轴向往复荷载作用下圆钢管混凝土柱恢复力模型研究

为研究钢管混凝土柱的轴向恢复力模型，设计制作了8个钢管混凝土柱试件并对其进行轴向往复加载，分析其受力机理和恢复力特性。基于试验结果，选用退化三线型模型，建立了钢管混凝土柱无量纲骨架曲线模型，并提出其轴拉与轴压方向的峰值承载力和位移的计算方法。鉴于钢管混凝土试件在轴拉与轴压方向受力机理的差异，对滞回曲线的正负向选用不同的滞回规则，建立了相应的卸载刚度函数。据此提出了钢管混凝土柱的轴向恢复力模型，并与试验滞回曲线进行对比，验证了恢复力模型的合理性，所建立的恢复力模型可为斜交网格结构体系的弹塑性分析提供依据。

RESEARCH ON RESTORING FORCE MODEL OF CONCRETE-FILLED STEEL TUBE COLUMNS UNDER AXIAL CYCLIC LOADING

To establish the axial restoring force model of inclined columns, 8 concrete-filled steel tube (CFST) columns were manufactured to conduct the axial cyclic loading test, and to investigate the mechanical mechanism and the restoring force characteristics. Based on the axial cyclic loading test results of CFST columns, the restoring force model of CFST column was fitted through a degenerated three-line model. The dimensionless skeleton curve model of CFST column was established, and the calculation method of the bearing capacity and the corresponding displacement of CFST columns were proposed. Due to the different performance of CFST specimens under axial tension and under axial compression, different hysteresis criteria and unloading stiffness functions were used in positive and negative directions to fit the corresponding unloading stiffness function. Based on these, the axial restoring force model of CFST columns was proposed. The validity of the restoring force model was verified through a comparison with the experimental hysteretic curve, which indicates that the restoring force model established in this paper can accurately predict the hysteretic behavior of CFST columns under axial cyclic load.