Design of cold-formed lean duplex stainless steel concentrically loaded compression members

Abstract

This paper describes a test program on cold-formed lean duplex stainless steel columns compressed between pinned ends. In this study, one square hollow section and two rectangular hollow sections were tested at different column lengths. The material properties were obtained from tensile coupon tests and stub column tests. The test specimens were cold-rolled from flat strips of lean duplex stainless steel (EN 1.4162). Initial overall geometric imperfections of the column specimens were measured prior to testing. The column specimens were concentrically loaded between pinned ends. The ultimate loads and the failure modes of each column are presented. The test strengths of the specimens were compared with the design strengths predicted by the American Specification, Australian/New Zealand Standard and European Code for stainless steel structures. Generally, the specifications are able to predict the strengths of the tested columns. The European Code provides the most conservative predictions, while the American Specification provides conservative predictions when the design strengths calculated using the material properties from tensile coupon tests. The design approach of using full cross-section area and material properties obtained by stub column tests for all classes of sections including slender sections was recommended. This recommended design approach does not require section classification and calculation of effective area. The design strengths calculated using the recommended design approach are generally more accurate than those using the current design rules.