Finite element investigation into the size effect of bidirectional fibre patch anchors used to enhance the performance of FRP-to-concrete joints

The introduction of fibre composite materials (FRPs) to strengthen concrete structures in flexure, shear and torsion has gained worldwide acceptance. In an effort to prevent the premature delamination of externally-bonded FRP from the concrete surface, investigations into FRP anchorage systems which utilise multiple layers of bi-directional fibre patches to restrain the ends of FRP laminates have shown promising results. This paper discusses the latest developments in the finite element modelling of the size effect of FRP patch anchors. A bond-slip model derived from experimental data was used to calibrate an interface model between the FRP and concrete materials to replicate the bond performance and failure modes of FRP-to-concrete joints. It is demonstrated that calibrated numerical models have the potential to reduce the number of experimental tests and parametric studies can provide extensive data to evaluate the influence of key parameters.