Numerical Study of Cold-Formed Steel Built-Up Compression Members for Long-Span Structures

As an alternative to hot-rolled steel, cold-formed steel (CFS) constructions such as beams, columns, trusses, wall frames, and portal frames as well as the usage of back-to-back built-up cold-formed steel channels as compression members are growing in popularity. However, for long-span structures, back-to-back built-up I sections as columns are not yet effective in replacing hot-rolled steel in terms of cost and profile stiffness. To address the instability problems in cold-formed steel sections, built-up sections are developed as innovative sectional profiles where the geometry of the section plays a vital role in enhancing the inherent resistance of such sections against premature buckling and increasing member capacity. In the literature, very few results for cold-formed steel have been reported for such conventional back-to-back built-up I sections and have never discussed the behavior of gapped built-up and built-up batten column sections on long-span structures. This paper presents a numerical investigation of the gapped built-up sections and built-up battened columns sections as alternatives to built-up section columns for long-span structures. The results show from a comparison of material weight with a gapped built-up column that an efficiency of 8.23 and 12.83% can be obtained from the built-up batten column compared to the standard back-to-back I section.