Discussion of “Calculating crack extension resistance of concrete based on a new crack propagation criterion” by Wei Dong, Zhimin Wu, Xiangming Zhou

Based on the original paper, a revised Young’s modulus E and a more accurate calculation of initial fracture toughness are proposed in present discussion. in contribution of the discussed paper is to develop a numerical method to simulate the whole crack propagation in concrete by considering the variation of FPZ length. Notched concrete beams were tested under three-point bending with P-CMOD curves obtained which were then compared with the numerical ones to validate the proposed numerical method. After that, the proposed method was employed to obtain KR-curve for the complete fracture process, taking into consideration the cohesive stress acting on FPZ. Finally, the effect of variation of FPZ length and fracture energy on KR-curve, as well as size effect on KR-curve, was discussed. The discusser appreciates the authors’ meaningful work. However some findings are interesting to the discusser and are worthy of further discussion.