A toughness-based crack initiation-propagation criterion using a modified fracture energy parameter

Using the energy balance relationship, a toughness-based crack initiation-propagation criterion using a modified fracture energy parameter is proposed in this paper for quasi-brittle materials. Validation of the proposed crack initiation-propagation criterion is carried out by performing three-point bending beam tests through finite element analysis. The classical crack initiation-propagation criterion with the fracture energy parameter is directly used, and better consistencies between the mechanical responses (P-Delta curves, P-CMOD curves, FPZ length variation, KR curves) obtained by the modified fracture energy-based crack propagation criterion and those obtained by experimental means are found. It should be emphasized that the ratio of elastic energy has an important inluence on the value of fracture energy involved in the crack initiation-propagation criterion. By this paper, it is found that introduction of the modified fracture energy in the toughness-based crack initiation-propagation criterion is necessary for getting better estimations of mechanical responses for crack initiation and growth analysis in quasi-brittle materials such as concretes.