Constitutive mixed mode model for cracks in concrete

The scope of the paper is to set up a constitutive mixed mode model for cracks in concrete. The model is formulated at macro level and includes the most important micro scale effects. An associated plasticity model inspired by the modified Cam clay model is established. The hardening parameters are based on the standard Mode I tensile softening response and the response for Mode I crushing. The roughness of the crack is included through a topographic description of the crack surface. The constitutive behavior is based on the integration of local contributions. The local mixed mode ratio is determined from the topographic information and the constitutive model is thereby purely mechanically based. Using the actual topographic description the model is validated against experimental results for mixed mode crack openings.