Numerical and experimental study of failure mode of reinforced concrete with CFRP sheet under tensile and shear loading

In this study, the bond strength and failure mode of CFRP strengthened concrete in tensile and shear stresses are investigated using nonlinear finite element and experimental method. Due to the fact that in the study of mechanical behavior of concrete strengthened with CFRP sheet, the assumption of homogeneity of concrete leads to unrealistic results, so in this study, a meso-scale model is used to model concrete. The mesoscopic model of concrete includes three-phase inhomogeneous material consisting of aggregate, mortar and Interfacial Transition Zone (ITZ). Tests performed include "pull-off" and "twist-off" to determine tensile and shear bond strength. The results show that the tensile and shear strength of the finite element model is 18% and 13% higher than the results of the "pull-off" and "twist-off" tests, respectively, which are due to laboratory influencing factors and ignoring They are acceptable in numerical modeling of this difference. Also, the tensile strength of the numerical and experimental models is 34% and 33% lower than the shear strength, respectively. According to the obtained results, the debonding in the CFRP strengthened concrete sample was from the substrate concrete. The results show that the micro-cracks, followed by debonding in the mortar and ITZ phases of concrete, due to high porosity and lower strength than the aggregate phase, spread easily.