不同构造异形截面多腔钢管混凝土分叉柱抗震性能试验

Experimental study on seismic behavior of special-shaped CFT bifurcate columns with multiple cavities and different cross-sectional constructions

为研究截面加强构造对异形截面多腔钢管混凝土分叉柱长轴方向抗震性能的影响,进行了5个试件在轴向压力作用下,水平荷载往复加载2次的低周反复荷载试验。截面构造主要包括1种基本构造和4种加强构造,加强构造主要有,上柱及下柱分叉面下一层纵向受力钢板加厚构造,下柱分叉面下一层增加腔体构造,及在多腔加强基础上角部腔体内设置角钢或圆钢管的加强构造。试验结果表明:试件破坏大多发生在下柱下水平隔板处,表现为焊缝边缘热影响区钢板开裂及延伸引起的钢板撕裂;焊缝布置位置是影响试件破坏形态的主要因素;角部腔体内设置角钢或圆钢管构造效果最好,增厚钢板构造效果次之,多腔加强构造效果最差;各试件承载力退化不明显,上柱变形、耗能较下柱高;各试件的屈服位移角均值约为1/101,峰值荷载对应位移角约为1/42,最大弹塑性位移角约为1/29,可用于超高层巨型框架结构设计。

In order to study the influence of cross-sectional constructions on seismic behavior of special-shaped CFT columns with multiple cavities in the long axis direction, five specimens were tested under the axial compression and twice loaded low-cyclic horizontal loads. There are one basic construction and four enhanced constructions in the cross-sectional constructions. The four enhanced constructions include the enhancement of increasing the thickness of the longitudinal steel plate in the lower layer of the lower column under bifurcate plane and the upper column, the enhancement of adding the cavities at the lower layer under bifurcate plane, and the enhancements of additionally installing steel angles or steel tubes in the comer cavities apart from the enhancement of adding the cavities. The test results show that most damages of specimens occur at the location of horizontal steel plate of the lower column, and appear to be cracking of steel plate in heat-affected zones at the weld edges and tearing of steel plate due to the propagation of the cracks. The location arrangement of welds shall be one of the major factors influencing the failure patterns of the specimens. The enhancement effect of installing steel angles or steel tube in the comer cavities shall be the best, the next is that of increasing the thickness of steel plate, while the worst is that of adding multiple cavities. The degradations of bearing capacity of all the specimens are not remarkable. The deformation and energy dissipation ability of the upper column is better than that of lower column. The average value of yield drift ratio of all the specimens is 1/101, the drift ratio corresponding to the peak load is about 1/42, and the maximum elasto-plastic drift ratio is about 1/29, indicating that the columns proposed in this work can be used in the design of mega frame structures of super high-rise buildings.