A generalized layered global-local beam theory for elasto-plastic analysis of thin-walled members

Based on a generalized layered global-local beam (GLGB) theory, a computationally low cost finite element model is presented for the elasto-plastic analysis of thin-walled beams. In the employed GLGB theory, the cross-section of the thin-walled beam is replaced with an equivalent layered composite one. For describing the displacement fields of the equivalent layered composite beam, the double superposition hypothesis in conjugate with an exponential shear stress function is employed. In contrast to the most of available advanced one-dimensional (1D) models proposed for thin-walled structures, the effects of the transverse normal stress and transverse flexibility are considered in the present GLGB theory. The proposed GLGB theory does not need the incorporation of any shear correction factor and it has only one general unknown parameter more than Timoshenko's beam theory. For plasticity modeling, von Mises yield criterion is employed. The non-linear 1D finite element formulations are solved using Newton-Raphson algorithm. The proposed nonlinear finite element model is validated through comparison with the three-dimensional (3D) finite element and other similar theoretical models available in the literature.