Behaviour, failure and DSM design of cold-formed steel beams: Influence of the load point of application

• Buckling, post-buckling, collapse and design of cold-formed steel beams.
• Elastic buckling behaviour of beams loaded away from the shear centre axis.
• Influence of the load point of application on the beam strength and failure.
• Numerical results for hat-section beam acted by upward and downward mid-span point loads.
• DSM design methodology accounting for the load point of application effects.

This work presents and discusses the results of an ongoing numerical investigation on the buckling, post-buckling, collapse and design of cold-formed steel beams subjected to non-uniform bending due to transverse loadings acting away from the shear centre (either at the top or bottom flange). These results consist of (i) elastic buckling loads and modes, obtained through analyses based on Generalised Beam Theory (GBT), and (ii) elastic–plastic equilibrium paths and collapse loads, yielded by Ansys geometrically and materially non-linear shell finite element analyses. The numerical ultimate strength values are compared with their estimates provided by the current Direct Strength Method (DSM) strength curves and, on the basis of this comparison, it is possible to assess the merits of the DSM approach to design beams subjected to transverse loadings acting away from the shear centre – moreover, novel features that may improve the performance of this approach are identified.