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

Abstract

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 reinforced concrete beams without web reinforcement were constructed and tested in four-point bending. The test variables were the reinforcement ratio and the modulus of elasticity of the longitudinal reinforcing bars as well as the shear span to depth ratio. The test beams included five beams reinforced with glass FRP bars and five beams reinforced with carbon FRP bars. The behavior of the deep beams is described in terms of load-deflection response, cracking patterns and modes of failure, strains in reinforcement and concrete, inclined cracking, and ultimate shear strengths. All ten beams showed significant reserve strength after the inclined cracking was fully developed. The test results also indicated that the ultimate shear strength of the tested beams considerably increased with the decrease of the shear span to depth ratio. In addition, the ultimate shear strengths of the tested beams were predicted using the shear design provisions recommended by the new version of the Canadian Standard CSA-S806-11 and compared with the experimental results, showing good agreement.Résumé : Cet article présente une étude expérimentale servant à évaluer la résistance en cisaillement et le comportement de poutres-cloisons en béton armées de tiges en polymère renforcé de fibres (PRF). Un total de 10 poutres en béton armé à pleine échelle sans armature d'âme a été construit et mis à l'épreuve sous flexion à quatre points. Les variables d'essai étaient le rapport d'armature et le module d'élasticité des tiges d'armature longitudinales ainsi que le rapport portée en cisaillement -profondeur. Les poutres à l'essai comprennent cinq poutres armées de tiges en polymère renforcé de fibres en verre (PRFV) et cinq poutres armées de tiges en polymère renforcé de fibres en carbone (PRFC). Le comportement des poutres-cloisons est décrit en termes de la réponse en déformation en raison de la charge, les motifs de fissuration et les modes de défaillance, les contraintes dans l'armature et le béton, la fissuration inclinée ainsi que les résistances à la rupture en cisaillement. Les 10 poutres ont montré de bonnes réserves de résistance une fois la fissuration inclinée pleinement dévelop-pée. Les résultats des essais ont également indiqué que la résistance à la rupture en cisaillement des poutres mises à l'é-preuve a considérablement augmenté avec la diminution du rapport portée en cisaillement -profondeur. De plus, les résistances à la rupture en cisaillement des poutres à l'essai ont été prédites en utilisant les dispositions de calcul du cisaillement recommandées dans la nouvelle version de la norme canadienne CSA-S806-11 et elles montraient une bonne concordance lorsque qu'elles étaient comparées aux résultats expérimentaux.

Two-Parameter Kinematic Approach for Shear Strength of Deep Concrete Beams with Internal FRP Reinforcement

“…For this purpose, a database of 39 tests of deep beams with FRP reinforcement was collected from five experimental studies (Andermatt and Lubell 2013b;El-Sayed et al 2012;Farghaly and Benmokrane 2013;Latosh 2014;Mohamed et al 2014). Only test series that contained at least several relatively large beams, i.e., d > 300 mm, were selected to avoid the inherent scatter in smaller members.…”

“…El-Sayed et al (2012) used CSA-S806-11 (CSA 2011) shear provisions to predict the shear strength of eight test specimens without web reinforcement and obtained experimental-to-predicted ratios with an average of 1.33 and a coefficient of variation (COV) of 12%. The code equations became less conservative as the stiffness of the longitudinal reinforcement decreased.…”

A feasibility study of BBP for predicting shear capacity of FRP reinforced concrete beams without stirrups

“…Based on the previous research studies, the basic effective parameters that affecting the shear capacity of FRP-RC beams are the width of web (b w ), effective depth of beam (d), shear span to depth ratio (a/d), concrete compressive strength (f c ′ ), longitudinal reinforcement ratio (ρ f ) and elastic modulus of FRP bars (E f ) [35,[45][46][47][48][49]. An experimental database of 138 test specimens failed in shear was obtained from different previous investigations [31,36,45,47,[49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65]. During the collection stage, specimens with shear span to depth ratios between 2.4 and 6.5 were included but deeper and slender beams were omitted from the database.…”

Shear Capacity of Non-Metallic (FRP) Reinforced Concrete Beams with Stirrups

“…Different mechanical properties between FRP and conventional steel bars may affect the shear carrying mechanism in concrete beams. More rapid deterioration in shear can be observed in concrete beams longitudinally reinforced by steel rather than those reinforced by FRP due to the reduction shear resistance offered by un-cracked concrete, V c [9,10]. The shear resistance of FRP RC beams also influences by the size-effect and shear-span-to-depth ratios [10,11].…”

“…More rapid deterioration in shear can be observed in concrete beams longitudinally reinforced by steel rather than those reinforced by FRP due to the reduction shear resistance offered by un-cracked concrete, V c [9,10]. The shear resistance of FRP RC beams also influences by the size-effect and shear-span-to-depth ratios [10,11]. The experimental results on the ratios of the reinforcement indicated that the beams provided with stirrups and multiple layers of flexural reinforcement is recommended in order to resist the weak bend area of FRP stirrup cages [12].…”