Application of A Nonlocal Damage Law to Model Concrete Fracture

A nonlocal damage model is presented which is based on the explicit introduction of the gradient of the damage field. The model is designed as nonlocal from the beginning so that to ensure its convergence towards a cohesive zone model for vanishing nonlocal length scales. In particular it alleviates the sensitive task of identifying the nonlocal length scale. Moreover, the model relies on a damage surface representative of concrete, even for bi-tension stress states that are characteristic of crack propagation. Finally, the physical validity of this new constitutive relation is assessed through comparisons with two experimental settings: a CLWL-DCB specimen submitted to mixed-mode loading and leading to crack branching and the Brokenshire torsion test resulting in non-planar 3D crack propagation.