Linear stability analysis of cold-formed steel members performed by finite strip and finite element methods

Two powerful numerical methods, finite strip and finite element, are used to perform a linear stability analysis of cold-formed steel structural member. The results, displaying de variation of the buckling stress and associated instability mode with the length of members, for C and rack cold-formed columns, are compared using both mentioned methods. In obtaining the results based on finite strip method, two computer programs developed by Prola [1] are used: (i(1)) Semi-Analytical Finite Strip Method (trigonometric functions are used in the approximation of the displacement), for simply supported boundary conditions, and (i(2)) Spline Finite Strip Method ("spline" functions are used in the approximation of the displacement), used for others boundary conditions. A commercial program, SAP 2000 [2], was chosen for obtaining the results given by Finite Element Method. The element used is four-node quadrilateral shell element with isotropic behaviour.