Experimental investigation into the axial compressive behavior of Q460 cold-formed lipped channel

The research and application of high-strength cold-formed thin-walled steel are primarily focused on zinc-coated lipped channels with a thickness of less than 1.5 mm. Despite their inherent material strength, these components experience premature buckling failure due to their extremely thin sheet thickness and high width-to-thickness ratio, limiting the utilization of high-yield strength. Therefore, a new cold-formed lipped channel fabricated via the cold bending process of the Q460 hot-rolled steel sheet is proposed. This design features larger crosssectional dimensions and a reduced width-to-thickness ratio of the constitutive plate, enhancing the component's load-carrying capacity and material utilization efficiency. The axial compression loading tests are conducted on 16 simply supported Q460 high-strength cold-formed lipped channel columns with thicknesses of 4 and 6 mm to investigate their load-carrying behavior. Specimens with high slenderness ratios tend to experience overall flexural-torsional buckling. In addition, specimens with medium slenderness ratios and lower aspect ratios are prone to distortional-overall interactive buckling. In contrast, specimens with medium slenderness ratios and higher aspect ratios are susceptible to distortional-local interactive buckling. Lastly, specimens with low slenderness ratios and high web height-to-thickness ratios tend to undergo local buckling. When keeping other dimensions constant, the column's axial load-carrying capacity exhibits a significant decrease with increasing length, an initial increase followed by a subsequent decrease with increasing web height, and a significant rise with increasing flange width and plate thickness. Compared to the loading test results, the predicted buckling capacities from the direct strength method stipulated in current standards generally display conservatism.