Local and distortional buckling of cold-formed steel beams with edge-stiffened flanges

Abstract The economic use of cold-formed steel members means that buckling and the possible loss of effectiveness it produces are important features of design. The prediction of the true buckling behaviour of cold-formed steel beams accounting for all governing features such as geometrical imperfections, material nonlinearity, postbuckling etc. has been possible with the development of advanced numerical modelling. The FE models developed in previous research have been used in this paper to investigate the effect of edge stiffeners (lips) and their interaction with compression flanges on the postbuckling of laterally restrained cold-formed Z-section beams. Depending on the lip size-to-flange width ratio and angle of inclination of the edge stiffener, the cross-sectional bending resistance varied and transitions between local, distortional and combined local/distortional buckling were observed. The suitability of the design treatments available in Eurocode 3 (EC3) for local and distortional buckling of cold-formed Z-section beams was assessed. Overall, the EC3 predictions for cross-sectional bending resistances were unconservative. Some shortcomings were identified and some suggestions for improvements were made. This included improvements in plate buckling factors for edge-stiffened compression flanges.

[1]  Benjamin W. Schafer,et al.  Simulation of cold-formed steel beams in local and distortional buckling with applications to the direct strength method , 2007 .

[2]  Benjamin W. Schafer,et al.  LATERALLY BRACED COLD-FORMED STEEL FLEXURAL MEMBERS WITH EDGE STIFFENED FLANGES , 1999 .

[3]  Teoman T Peköz,et al.  Direct Strength Prediction of Cold-formed Steel Members Using Numerical Elastic Buckling Solutions , 1998 .

[4]  Mahmud Ashraf,et al.  Structural design for non-linear metallic materials , 2006 .

[5]  Christopher T. Willis,et al.  Behavior of Cold-Formed Steel Purlins Under Gravity Loading , 1990 .

[6]  Teoman Pekoz,et al.  Finite Element Studies on Lipped Channel Flexural Members , 1994 .

[7]  Cheng Yu,et al.  Local Buckling Tests on Cold-Formed Steel Beams , 2003 .

[8]  Federico M. Mazzolani,et al.  Design of Metallic Cold-Formed Thin-Walled Members , 2002 .

[9]  Haiming Wang,et al.  Experimental and numerical investigation on cold-formed steel C-section flexural members , 2009 .

[10]  Mohammad Reza Haidarali.  Local and distortional buckling behaviour of cold-formed steel Z section beams , 2011 .

[11]  Benjamin W. Schafer,et al.  Distortional Buckling Tests on Cold-Formed Steel Beams , 2006 .

[12]  Benjamin W. Schafer,et al.  Computational modeling of cold-formed steel: characterizing geometric imperfections and residual stresses , 1998 .

[13]  David A. Nethercot,et al.  Finite element modelling of cold-formed steel beams under local buckling or combined local/distortional buckling , 2011 .