An empirical FRP-concrete bond-slip model for externally-bonded reinforcement on grooves

•A bilinear bond-slip model was proposed for EBROG FRP-concrete joints.•The equation of proposed bond-slip model was different for on-groove and out-of-groove regions in the EBROG joints.•Effect of different parameters on bond-slip behavior of EBROG FRP-concrete joints were investigated.•PIV method was utilized to study FRP-concrete bond behavior. The externally-bonded reinforcement on grooves (EBROG) has been recently developed as a substitute for the conventional externally-bonded reinforcement (EBR) technique used to retrofit reinforced concrete (RC) structural members with fiber-reinforced polymer (FRP) composites. While the presently available bond-slip models predict the bond-slip behavior of FRP composites adhered to the concrete surface via the conventional EBR method, there is a lack of reports in the literature on rigorous bond-slip model for FRP composites attached to concrete surfaces via the EBROG technique. Using a nonlinear regression on experimental data, the current research attempts to introduce an empirical model for such bond-slips. For this purpose, FRP composite strips were bonded to 68 concrete prism specimens retrofitted through the EBR and EBROG technique, before subjecting them to the single lap-shear experiment (108 tests in all). The test parameters included compressive strength of concrete, grooves dimensions (width and depth), composite strip width, and composite stiffness. A bilinear bond-slip model was proposed. Maximum shear stress, fracture energy, and associated slip were determined by analyzing on-groove and out-of-groove stresses and strains via the image processing method of particle image velocimetry (PIV). Finally, analysis of variance and different statistical tools were employed to validate the results obtained from the bond-slip model developed.