Flexural Behavior Of RC Beams Research Articles

Flexural Analysis of Full-Scale RC Beam Strengthened with Steel Rods

This paper presents an analytical method of evaluating the flexural behavior of RC beams externally strengthened with unbonded high-tension steel rod. A simple summation method proposed in this paper basically assumes that the total strength of RC beams strengthened with rod is equal to the sum of the strength of RC beam and the strength of rod. The strengthening steel rods connected to beam with U and V shape profile are considered as a truss system for the analysis. This analytical method also includes the effect of compressive force applied to RC beam due to the tension of rod as well as the effect of effective prestress in steel rod. A comparison of the analytical and experimental results leads to the conclusion that the simple summation method can simulate the flexural behavior of RC beam strengthened with rod with a good level of accuracy.

Flexural behaviour of RC beams in fibre reinforced concrete

Even though a number of research studies have demonstrated the effectiveness of Fibre Reinforced Concrete (FRC) in improving the structural response of RC members under different loading conditions, some concerns recently arose on the sectional ductility under flexure which can be reduced under specific conditions. In fact, fibres do not significantly increase the ultimate moment of RC members and, with rather tough FRC and low strain-hardening ratio of the longitudinal rebars, the rotation capacity can substantially decrease owing to a cracking localization at ultimate limit state.This paper focuses on this topic with a number of experimental results on full-scale FRC beams tested under flexure.Experimental results evidence that fibres, when provided in sufficient amount, are able to move the beam failure from concrete crushing to steel rupture. Under certain circumstances, the overall ductility, measured in terms of displacements, may decrease.On the other hand, in all cases the addition of fibres determines a stiffer and in general enhanced post-cracking behaviour in service conditions.

Nonlinear Analysis on Flexural Behavior of RC Beam Strengthened with CFRP Sheets on Lateral Side

The technology of strengthening RC beam with CFRP sheets is now a hotspot of research in civil engineering. The FEM analysis was made for the whole deformation course of the flexural behavior of RC beam with CFRP sheets on lateral side, and the result was coincided with the experimental results.

Flexural Behaviour of RC Beams Strengthened with Prestressed CFRP Plates：Comparisons of Bonded and Unbonded Method

In this study, a total of 5 CFRP-strengthened reinforced concrete beams were tested in flexure based on the independent development prestressing anchorage system. The various variables included bonding or no bonding of the CFRP and the amount of prestressing. The experiments consisted of one control beam, two prestressed CFRP-unbonded beams, and two prestressed CFRP-bonded beams, all the beams were subjected to four-point bending tests. The ultimate load, deformation, and CFRP strain were examined. The aim of this investigation was to study the flexural performance of reinforced concrete members strengthened using CFRP plates, employing different CFRP bonding and prestressing methods. The failure mode of the prestressed CFRP-plated beams was not debonding, but concrete crushing or FRP rupture. For the reinforced concrete members strengthened with externally bonded prestressed CFRP plates, after the debonding of the CFRP plates that occurred in the bonded cases, the behaviour of the bonded CFRP-plated beams changed to that of the unbonded CFRP-plated beams due to the effect of the anchorage system. The ductility indices of the beams in an unbonded system were less than that of those in a bonded system.

Simulation Analysis on Repair of Concrete Beams Using Near-Surface Mounted GFRP Bars

This paper focuses on the characterization of flexural behavior of RC beams strengthened with Near-Surface Mounted (NSM) GFRP bars. Based on ABAQUS, the finite element model for the flexural behavior is established and the simulated results are compared with the test results. The parameters including the amount of GFRP bars, the embedment length of GFRP bars, the types of FRP bars, and the ratio of internal steel reinforcement in the beam for the flexural behavior are discussed. The simulated results show that there has a good agreement with the experiment results. The beams strengthened with NSM GFRP bars have a significant improvement in flexural stiffness and bending capacity. Further more, the analysis results on the parameters indicate that ultimate bearing capacity of the beam strengthened with NSM-GFRP bars gradually increases with the amount of FRP bars and the ratio of the longitudinal steel reinforcement. The mode of failure of the beam strengthened with the smaller embedment length of GFRP bars is not the rupture of GFRP bars. The different types of FRP bars have a great influence on the load-deflection curves of the beams.

Effect of CFRP Plate Location on Flexural Behavior of RC Beam Strengthened with CFRP Plate

Location of CFRP plate, as a mode of failure, is one of the major limitations when using externally bonded carbon fiber reinforced polymer (CFRP) plates in strengthening of RC beams. In this work, mode of CFRP plate location was analytically investigated. A non-linear finite element model is proposed in order to analyze experimental data presented by David et.al.[1]. The eight node brick element (SOLID65 as denoted in ANSYS) is used to model reinforced concrete and four node shell element (SHELL41) is used to represented CFRP plate, bond between concrete and CFRP plate represented by interface element (CONTAC52). The results obtained from analytical study explained that the best location of CFRP is at lower edges of concrete beam.

Finite element computational modeling of externally bonded CFRP composites flexural behavior in RC beams

This paper focuses on the flexural behavior of RC beams externally strengthened with Carbon Fiber Reinforced Polymers (CFRP) fabric. A non-linear finite element (FE) analysis strategy is proposed to support the beam flexural behavior experimental analysis. A development system (QUEBRA2D/FEMOOP programs) has been used to accomplish the numerical simulation. Appropriate constitutive models for concrete, rebars, CFRP and bond-slip interfaces have been implemented and adjusted to represent the composite system behavior. Interface and truss finite elements have been implemented (discrete and embedded approaches) for the numerical representation of rebars, interfaces and composites.

An experimental study on the flexural behaviour of RC beams strengthened with high-strength bars

External unbonded strengthening offers advantages in speed and simplicity of installation over other strengthening techniques. Unlike externally bonded steel plate or carbon fibre sheet, surface preparation of the concrete for installation of a high-tension bar is not required and installation is not affected by environmental conditions. An anchoring pin or anchoring plate is installed at the end of the beam to connect the high-tension bar to the concrete beam. The deviators are used so that supplementary external bars follow the curvature of the tested beam. The main test parameters are the section area of strengthening bar, the depth of deviator and the number of deviators. The current paper provides a general description of the structural behaviour of beams strengthened using the technique. The test results of a strengthened beam are compared with those from a reference specimen. It is shown that the reinforcing technique can provide greater strength enhancements to an unstrengthened beam and that the provision of deviator enhances efficiency. The ultimate moment of the specimen with two deviators was higher than that of specimens with one deviator.

Relation between total degradation of steel concrete bond and degree of corrosion of RC beams experimental and computational studies

This paper presents a study on the effects of localized steel-concrete bond degradation on the flexural behaviour of RC beams. A finite element analysis is undertaken to complete the experimental analysis. The first part deals with an experimental study on beams where bond was removed by using plastic tube at different locations and for various lengths. The flexural behaviour was studied at global scale (load-deflection) and local scale (moment-curvature). The second part, a numerical study using a simplified special finite element (rust element) modelling the rust layer occurring between reinforcement and concrete with corrosion was conducted in order to find the relation between the degree of corrosion and the degradation of the steel-concrete bond. The computed value of the corrosion degree corresponding to the total degradation of bond has been used in a second time to model the tests, in order to evaluate the influence of the loss of bond, the steel cross section reduction, and the combination of both. The results enable to evaluate the influence of the different corrosion effects on the flexural behaviour, according to the length and the location of the corroded zone.

Modelling of the flexural behaviour of RC beams subjected to localised and uniform corrosion

This paper presents a finite element study of corroded concrete beam flexural behaviour in which the influence of the percentage of corrosion on the load–deflection curve was studied. CASTEM 2000 computation software was used and the output compared with two experimental studies, the first on uniformly corroded beams, and the second based on a long-term experimental program inducing heterogeneously localised corrosion of beams. For the computation special elements were used to represent the interface between steel and concrete, named rust elements. A sensitivity analysis was carried out using different sizes of rust elements, in order to study their influence on analysis accuracy. The element sizes used were 1, 2, 3, 5, 10 mm. An analysis with only steel cross section reduction (PS, in French “perte de section”) was also made and two concrete behaviour models were used. Comparison of the results showed good correlation between the finite element computation and the experimental studies, and highlighted the efficiency of the rust elements for the flexural behaviour study. In particular, the ultimate load and the deterioration in the stiffness with corrosion were accurately modelled. The prediction of the ultimate deflection required the use of an appropriate damage model for the concrete behaviour.

Experimental analysis of flexural behaviour of externally bonded CFRP reinforced concrete structures

This pper focuses on the flexural behaviour of RC beams strengthened using carbon fibre pultruded plates. Several parameters (number of layers, effect of a precracking) are experimentally investigated on full-scale beams.

Finite element modelling of flexural behaviour of externally bonded CFRP reinforced concrete structures

This paper focuses on the flexural behaviour of RC beams externally reinforced using Carbon Fibre Reinforced Plastics (CFRP) plates. A non-linear finite element (FE) analysis is proposed in order to complete the experimental analysis of the flexural behaviour of the beams. An elasto-plastic behaviour is assumed for reinforced concrete and interface elements are used to model the steel-concrete bond and the adhesive. The numerical analysis also includes simulations on pre-cracked beams.

강연선 및 탄소섬유쉬트로 보강된 철근 콘크리트 보의 휨거동 특성

강연선 및 탄소섬유쉬트로 보강된 철근 콘크리트 보의 휨거동 특성

An experimental study on the flexural behavior of RC beams with cementitious repair materials

The repair and rehabilitation of structures have recently become of great concern due to an increase in loadings and the degradation of structures with time. Considerable efforts are still being undertaken to develop new construction materials. This experimental study describes the flexural behavior of reinforced concrete beams repaired by Polymer Cementitious Mortar and Cement Mortar in the tension zone. Preliminary trials in which beams tensile reinforcing steel was exposed over 100%, 80% and 60% of their length have led to tests on 15×25 cm beams over a 200 cm span. The test parameters of this experimental study, such as the ratio of tensile steel, repair materials and repair length, are discussed here. Emphasis is given to overall bending capacity, deflection, ductility index, failure mode and crack development of repaired beams.

Etude expérimentale et modélisation du comportement en flexion de poutres BA renforcées par collage de composites

ABSTRACT This paper focuses on the flexural behaviour of RC beams strengthened using carbon fibre pultruded plates. Several parameters (number of layers, effect of a pre-cracking) are investigated in a first experimental part on full-scale beams. Then a non linear finite element (FE) analysis is proposed in order to complete the analysis of the behaviour of the strengthened beams. An elastoplastic behaviour with hardening is assumed for reinforced concrete and interface elements are used to model the steel-concrete bond and the adhesive. They enable to study the normal and shear stress distribution in the adhesive. This numerical analysis also includes simulations on pre-cracked beams.

Etude expérimentale et modélisation du comportement en flexion de poutres BA renforcées par collage de composites

ABSTRACT This paper focuses on the flexural behaviour of RC beams strengthened using carbon fibre pultruded plates. Several parameters (number of layers, effect of a pre-cracking) are investigated in a first experimental part on full-scale beams. Then a non linear finite element (FE) analysis is proposed in order to complete the analysis of the behaviour of the strengthened beams. An elastoplastic behaviour with hardening is assumed for reinforced concrete and interface elements are used to model the steel-concrete bond and the adhesive. They enable to study the normal and shear stress distribution in the adhesive. This numerical analysis also includes simulations on pre-cracked beams.

Effect of fire on flexural behaviour of rc beams

The effect of fire on the flexural behaviour of rc beams is investigated. Four groups of rc beams were cast, exposed to fire at 650 °C for time durations of 0, 30, 60 and 120 min and then cooled by water. The concrete compressive strengths of the beams were determined nondestructively using a Schmidt hammer. The beams were tested in flexure by applying two transverse loads incrementally. Strains and deflections were measured at each load increment. Cracking loads, crack propagation and ultimate loads were recorded for each beam. A reduction of ultimate loads, increase in deflection, increase in both compressive and tensile strains and reduction in concrete compressive strength due to fire exposure were observed.