Distortional Buckling of Cold-Formed Stainless Steel Sections: Finite-Element Modeling and Design

A recent experimental and finite-element research program was conducted on the distortional buckling of axially compressed, cold-formed stainless steel simple lipped channels. Austenitic 304 (1.4301), ferritic 430 (1.4016), and ferritic-like 3Cr12 (1.4003) chromium weldable steel were considered. Finite-element analyses demonstrate that material anisotropy can be ignored. A total of 281 distortional buckling analyses of simple lipped channels with r/t ratios of 1 and 2.5 show that enhanced corner properties may be important for sections which have a slenderness (lambda) d<1.0 and at least 10% corner area but have little effect on sections with (lambda) d>1.0. Evaluation of current stainless steel design codes show that the Australian/New Zealand Standard AS/NZS 4673 and the ASCE Specification effective width procedures are unconservative for austenitic and ferritic stainless steels. The Eurocode 3 prEN Part 1-4/preEN Part 1-3 effective width procedures are unconservative for austenitic stainless steel but provide reasonably conservative results for ferritic 430 and 3Cr12 alloys, provided enhanced corner properties are ignored. Direct strength design guidelines for the distortional buckling mode are proposed for austenitic and ferritic stainless steels.