An extended average strain energy density criterion for predicting crack propagation of mixed mode I-II fracture in concrete

Three-point bend and four-point shear tests were conducted to analyze the crack initiation and propagation of mixed mode I-II fracture in concrete under different mode mixity ratios. The digital image correlation technique was employed to monitor the crack propagation process. Then, the critical average strain energy densities were numerically calculated for crack initiation and different loading stages of crack propagation. Subsequently, an extended average strain energy density (EASED) criterion was proposed to predict the crack propagation of mixed mode I-II fracture in concrete. A numerical analysis method integrating both the EASED criterion and fictitious crack model was proposed and validated to predict the crack initiation and propagation process of mixed mode I-II fracture in concrete. The EASED criterion enhances the accuracy of predicting fracture behavior of mixed mode I-II crack in concrete, offering a more reliable approach for assessing fracture processes.