Optimization design of high-strength cold-formed web-stiffened lipped channel steel columns under compression

With rapid urbanization and development, high-strength cold-formed thin-walled steel structures are gaining significant attention in China's low-rise construction industry. For the same cross-sectional area, varying section profile sizes result in distinct buckling modes and divergent load-carrying capacities. The cold-formed thinwalled lipped channel column is prone to local web buckling due to the large width-to-thickness ratio. A Vshaped stiffener is set in the middle of the web to enhance local stability. Hence, investigating the section with higher load-carrying capacity is critical for optimizing the design. In this study, a program was first developed to identify several candidate sections with higher load-carrying capacity based on theoretical calculations. Then, finite element analyses and loading tests were conducted to determine the optimal section. It was found that the stiffener significantly improved load-carrying capacity. The results from theoretical calculations, finite element simulations, and loading tests exhibited the consistent variation trend of load-carrying capacities of columns with different cross-sections. The short columns with the optimal section underwent distortional buckling, while the long columns with the optimal section exhibited both distortional and overall flexural buckling. A relatively high axial load-carrying capacity is achieved when the ratio of the web height to the sum of the flange and lip width is between 1 and 2. For the commonly used 180 mm wide sheet, the optimal section features a web height of 67 mm, a flange width of 38 mm, and a lip width of 12 mm.