Research On The In-Plan Effective Length Factor Of Brace In SHS Truss With Overlap Joints

The effective length factor of steel tubular truss in the design code of steel structure in china is not specified. The brace of the truss which use directly welded SHS joints is supposed to be pinned in designs. Overlap SHS joints are one of the common joint configurations used in the space truss. So the research on stability of brace restrained by overlap joints in truss is necessary. In this paper, an extensive parametric research on the rotational stiffness and the effective length factor of compression brace of the truss restrained by overlap K joint is carried out by an ANSYS nonlinear finite element analysis.Firstly, the restriction of brace from joint is simplified as semi-rigid restriction against rotation so that the rotation stiffness of overlap K joints can be obtained in theory. Then the relationship between effective length factor and rational stiffness and other parameters such as rotational inertia is found by stability formula and Euler formula.A parameter analysis, including about 300 joints cases, is carried out to investigate the variation of rotational stiffness and effective length with the geometric parameters varying slenderness ratioλ, brace to chord ratioβ, ratio of brace thickness to chord'sτ, ratio of chord width to thicknessγ, angle of brace to chordθ, overlap ratio ov and factor of whole size C .At the same time, the variation of rotational stiffness and effective length with parameters varying when brace is restrained by gap K joints is compared with overlap K joints. The similarities and differences of the two kinds of joints are obtained in this paper.