Post Critical Behaviour of Shells: a Sequential Limit Analysis Approach

The prediction of the post collapse behaviour of structures, in particular of shell structures, has been for longtime a challenging problem, solved by modern solution methods at the price of significant computational cost. Different methods may be employed to predict the post-collapse curve. In this work the sequential limit analysis method has been adopted. As its name suggests, the method is based on a sequence of limit analyses carried out on updated meshes leading to the solution of a large displacement problem. Since in limit analysis elastic strains are neglected, only the rigid-plastic collapse curve is obtained but this is a minor limitation in the study of structures that undergo large deformations and for which the elastic contribution is negligible.
Some examples, performed on different shell structures, will be presented. They show the effectiveness of the approach adopted while comparisons with incremental solutions point out its robustness and velocity.