Adaptive quadtree edge-based smoothed finite element method for limit state analysis of structures

This study presents an efficient numerical approach for pseudo-lower bound limit analysis of structures. The total stress field is decomposed into two components: an elastic component associated with the safety factor and a self-equilibrating residual component. Subsequently, equilibrium conditions within the optimization problem are satisfied in a weak manner. The application of the adaptive quadtree edge-based smoothed finite element method (ES-FEM), combined with the transformation into the second-order cone programming (SOCP) form, ensures the resulting optimization problem remains minimal in size. Moreover, employing a yield stress-based adaptive strategy in the proposed procedure either accurately provides limit loads with low computational effort or effectively predicts the collapse mechanism through the concentration of elements after mesh refinement progress. The investigation of a series of numerical tests confirms the effectiveness and reliability of the proposed method.