Effectiveness of some technical standards for debonding analysis in FRP-concrete systems

Debonding failure is a key issue in strengthening and retrofitting of existing concrete structures via fiber-reinforced polymers (FRP). In this paper, strength models proposed by different technical guidelines for predicting the debonding load and the effective bond length in FRP-concrete systems are consistently summarized and compared. By referring to the recent specialized literature, a wide database of experimental data - collected from debonding tests associated to FRP based on carbon, glass and basalt fibers - is defined and analyzed. As a result, soundness and effectiveness of some available technical indications are critically assessed, by highlighting the influence of both FRP stiffness (mainly related to the fiber type) and FRP application system. Moreover, a least-square-fitting calibration of theoretical predictions with respect to the experimental evidence is proposed and applied, resulting in the definition of a novel set of values for the empirical correction coefficients occurring in the analyzed strength models. Accordingly, proposed results pave the way towards the effective refinement of actual technical standards for debonding analysis in FRP-concrete systems.