Study on distortional buckling performance of cold-formed thin-walled steel flexural Members with stiffeners in the flange

• Instability mode may be distortional buckling because of complex stiffened types.
• CUFSM is used to calculate and analyze the elastic distortional buckling.
• Distortional buckling coefficient is calculated according to the classical buckling stress formula.
• Influence of geometric parameters on distortional buckling coefficient is analyzed.
• Simplified formula of distortional buckling stress is proposed in this article.

This paper presents a finite strip program CUFSM used to calculate and analyze the elastic distortional buckling of cold-formed thin-walled steel flexural members with stiffeners in the flange, which has different sectional geometric parameters. According to the classical buckling stress formula, the distortional buckling coefficient of the flange can be calculated so as to analyze the influence of changed sectional geometric parameters on it. On this basis, this study provides a simplified formula of distortional buckling stress to calculate 40 members with different sections which are selected from the Technical Code of Cold-Formed Thin-Wall Steel Structures of China but not contained in this paper. Compared with the analysis results of CUFSM, it shows that the two simplified formulas have quite high accuracy and wide applicability for general members provided by the specification. So it is suggested that they can be used for engineering design and standard revision.