Engineering analysis and monitoring to preserve the Colosseum

The Flavian Amphitheater, known worldwide as the Colosseum, is beyond doubt the most famous monument of ancient Rome. The amphitheater is elliptical in shape, based on the well-tried construction technique adopted in Roman times for masonry buildings with orthogonal walls, adapted to the elliptical shape. Its foundations stand in heterogeneous soil formed by alluvial deposits in an area that had previously been filled by the artificial lake of the Domus Aurea. The heterogeneity of the soil and various earthquakes have caused settlement and led to the collapses that give the Colosseum its present shape, in which the original symmetry is partially lost. A number of structural interventions were made during the 19th century. The two buttresses that support the remaining part of the external wall were built at the eastern and western ends. Other interventions involved restoration of the connections between radial and annular elements. The Colosseum, in its actual shape, has to be preserved to posterity. To this aim, engineering science provides knowledge on how to evaluate its health state, by the monitoring of its dynamic response, as described in this contribution. The response of a structure to a dynamic environment contains information that is related to the structure characteristics. The comparison and correlation between experimental dynamic properties and those predicted by a mathematical model enable us to identify the possible effects of degradation and material decay.