  In this paper, we study the progressive collapse of 3D framed structures made
of reinforced concrete after the sudden loss of a column. The structures are
represented by elasto-plastic Euler Bernoulli beams with elongation-rotation
failure threshold. We performed simulations using the Discrete Element Method
considering inelastic collisions between the structural elements. The results
show what collapse initiation and impact-driven propagation mechanisms are
activated in structures with different geometric and mechanical features.
Namely, we investigate the influence of the cross sectional size and
reinforcement $\alpha$ and of the plastic capacity $\beta$ of the structural
elements. We also study the final collapse extent and the fragment size
distribution and their relation to $\alpha$, $\beta$ and to the observed
collapse mechanisms. Finally, we compare the damage response of structures with
symmetric and asymmetric reinforcement in the beams.
