Collapse analysis of thin-walled structures by finite element limit analysis

A limit analysis formulation with degenerated four-node shell elements has been derived for collapse analysis of thin-walled structures. In finite element approximation, the reduced integration technique with a physical stabilization scheme is employed for prevention of locking and computational efficiency. The analysis considers sequential deformation of structures with strain-hardening effects. The collapse analysis for square tubes are carried out using the finite element limit analysis code developed and results are compared with experimental ones for load-carrying capacity and deformation modes. The present algorithm with a simple formulation has the advantage of stable convergence, computational efficiency and easy access to strain-hardening materials compared to elasto-plastic finite element analysis. Results demonstrate that the finite element limit analysis can predict the plastic collapse load and collapse mode of thin-walled structures effectively and systematically.