Hierarchical structures for a robustness-oriented capacity design

In this paper, we study the response of 2D framed structures made of rectangular cells, to the sudden removal of columns. We employ a simulation algorithm based on the Discrete Element Method, where the structural elements are represented by elasto-plastic Euler Bernoulli beams with elongation-rotation failure threshold. The effect of structural cell slenderness and of topological hierarchy on the dynamic residual strength after damage R1 is investigated. Topologically hierarchical frames have a primary structure made of few massive elements, while homogeneous frames are made of many thin elements. We also show how R1 depends on the activated collapse mechanisms, which are determined by the mechanical hierarchy between beams and columns, i.e. by their relative strength and stiffness. Finally, principles of robustness-oriented capacity design which seem to be in contrast to the conventional anti-seismic capacity design are addressed. Copyright c © 2010 John Wiley & Sons, Ltd.