Soil-structure interaction effects on the dynamic behaviour of a masonry school damaged by the 2016–2017 Central Italy earthquake sequence

The paper investigates the potential relevance of soil-foundation-structure interaction for the dynamic behavior of a two-story masonry school, which is located in the alluvial valley of Visso (Italy) and was severely damaged by the 2016-2017 Central Italy earthquakes. The main periods and deformed shapes of the structure were identified from the response under ambient noise, recorded on site by the Italian Seismic Observatory of Structures. Modal analyses were performed on 3D models of the fixed-base structure and of the structure placed on springs simulating the soil-foundation impedance. Geometrical and mechanical parameters were accurately calibrated against data acquired from a previous structural survey and a soil investigation carried out during the seismic microzonation of the village. The fixed-base structure model failed to reproduce the dynamic behavior recorded on site, whereas a successful comparison was found between the experimental data and the predicted main vibration periods and modal shapes of the compliant-base structure.