concrete (normal and high-strength), longitudinal rebars ratio and transverse reinforcement spacing in the beam on the behaviour of exterior concrete beam-column connection produced by different SF-reinforced concrete patterns. Evaluation of the maximum lateral load-bearing capacity, drift ratio, maximum displacement, ductility, efficiency and energy absorption of connections were the main aims of this study. The results showed that using SF-reinforced concrete in the connection zone was the best pattern in terms of maximum lateral resistance and deformation of the connections, especially when a 135° bent angle was provided for the longitudinal rebars. In addition, using high-strength concrete led to reducing the ductility and efficiency of connections, particularly when a 90° bent angle were performed for the longitudinal rebar in the connection region.

Experimental study of the resistance of RC walls with different transverse reinforcements subjected to large-scale rigid projectile impacts

After the 9/11 terrorist attacks, the nuclear power plants (NPPs) containment resisted a commercial aircraft or wind-borne missile impact has become one of the focus issues in the nuclear security field. Transverse reinforcement is typically used in reinforced concrete (RC) walls for nuclear engineering. However, there is little research related to the damage characteristics of RC walls with transverse reinforcement under the impact of a large-scale rigid projectile, and the effect of transverse reinforcement on penetration or perforation under projectile impact is still unclear. In this paper, according to different forms of transverse reinforcement, three types of RC walls were designed, and a total of eight large-scale rigid projectile impact tests for RC walls were performed. The failure mode of the walls, the concrete scabbed area, the penetration depth and the total failure number of longitudinal reinforcement were measured for comparison. The conclusion is that the form of transverse reinforcement influences the failure mode of an RC wall subjected to a rigid projectile impact. Transverse reinforcement plays a significant role in reducing the rear scabbing of the concrete. The tested walls with U-shaped transverse reinforcement show better performance than the walls in the form of classic stirrups with hooks with regard to perforation capacity under rigid projectile impact. In addition, the dynamic response characteristics of RC walls subjected to large-scale rigid projectile impacts are analyzed preliminarily, and the impact test results are consistent with the predictions of the Chang’s empirical formula on damage modes. The related works and conclusions can provide a basis for NPP structural optimization and the safety assessment of large commercial aircraft collision problems and can also provide experimental data to verify finite element methodology.

Numerička analiza cikličnog jednoosnog i dvoosnog bočnog opterećenja AB stupova

A numerical finite element study is conducted in this paper to examine structural behaviour of high strength RC columns exposed to biaxial and uniaxial lateral displacement histories with constant axial load. The numerical analysis of 24 models was made using ABAQUS / CAE. The comparison between numerical analysis and experimental results shows good agreement through validations. The considered parametric study involves determination of the longitudinal reinforcement ratio, total cross-sectional area of confinement steel (Ash), and uniaxial and biaxial cyclic shear load. Numerical analysis results show that an increase of longitudinal reinforcement for a uniaxial and biaxial lateral historic load will significantly increase maximum and ultimate load of columns, corresponding deflections, number of cycles at maximum and ultimate loads, and initial stiffness Ki, while the effect of transverse reinforcement is less pronounced. The columns load and deformation capacity decreases significantly with application of biaxial cyclic shear load, compared with uniaxial load. Also, this effect reduces with an increase in longitudinal reinforcement ratio (%ρl) and Ash.

Effect of transverse reinforcement on cracking of CFRP composite laminates under static and fatigue loads

Several CFRP laminates with various layups, possessing two distinctive forms of transverse reinforcement either UD 90° or fabric 0°/90°, were tested in both static and fatigue tests. All examined layups were considered to be used in the wingbox design of the multipurpose turboprop aircraft. In-situ microscopic observations were carried out during the tests. Static tensile tests allowed to find the strength of the laminas, stress, and strains at which cracks started to propagate, crack density during the test. The microscopic observations allowed to establish cracks’ growth paths. The first crack in laminates having fabric 0°/90° laminas usually was observed for higher stress and strain than in laminates with UD 90° laminas. Also, the later ones showed a tendency to significantly delaminate along the interface between UD 90° and UD 45° laminas. The fatigue test was carried out in order to find how to distinguish damage growth in both families of laminates that affects their fatigue life. As an outcome, S-N lines were determined. During the test the microscopic observations were made, which allowed to show crack and delamination growth during successive load cycles. The microscopic observations showed that cyclic loading leads to the fast growth of delaminations at the interface of fabric 0°/90°ply or UD 90° laminas.

Effect of transverse reinforcement on the seismic behavior of diagonally reinforced concrete coupling beams

Coupled shear wall systems have been more popularly used in high-rise building construction in urban areas due to their efficiency in sustaining lateral loads as well as economic effectiveness. During earthquakes, coupling beams in the coupled wall system act as a seismic fuse element that dissipate most of seismic input energy exerted in the system. Diagonally reinforced concrete coupling beams (DRCBs) have been developed for this purpose. The objective of this study was to acquire test data of DRCBs of with different amount of transverse reinforcement and to evaluate the seismic behavior of these DRCBs. Quasi-static cyclic tests were conducted using seven DRCB specimens with different amounts of transverse reinforcement and different aspect ratios. Four specimens had Ln/h of 2.0, whereas it was 3.5 for the other three specimens. The shear strengths of individual specimens were compared to that calculated from the shear strength equation specified in ACI 318-14, and their deformation capacities were compared to those specified in ASCE 41-17. It is observed that the amount of transverse reinforcement in DRCBs played an important role in their shear strength and deformation capacities, indicating that the contribution of transverse reinforcement needs to be incorporated to ACI 318 shear strength equation and ASCE 41-17 model parameters.

Effect of transverse reinforcement on rectangular concrete columns with MTSTR

To better understand the confining effect of multiple-tied-spiral transverse reinforcement (MTSTR) for concrete with rectangular cross-section, eight rectangular concrete columns were fabricated and tested under axial compression; four columns used MTSTR, while the remainder were counterpart reference columns reinforced by conventional stirrups. The main variable considered was the confinement index of transverse reinforcement; this index includes the ratio of the confinement index of interior circular spirals to that of exterior rectangular hoops and the sum of the confinement indices. The results showed that rectangular concrete columns with MTSTR exhibited better ductility than reference columns with the same confinement index of transverse reinforcement; however, the peak load for reinforced columns with MTSTR increased depending on the ratio of the confinement index of circular spirals to that of rectangular hoops; the critical ratio of the confinement index was approximately 2·72. Moreover, compared with previous investigations, the influence of the yield strength ratio of interior circular spirals to exterior rectangular hoops on the load-carrying capacity of the concrete columns with MTSTR was linear. Finally, a simplified method based on the models of Mander et al. is proposed to predict the peak strength of rectangular concrete columns with MTSTR.

Bond strength of confined normal strength concrete beam-column joints

The article presents the results of a research study that was conducted at the American University of Beirut (AUB) on the effect of transverse reinforcement crossing the critical hooked bars region of normal strength concrete (NSC) beam-column joints on the bond strength and ductility of the mode of failure of the hooked bars. Nine full-scale beam-column joint specimens were tested. The specimen simulated the rigid connection of a cantilever vertical beam to a base column. The load was applied near the tip of the beam while the column was fixed to the strong floor. The tensile beam bars were anchored in the column using hooked-bar anchorages. In previous research, confinement to the joint was provided either by carbon fiber reinforced polymer (CFRP) sheets externally confining the joint or steel fibers incorporated in the concrete mix. Results revealed that the transverse reinforcement crossing the hooked bars region was effective in increasing the anchorage capacity and the ductility of the load-deflection history of the specimens. Correlation of the effects of the three different confinement modes is presented.

Cyclic behaviour of slender diagonally reinforced coupling beams with various amounts of transverse reinforcement

Coupled shear wall systems are very efficient in resisting lateral forces induced by wind and earthquake loads. Recently, slender diagonally reinforced coupling (DRC) beams have been commonly used for coupled shear wall systems in high-rise building construction, which allows reduction of storey height and construction cost. The objective of the present study is to investigate the effect of transverse reinforcement on the cyclic behaviour of slender DRC beams. For this purpose, experiments were conducted using three DRC specimens with various amounts of transverse reinforcement. An equation for accurately predicting the shear strength of slender DRC beams is proposed.

시공줄눈이 있는 콘크리트 경계면의 전단마찰 내력에 대한 보강철근의 영향

시공줄눈이 있는 콘크리트 경계면의 전단마찰 내력에 대한 보강철근의 영향

Determination of strut efficiency factor for concrete deep beams with and without fibre

Based on the variation of strain along the cross section, any region in a structural member can be classified into two regions namely, Bernoulli´s region (B-region) and Disturbed region (D-region). Since the variation of strain along the cross section for a B-region is linear, well-developed theories are available for their analysis and design. On the other hand, the design of D-region is carried out based on thumb rules and past experience due to the presence of nonlinear strain distribution. Strut-and-Tie method is a novel approach that can be used for the analysis and design of both B-region as well as D-region with equal importance. The strut efficiency factor (βs) is needed for the design and analysis of concrete members using Strut and Tie method. In this paper, equations for finding βs for bottle shaped struts in concrete deep beams (a D-region) with and without steel fibres are developed. The effects of transverse reinforcement on βs are also considered. Numerical studies using commercially available finite element software along with limited amount of experimental studies were used to find βs.

축응력 및 횡보강근을 고려한 콘크리트의 전단마찰내력 평가모델

Dept. of Plant·Architectural Engineering, Kyonggi University, Suwon 16227, Rep. of KoreaABSTRACT Shear friction strength model of concrete was proposed to explain the direct friction mechanism at the concrete interfaces intersecting two structural elements. The model was derived from a mechanism analysis based on the upper-bound theor em of concrete plasticity considering the effect of transverse reinforcement and applied axial loads on the shear strength at concrete interfaces. Concrete was modelled as a rigid–perfectly plastic material obeying modified Coulomb failure criteria. To allow the influence of concrete type and maximum aggregate size on the effectiveness strength of concrete, the stress-strain models proposed by Yang et al. and Hordijk were employed in compression and tension, respectively. From the conversion of these stress-strain models into rigidly perfect materials, the effectiveness factor for compression, ratio of effective tensile strength to compressive strength and angle of concrete friction were then mathematically generalized. The proposed shear friction strength model was compared with 91 push-off specimens compiled from the available literature. Unlike the existing equations or code equations, the proposed model possessed an application of diversity against various parameters. As a result, the mean and standard deviation o f the ratios between experiments and predictions using the present model are 0.95 and 0.15, respectively, indicating a better accurac y and less variation than the other equations, regardless of concrete type, the amount of transverse reinforcement, and the magnitude of applied axial stresses.Keywords : shear friction strength, upper-bound theorem, transverse reinforcement, axial stresses

Bond Strength of Lap-Spliced GFRP Bars in Concrete Beams

In this paper, the bond strength of lap-spliced glass fiber–reinforced polymer (GFRP) bars in concrete beams is experimentally investigated. Thirteen beam specimens were manufactured for laboratory experiments. The parameter of transverse reinforcement along the splice length was selected as the main variable for the beam specimens. Other variables were surface properties of GFRP bars, bar diameter, and concrete compressive strength. Test results show that the effect of transverse reinforcement on bond strength between GFRP bars and concrete depends on the surface properties of reinforcing bars. The experimental results obtained in the present study and the results reported in the literature are compared with the current design equation provided by the American Concrete Institute (ACI) Committee 440 guidelines. The equation of ACI Committee 440 for evaluating the bond strength of GFRP bars underestimates the bond strength of spliced GFRP bars confined with large amounts of transverse reinforcement. For cases of small values of transverse reinforcement and splices without transverse reinforcement, the equation of ACI Committee 440 is unconservative and overestimates the bond strength. In this paper, an equation for predicting the bond strength of GFRP bars is also proposed on the basis of test results and the Monte Carlo simulation method.

Effects of the Transverse Reinforcement on the Shear Behaviour of High Strength Concrete Beams

This paper presents the results of an experimental investigation dealing with the effects of transverse reinforcement on the crack patterns, the ultimate carrying capacity and the ductility of beams made of high strength concrete and normal strength concrete for comparison purposes. The test results are analyzed and compared with the shear provisions in the four major universal codes (ACI-318; BS-8110; Eurocode 2; BAEL 99). Twenty six reinforced concrete beams with and without transverse reinforcement were constructed using different shear-span to depth ratios (a/d = 1.5, 2.0 and 3.0) and different compressive strengths of concrete (44 MPa, 65 MPa and 86 MPa). The test results indicate that the presence of transverse reinforcement had controlled efficiently the crack width by enhancing the aggregate interlocking on the crack surface, increased moderately the shear strengths of the beams by factors ranging from 1.14 to 1.86, and increased appreciably the ductility of beams at the ultimate state. It should be noted, however, that the beams failed at shear strength contributions of transverse reinforcement ( Vs) considerably lower than the values predicted by the models used in the four major universal codes. This translates that the existing universal design codes may not be rationally safe against shear design of high strength concrete beams containing transverse reinforcement.

Effect of Transverse Reinforcement on the Flexural Behavior of Continuous Concrete Beams Reinforced with FRP

Continuous concrete beams are structural elements commonly used in structures that might be exposed to extreme weather conditions and the application of deicing salts, such as bridge overpasses and parking garages. In such structures, reinforcing continuous concrete beams with the noncorrodible fiber-reinforced polymer (FRP) bars is beneficial to avoid steel corrosion. However, the linear-elastic behavior of FRP materials makes the ability of continuous beams to redistribute loads and moments questionable. A total of seven full-scale continuous concrete beams were tested to failure. Six beams were reinforced with glass fiber-reinforced polymer (GFRP) longitudinal bars, whereas one was reinforced with steel as control. The specimens have rectangular cross section of 200×300 mm and are continuous over two spans of 2,800 mm each. Both steel and GFRP stirrups were used as transverse reinforcement. The material, spacing, and amount of transverse reinforcement were the primary investigated parameters in this s...

A study on the bond strength of tension lap splices in self compacting concrete

The primary objective of the research reported in this paper was to evaluate the effect of using self compacting concrete on the bond strength and mode of bond failure of tension lap splices anchored in normal strength concrete (NSC). Studies on the effect of transverse reinforcement on anchored reinforcement in self compacting concrete to prevent brittle mode of failure is limited. To meet this objective, full-scale NSC beam specimens were tested. Each beam was designed with bars spliced in a constant moment region at mid-span with various levels of stirrup confinement. The slip of the reinforcement with respect to concrete is also measured by providing notches at the end of the splices. Test results indicated that there is an increase in the bond strength when self compacting concrete is used in place of vibrated concrete. Ductility and splice strength increased as the confinement increased. When the stirrup spacing is less than 150 mm, the failure in the splice region was by yielding of steel. The influence of confinement on the crack formation of the beams is also reported.

Investigation on Effect of Transverse Reinforcement on Performance of Diagonally Reinforced Coupling Beams

First Name is required invalid characters Last Name is required invalid characters Email Address is required Invalid Email Address Invalid Email Address

Effects of transverse reinforcement on flexural behaviour of high-strength concrete columns

This experimental investigation was conducted to examine the behaviour of eight one-third scale columns made of high-strength concrete (HSC). Each column was subjected to a constant axial load corresponding to 30% of the column axial-load capacity and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement ( ρ s=1.58, 2.25%), tie configuration (Type H, Type C and Type D) and tie yield strength ( f yh=549 and 779 MPa). Test results show that the flexural strength of every column exceeds the calculated flexural capacity based on the equivalent concrete stress block used in the current design code. Columns with 42% higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour. With an axial-load of 30% of the axial load capacity, it is recommended that the yield strength of transverse reinforcement be held equal to or below 549 MPa. Analysis of the flexural strength using the confinement model presented by Yong et al. enabled the experimental moment capacities to be predicted accurately.