Single Crack–Based Model for FRP Shear-Strengthened RC Beams

Abstract

In this study, a single crack–based model is proposed for predicting the contribution of fiber-reinforced polymer (FRP) reinforcement to the shear resistance of FRP shear-strengthened reinforced concrete beams. This critical single shear crack has been found to be dominant within the shear span of many RC beams strengthened with externally bonded (EB) FRP and RC beams with near-surface mounted (NSM) FRP at large spacings. In this study, the single shear crack was assumed to occur along the principal stress trajectory (PST), along which concrete is subject to principal tensile stresses. A bilinear bond-slip model was adopted for the cohesive stresses due to FRP reinforcement and steel stirrups, and an exponential model was chosen for the cohesive stress due to aggregates. The shear crack configuration (e.g., crack width and length) was an implicit function of the external loading and cohesive stresses, which was obtained by numerical iterations. To verify the precision of the proposed model, several viable experimental studies on FRP shear-strengthened RC beams using either EB or NSM techniques were selected for comparisons. The model predicted shear crack trajectory, FRP strain distribution, stirrup strain distribution, and FRP contribution to the overall shear resistance well.