Shear deformable beam model for stability analysis of beam-type structures with composite thin-walled cross sections

This paper presents a shear deformable numerical model for nonlinear stability analysis of beam-type structures. The incremental equilibrium equations for a straight thin-walled beam element are derived within the framework of updated Lagrangian formulation and the nonlinear displacement field of cross-sections, which accounts for the restrained warping and the large rotations effects. Shear deformation effects are accounted for the composite cross-section considering bending-bending and bending-warping torsion coupling effects. Cross-section properties are calculated based on the reference modulus, with ability to model different material configurations. A numerical algorithm for calculation of the geometric properties of composite cross-section is developed. Various material configurations are considered. Several benchmark examples are demonstrated for verification purposes. The obtained results indicate that the proposed model can be classified as shear locking free one.