Interface law for FRP–concrete delamination

A procedure is developed for deriving a non-linear mode II interface law for Fibre Reinforced Polymer (FRP)–concrete bonding, starting from experimental data. The proposed interface law is based on a fractional formula and includes non-linear contributions of adhesive and concrete cover at high shear stresses. Parameters of the law are calibrated considering pull-pull delamination tests. Maximum transmissible load as well as strains along FRP-plates at different loading levels and bond lengths are used. In particular, the estimated value of maximum transmissible force by an anchorage of infinite length, is used to determine the fracture energy of interface law, whereas strains are used to obtain shear stress–slip data. A parameter optimization procedure is then applied to a series of experimental results reported in the literature. The proposed interface law is then adopted to perform numerical simulations making use of a bond-slip model. FRP strains, shear stresses and slips in the bonded region obtained numerically are in good agreement with experimental results.