Distortional Buckling Strength and Interaction Bending Capacity of Flexural Cold-Formed Lipped Channels

For flexural cold-formed thin-walled lipped channels,there are three fundamental buckling modes,which are plate local,section distortional and member flexural-torsional.The interactive buckling may also occur.The post-buckling strength of distortional mode is lower than that of local mode due to the heightened imperfection sensitivity.However comparing with local mode,the distortional mode has higher ability to control the failure mechanism.The distortional buckling stress of flexural lipped channel may be calculated by finite element method.Based on AS/NZS 4600-2005 Australian/New Zealand Standard,this paper introduces a simple method to calculate elastic distortional buckling stress for flexural lipped channels.The corresponding interactive bending capacity is also obtained by direct strength method.