Geotechnical Analyses for the Preservation of Historical Churches: A Case-History in Eastern Sicily (Italy)

The economic and social damage caused by earthquakes is often tremendous, especially in historical sites where the buildings often have inadequate earthquake-resistant seismic structures. The damage caused by past and recent earthquakes demonstrates the necessity to promote specific actions for renovating historic buildings, highlighting the decisive role of the soil filter effect and dynamic soil-structure (DSSI) interaction. The eastern part of the Sicilian area (Italy) is characterized by high seismic hazard, and it is rich in historical churches with a great cultural heritage value. In this context, a great challenge is to evaluate their seismic risk and establish which of them are affected mainly by DSSI effects. This paper deals with a set of investigations for large-scale estimation of DSSI effects for historical churches of the eastern Sicilian area with the goal of establishing a priority for planning the seismic retrofitting tasks, suggesting more detailed analyses of DSSI phenomena. The analyses are performed on different historical churches, varying the properties of the masonry. Specifically, the effects of the number of seismic motions and the seismic behavior of the soil on the spectral accelerations are investigated, considering a fixed-base configuration and a flexible-base configuration that takes into account DSSI.