| The web members in cold-formed steel trusses are usually assumed to have pinned connections at the ends. However, the study of the real behavior of bolted joints is not sufficient at present. The related design rules have not considered stiffness of joints in Chinese code. Based on the latest experimental study abroad, this paper works some numerical analysis, aimed at evaluating the real behavior of bolted joints in cold-formed steel trusses.In this paper the finite element program ANSYS10.0 is applied to carry out the finite nonlinear analysis of single lap joints and T-joints. The FEM models were then verified by the experimental results. In the FEM model of single lap joints and T-joints, the thickness of the plates and the effect of bolt diameter are considered. The result shows that the plate thickness and bolt diameter are main factors to influence the stiffness of joints.Based on the finite element nonlinear analysis, the semi-rigid properties of joints in bolted connected cold-forme' steel trusses were studied. The buckling lengths of the web members will decreases, due to the rotational stiffness of joints providing rotational restraints at the end of web members. Consequently, the influence of semi-rigid joints to cold-formed steel truss is obvious. According to results of finite element analysis, a formula for calculating the buckling length of truss web members is fitted, which considers the influence of semi-rigid joints.
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