Nonlinear behaviour of axially loaded back-to-back built-up cold-formed austenitic stainless-steel channel sections

Abstract

The use of stainless-steel as structural members is increasing due to its corrosion resistance and durability. In cold-formed steel (CFS) structures, the back-to-back built-up stainless-steel channel sections are becoming popular as compression members. Current guidance by the American Iron and Steel Institute (AISI) and the Australian and New Zealand standards (AS/NZS) do not include specifically the design of stainless-steel built-up columns. No results are available in the literature for such back-to-back cold-formed (CF) austenitic stainless-steel channel sections, under axial compression. This paper presents a numerical investigation into the behaviour of back-to-back built-up CF austenitic (EN1.4404) stainless-steel channel sections under axial compression. A parametric study was carried out, comprising of 68 finite element (FE) models to cover a wide range of slenderness’s by considering various lengths and cross-sectional geometries of the built-up columns. The effect of screw spacing on axial strength of such columns was investigated. The finite element results were used to assess the performance of the current design guidelines by the AISI & AS/NZS. It was found that the current design guidelines by the AISI & AS/NZS are conservative by around 10% for intermediate and slender columns, however the AISI & AS/NZS are overdesign by around 8% for stub and short columns of back-to-back built-up austenitic stainless-steel channel sections