Calculating crack extension resistance of concrete based on a new crack propagation criterion

► The initial fracture toughness was proposed as crack propagation criterion for concrete. ► A FE analysis was carried out to simulate the complete fracture process in concrete. ► KR-curve which is able to consider the variation of FPZ was investigated. ► The shape of KR-curve was found to be affected by the FPZ variation and boundary effect. ► KR-curve was found to be size dependent.