Geometric and structural information for the analysis of historical domes: the case of SS. Trinità church in Torino

Investigation into the geometric configuration of historical masonry domes is fundamental when studying the structural behaviour of these architectural elements, above all if they have historical and artistic relevance. Indeed, accurate geometric information is essential also for the construction of reliable mechanical models, to monitor the condition state of the building and to plan strengthening and conservation interventions. To this aim, a multidisciplinary approach is required to collate the highest possible amount of data useful for the numerical modelling, including historical and archival research. The "SS. Trinità" church is a 16th century building of great historical, architectural and structural significance in the historic centre of Turin. It owes its fame primarily to the architect who built it, Ascanio Vitozzi, and to its large dome, built after the architect’s death. The availability of a recently undertaken laser scanner survey of the intrados of the dome made it possible to detect several depressions of the masonry cap. These findings can be either due to construction defects, or to structural problems that developed over centuries, or to the severe fire which struck the dome in 1942. In this multidisciplinary research, different numerical models of the masonry dome of SS.Trinità church were built. As a first step, a geometric study was based on the point cloud from the laser scanning. Then, structural analyses were conducted on the two different models of the dome-tambour system of the building, in order to try to explain the observed deformation behaviour