Concrete is a quasi-brittle material which may undergo repetitive loading during its service life, presenting challenges in understanding its fracture behavior. The fracture process zone (FPZ) ahead of the crack tip behaves differently under fatigue loading than monotonic loading, making…
Concrete is a quasi-brittle material which may undergo repetitive loading during its service life, presenting challenges in understanding its fracture behavior. The fracture process zone (FPZ) ahead of the crack tip behaves differently under fatigue loading than monotonic loading, making it crucial to comprehend the energy dissipation associated with the FPZ. Concrete members exhibit a two-stage stiffness degradation process under repetitive load cycles, with the first stage being the toughening stage (FPZ development stage) that resists crack propagation and the second stage being the stage in which catastrophic failure takes place once the FPZ is fully developed. Therefore, to better understand the fracture behavior of concrete under cyclic loading, it is important to consider stiffness degradation. This work proposes an analytical expression that predicts energy dissipation and stiffness degradation approach as functions of crack length. This expression can be utilized to characterize the damage behavior and fatigue life of structures. In this study, specimens with a center notch have been utilized to develop formulations. Furthermore, the formulation for stiffness degradationhasbeendevelopedbyrelatingthedissipatedenergywiththeworkdonebytheexternally applied load. This expression has been used to determine the fully developed fracture process zone (FPZ) length at the switchover point when stiffness degradation begins to increase.