Modeling mixed mode cracking in concrete through a regularized extended finite element formulation considering aggregate interlock

Abstract

Mixed mode cracking in concrete keeps being a challenging issue in computational fracture mechanics. While uncracked concrete develops cracks perpendicular to the direction of the maximum principal tensile stress, the crack edges will expectedly open, mutually slide, and transmit both normal and shearing stresses. In the present formulation, we replace the damage band with a regularized strain band by enriching the space of the approximating functions in compliance with the regularized extended finite element model developed by the authors. Our clue is that a discriminant factor to choose the appropriate expression of the regularized strain relies upon the concept of stress compatibility modified to consider aggregate interlock. In particular, we resort to a simplified phenomenological saw-tooth model of the crack surface asperities. We show the capability of the methodology to capture both structural behavior and crack paths in a set of bending tests carried out on concrete specimens. Though phenomenological, the resulting approach is novel, conceptually simple and reliable for it directly reproduces the expected kinematics and structural results.