(中国建筑科学研究院建筑结构研究所，北京 100013)

［摘要］在一些受较大向上风载的屋架或连接不同单体建筑步行桥的两侧桁架等结构中，由于受到使用条件限制而无法为受压弦杆设置平面外的支撑系统，因此这些结构中受压弦杆在平面外的稳定问题就显得格外突出。阐述了这类稳定问题的力学机制，归纳和讨论了在桁架结构中无支撑受压弦杆出平面稳定问题的理论分析方法及结果，通过算例验证了数值方法的有效性，并通过数值方法分析了弦杆的轴力变化对面外计算长度的影响，随后对北京当代MOMA工程连接周边建筑与电影院屋顶之间步行桥桁架中的相关问题进行了分析，最后给出了对于实际工程问题的分析方法和设计建议。

［关键词］弹性支撑；受压弦杆；面外计算长度

Discuss on outplane effective length of compressive chord members in truss without lateral supports

Shang Xiaojiang, Xiao Congzhen, Zhang Liruo

(Institute of Building Structures, China Academy of Building Research, Beijing 100013, China)

Abstract:In some truss structures, such as the roof truss undergoing heavy upward wind load, or the truss on both sides of a footbridge connecting different buildings, the service conditions do not allow us to place lateral support for the compressive chord members. In these structures, the out-plane stability problem of the compressive chord members becomes very significant. The mechanism of such stability problem is explained, the related theoretical method is summarized and discussed, the validity of numerical analysis is verified, and the effect of varied axial force on the effective length is analyzed through numerical examples. Then the relevant problem in the footbridge to the cinema roof of Beijing Grand MOMA is analyzed, and at last the design methods and suggestions are provided.

Keywords:flexural lateral support; compressive chord member; out-plane effective length

作者简介：尚晓江，博士研究生。Email:shj-cas@sina.com。