Local and distortional buckling of cold-formed steel beams with both edge and intermediate stiffeners in their compression flanges

The true buckling behaviour of cold-formed steel beams with both edge and intermediate stiffeners in their compression flanges has been predicted with the aid of advanced numerical modelling. A series of nonlinear finite element analyses has been carried out to investigate the flexural behaviour of cold-formed Z sections with both edge and intermediate stiffeners in their flanges, when the failure is controlled by local and/or distortional buckling. The effect of the size and position of intermediate stiffeners as well as the effect of the edge stiffener/intermediate stiffener interaction on the buckling behaviour and ultimate strength of these sections has been studied. The knowledge gained from FE analyses was used to check the accuracy of the Eurocode design rules in predicting the ultimate strengths for these sections.

► Uses a proven FE ultimate strength model to investigate the buckling of flange stiffened cold formed section beams.
► Results allow for local, distortional and combined local/distortional buckling.
► Interaction between stiffener within the flange and edge stiffening lip is examined.
► Key to understanding behaviour is the exact form of buckling.
► Some limitations on EC3 provisions identified.