Abstract:

Based on the bilinear bond-slip model of the interface between fiber-reinforced polymer （FRP） and concrete, the interfacial bonding shear stress in the intermediate cracking zone of the reinforced concrete （RC） beam strengthened with prestressed FRP laminates under bending load was analyzed, and the effects of the prestress level and the crack spacing on the debonding load-carrying capacity were discussed. Moreover, some theoretical models to predict the initial debonding and the debonding failure were established, with the critical slip corresponding to the interfacial fracture energy as the debonding criterion. Some experiments were finally performed to verify the models. It is indicated that the proposed models effectively predict the debonding and the corresponding load-carrying capacity of RC beams strengthened with prestressed FRP laminates under bending load, and that the debonding load-carrying capacity improves with the increase of the prestress level of FRP and with the decrease of the crack spacing.

Key words: fiber-reinforced polymer, reinforced concrete beam, strengthening, debonding, shear stress, prestress, crack