ELASTO-PLASTIC LARGE DEFORMATION ANALYSIS OF THIN-WALLED STRUCTURES

This paper presents an elasto-plastic, large deformation analysis of thin-walled structures. A solution procedure for treating both the geometric and material nonlinearities, based on an updated Lagrangian formulation, is proposed. The procedure is suitable for analysing large-scale space frames since the structures may be modelled using only a single beam-column element per member. It is achieved by incorporating a displacement stiffness matrix which provides the necessary coupling between the axial stretching and the flexural and torsional deformations. The geometric and the displacement stiffness matrices for a general, thin-walled, beam-column element previously derived in References 1 and 2 are used. Plastic hinge formation, the interaction of element forces at the hinges and elastic unloading are taken into account in the analysis. In particular, a single-equation, stress-resultant yield surface has been developed to model the plastification of structural steel angle sections under a combination of axial force and moments about the principal axes. Yield surfaces for tubular sections and American wide flange sections are also considered. Several numerical examples are presented to demonstrate the accuracy and efficiency of the method. © 1990.