Local And Distortional Buckling Analysis Of Cold-Formed Lipped-Channel With V-Stiffened Web Under Axial Compression Force

Local and distortional buckling of cold-formed lipped-channel column with V-stiffened web under axial compression force are investigated in this paper, the paper includes the fallowing main contents: (1)Elastic local buckling critical stress is predicted by eigenvalue buckling analysis of ANSYS, including interaction of the connected element. The empirical closed-form prediction is provided by Boltzmann fit of numerical analysis results. (2)An approximate model of the distortional buckling mode is built, explicit analytical expressions are derived to predict the elastic distortional buckling stress. The expressions agree well with ANSYS eigenvalue buckling analysis results, when the ratio of width of web to flange is not greater than 2.5. (3) The ultimate strengths of columns between pinned ends and fixed ends under axial compression force are predicted by nonlinear buckling analysis of ANSYS, including consideration of initial imperfections, plastic behavior and large-deflection response. The ultimate strengths also are predicted by effective width method of American Iron and Steel Institute(AISI1996) and Technical Code of Cold-formed Thin-wall Steel Structures(GB50018-2002)and direct strength method. The results indicate that when the failure mode is local buckling, the ultimate strengths calculated from effective width method and direct strength method are generally unconservative, when the failure mode is distortional buckling, the ultimate strengths calculated from direct strength method are generally conservative. Effective width method and direct strength method are modified to make them applicable to predict the ultimate strength of cold-formed lipped-channel column with V-stiffened web under axial compression force.