The Sanctuary of Santa Maria delle Grazie at Fornò. A FEM approach to seismic structural analysis

The Sanctuary of Santa Maria delle Grazie at Fornò, located in the countryside near Forli, was constructed between 1450 and the early years of the sixteenth century. The Sanctuary externally consists of a circular masonry structure 15 m high and 33 m in diameter, with four semi-circular niches protruding to the outside; inside, a similar circular structure 20 meters high delimits a central area, covered by an octagonal dome. The space between the two circular structures is covered with a wooden roof resting on thirty-six main wooden beams. The building has been subject to various interventions due both by static requirements (i.e. damage caused by several historical earthquakes), both for changes related to epoch's style (the four semicircular niches realized in 1686). Finally, the events of World War II, with the demolition of the bell tower and part of the adjacent monastery, have brought the building back to the clear original shape. Recently an entire laser survey was carried out, providing comprehensive measurements for reconstructing the Sanctuary’s shape and overall size. After the laser survey, several structural analyses are executed. Lately it was possible to study the effect of the possible consolidation works under the strain, even seismic, expected by the new national rules particularly in the light of the guidelines (2011) for the "Assessment and reduction of seismic risk of cultural heritage with regarding to the technical standards for construction in DM 14/01/2008 ".