Direct Strength Design of Cold-Formed Steel Members Using Constrained Spline Finite Strip Method

Direct strength method (DSM) for the design of cold-formed steel members recommends finite strip method (FSM) for calculating the elastic buckling stresses corresponding to local, distortional and global buckling, which are considered to be the basic input parameters for design. This paper presents application of constrained spline finite strip method (cSFSM) developed by authors for calculating pure elastic buckling stresses in DSM and hence predicting the ultimate member capacity in uniform flexure and axial compression. The elastic buckling stresses are determined for a specified set of experiments available in literature using cSFSM by considering different end conditions and failure modes and the elastic stress values are applied in DSM for calculating ultimate member capacity. For beams with simply supported-warping free ends and columns with simply supported-warping fixed ends, the DSM evaluated results using cSFSM produces results comparable with experiments. The results obtained by the comparison of DSM with experiments were not satisfactory for fixed columns and beams with simply supported-warping fixed ends.