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在高层筒中筒结构中由于某一层楼板抽空,导致两层通高区中外筒框架柱无明确面外支撑,此时通高区群柱面外失稳往往成为结构设计的控制因素之一。该文针对等轴压的两层多跨平面群柱模型,首先通过理论推导得出各柱面外等效支撑刚度的表达式,将两层群柱的面外稳定性研究模型简化柱跨中带侧向弹簧支撑的轴压单柱模型;然后,运用既有单柱简化模型的研究成果得到柱子弹性屈曲荷载和计算长度系数与等效支撑刚度的关系,并通过弹性屈曲有限元分析验证了该文提出的等效支撑刚度和屈曲荷载简化计算公式的准确性;最后,考虑群柱中各柱平面外几何初始缺陷随机分布的影响,对两层通高区群柱的弹塑性极限承载力进行多参数分析,验证了在柱跨中面外支撑刚度相同的前提下,单柱简化模型的轴压稳定设计方法仍然适用于两层通高区群柱的面外稳定性设计。
In the high-rise tube-in-tube structure, because of the evacuation of a certain floor, the outer and middle cylindrical frame columns in the two-storey high zone have no clear out-of-plane support. At this moment, the out-of-plane instability of Tonggao area group often becomes one of the control factors of structural design. In this paper, based on the two-level multi-span plane group model with equiaxial pressure, the equivalent stiffness of each cylinder is deduced by theoretical derivation. The two-layer group stability model is simplified. Then, using the existing research results of single-column simplified model, the relationship between the elastic buckling load of column and the calculated stiffness coefficient and the equivalent support stiffness was obtained. The elastic buckling finite element analysis In this paper, the equivalent support stiffness and buckling load are deduced to simplify the calculation formula. Finally, considering the random distribution of out-of-plane geometric initial defects of each column, the elastic-plastic ultimate bearing capacity The multi-parameter analysis is carried out to verify that the design method of single-column simplified model under axial compression is still suitable for out-of-plane stability design of group columns with two layers of through-going zones under the premise of the same stiffness of the outer and middle supports.