To investigate the degradation of the residual fracture energy of concrete suffering from fatigue loading, 150 three-point bending (TPB) beams were first subjected to a fatigue load until the preset number of fatigue cycles was reached, and then the static load was applied to these specimens until failure occurred. Based on the equilibrium relationship between the energy dissipated by the fatigue fracture process zone (FPZ) under static loading and the external work, a calculation method for the residual fracture energy of concrete suffering from fatigue loading was proposed. The effects of the number of fatigue cycles, the fatigue crack opening displacement, and the fatigue load level on the residual fracture energy of concrete were evaluated, and an empirical model for predicting the residual fracture energy was proposed. The results showed that in the initial stage of fatigue loading, there was a rapid drop of the residual fracture energy with a decelerated degradation rate. With the increases of the number of fatigue cycles and the fatigue crack opening displacement, a stable degradation stage of the residual fracture energy with an approximately constant degradation rate was observed. Furthermore, with the decreasing fatigue load level, the residual fracture energy increased for the same fatigue cycles, while the residual fracture energy decreased for the same fatigue crack opening displacement. The residual fracture energy obtained in this study is essential for the numerical calculation of the residual bearing capacity of concrete structures.

为了研究疲劳荷载作用下混凝土残余断裂能的退化情况，首先对 150 根三点弯曲 (TPB) 梁施加疲劳荷载，直到达到预设的疲劳循环次数，然后将静荷载施加到这些试样直到发生故障。基于静载荷下疲劳断裂过程区（FPZ）耗散能量与外功之间的平衡关系，提出了混凝土疲劳载荷下残余断裂能的计算方法。评估了疲劳循环次数、疲劳裂纹张开位移和疲劳载荷水平对混凝土残余断裂能的影响，提出了预测残余断裂能的经验模型。结果表明，在疲劳加载初始阶段，残余断裂能迅速下降，退化速度减慢。随着疲劳循环次数和疲劳裂纹张开位移的增加，残余断裂能进入稳定的退化阶段，退化速率近似恒定。此外，随着疲劳载荷水平的降低，相同疲劳循环的残余断裂能增加，而相同疲劳裂纹张开位移的残余断裂能减少。本研究中获得的残余断裂能对于混凝土结构残余承载力的数值计算至关重要。残余断裂能迅速下降，降解速度减慢。随着疲劳循环次数和疲劳裂纹张开位移的增加，残余断裂能进入稳定的退化阶段，退化速率近似恒定。此外，随着疲劳载荷水平的降低，相同疲劳循环的残余断裂能增加，而相同疲劳裂纹张开位移的残余断裂能减少。本研究中获得的残余断裂能对于混凝土结构残余承载力的数值计算至关重要。残余断裂能迅速下降，降解速度减慢。随着疲劳循环次数和疲劳裂纹张开位移的增加，残余断裂能进入稳定的退化阶段，退化速率近似恒定。此外，随着疲劳载荷水平的降低，相同疲劳循环的残余断裂能增加，而相同疲劳裂纹张开位移的残余断裂能减少。本研究中获得的残余断裂能对于混凝土结构残余承载力的数值计算至关重要。观察到具有近似恒定降解速率的残余断裂能的稳定降解阶段。此外，随着疲劳载荷水平的降低，相同疲劳循环的残余断裂能增加，而相同疲劳裂纹张开位移的残余断裂能减少。本研究中获得的残余断裂能对于混凝土结构残余承载力的数值计算至关重要。观察到具有近似恒定降解速率的残余断裂能的稳定降解阶段。此外，随着疲劳载荷水平的降低，相同疲劳循环的残余断裂能增加，而相同疲劳裂纹张开位移的残余断裂能减少。本研究中获得的残余断裂能对于混凝土结构残余承载力的数值计算至关重要。