Design of Cold-Formed Steel Channel Columns with Complex Edge Stiffeners by Direct Strength Method

The design of cold-formed steel channels with complex stiffeners could be quite tedious in calculating the effective area using the effective width method in the current design rules of North American Specification and Australian/New Zealand Standard. The direct strength method could be used in the design without calculating the effective area. An experimental investigation of fixed-ended cold-formed steel channel columns with complex edge stiffeners has been reported. The test strengths were compared with design strengths predicted using the direct strength method as well as the North American Specification and Australian/New Zealand Standard for cold-formed steel structures. The failure modes observed in the tests were also compared with the failure modes predicted by the direct strength method. It is shown that the design strengths predicted by the direct strength method are generally conservative for the channel columns with complex edge stiffeners. Furthermore, the reliability of the direct strength method was evaluated using reliability analysis. It is shown that the direct strength method is reliable using the existing resistance factor as recommended by the current North American Specification and Australian/New Zealand Standard.