Determination of boundary effect on mode II fracture energy of FRP sheet-to-concrete bonded joints

Fracture energy is a crucial parameter in describing the interfacial debonding process in concrete structures externally bonded with FRP plates or sheets. This paper is mainly concerned with the boundary effect on the mode II (shear) fracture energy of FRP-to-concrete bonded joints. An analytical model was proposed to predict the maximum pull-out load of FRP sheet from concrete, which is then related to the local fracture energy at the shear crack-tip region. Based on the comparisons between the analytically predicted and experimentally determined load-carrying capacity, the crack-tip local fracture energy indeed varies with the initial shear crack length. A bi-linear model was presented to well describe the mode II local fracture energy distribution along the overlapping length indicating the boundary effect. The size-independent mode II fracture energy is 550 N/m.