On the reasons of the Coliseum structural damagement

The paper concerns with the analysis of the structural damage suffered by the Coliseum, one of the most important monuments of the Roman architecture. After a description of the structure of the monument, the following topics are carried out: a) description of the damage heaped by the monument during its whole life and description of the past restoration works b) analysis of the two conjectures concerning if the past earthquakes or, on the contrary, the past dismantlement works, were responsible for the damage. The study is developed by means of the common static approach, the limit analysis and the use of non linear programs. As far as the first conjecture is concerned, it is shown that the monument is little sensitive to the seismic actions because of the presence of soft foundation soils, of its large mass, stiffness and lateral strength. The second conjecture, that of the dismantlement, has been then also taken into account. It is shown that the demolition of at least two adjacent outside piers can produce collapse of an entire vertical strip of the outer wall. In conclusion, contrarily to a common supposition that the damage of the monument is due to past earthquakes, it turns out to be consequence of dismantlement works, carried out, step by step, by destruction of piers at the first level of the external wall, probably by using fire. Only after the dismantlement, the earthquakes, acting on a weakened structure, could have produced further damage