变轴力钢管混凝土柱抗震性能试验研究

Seismic Behaviors of CFST Columns under Variable Axial Force

为了研究地震作用下轴力变化对圆截面钢管混凝土框架柱抗震性能的影响,采用子结构拟动力试验方法进行了4个水准地震作用下的框架结构拟动力试验。试验程序利用有限元程序OpenSees进行数值计算,并与拟动力试验控制系统实现数据实时交互传递。建立了一个4层钢管混凝土框架模型,将首层钢管混凝土柱作为试验子结构进行变轴力作用下钢管混凝土柱抗震性能试验。分析轴力变化对钢管混凝土柱滞回特性、耗能能力、塑性变形等性能的影响,并对比研究地震作用对边柱与角柱的影响。试验结果表明:地震作用下框架柱的轴力会发生较大变化;轴力变化导致钢管混凝土框架柱滞回曲线"捏缩效应"更加明显,塑性铰区域塑性变形累积增长较快、局部屈曲提前出现;与定轴力作用相比,变轴力下框架柱耗能能力受到削弱,抗震性能降低。

To investigate the influence of variable axial force on seismic behavior of circular CFST frame columns under earthquake action,substructure pseudo-dynamic tests of frame under 4 levels of earthquake excitation are carried out. The program used in the tests can transfer data in real time between control system of testing facilities and Open Sees which is used for numerical simulation. A four-story CFST frame model is built and the columns of the first floor are taken as test substructures for conducting seismic performance test. Based on the experiments,hysteretic behavior,energy dissipation,and plastic deformation of CFST side columns and corner ones under variable axial force are discussed. The test results show that the axial force of frame column varies intensely during earthquake,which aggravates the pinch effect of hysteretic curves and accelerates the plastic strain,and the yielding and local buckling at plastic hinge area of CFTS model columns appear in earlier stage. The energy dissipation capacity and seismic performance of CFST columns also degrade because of the variable axial force.