Parametric study and simplified design equations for cold-formed steel channels with edge-stiffened holes under axial compression

Abstract

The use of cold-formed steel (CFS) channels with web holes are becoming increasingly popular. Such holes, however, result in sections becoming more susceptible to lower axial compressive resistance. Traditional holes are normally punched at the web and un-stiffened. Recently, a new generation of CFS channels with edge-stiffened holes has been developed by the CFS industry but no information is available in the literature to accurately predict the axial capacity of such sections. The current design guidelines in accordance with the American Iron and Steel Institute (AISI 2016) and Australia New Zealand standards (AS/NZ 4600:2018) do not provide any design rules for CFS channels with edge-stiffened holes. In this paper, a numerical model that accurately simulated results from the experimental testing of CFS channels with edge-stiffened holes under axial compression as published in a previous paper by the authors was employed to carry out a parametric study which involved 348 finite element (FE) models. Variables which were examined included column slenderness, stiffener length, fillet radius, hole size, hole location and hole spacing. A comparison of the numerical results with current design rules for CFS channels with un-stiffened holes revealed that the design equations were not accurate for such sections; design equations are therefore proposed in which an enhancement factor is applied to the original equations. The enhancement factor was obtained using bivariate linear regression analysis. The proposed design equations closely predict the enhanced axial capacity of CFS channels with edge-stiffened holes.