外方内圆复合钢管高强混凝土柱抗震性能试验研究

Experimental study on seismic behavior of composite-sectioned high strength concrete filled steel tubular columns

为研究外方内圆复合钢管高强混凝土柱的抗震性能,完成了6个试件的拟静力试验。试验主要变化参数为轴压比、方钢管壁板厚度及其宽厚比、圆钢管混凝土套箍指标。试验结果表明:6个试件的破坏形态基本相同,均为距柱底约300mm高度范围内方钢管外鼓屈曲,方、圆钢管之间混凝土局部破坏;试件的水平荷载-位移滞回曲线饱满,无明显捏拢;峰值水平荷载时,轴压比设计值约为1.0的试件位移角略小于1/100,其它5个试件位移角均大于1/100;减小方钢管壁板的宽厚比,或增大圆钢管混凝土的套箍指标,可增大试件的初始割线刚度以及极限位移角;增大方钢管壁板的厚度,可提高试件在轴压力作用下的正截面受弯承载力。采用叠加方法与平截面假定方法计算试件在轴压力作用下的正截面受弯承载力,计算值与实测值吻合较好。

To study the seismic behavior of composite-sectioned high strength concrete filled steel tubular （CSCFT） columns, quasi-static tests on six specimens were conducted. The test variables included the axial force ratio, wall thickness and width-to-thickness ratio of square steel tube, confinement index of circular concrete filled steel tube （CFT）. Test results indicate that the failure mode of the CSCFT column specimens is characterized by wall buckling of square steel tube and crushing of partial concrete between the square steel tube and the circular steel tube within a height of 300ram from the column base. The lateral force-displacement hysteretic loops are plump. At the peak lateral force, the drift ratio of one specimen is a little bit less than 1/100 since it has a design value of axial force ratio close to 1.0, and the drift ratios of other 5 specimens are larger than 1/100. As the wall width-to-thickness ratio of square steel tube reduced, or the confinement index of CFT increased, the initial secant stiffness and the ultimate drift ratio are increased. As the wall thickness of square steel tube increased, the bending strength of specimen under axial compressive force is enhanced. The bending strength of the specimens calculated by the superposition method and by the plane section assumption has good agreement with the test results.