Debonding analysis of curved RC beams externally bonded with FRP plates using CZM

Abstract

External bonding of fiber-reinforced polymer (FRP) plates has been widely used to strengthen reinforced concrete (RC) structures. The effectiveness and efficiency of this technique largely depend on the bonding behavior between the strengthening FRP plate and the RC substrate. This work initially extends the state space method combined with its numerically stable solution to present an elastic analysis of the interfacial shear stress in curved RC beams externally strengthened by FRP plates. The processes of the plate end debonding and intermediate crack-induced (IC) debonding in the FRP-strengthened curved beam is analyzed for the first time by introducing the cohesive zone model (CZM) for simulation of the adhesive layers. Compared with other analytical methods, the present method is advantageous in its application to much more complex situations, such as the general bond-slip laws, arbitrary boundary conditions and load cases, and variable cross-sectional properties of the curved beams and FRP plates. Finally, some numerical examples are given, and the results demonstrate that the tapering at the ends of FRP plates can significantly reduce the interfacial shear stress, and the debonding area will extend to the whole interface immediately once the load reaches the peak value for the plate end debonding.