Buckling mode identification of perforated thin-walled members by using GBT and shell FEA

•Buckling shell Finite Element Analysis of perforated thin-walled members.•FEA provides the displacement field of the buckling shapes.•GBT 1st step yields the cross-sectional pure modes.•Pure modes are extracted from FEA using the GBT cross-sectional pure modes.•Modal participation of each pure buckling mode is quantified.

The paper presents an original method based on the Generalised Beam Theory (GBT) whereby the general buckling modes, provided by the shell Finite Element Analysis (SFEA) of perforated thin-walled members, are expressed in terms of the fundamental (pure) buckling types (global, distortional and local). The contribution of each pure buckling mode to a coupled instability can be quantified, allowing a better understanding of the member buckling behaviour and post-buckling strength reserve. The main advantage of this method lies in using only the GBT cross-sectional pure deformation modes instead of member pure modal shapes. There are no restrictions regarding the element cross-sectional shape, loading and boundary conditions.