Buckling analysis through a generalized beam model including section distortions

•The beam model accounts for non-uniform warpings and section distortions.•They are evaluated through a semi-analytic solution, based on a FEM description of the cross section.•The model includes the generalized Saint Venant solution for heterogeneous and anisotropic materials.•The nonlinear model, obtained using the ICM strategy, exactly accounts for mean section rotations and translations.•The buckling results have been validated using ABAQUS shell FE analyses.

A geometrically nonlinear beam model suitable for describing complex 3D effects due to non-uniform warpings including non-standard in-plane distortions of the cross-section is presented and applied to the buckling analysis of beams. Each section is endowed with a corotational frame where statics and kinematics are described using a refined linear elastic model which exploits a semi-analytical solution of the Cauchy continuum problem based on a FEM discretization of the cross-section. The stress field in this way is fully 3D, allowing both the exact recovery of the standard Saint Venant solution and the consideration of some additional relevant strain modes of the cross-section that are evaluated in a simple and effective way. Numerical results are presented and compared with 3D shell reference solutions obtained by using the commercial code ABAQUS.