Experimental and analytical investigations on debonding of hybrid FRPs for flexural strengthening of RC beams

This paper presents experimental and analytical studies aimed at investigating debonding of hybrid fiber reinforced polymers (FRPs) used to strengthen reinforced concrete (RC) beams. Towards this goal, an existing bending test method for small RC beams is modified to induce debonding failure and is adopted for reinforced concrete beams strengthened with one or two layers of carbon FRP (CFRP) or glass FRP (GFRP). From the experiments, strains on FRPs are measured and used to calculate interfacial stress between the concrete and FRP surfaces. Finite element (FE) models including debonding behavior in cohesive elements are generated to verify experimental results. Further, parametric studies are performed to predict the structural behaviors of RC beams strengthened with three layers of hybrid FRPs.