Numerical and Experimental Investigation on the Post-Buckling Behavior, Ultimate Strength and DSM Design of Thin-Walled Cruciform Steel Columns

This work reports on a numerical and experimental investigation concerning the buckling, post-buckling (elastic and elastic-plastic) and ultimate strength behavior of short-to-intermediate thin-walled equal-leg cruciform steel columns, as well as their Direct Strength Method (DSM) design. First, the main features of the column buckling and post-buckling behaviors are unveiled by means of GBT and ABAQUS shell finite element analyses (SFEA), evidencing the great similarities between the pin-ended (but with the end section secondary warping prevented) and fixed-ended column responses. Next, after revisiting an experimental investigation recently reported by Green (2012), the paper gathers a large column ultimate strength data bank comprising (i) a large number of numerical values, obtained from ABAQUS SFEA, and (ii) the experimental results available in the literature. The data bank, covering a wide column slenderness range, is then used to assess the quality of the estimates provided by the current DSM strength curves for the design against local, global and local-global interactive failures. On the basis of the above assessment, a novel DSM design approach is proposed, which leads to efficient (safe and accurate) ultimate strength predictions for the entire set of column failure loads considered in this work. 

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