PSI - Issue 78

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

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Essentially, an annular epoxy ring was created to rigidly connect the two portions that had been previously separated due to the mortar’s decay. Moreover, the various parts constituting the quadrangular base underneath were tied together by four reinforced microdrillings at the corners of the quadrangular base, drilled from top to bottom (holes 6 mm and bars 4 mm). Finally, to rigidly connect the quadrangular base of the column to the new reinforced concrete slab underneath, epoxy adhesive was placed between the two contact surfaces, so that the now “monolithic” column rested on the isolation plane. Same intervention by epoxy adhesive was carried out to rigid connect the base of the quadrangular column to the underlying structure. Once the monolithic behavior of the column was ensured, a reinforced concrete slab about 40 cm thick was constructed under the Ciborium to serve as the rigid plane above the isolation system. Below this slab, a technical accessible chamber was built, allowing the installation of the isolators and enabling future inspections of the isolation system. This reinforced concrete structure was fitted with support pads on which four seismic isolators were placed. These “ISOLArt ® Pendulum” double-curved surface sliding isolators are specially designed for the seismic protection of works of art, characterized by a very low coefficient of friction. The displacement capacity was conservatively set at ±370 mm, with a curvature radius of 3100 mm. 5. Analyses performed Simplified analyses were initially carried out using basic calculations of the isolation system. However, these calculations proved to be extremely precise and accurate, since the isolation system is geometrically and mechanically defined in all its properties. A linear spectral dynamic analysis was then carried out using response spectrum; this is a primary and most straightforward analysis, admissible and particularly suitable because the superstructure remains substantially elastic and the isolation system can be modeled as equivalent-linear according to code indications. Subsequently, nonlinear modeling and analyses were performed (nonlinear dynamic time history analysis), adopting both simplified models of the isolation system alone and global models of the entire structure. From the comparison of the resulting strain and stress states (Figure 5), it was first possible to observe the impressive reduction of lateral deformations acting on the columns; in the isolated configuration, in fact, the superstructure displayed a substantially rigid-body behavior. Consequently, the stresses acting at the base of the columns were significantly reduced under the design conditions, achieving the seismic upgrading of the structure.