Local-plate and Distortional Post-buckling Behavior of Cold-formed Steel Lipped Channel Columns with Intermediate Stiffeners

This paper reports the results of an investigation concerning the local-plate and distortional post-buckling behavior of cold-formed steel lipped channel columns with web and flange intermediate stiffeners. They have all been obtained through geometrically non-linear analyses based on a recently developed and implemented Generalized Beam Theory (GBT) formulation that incorporates (i) conventional (shear undeformable), (ii) shear (non-linear warping) and (iii) transverse extension deformation modes. These results, some of which are compared with values yielded by shell finite element analyses performed in the code ABAQUS (mostly for validation purposes), provide the evolution, along a given local-plate or distortional post-buckling equilibrium path, of the column deformed configuration and relevant displacement profiles and/or stress diagrams. In order to assess the influence of the member end support conditions, one also compares the distortional post-buckling behaviors of columns having pinned/free-to-warp and fixed/warping-prevented end sections. Taking full advantage of the GBT unique modal features, all the above results are discussed in great detail and it becomes possible to unveil, explain and/or shed some new light on several interesting and scarcely known behavioral aspects. In particular, one is able to provide very clear and structurally meaningful explanations for the qualitative differences existing between the local-plate and distortional post-buckling behavior of lipped channel columns with and without intermediate stiffeners