Compression Capacity of Short Cold-Formed Steel Built-Up Columns with Double-Lacing Configuration and Low Sectional Compactness

Built-up columns composed of multiple cold-formed steel (CFS) sections are often used as structural members to carry the high axial force demand as they are considered as economical and efficient. Though built-up CFS columns with intermediate lacing plates are widely adopted in the practice, very limited studies have been conducted in the past to investigate their performance under various loading conditions. This study presents an experimental investigation on the built-up CFS column specimens with double-lacing configuration and large flat width-to-thickness ratio. Pin-ended support conditions allowing uniaxial bending are adopted in this study. The main parameters varied in this study are the sectional compactness of chord sections, the column slenderness ratio, and the slenderness ratio of lacing elements. The slenderness ratio of the unbraced chord elements is kept constant in all test specimens. The design strengths of builtup CFS columns are computed using North American and Eurocode specifications for CFS structures for the comparison the test results. The design strength predictions of both these standards are found to be conservative.

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