Chapels with Domes on Squinches in Sicily (XV-XVI century). Constructive Systems and Structural Vulnerability

A series of chapels with an architectural solution of a great constructive meaning arose in Sicily (Italy) between the 15th and the 16th century: the so called chapels with domes on squinches. This kind of attachment between the square shape of the lower structure and the upper dome circumference is clearly distinguished from the commonly used pendentives. It represents a continuity in the local constructive tradition, deriving from the Islamic and Norman heritage. Thus, we find a lot of structures with such constant elements as the squinches delimitated by recessed arches. Few remains, situated in the western part of the island and in the Val di Noto, show masonry constructive details and structural elements, which often differs from each other both in arrangement and materials. This circumstance, also in the light of the seismic history of this territory, draws our attention to the relation between the constructive techniques and the local context in order to assess the vulnerability level. Therefore, this research aims: - at analyzing these structures from the points of view of geometry, construction, materials, resistance and damage phenomena; - at considering these buildings in the light of the seismic hazard assessment; - at defining the vulnerability of these structures in relation to the conservation aims.