Three-Dimensional Numerical Modeling of Single-Lap Direct Shear Tests of FRCM-Concrete Joints Using a Cohesive Damaged Contact Approach

The bond behavior of fiber-reinforced cementitious matrix (FRCM) composites applied as externally bonded reinforcement is the most critical concern in this type of application. FRCM-concrete joints are generally reported to fail because of debonding (slippage) of the fibers from the embedding matrix. However, depending on the characteristics of the composite and substrate used, failure may also occur as a result of detachment of the composite strip at the FRCM-support interface, interlaminar failure (delamination) of the matrix, or tensile failure of the fibers. In this paper, a three-dimensional (3D) numerical model is developed to reproduce the behavior of polyparaphenylene benzo-bisoxazole (PBO) FRCM-concrete joints. The numerical model accounts for the fracture mechanics mixed Mode-I and Mode-II loading condition observed in single-lap direct shear tests by means of nonlinear damaged contact law associated with different interfaces considered in the analysis. The numerical results obtained are compared with those obtained by experimental tests of PBO FRCM-concrete joints. The model is capable of predicting the different failure modes, and it correctly reproduces the experimental load responses including the contribution of friction to the applied stress.