轴拉力作用下异形截面多腔钢管混凝土巨型分叉柱抗震性能试验研究

针对某超高层建筑巨型柱在罕遇地震作用下轴向受拉的情况，研究了异形截面多腔钢管混凝土巨型分叉柱抗震性能，考虑水平力作用方向和分叉界面下一层构造的影响，进行了4个模型试件的低周反复荷载试验。试验结果表明：分叉柱的破坏大多发生在截面突变的分叉界面处，其水平力-位移角滞回曲线饱满程度一般，但无明显捏拢现象；分叉柱均出现了承载能力退化现象；分叉柱的变形和耗能主要在上柱部分，并随位移的增大，所占比例提高；较沿截面短轴方向加载，沿截面长轴方向加载时分叉柱的抗震性能明显提高；分叉界面下一层增加腔体加强的分叉柱较未加强分叉柱的承载力提高16.6%~29.7%，极限位移角增大13.1%~13.2%，位移角为1%时综合耗能提高10.0%~16.7%。

Seismic behavior of special-shaped CFT mega bifurcate column coupled with multiple cavities under axial tensile force

Mega columns are often in axial tensile stress state under rare earthquake in super high-rise buildings. Seismic behavior of special-shaped CFT mega bifurcate column coupled with multiple cavities was investigated. Considering the influence of horizontal force direction and construction of the story under bifurcate interface, low cyclic test of four modelling specimens was conducted. The test results show that the main damage appears at the bifurcate interface where the cross-section abruptly changes. The horizontal load-drift ratio curves are generally full, but there’s no obvious rheostriction. Bearing capacity degradation occurs in all bifurcate columns. Deformation and energy dissipation concentrate in upper column, and the proportion increases along with the loading displacement. The seismic behavior in long axis direction is much better than that in short axis direction. Compared with the unstrengthened specimens, the bearing capacity of the specimens with the next story under bifurcate interface strengthened is increased by 16.6%~29.7%, the ultimate drift ratio is increased by 13.1%~13.2%, and the energy dissipation ability is increased by 10.0%~16.7% under 1% drift ratio.