The Sanctuary of Santa Maria delle Grazie at Fornò: studies for the restoration and seismic strengthening

The Sanctuary of “Santa Maria delle Grazie” is located at Fornò in the countryside near Forlì (Italy). The first temple, built in 1450, assumes today’s configuration at the begin- ning of the sixteenth century, to undergo various modifica- tions, both for static necessities and for changes in tastes related to the time, as well as for natural disasters and war damage. Structurally, the Sanctuary consists of an exter- nal masonry cylinder, around 33m diameter and 15m in height, with four semicircular niches protruding outwardly; inside there is a similar concentric structure, the oldest temple, about 14m diameter and 20m tall, covered by a dome supported by an octagonal masonry structure. The space between the two circular structures is covered with a wooden roof resting on thirty-six main wooden beams. In the last years the Sanctuary has been subjected to numerous studies, surveys and analysis, including FEM structural analysis (also due to singular curvilinear typol- ogy of all masonry structures). To regard seismic risk, the building was studied focusing on the Guidelines (2011) for the “Evaluation and Reduction of Seismic Risk of Cul- tural Heritage.” Today, following the entry into force of the new technical standards NTC2018 (January 2018) we have scheduled an update of the structural analysis and a series of proposals for restoration, anti-seismic improve- ment and dehumidification works, on regard to effects of decay caused by soaking on the mechanical characteris- tics of the masonry.