Seismic response of a R.C. viaduct during different earthquakes

The experimental seismic behavior of a typical viaduct in Italy subjected to subsequent events is analyzed. The structure is located along a freeway in Umbria region. Two spans and two piers were monitored in the framework of the Osservatorio Sismico delle Strutture monitoring network, managed by the Italian Civil Protection Department. The changes of the dynamic characteristics of the structures were analyzed through the analysis of the data recorded during five recent seismic events. These five earthquakes were characterized by different magnitude and different Arias Intensity at the site. The analysis allowed determining the first natural vibration frequencies of the structure in three perpendicular directions and the associated modal shapes. The results pointed that the horizontal vibration frequencies of the structure changed significantly during the different earthquakes, which had different effects at the site. Anyway, the bridge recovered its dynamic characteristics also after the strongest events, shoving a linear behavior. This work is part of research project on the use of SHM to support the road and highway operators in the knowledge of the health status of the existing bridge and viaduct network and for an effective and prompt response to any emergencies.