Prediction of intermediate crack debonding failure in FRP-strengthened reinforced concrete beams

The present paper addresses with intermediate crack (IC) debonding failure modes in FRP-strengthened reinforced concrete beams; a non-linear local deformation model, derived from a cracking analysis based on slip and bond stress, is adopted to predict the stresses and strains distribution at failure. Local bond-slip laws at the longitudinal steel-to-concrete and FRP-to-concrete interfaces, as well as the tension stiffening effect of the reinforcement (steel and FRP) to the concrete, are considered. Model predictions are compared to experimental results available in the literature together with predictions of other models. Reasonable agreement with experimentally measured IC debonding loads and FRP strains is observed for all examined strengthened beams. Results of a parametric analysis, varying geometrical and mechanical parameters involved in the physical problem are also presented and discussed.