Thermodynamically based fictitious crack/interface model for general normal and shear loading

For small deformations a crack/interface model that considers general 3D normal and shear loading is proposed. It involves elasticity, plasticity and damage and it is thermodynamically based. An essential feature of the model is its consistency with the concepts behind the fictitious crack model. In particular, no crack deformation occurs before the crack is initiated and when a crack has just been initiated the proposed model provides an unloading stiffness that is infinitely large. For the same set of parameters, it is demonstrated that the proposed model is able to provide predictions that are in close agreement with experimental data for concrete for a wide range of loading situations.