Design of uniformly compressed edge-stiffened flanges and sections that contain them

Recent developments in the section approach to the design of cold-formed steel structures have led to design rules that address sections with edge-stiffened flanges, where the edge stiffeners give rise to the distortional buckling mode. However, the element approach to design (effective width method) remains unable to deal with this mode of buckling, and has been shown to routinely provide unconservative design capacities for such sections. This paper provides design rules for edge-stiffened elements that may be used in conjunction with the existing element approach in specifications, in order to determine the capacity of sections with edge-stiffened flanges in compression. The design rules are developed from an extensive analysis of the fundamental behaviour of plates simply supported on three sides with the remaining (longitudinal) edge stiffened with an edge stiffener. When used in conjunction with the effective width method they are shown to provide excellent agreement with tests of sections that contain edge-stiffened flanges in compression, thus removing the unconservatism in current specifications.