PSI - Issue 78

Mattia Zizi et al. / Procedia Structural Integrity 78 (2026) 1721–1728

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Fig. 1. Representative views of the transept arm of the Church of San Michele Arcangelo: a) axonometric view of the point cloud model; (b) intrados of the ribbed cross vault; (c) entrance from the side nave; (d) opening towards the central dome.

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Fig. 2. Location and geometry of the transept vault in the Church of San Michele Arcangelo: (a) transversal section; (b) ground floor plan.

The transept section containing the vault is open towards the central nave, while the other three sides are infilled by masonry walls having a thickness of approximately 0.8 m. Each of these walls includes narrow monofora windows, which provide limited daylight while preserving the overall structural continuity. The masonry perimeter walls are built using a three-headed isodomic technique, employing regular blocks of grey Campanian tuff, in accordance with the typical construction practices of Gothic architecture in the region . In contrast, the vault itself is built using tuff blocks arranged according to the curvature of the ogival arches, each with an apparent face measuring approximately 16 × 36 cm. The thickness of the vault remains unknown at this preliminary stage. The transept vault of the Church of San Michele Arcangelo represents a particularly relevant case for structural investigation, given its complex geometry. Moreover, the support system is composite: while the ogival arches are embedded in the perimeter walls, the diagonal ribs rest on free-standing piers, resulting in a heterogeneous structural response. These characteristics are expected to affect the vault’s seismic behaviour ; consequently, the study carried out within the GENESIS project incorporates an experimental activity designed to simulate the vault's behaviour under realistic loading and support conditions, as well as proposing non-invasive retrofitting solutions.