Introduction of a Stress State Criterion to Predict Bond Strength between FRP and Concrete Substrate

Abstract

To evaluate the performance of externally bonded fiber-reinforced polymer (FRP) composites to concrete structures, the bond strength is predicted at the maximum transferable load. Most of the existing prediction models neglect the adhesive material properties. As such, a previously proposed criterion on the FRP debonding initiation considering the adhesive material properties is extended by determining the fracture depth parameter and introducing a strength factor. The fracture depth represents a certain depth of a failure in concrete substrate and the strength factor revises the concrete tensile strength to be applied as the limit bond stress. Both the fracture depth parameter and strength factor are determined as a function of concrete compressive strength through experimental measurements and regression analysis, respectively. The proposed criterion is validated through the collected 342 experimental data points. Comparison between the predicted and the experiment results shows good agreement, providing a relatively high correlation factor. In addition, the predicted results are compared with existing prediction models.