Influence of FRP thickness and confining effect on flexural performance of HB-strengthened RC beams

Abstract

This paper presents details of an experimental study and an analytical model that investigates the influence of fiber reinforced polymer (FRP) thickness and confining effect on the flexural performance of hybrid bonded (HB) FRP strengthened reinforced concrete (RC) beams. In the experimental study, a total of ten 150 × 250 × 2400-mm RC beams, with and without HB strengthening, were tested under four-point bending. Each specimen varied in the thickness of FRP plate and the confining effects of HB fastener. Fastener detachment and FRP rupture were identified as the dominant failure modes. The load-carrying capacity increased when thicker FRP plate and higher confining effect were used. The best ductility performance was reached when the fastener detachment and the FRP rupture occurred simultaneously. An analytical model is developed to predict the load-carrying capacity of HB-strengthened RC beams, showing satisfactory precision as compared to the experimental data. The parametric study shows that increasing the FRP thickness increases the load-carrying capacity when the failure mode is FRP rupture, whereas increasing the confining effect increases the load-carrying capacity when the failure mode is FRP rupture. A design method is proposed to obtain satisfactory load-carrying capacity and ductility performance.