Investigation on fracture behavior of FRP-concrete interface under direct shear

Abstract

In this study, the existing researches on debonding performance of FRP-Concrete Interface under direct shear are reviewed and compared at first, and then the hypothesis is put forward that ultimate bearing capacity of FRP-Concrete Interface under pure shear is combined of fracture-resisting force at the undamaged area and friction stress transferred along the already debonded surface. Following that, the formulae on fracture energy and friction stress for FRP-Concrete Interface under pure shear are deduced, through which the values for fracture energy and friction stress at the FRP-Concrete Interface are obtained based on the experimental results of eight specimens with FRP-Concrete Interface. On the basis of theoretical analysis mentioned above, such conclusions can be reached that the friction-resisting stress transferred along the already deteriorated bi-material interface is independent of length of FRP bonded onto concrete substrates and concrete strength, but relies on the tension rigidity; on the contrary, cohesive fracture energy is dependent on length and tension stiffness of FRP bonded to concrete substrate. Besides, the percentage of the fracture-resisting force in the ultimate debonding load for the interface decreases with the bonding length of FRP increasing, but increases with the increase of the layers of the FRP. © Tsinghua University Press, Beijing and Springer-Verlag Berlin Heidelberg 2011.