GBT-based buckling mode decomposition from finite element analysis of thin-walled members

This paper presents an original method based on the Generalised Beam Theory (GBT) capable to decompose the elastic buckling modes from a shell finite element analysis (FEA) of an isotropic thin-walled member, into pure buckling modes of global, distorsional or local nature. The main novelty lies in using only the GBT cross-sectional deformation modes instead of member base mode shapes. The contribution of each pure buckling mode can be calculated, allowing a better understanding of the member post-buckling behaviour and strength reserve. Following the GBT classical assumptions, the membrane shear strains and transverse extensions are neglected. The modal participations obtained from FEA are in good agreement with the values calculated via classical GBT approach.

► The method starts with a buckling Finite Element Analysis of thin-walled member.
► FEA provides critical loading factors and buckling shapes.
► GBT cross-section analysis yields the unit deformation modes.
► Pure mode shapes are extracted from FEA using the GBT unit deformation modes.
► Results are given in the form of modal participation of each pure buckling mode.