中文摘要：

介绍了混凝土在承受疲劳荷载时内部微裂纹的扩展规律,根据疲劳损伤变形的3阶段特征,可知混凝土内部微裂纹的扩展是导致其疲劳损伤的本质原因,提出了残余应变可作为建立疲劳损伤模型的基础.研究并介绍了混凝土疲劳损伤破坏时峰值应变εunstab的确定、等幅或变幅荷载作用下残余应变ε残和总应变ε总的计算理论.根据疲劳等效累积原则和混凝土疲劳残余应变的计算理论,推导出混凝土在疲劳荷载作用下基于残余应变的疲劳损伤模型,并提出了建立混凝土疲劳损伤模型需要进一步研究的重点和难点.

英文摘要：

The internal micro-crack growth law of concrete under fatigue loads are introduced.According to the three stages law of fatigue damage deformation,extension of the internal micro-crack is the essential reason of fatigue damage.And it also proposes that fatigue residual strain can be used as the basis for establishing fatigue model.The determination of the peak strain was studied,when the fatigue damage of concrete occurs.The calculation of residual strain and total strain under constant amplitude or variable amplitude loads was also studied.According to the equivalent cumulative fatigue principle and calculation theory of concrete fatigue residual strain,the fatigue damage model for concrete under fatigue loads and based on residual strain was deduced.And the importance and difficulty of further study on the establishment of fatigue damage model for concrete are pointed out.