| The stability is always the key problem in the area of cold-formed thin-walled steel structures. With the cold-formed steel members tending to higher strength, thinner thickness and more complex section shapes, the buckling mode of members becomes more complex. Therefore, the stability behavior of new section cold-formed thin-walled steel members remains to be further research.This paper selects three kinds of cold-formed thin-walled steel members with complex edge stiffeners including C-section members,∑-section members and C-section members with V-section stiffener rib in the web. And this paper investigates the stability behavior of cold-formed steel members under pure bending and non-pure bending states by test investigation, finite element and finite strip parametric analysis.A total of12specimens that divided into6tests including3pure bending tests and3non-pure bending tests had been conducted. Local buckling, distortional buckling and interaction between local and distortional buckling were observed in the tests. All the tests were simulated by the finite element program of ANSYS which considered geometric and material non-linearity. The simulated results showed good agreement with the tests results, which proved by the finite element model for the accuracy of the member analysis. Finite element parametric analysis were performed for C-section flexural members with upright stiffeners and complex edge stiffeners, E-section flexural members and members with V-section stiffener rib in the web, and the failure modes and bending strengths under pure bending and non-pure bending states were got. Through comparing the finite element parametric results of the steel channels with upright stiffeners and complex edge stiffeners to get the influence of the failure modes and bending strengths by edge forms. Through comparing the finite element parametric results of the steel channels with different kinds of sections to get the influence of the failure modes and bending strengths by different forms of stiffening rib in the web. By comparing the bending strengths of the same member under the two bending states shows the difference of the failure modes and bending strengths.Due to the existing methods for calculate the elastic distortional buckling stress of flexural members are too fussy, simplified formulas for calculate the elastic distortional buckling stress of new section members has to be researched. This paper used the finite strip program of CUFSM to calculate the elastic distortional buckling stress of new section members and analyzed the effect rule of every parameter. So this paper established simplified formulas to calculate the elastic distortional buckling stress of the cold-formed thin-walled steel members with complex edge stiffeners including C-section members,∑-section members and C-section members with V-section stiffener rib in the web, and then combined the simplified formulas of the two kinds of C-section members. The comparison between the results got from the simplified formulas and which got from CUFSM showed that the errors of the simplified formulas were small and can satisfy the calculating precision. |
