Mechanics of fibre-reinforced polymer-concrete interfaces

A finite element model is developed for analyzing the interfacial behaviour for fibre-reinforced polymer (FRP) laminates externally bonded to concrete prisms and subjected to direct shear. The element sizes of the FRP, adhesive, and concrete at the interface were chosen to be very small (0.25-0.5 mm) so that the debonding behaviour could be properly captured. The behaviour at the interface between the FRP composite and the concrete is modelled using truss elements connecting the FRP laminate to the concrete block. The truss elements incorporate a nonlinear bond stress-slip relationship controlled by several parameters related to the characteristics of the FRP composite, adhesive, and concrete. Results are given in terms of the load capacity of the joint and the stress and strain distributions in the FRP, at the inter-face, and in the concrete. In addition, the transfer lengths, as well as the force transfer between the FRP laminate and the concrete block, are investigated. Comparisons between the finite element results and available experimental data are presented.