混凝土多级等幅疲劳的变形发展规律试验研究

首先试验验证和揭示了混凝土单级和两级等幅疲劳损伤（变形）发展三阶段规律的普遍性和级间相似性。其次，根据混凝土疲劳变形发展三阶段规律的具体特征以及考虑变幅增量与当前损伤状态的耦合效应，由试验数据得到了单级和两级等幅疲劳损伤第二阶段规范化疲劳变形及其发展速率的经验公式；最后将上述公式推广到了混凝土的多级等幅疲劳的情况。

Experimental Study on Fatigue Deformation of Plain Concrete under Multi-stage Constant Amplitude Loading

Firstly, this contribution carries out the uniaxial high - cycle fatigue tests of plain concrete under one and two stages constant repeated compressive loading to verify and discover the general law that the fatigue damage development of plain concrete possesses three separate phases and it is multi - stage - similar.Secondly, based on the particular characteristics of the general law, and, thought about the interaction effect between the increments of loading amplitude and the pressent damage status, the empirical expressions of the normalized fatigue deformation and its developing rate in second phases under one and two stages constant repeated compressive loading are obtained by using the tests' results. Finally, the above expressions are extended to multi - stage high - cycle fatigue loading.