Buckling strength of axially loaded cold formed built-up I-sections with and without stiffened web

Abstract

This paper presents a numerical procedure using finite element analysis for the calculation of axial strength of cold formed steel built-up I-sections composed of two back-to-back channels or stiffened web sigma (Σ). The material nonlinearity of the plane and curved parts of the section were considered in the model. The effects of initial local and global geometric imperfections as well as the membrane residual stresses have been taken into consideration in the FE model. The results of the nonlinear FEA were compared with the available experimental data, and with the calculated theoretical buckling capacities based on the AISI design provisions. A parametric study was performed using the developed FE model to investigate the effects of member and geometries and imperfection values on the capacity of CFS built-up I-columns. A comparison is performed between the member’s axial capacities results from the parametric study and the design capacities calculated using the AISI. The results of the parametric study state that the design specification noted in the AISI are generally conservative for long and medium length columns, but may give un-conservative estimates for some of the short columns. Keywords: Cold-formed-steel, Nonlinear parametric columns, Finite-element, Buckling