Study On Distortional Buckling And Reinforcing Measures Of Cold-formed Thin-walled Lipped Channel Beams

Cold-formed thin-walled channels have been widely used as studs, joists and rafters in residential construction due to their ease of fabrication and high strength-to-weight ratios. As we notice that the section of this kind of beams usually has high strength and big opening, it will lose stability before its failure pressure. Distortional buckling on cold-formed thin-walled channels under bending is the main adverse effect in the three common unstable modes, but it has not made a world-wide agreement on the code. This paper introduces and compares some existing calculation methods. Based on the existing achievements and distortional property, several strengthening measures are proposed. Three different scales of cold-formed thin-walled channels are studied using certain amount of connected-bars or connected-slabs in special longitudinal direction of the channels. FEM elastic and nonlinear analyses are conducted on strengthened channels, experimental studies are also made, comparisons are made between each strengthening measure and the most effective strengthening measure is proposed. Feasibility of applying these strengthening measures into engineering practice is analyzed economically.