Full-range mechanical behavior study of FRP-to-concrete interface for pull-pull bonded joints

External bonding of fiber reinforced polymer (FRP) has become a popular technique for strengthening concrete structures all over the world. The mechanical performance of the interface between FRP and concrete is one of the key factors affecting the behavior of the strengthened structure. The debonding behavior of FRP-to-concrete interface is related to specific bonded joint. Compared with the pull-push bonded joint, there are few studies revealing the interface mechanical behavior of pull-pull bonded joint so far, and in-depth theoretical study is not profound enough either. This paper presents an analytical solution for the debonding process in such an FRP-toconcrete bonded joint in single-shear model. Base on the realistic bi-linear local bond-slip law, two critical lengths are obtained, and the interface debonding failure follows different regimes. Closed form expressions for the interfacial relative slip, shear stress distribution, normal stress in the FRP plate and the load-displacement response at the loaded end are derived for different loading stages, whose accuracy is verified by finite element numerical simulation. While the solution is developed with particular reference to FRP-to-concrete bonded joints, it can be equally applicable to similar bonded joints made of other materials (e.g. FRP-to-steel).