PSI - Issue 78

Riccardo Vetturini et al. / Procedia Structural Integrity 78 (2026) 734–744

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Fig. 5. Comparison of the stress and deformation state of the Ciborium structure under fixed-base (left) and isolated (right) conditions

6. Conclusions A series of surveys with measurements and investigations on the monument were carried out, leading to a deeper understanding and structural characterization. In particular, in-situ tests allowed to interpret the construction rules and the dynamic behavior of the structure (see the experimental investigation report conducted by the Department of Civil and Environmental Engineering “UNIPG,” Scientific Coordinator Prof. Filippo Ubertini, and the Working Group Eng. Nicola Cavalagli and Eng. Enriche Garcia-Macias regarding “the dynamic characterization of the Ciborium of Santa Maria Maggiore in Spello, and related numerical elaborations aimed at identifying the frequencies of the first vibration modes and their modal shapes”). Based on this information, a “disarticulated” behavior of the system was deduced, which results in a risk index certainly not exceeding 20%. Moreover, the natural period of the “disarticulated” system and its lateral deformability would not have allowed base seismic isolation of the structure, making such an intervention strategy impractical. It was therefore essential to make each column “monolithic.” The designed intervention identified the least invasive solution to achieve this goal, which involved the use of epoxy adhesives between the contact surfaces of the cylindrical Corinthian column and the quadrangular base, as well as joining the elements constituting the quadrangular base through microdrillings.