Section compression capacity of high strength cold-formed hollow flange channels

Thin-walled cold-formed hollow flange channel (HFC) sections are increasingly becoming popular due to their potential benefits such as increase in buckling capacities provided by the presence of two torsionally rigid hollow flanges and the elimination of free edges. Past research studies of HFC sections were limited to their shear and bending capacities. This paper investigates their section compression capacities through a series of stub column tests, followed by finite element modelling of welded HFC columns. The developed finite element models were validated using experimental results, and then used to investigate the section compression capacity of HFCs made by welding rectangular sections to a steel plate or cold-forming and rivet/screw fastening to hollow flanges, where steel plates with different strengths and thicknesses were used as web and flange elements. Extensive structural performance data of HFC stub columns subject to local buckling was thus obtained covering the effects of varying slenderness of plate elements and the use of different strength steels for web and flange elements. Furthermore, the applicability of the available design rules such as effective width and direct strength methods to predict the compression capacity of such HFC sections was also evaluated. Suitable recommendations are then proposed to improve their accuracy. This study facilitates and advances the use of HFC sections as compression members.