  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 $\ROne$ is investigated. Topologically \textit{hierarchical} frames have
a primary structure made of few massive elements, while \textit{homogeneous}
frames are made of many thin elements. We also show how $\ROne$ 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.
