On the strength and DSM design of end-bolted cold-formed steel columns buckling in distortional modes

Abstract

Reports an experimental investigation on the behavior and ultimate strength of end-bolted cold-formed steel lipped channel columns selected to fail in distortional modes. Besides describing the test set-up and procedure, the available results are presented and discussed: they concern three tests and consist of (i) initial imperfection measurements, (ii) equilibrium paths relating the applied load to key column displacements and (iii) deformed configurations (including the collapse mode) and failure loads. The experimental results are used to validate ANSYS shell finite models intended to analyze the column geometrically and materially non-linear behavior. These models are then employed to perform a parametric study involving end-bolted lipped channel columns with various combinations of geometry (length and cross-section dimensions) and elastic-perfectly plastic material behavior (yield stress), aimed at (i) acquiring knowledge on the column post-buckling mechanics and strength reserve, and (ii) gathering ultimate strength data. Finally, the experimental and numerical failure load data obtained are used to assess the quality of their predictions by the current DSM distortional design curve and, if needed, provide preliminary guidelines on how to improve them.