Beam-column behaviour of cold-formed steel lipped channel sections

The current cold formed steel design specifications' beam-column design equations, which were derived primarily based on the experimental investigations on hot-rolled I-beams, may not be appropriate for use for cold-formed steel members which are usually mono-symmetric. Recently, beamcolumn tests were conducted on cold-formed steel lipped channel sections in order to validate the code design equations. The purpose of this paper is to report the test details and the results. The test program considered four different galvanized lipped channel shaped beam-columns having slenderness ratios of 65, 101, 142, 177 & 225. These beam columns were subjected to combined axial load - bending moment ratios of 2.5, 1.0, & 0.4, and to limiting cases of pure axial compression and pure bending moments. This paper elaborates on a unified test set-up that was used for all these tests. The beam-columns were pinpin supported and were subjected to major axis moments only. The test program consisted of 15 pure axial compression tests, 15 pure bending tests and 25 beam-column tests. In general three identical tests were considered, and consistent results were obtained. Experimental axial load-bending moment interaction diagrams for these beam - column members were constructed and were compared with current North American Design Code (AISI, 2002).