Comparative Study of Analytical Methods for Buckling Behavior of Cold-Formed Purlins

The direct strength method (DSM) has become an alternative to the effective width method (EWM) to compute the bending moment capacity of cold-formed channel sections. The traditional EWM examines the nominal moment capacity by the PURLIN program. DSM uses a signature curve from tests on many Australian channel sections to obtain design moment capacity for local and distortional buckling modes. Moreover, the non-linear analysis performed by Strand7 will be compared with the current DSM curve. In general, these comparisons of results are in good agreement: the THIN-WALL program results and the linear static analysis results in Strand7; the moment capacity calculated by the PURLIN program (EWM) and the DSM curve in the local buckling mode; the non-linear analysis results in Strand7 and the DSM curve for each buckling mode. The outcome of this study will benefit structural engineers by providing them with design methods analysis.