Elastoplastic buckling analysis of thin-walled structures

The study is concerned with the elastoplastic buckling of thin-walled beams and stiffened plates, subjected to in-plane, uniformly distributed, uniaxial and biaxial load. The ruling differential equations have been solved analytically by using the Kantorovich technique and the obtained displacement field has been employed in a general procedure that, by using the framework derived by the finite element method, is able to analyze the elastoplastic buckling behavior of prismatic beams and stiffened plates with arbitrary cross-section. The inelastic effect is modeled through a stress-strain law of the Ramberg-Osgood type, and both the incremental deformation theory and the J2 flow theory are here considered. The reliability of the numerical procedure is illustrated for rectangular plates, and the contradicting results obtained by using the two plastic theories are discussed in detail. Finally, the performance of the method is illustrated through the analysis of a C-section and five different closed section columns.