Influence of Matrix and Cohesive Material Law Characteristics on the Tensile and Bond Behavior of FRCM Systems

This study proposes numerical modeling of fiber-reinforced cementitious matrix (FRCM) composite systems in direct shear (DST) or tensile (DTT) tests with any setup. In the interfacial fracture theory framework, the nonlinear differential problem is treated through the finite difference method and the incremental solution to the equilibrium in terms of displacements is found by updating the secant stiffness of the cohesive material law. Relying on independent solutions which consider the system in the different phases since the initial condition, without and with fractures, and reconnecting the related solutions, a new procedure for the construction of the load slip diagram of DTT is implemented, allowing estimation of load drops and stiffness degradation caused by cracks opening. The model is benchmarked on results available in the literature and experimental tests carried out by the authors. A thorough parametric analysis of DTT highlights the influence on the response of matrix tensile strength and its distribution along the reinforcement. In particular, it is shown that the ratio between bond stress and mortar tensile strength can determine bilinear or trilinear diagrams and that the position of cracks widely influences the load and slip capacity of the system.