Cold-formed Steel Lipped Channel Columns Affected by Distortional-Global Interaction at Elevated Temperatures

Resumo

This work reports the recent results of an ongoing numerical investigation on the post-buckling behavior and strength of cold-formed steel lipped channel columns affected by distortional and major axis flexural-torsional buckling mode interaction (D-FMT interaction) at elevated temperatures. It includes an extensive set of failure load data, encompassing columns with various cross-section dimensions, lengths and different levels of D-FMT interactions (“True” or “Secondary global or distortional” D-FMT interaction). The results were obtained by means of geometrically and materially non-linear analyses conducted with shell finite element models developed in ABAQUS. The EC3-1.2 constitutive model was employed to simulate the steel material behavior, specifically addressing the temperature-dependent stress-strain relationship. The results presented and discussed consist of post-buckling equilibrium paths, collapse modes and failure loads of fixed-ended columns at elevated temperatures (up to 800 °C). The results allowed for drawing a few conclusions concerning the available Direct Strength Method (DSM) curves for distortional and flexural torsional modes at elevated temperatures. The success of this endeavor encourages the authors in the search for a safe and effective design approach for CFS columns with fixed-ended (and other support conditions) undergoing distortional-global interaction and at elevated temperatures.