Generalised Beam Theory (GBT) is an efficient and elegant method of analysis to describe the behaviour of steel and composite members that include thin-walled sections. This paper presents an overview of the work carried out to date on a particular GBT approach whose distinguishing feature is to use dynamic analyses for the identification of a suitable set of deformation modes that, in the general version of the methodology, includes conventional, extension and shear modes. With this approach,

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... he deformation modes are selected as the dynamic eigenmodes of an unrestrained planar frame representing the cross-section. The initial formulations of this approach considered the full shear interaction analysis of steel and composite members. These were later extended to account for the partial interaction that can exist within parts of two-layered and multi-component sections. Numerical examples are presented to highlight the ease of use of the GBT formulation and the accuracy of the numerical results is validated against those calculated with a shell finite element model developed in ABAQUS.