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利用大型多轴疲劳试验机,进行了拉压双轴和拉压压三轴荷载作用下混凝土两级、三级变幅疲劳试验研究,重点分析了残余应变的变化规律。试验结果表明:混凝土在拉压和拉压压加载工况下的残余应变主要与相对疲劳次数和侧压应力比有关,基本不受加载历程因素的影响。定义相对残余应变为损伤变量,建立了损伤演变方程,并进行了疲劳损伤分析和剩余疲劳寿命预测,为混凝土在多轴变幅疲劳试验研究及疲劳损伤评价提供参考。
The large-scale multi-axial fatigue testing machine was used to study the two-stage and three-stage luffing fatigue tests of concrete under triaxial load with biaxial tension and compression. The variation of residual strain was analyzed emphatically. The test results show that the residual strain of concrete under the conditions of tension, compression and tension and compression are mainly related to the relative fatigue times and lateral compression stress ratio, which are basically unaffected by the loading process factors. The relative residual strain is defined as the damage variable, the damage evolution equation is established, and the fatigue damage analysis and residual fatigue life prediction are carried out. The results provide a reference for the concrete in the multiaxial axial fatigue test and the fatigue damage assessment.