Design of stainless steel lipped channel columns subjected to distortional-global interactive buckling using the direct strength method

Abstract

Currently, there is no detailed approach for designing cold-formed stainless steel lipped channel columns which fail by an interaction between distortional and global buckling. In this paper, the structural behavior of cold-formed stainless steel lipped channel columns that fail in distortional-global interactive buckling is presented. Finite element (FE) models were developed to simulate the members under axial compression. The results obtained from the finite element analysis (FEA) were compared with the test results in terms of failure modes, strengths and load–deformation curves. After successful verification, a comprehensive numerical investigation was undertaken to provide benchmark data for the assessment the nominal strengths predicted by using the current specifications (based on standards from AISI and AS/NZS) and the design equations proposed by Lecce and Rasmussen. The distortional buckling equation in the AISI code leads to overestimation of predicted resistances, while Lecce and Rasmussen’s formula provides conservative predicted resistances for stainless steel lipped channel columns. The AS/NZS code provides a relatively accurate prediction of the strengths. Finally, a design method for stainless steel lipped channel columns is proposed, which provides considerably more accurate predictions. The proposed Direct strength method (DSM) equation has been proven to accurately predict the ultimate capacities of stainless steel lipped channel columns in compression.