国家体育场焊接方管桁架双弦杆KK型节点试验研究

正在建设的国家体育场两两斜交的主桁架构成了许多双弦杆焊接方管KK型节点,该节点连接焊缝密集,构造极其复杂。本文对这种在管结构中较为独特的节点进行了1∶4的缩尺模型承载力试验研究,详细介绍了节点的试验方法和结果,讨论了节点的受力性能、破坏模式以及节点内部加劲肋的作用。研究表明该节点的构造措施较完善可靠,节点具有较高的承载力。节点的薄弱部位处在受压腹杆端部,发生局部屈曲。弦杆内部纵横向加劲肋的设置有效地增强了节点强度和刚度。腹杆端部的局部放大改善了腹杆向弦杆的传力,降低了应力集中。

Experimental study on KK-joint between two welded square hollow section trusses in the National Stadium

There were many KK-type joints with double chords made of welded square hollow sections in the National Stadium under construction,which is formed by two trusses from different directions.The joint was fabricated with serried welds and its construction details were quite complicated.The load carrying capacity of the special joint in tubular structures was investigated experimentally, based on a 1∶4 scale model test.Experimental method and results are presented in this paper.The joint behaviour,failure mode and effect of stiffeners inside the joint are discussed.It is concluded that the joint had high loading capacity because of its better structural arrangements.The weak area was located at the ends of compressive web members where local buckling occurred.The arrangement of both longitudinal and transverse stiffeners inside chord members enhanced both strength and stiffness of the joint.Local enlargement at the ends of web members improved force transfer from webs to chords,decreasing the stress concentration there.