Three-dimensional modelling of bond behaviour between concrete and FRP reinforcement

Purpose – The purpose of this paper is to investigate the bond behaviour between fiber reinforced polymer (FRP) sheets and concrete elements, starting from available experimental evidences, through a calibrated and upgraded 3D mathematical-numerical model. Design/methodology/approach – The complex mechanism of debonding/peeling failure of FRP reinforcement is studied within the context of damage mechanics to appropriately catch transversal effects and developing a more realistic and comprehensive study of the delamination process. The FE ABAQUSq code has been supplemented with a numerical procedure accounting for Mazars’s damage law inside the contact algorithm. Findings – It has been shown that such an approach is able to catch the delamination evolution during loading processes as well. Originality/value – A Drucker-Prager constitutive law is adopted for concrete whereas FRP elements are assumed to behave in a linear-elastic manner, possibly undertaking large strains/displacements. Surface-to-surface contact conditions have been applied between FRP and adjacent concrete, including the enhancement given by the strain-softening law according to Mazars’ damage model. The procedure has been introduced to describe the coupled behaviour between concrete, FRP and adhesive resulting in specific bonding-debonding features under different load levels.