PSI - Issue 78

Marco Peroni et al. / Procedia Structural Integrity 78 (2026) 2110–2117

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2. General description of the building The building, with a load-bearing masonry structure (Fig. 1), dates to the 17th century and has a cruciform plan (ref. Malpezzi, Carroli). It is inserted within the building fabric of the historic center of the Municipality of Brisighella, presenting only two of the four sides completely free of buildings. To the south, the right apse of the church is bordered by a series of smaller bodies attached to it and housing service rooms and the thermal power plant. To the east, on the other hand, the urban development continues, formed by buildings of lesser height with a simple layout overlooking Via Fossa. The site is classified in seismic zone II category, i.e. medium seismicity (0.15g < PGA < 0.25g), according to the indications of the Italian national rules NTC2018. The monumental complex is made up of generous solid brick walls with sack fills and mixed masonry in stone and brick, with thicknesses up to a few meters at the corners. However, there are many holes, niches and irregularities in the masonry, which, also due to the cruciform layout, consists of a series of large masonry pillars. The roof of the chapel is of recent reconstruction (probably, the second half of the last century) and is entirely composed of ‘Varese’ type prestressed concrete beams and brick hollow blocks. Underneath, there are large domed vaults made of solid knife-edged brickwork, with extrados stiffening ribs that are also matched by pilasters in the wall elevations.

Fig. 1. External view of the monumental complex of San Michele Arcangelo in Brisighella.

The stability of the built complex is therefore based on the balance between the numerous thrusts generated by the arches and domes, which are balanced thanks to the rigorous symmetry of the layout and the weight of the vertical masonry. The alteration of this delicate balance between thrusts and contrasts triggered, for example, by a subsidence of the foundation can undoubtedly exacerbate the cracking framework to the point of triggering chain collapse phenomena of the various architectural and structural elements that make up the building. At the geological-geotechnical level, 2 continuous core drilling and 5 dynamics + one Geo-radar and one VS30 test were carried out to determine the seismic category of the ground.