A new single-shear set-up for stable debonding of FRP–concrete joints

A new experimental set-up to perform single-lap shear debonding tests on fiber reinforced polymer (FRP) reinforcements bonded to concrete is presented. Back sides of both FRP reinforcement (sheet or plate) and concrete specimen are fixed to an external restraining system and the force is applied to the other side of FRP reinforcement. Hence, a stable debonding process can be experimentally followed, corresponding to the transition between two limit states of perfect bonding and fully debonded reinforcement. Both strain gauges along the FRP reinforcement and LVDT transducers have been used. Tests have been performed on both plates and sheets bonded to concrete specimens with different surface preparations before adhesive application. Shear stress–slips data have been computed from the experimental FRP strain measures. The parameters of a non-linear interface law have been then calibrated and compared with analogous results from experimental data obtained with a conventional set-up. A numerical bond–slip model has been finally used to simulate the experimental tests, adopting the above-mentioned law for the FRP–concrete interface. Numerical results in good agreement with experimental results have been obtained.