Progressive collapse mechanisms of brittle and ductile framed structures

In this paper, we study the progressive collapse of three-dimensional framed structures made of reinforced concrete after the sudden loss of a column. The structures are represented by elastoplastic 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 α and of the plastic capacity β of the structural elements. We also study the final collapse extent and the fragment size distribution and their relation to α, β, and to the observed collapse mechanisms. Finally, we compare the damage response of structures with symmetric and asymmetric reinforcement in the beams. © 2010 ASCE.