Experimental and numerical investigation on stub column behaviour of cold-formed octagonal hollow sections

This paper presents an experimental and numerical investigation into stub column behaviour of cold-formed steel octagonal hollow sections (OctHSs). A total of 16 OctHS stub columns were tested. Tensile coupons were extracted from both flat and corner portions of hollow sections to determine corresponding material properties. Finite element (FE) models were developed using commercially available software ABAQUS to replicate the test results generated in this study. The degree to which the enhanced material properties at corners should be extended was investigated. It was found that FE models with corner material properties extended to a width of material thickness beyond the corner portions offer the best agreement with test observations. The validated FE models were then adopted to conduct parametric studies to supplement test database. Cross-sectional slenderness limits specified in current design codes, including EN 1993-1-1, ANSI/AISC 360-16, ASCE/SEI 48-11 and AISI S100-16 (DSM) were evaluated against the test results in conjunction with the FE results. It was found that current limits are not suitable for the design of OctHSs. New cross-sectional slenderness limits in accordance with EN 1993-1-1, ANSI/AISC 360-16, ASCE/SEI 48-11 and DSM were then proposed based on the test and FE results. Cross-sectional capacity predictions obtained from EN 1993-1-1, ANSI/AISC 360-16, ASCE/SEI 48-11 and DSM were also compared with test and FE results. It is shown that the capacity predictions for slender sections from ASCE/SEI 48-11 are slightly unsafe, and ANSI/AISC 360-16 produces relatively satisfactory capacity predictions.