楔形变壁厚排架柱设计研究

Research on design of wedge⁃shaped variable thickness bent column

丽江三义机场T3航站楼屋盖采用排架结构体系,由楔形变壁厚排架柱支承。沿排架柱网布置立体桁架,在立体桁架间布置网架。结构竖向传力体系由网架、立体桁架与楔形变壁厚排架柱组成。现行规范中尚未明确楔形变壁厚排架柱的稳定承载力计算方法,设计中通常采用门式刚架的变截面柱计算公式进行计算长度法验算。基于直接分析法,对应排架柱构件不同失稳模态,分别采用了相应的初始构件缺陷分布,考虑了整体初始几何缺陷下结构的一阶弯矩方向,通过条件极值方法判断了构件初始缺陷的最不利方向,建立对应的分析流程,并与计算长度法结果进行对比。结果表明:楔形变壁厚排架柱构件初始缺陷采用一端约束、一端自由构件的失稳模态更加合理,计算长度法的冗余度及安全性均优于直接分析法。

The roof of T3 terminal building of Lijiang Sanyi Airport is a bent structure system,which is supported by wedge⁃shaped variable thickness bent columns.The three⁃dimensional truss is arranged along the column grid of the bent,and space truss is arranged between the three⁃dimensional trusses.The vertical force transmission system of structure is composed of space truss,three⁃dimensional truss and wedge⁃shaped variable thickness bent column.The calculation method of the stability bearing capacity of the wedge⁃shaped variable thickness bent column has not been clearly defined in the current specification.In the design,the calculation formula of the variable cross⁃section column of the portal frame is usually used for the calculation of the effective length method.Based on the direct analysis method,the corresponding initial component defect distribution was adopted for different instability modes of bent column members,and the first⁃order bending moment direction of the structure under the overall initial geometric defect was considered.The most unfavorable direction of the initial defect of the members was determined by the conditional extreme value method,and the corresponding analysis process was established and compared with the results of the effective length method.The results show that it is more reasonable to adopt the instability mode of one end constraint and one end free member for the initial defect of wedge⁃shaped variable thickness bent column.The redundancy and safety of the effective length method are better than those of the direct analysis method.