Behavior Of RC Beams Research Articles

Experimental Study on Behavior of RC Beam Strengthened with Ridged Aramid Fiber Plate Strip

In this study, to evaluate the bending performance and the shear performance of Aramid Fiber Plate Strip with enhanced attachment, 8 specimens were made for experiment. Most flexural failure specimens showed AFPS rip-off failure or separation failure. In the shear failure specimens, the specimens showed a brittle failure in which the concrete compression edge was broken. Compared with the control beam, the maximum ultimate strength increased by 164~193% for the flexural failure specimen, and by 218~259% for the shear failure specimen. The ductility, however, decreased steeply in the shear-failure specimen as the amount of reinforcement grew.

Test of High Performance Reinforced Concrete Beams with Web Openings Using Fly-Ash

The purpose of this study is to evaluate the flexural behavior of RC beams with web openings (HPRWO) that are constructed by using square steel tube, fibers and fly-ash. One regular RC beam with openings (HPRS) and three HPRWO specimens were manufactured and tested under monotonic loading. It was evaluated by flexural experiment of HPRWO through comparison of failure mode, load-deflection curves, ductility and ultimate load (Vu). Test results showed that the ultimate load of the HPRFPS specimens were approximately 11.2% to 51.3% better than that of the HPRS, in addition their ductility behavior was better than the HPRS.

Modelling of flexural behaviour of RC beams strengthened with NSM CFRP rods including serviceability

The proposed model calculates the deflection of carbon fibre-reinforced polymer (CFRP) strengthened beams. In this model, the beams were strengthened before loading, so in an uncracked state. The calculation before cracking uses conventional existing models. The calculation of the deflection after cracking is based on a non-linear Macro-Finite-Element (M.F.E.). This M.F.E. is a beam Finite Element characterised mainly (for the bending problems) by its homogeneous average moment of inertia. The typical global behaviour of beams strengthened by NSM rods s was modelled as well as repeated loading cycles. The model is validated experimentally on two CFRP strengthened concrete beams with two sections of CFRP rods subjected to four-point flexure under repeated loading cycles after cracking and then a constant loading rate until failure. Results show that the model gives good predictions of the bending stiffness of the beam during the loading cycle and the permanent residual deflection after unloading due to crack propagation.

Short-Term Partial-Interaction Behavior of RC Beams with Prestressed FRP and Steel

AbstractThe deformation of a prestressed concrete (PC) member is controlled by the variation in flexural rigidity (EI) both along the length of the member and with applied loads. Typically, the moment-curvature M/χ approach is used to quantify EI with the analysis being mechanically correct prior to cracking as the only empirically derived components are the material stress-strain relationships. Postcracking, however, the M/χ approach has to be semi-empirical as it cannot directly simulate the effects of tension stiffening. This paper presents a displacement-based M/Θ approach for determining the behavior of PC members, with and without supplementary tension reinforcement. Applying the mechanics of partial-interaction (PI) theory, the approach directly simulates the formation and widening of cracks as the reinforcement pulls from the crack face, thus directly allowing for tension stiffening. The PI M/Θ approach can quantify the equivalent flexural rigidities (EIequ) associated with tension-stiffening whic...

Flexure Behaviour the Concrete Beams Reinforcement with Polymer Materials

Improvement of flexure behavior using the polymer materials is one of the very important factors in analyzing the concrete elements, especially concrete beams. In this case we analyze two different cases: • Improvement using the polypropylene microfibers in ready mix concrete • Improvement using the carbon fibers in external reinforcement In both case studies we used three-point-load experimental beam-bending tests for: three conventional RC beams (referent beams), three RC beams with polypropylene fibers and three RC beams with carbon fibers. All results concern comparing the effect of fibers on improvement of energy capacity of concrete elements, and increasing the bearing capacity of concrete beams. One of the most important values based on the behavior of the structure is ductility. The ductility is a structural design requirement in most design codes. The traditional definition of ductility cannot be applied in structures reinforced with FRP reinforcement. Several methods, such as the energy based method and the deformation based method have been suggested to calculate the ductility index for FRP reinforced structures. Furthermore the behavior of RC beams is analyzed with the help of cracks, their position and width under the loads.

Experimental Study of Flexural Behavior of RC Beams Strengthening with BFRP Sheets

This paper presented the results of testing reinforced concrete beams strengthening with the BFRP sheets. Five specimens were cast and tested. All specimens were 2600 mm total span with a cross section of 150mm width and 250mm depth. Out of the specimens, two specimens were designed as reference specimens. The rest specimens were repaired with the BFRP sheets. The variables examine in the experiment were the longitudinal tensile reinforcement ratio, the different layers of the BFRP sheets and the anchoring measures of BFRP sheets. All specimens were tested under simply supported condition. 3D nonlinear finite element (FE) numerical models by ANSYS10.0 software were conducted to accurately predict the ultimate bearing capacity and response of reinforced concrete specimens strengthening with BFRP sheets subjected to four-point bending loading. The nonlinear constitutive material properties of concrete and steel reinforcement were considered in the finite element model. The results of the FEM simulation were compared with that of the experimental specimens. The results showed that it was significantly effective for the flexural capacity of the BFRP sheet-bonded reinforcement in tensile zone for reinforced concrete beams. Moreover, it implied excellent results on the stiffness of the reinforced concrete beams. The flexural strength enhancement of the reinforced concrete beams strengthening with the BFRP sheets varied between 19% ~ 44% over the control beam. This study further identified that the BFRP sheet technique significantly enhanced the stiffness and flexural capacity of reinforced concrete beams.

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.

Simulation on Bond Behavior of RC Beams Strengthened with FRP

The bond behavior on the FRP-concrete interface is a key factor to affect the behavior of members strengthened with FRP. In this paper, an analytical model to simulate the bond behavior on FRP-concrete interface between two adjacent cracks is derived; furthermore, the calculation method of the steel strain at the crack which is the key parameter in this model is given. Comparison between experimental result and theoretical calculation on FRP stain distribution in beam indicates that the analytical model can well predict the test results.

Behaviour of RC beams under combined shear and torsion according to AASHTO LRFD and ACI equations

In this study, the AASHTO LRFD provisions for combined shear and torsion have been investigated and their accuracy has been validated against experimental data. AASHTO LRFD (2008) provisions on combined shear and torsion have also been compared to the pertinent ACI code requirements for the behaviour of reinforced concrete beams subjected to combined shear and torsion. In this comprehensive comparison, different sections with high strength and normal strength concrete as well as over-reinforced, moderately-reinforced and, under-reinforced solid and hollow sections were analysed. This study resulted in findings on the applicability of both code procedures to different sectional material and geometry values under these load combinations.

Load-Deflection Analysis of RC Beams Strengthened with External CFRP Sheets

Abstract. This paper is dedicated to the load-deflection analysis of RC beams strengthened with external CFRP sheets. A theoretical nonlinear model, based on slip and bond stresses, is described and adopted for the deformability predicition of beams. The model allows considering the bond-slip relationships both between concrete and steel bar and between concrete and CFRP. Comparisons between the simulated midspan deflection and that of experiment indicate that the proposed nonlinear model is able to predict the deformability behavior of RC beams strengthened with external CFRP sheets.

Behavior of RC Beams Strengthened with CFRP Laminates and Exposed to Fire Under Loading

This research focuses on studying the flexural behaviour of reinforced concrete beams externally strengthened with bonded CFRP laminates and subjected to high temperature (fire) for different exposure time and two cooling schemes (air and water). 12 reinforced concrete beams with 1,000 mm loading span and cross-sectional area of 100 × 200 mm and reinforced with 2 bars 12 mm diameter as main reinforcement were tested. The CFRP used was laminates of 50 mm width and 1.2 mm thick which were protected from fire using a perlite mortar cover of thickness 5 cm. The beams were loaded to their working load, and while maintaining the load, they were subjected to fire for 1, 2 and 3 h, respectively, then followed by cooling either by water or by left to slow cool in air at room temperature. After cooling, the load was increased up to failure. The structural behaviour of the tested beams was studied by applying a three-point bending test and the mid-span deflection was recorded using LVDT. The mode of failure was investigated and presented. Also, a comparison between strengthened and unstrengthened beams was performed and presented. The results show that the fire protective layer is essential to maintain and minimize the loss in the strength gained by applying CFRP laminates. Also, it indicates that abrupt water cooling reduces the strength gained by about 15–29%.

Finite Element Analysis on Flexural Fatigue Behavior of RC Beams Strengthened with CFRP

Numerical simulation methods were used in this paper , and the bending fatigue performance of reinforced concrete beam with CFRP by ANSYS were analyzed . the Fatigue Mechanism was studied , and obtained the raise the level of fatigue life of reinforced concrete beam with CFRP .The result shows CFRP can increase greatly its fatigue life and play a practical engineering guide.

Deflection and cracking behavior of RC beams externally reinforced with carbon fiber laminates

This article presents the results and discussions of experimental and analytical work on CFRP-strengthened RC beams investigating the cracking and deflection performance. The aim of this study is to evaluate the time-dependent behavior by different degrees of strengthening scheme and two types of sustained loads. Eight RC beams were cast and tested under sustained loads for cracked and uncracked section. An analytical method based on EMM is developed to predict the time-dependent behavior of CFRP externally bonded RC beams. A simplified tension stiffening model for calculating the time-dependent deflection is modified for CFRP-reinforced concrete beams.

Modeling of Tension-Stiffening Behavior of Reinforced Concrete Beams

A model is proposed to analyze the tension-stiffening behavior of RC beams. The model takes into account the constitutive laws of constituent materials and the bond-slip relationship at the steel-concrete interface so that reliable responses of the RC beams in the post-cracking range can be obtained. It also allows the local behavior of RC beams to be studied in details due to the bond interaction between steel and concrete. Finally, the model capabilities are employed to analyze own experimental results. The midspan deflection and the mean steel strain of RC beams, computed with the proposed model, seem to be in good agreement with those measured in the tests.

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.

A Study on the Estimation of Failure Mode in Impact Analysis Using SPH Method

This paper proposes an analysis algorithm that can appropriately distinguish shear failure from bending failure of an RC beam under impact load, by using the SPH method. As structural members, beams generally fail by one of two modes: bending failure caused by excessive bending deformation of the member, and shear failure caused by shear crack growth, leading to rapid destruction at an angle in the web. In this study, to calculate the failure behavior accurately in the local stress field in which shear stress prevails such as when a shear crack occurs, an orthotropic constitutive equation is used. This equation is derived by applying the integrity tensor proposed by Ignacio Carol, Egidio Rizzi and Kasper William, to the usual SPH method. This operation is also extended to the tensile softening characteristic of concrete material. The results confirm that the failure behavior of RC beams under a wide range of conditions can be analyzed accurately by using the proposed algorithm.

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.

Experimental Study on Shear Behavior of RC Beams Strengthened with Stainless Steel Wire Mesh

Rehabilitation of RC members with stainless steel wire mesh and permeability polymer mortar is a new method of structural strengthening with the advantages of resistance to fire, corrosion and ageing. Experiments were conducted to investigate the shear behavior of eight strengthened RC rectangular beams and one comparative RC beam. The shear mechanism of strengthened beams was analyzed, and the influences of the strengthening manners, bolts’ amount, bolts’ distance on the shear behavior of strengthened beams were discussed. The test results show that the rehabilitation greatly increase the beam’s shear load-carrying capacity, shear stiffness, and its ductility. But the range of load capacity improvement is greatly influenced by the bolts’ amount and distance, too much and dense bolts badly weaken the shear behavior of beam itself. The influences of the strengthening manners on the load capacity are puny, but the beams’ failure modes are different.

On the Effect of Time-Dependent Deformations on the Interface Behaviour of RC Beams Strengthened by FRP Plates

In this paper, the effect of time-dependent deformations (such as shrinkage and creep) on the interfacial stresses between a concrete beam and a fibre reinforced polymer plate is presented. The analysis given here involves a closed-form solution for such stresses and includes creep and shrinkage effects. The adherend shear deformations have been included in the present theoretical analysis by assuming a parabolic shear stress through the thickness of both concrete beam and fibre reinforced polymer panel. Contrary to some existing studies, the assumption that both the concrete beam and the fibre reinforced polymer panel have the same curvature is not used in this investigation. The influence of creep and shrinkage effect relative to the time of the casting and the time of the loading of the beams is taken into account. Numerical examples of a typical concrete beam strengthened with an externally bonded fibre reinforced polymer plate are discussed with the emphasis on the shear and normal stresses at the edge of the plate.

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.