Generalised beam theory (GBT) for stiffened sections

This paper outlines the use of the Generalised Beam Theory (GBT) approach to study the structural behaviour of prismatic thin-walled members with stiffeners of arbitrary geometries. This is particular relevant for bridge applications, where the stiffeners' arrangements are usually optimized in the design. The proposed GBT procedure is expressed in the spirit of Kantorovich's semi-variational method, using the dynamic modes of an unconstrained planar frame as the in-plane conventional deformation modes. The corresponding warping deformations are then evaluated from the post-processing of these in-plane modes, thus reversing the strategy of the classical GBT procedure. Constraint conditions are applied to the stiffened plate elements to provide the rigidity exhibited by the specified stiffeners. The method used is applicable to open, closed and partially closed cross-sections. The efficiency and ease of use of the method are outlined by means of two examples, aimed to describe the linear-elastic behaviour of thin-walled members. The numerical results obtained with the proposed approach are validated against those calculated with a shell finite element model developed in Abaqus.