PSI - Issue 78

Alessandro Fulco et al. / Procedia Structural Integrity 78 (2026) 2054–2061

2060

4. Construction phases The described design intervention is currently being implemented and the completion of the works is expected by the end of the current year. All the main planned works that have already been carried out or are being carried out have allowed and are allowing the full use of the building without any interruption of the developed strategic activities. No clearing of offices and/or significant changes to operational protocols were required: therefore the building maintained its functional characteristics unchanged. These aspects also had a significantly positive impact in economic terms by avoiding downtime costs related to the temporary relocation of services and personnel, Fulco et. al. (2020). The site activities were divided into 3 main phases: Phase 1 - Solution of the perimeter joints; Phase 2 - Installation of seismic isolation devices (phase is currently being completed); Phase 3 - Architectural-functional renovations. Fig. 6 shows the construction of part of the new walls against the ground (a) and the subsequent installation of the sliding plate on neoprene strip (b). Concerning Phase 1, Fig. 6 c) e d) shows the images of the cut made on the interfering "buffer" slab and the installation of the metal frame to support the fixed portion. As part of Phase 2, the devices were installed individually on each column, operating alternately in 4 zones of the structure in order to minimise interference and mitigate the gradual change in the stiffness conditions of the entire structure. For the temporary load support, the "clamps" system was adopted, which consists of the installation of a pair of steel beams above and below the cut zone of the column. The bars are tensioned so that the steel-concrete friction force exceeds the axial load to which the columns under work is subjected. Subsequently, four hydraulic jacks were placed between the clamps and loaded until the service load in column was reached. Once the jacks were loaded against the clamps, it was possible to cut the portion of the column with a diamond wire saw, then proceeding with the subsequent installation of the isolation devices. Fig. 7a shows the operation scheme of the support system described above and a photo of its installation on one of the columns of the structure. Fig. 7b shows the installation steps of the isolation system to an individual column: (a) column support and cutting with a diamond wire saw; (b) removal of the concrete ashlar; (c) installation of the upper cap; (d) installation of the bolted seismic isolation device on the lower plate; (e) insertion of the disposable flat jack and centring of the system with respect to the axis of the column; (f) injection of superfluid mortar into the flat jack and loading of the device; (g) sealing the lower cap with cement mortar, (h) final conditions.

Fig. 6 Phase 1: a) construction of new perimeter walls for seismic joint, b) installation of sliding plate on neoprene strip, c) cutting the interfering "buffer" slab; c) installation of the steel frame to support the fixed portion

Fig. 7 Phase 2 - a) scheme and installation system on one sample column; b) installation of isolation devices: sub-phases a,b,c,d,e,f,g,h