Modelling of seismic urban wavefield in highly heterogeneous Site- City configurations

The Fosso di Vallerano valley, Rome (Italy), is an alluvial valley characterized by a complex geological setting which implies significant vertical and horizontal heterogene- ities. In the last decade, this area experienced an intense urbanization which changes the ori- ginal seismic response conditions of free field. According to these features, the Fosso di Vallerano valley has been chosen as case study to analyze the influence of buildings on the local seismic response (Site-City Interaction – SCI). A high resolution geological model of the valley has been reconstructed and the dynamic behavior of the buildings has been evaluated. A 2D finite element modelling has been performed by assuming an elastic rheology and accounting for the progressive urban expansions of the Fosso di Vallerano valley. The results point out that the presence of buildings significantly influences the spatial distribution of the urban ground motion within the entire valley and not only close to the buildings.