PSI - Issue 78

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

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4. Emergency safety operations and the renovation project In order to ensure the urgent and unavoidable safety of the complex, to ensure public and private safety first and foremost, and to prevent the deterioration of the cracks and the deterioration of the property to the point of collapse, in addition to the obvious and already existing prohibition on access to the rooms inside the church and the courtyard area in front of the southern apse, it was deemed urgent (with an application to the Superintendency) to put in place a provisional safeguard against the further overturning of the masonry wedge of the southern apse basin by positioning a series of three rows of stainless steel strands running horizontally to belt the semicircular outer perimeter of the apse, anchoring them on both sides to the straight sections of the church transept masonry that rise above the side chapels. The construction methods for this intervention were agreed upon with the contractor by means of an on-site inspection, since in the absence of a geometric survey of this portion of masonry, it was impossible to draw up an executive design for the various anchoring and restraining elements, which were then designed to adapt to the thicknesses and measurements of the protrusions that would later be found in situ. The portions of the roof that had collapsed (due to beams slipping from their supports on the walls as a result of overturning displacements) were then sealed with waterproofing sheathing to preserve the vaults below from rainwater infiltration. Once these emergency safety measures had been carried out, the demolition of the collapsed buildings leaning against the south front of the Collegiate Church and the cleaning of the courtyard area were carried out in order to prepare a structural geometric survey of the basement area of the right apse, to carry out the necessary soil and geognostic surveys, and to prepare the executive structural design for the strengthening of the building's foundations. At the same time, a series of centesimal displacement detectors and inclinometers were installed to monitor the progress of the cracks and the behavior of the masonry throughout the works (ref. Cangi, Mariani e Donà). The first intervention put in place to safeguard the building was at the foundation level in order to stop the root cause of all the cracks later detected in the elevation. The ground-level intervention involved both the southern chapel of the church and the masonry leaning against the southern body, now stripped bare by the demolition of the incongruous outbuildings that were no longer salvageable. To avoid soil removals that would perhaps have further weakened the already precarious state of the foundation, it was decided to build piles driven in with a jack and then anchored to a reinforced concrete foundation built along the masonry to be supported by steel beam brackets to support the wall throughout its internal thickness (Fig. 5).

Fig. 5. The consolidation of the foundations.

The work phases first included the construction of the ring foundation, complete with grafts made of steel girders