Analysis of the load-deformation behaviour and debonding for FRP-strengthened concrete structures

Results from nonlinear finite element analyses of fibre reinforced polymer (FRP)-strengthened concrete beams and slabs are presented. The direct shear test, a basic application that provides insight into FRP-concrete interfacial behaviour, is also considered. The motivation for this work is the fact that, although there is a large amount of experimental data available on the FRP strengthening of concrete structures, a full understanding of the various load-deformation behaviours and debonding phenomenon is still lacking. The numerical models presented in this paper adopt a displacement-controlled solution and are capable of simulating FRP-strengthened beams either in shear or in flexure, as well as slabs strengthened using either passive or prestressed FRP laminates. Results of the different applications are presented and compared with published test data, and a very good agreement in terms of the ultimate load carrying capacities, load-deflection behaviour and modes of failure, is obtained.