General cohesive zone model for prediction of interfacial stresses induced by intermediate flexural crack of FRP-plated RC beams

In this paper, a general model is developed to predict the distribution of interfacial shear and normal stresses induced by intermediate flexural crack of FRP-plated reinforced concrete beam. For that, a new theoretical model based on the bi-linear cohesive zone model for intermediate crack-induced debonding is established, with the unique feature of unifying debonding initiation and growth. The stress deformation relationship is generally referred to as bond-slip law since the deformation of the interface is mainly the relative displacement (slip) between the FRP plate and the reinforced concrete beam (RC beam). Adherent shear deformations have been included by assuming a parabolic shear stress through the thickness of the adherents, verifying the cubic variation of the longitudinal displacement function, whereas all existing solutions neglect this effect. To obtain interfacial normal stress, the adhesive layer is assumed in linearly elastic stage in normal direction. This assumption is adopted in this study, because the FRP plate and RC beam are in contact during the whole debonding process. A complementary experimental study is made in order to show the debonding process according to mechanical and geometrical characteristics of adhesive and FRP plate. Analytical results obtained through the closed-form of interface stresses are in good agreement with those given by numerical and experimental models. Finally, parametric studies are carried out to demonstrate the effect of the mechanical properties and thickness variations of FRP, concrete and adhesive on interface debonding.