等幅侧向位移循环下柱混凝土纤维应变规律的试验研究

在已完成的包括16个构件的等位移循环加载钢筋混凝土柱的系列试验中，通过在其中3根柱的塑性铰区沿混凝土受力方向安设位移计，较准确测定了混凝土测试标距内的平均应变在一个加载循环内的变化规律及其随周数增长的变化规律；发现了单周最大压应变随周数的增长而持续增大，单周最大名义拉应变随周数增长而持续减小的重要现象；并与柱顶水平力-水平位移滞回规律实测结果相对应，结合截面受力特征对所得单周和多周应变变化规律的成因作了分析。

Experimental research on changing trend of strain of concrete fiber of RC columns under low-cycle fatigue loading with symmetric displacement amplitude

Three low-cycle fatigue tests of RC columns with symmetric displacement amplitude were carried out. The trend of the change of the average strain of concrete in a cycle and the trend of the change with the increase of cycles within the gauge length were measured by displacement transducers installed along the direction of the force acting on the concrete in the plastic hinge regions of the columns . It is found that with the increase of cycles the maximum compressive strain in each cycle increases and the maximum nominal tensile strain in each cycle decreases. Based on the level force-displacement hysteretic curve of the top of column and the state of cross section under the given force, the cause of the trend of the change of strain in one cycle or many cycles is analyzed in this paper.