PSI - Issue 78

Michele Morici et al. / Procedia Structural Integrity 78 (2026) 1673–1680

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(2023). Finally, given the strategic relevance of the structure, continuous SHM system was installed from the early stages of construction. Long-term vibration-based monitoring enables the assessment of time-dependent variations in structural modal properties (Ierimonti et al., 2020), which can indicate material degradation, aging effects, or abrupt structural changes resulting from extreme events such as earthquakes or strong wind loads. This study presents the implementation and results of a permanent SHM system installed in the ChIP Research Centre. Over a year-long observation period, the system conducted periodic Operational Modal Analysis (OMA) to evaluate the modal characteristics under ambient excitations. Additionally, the response to a real seismic event of Mw = 3.4 earthquake near Foligno, recorded on March 4, 2025 was captured and analyzed. The findings contribute to a deeper understanding of the behavior of hybrid base-isolated structures, highlighting the critical value of long-term SHM data for performance verification, model updating, and lifecycle management in seismically active regions. 2. The ChIP Research Centre A synthetic overview of the building’s structural configuration is provided. The superstructure consists of a two story steel braced frame with pinned joints (Figure 1a), developed according to a 7.2 m x 7.2 m modular layout, comprising seven modules in each principal direction (Figure 1b). An additional cantilevered zone extends 1.9 m along the entire building perimeter, resulting in an overall floor plan of 54.20 m x 54.20 m (Figure 1b). Four concentric inverted-V bracing systems are implemented along each main direction (Figure 1b) to resist horizontal actions . The substructure was designed to follow the site’s complex topography, which is characterized by a significant slope. This required the use of reinforced concrete (RC) foundations with a geometrically complex yet regular layout, and rigid RC columns connecting the deeper foundation levels to the isolation interface (Figure 1b). Due to the geotechnical conditions of the site, particularly the variability in the thickness of the underlying deformable soil layer, deep foundations were adopted. The isolation system (Figure 1c) adopts a hybrid configuration with 28 High-Damping Rubber Bearings (HDRBs) placed along the perimeter to improve torsional stiffness, and 36 Low-Friction Sliding Bearings (LFSBs) located centrally to sustain higher vertical loads. The system was designed for an isolation period T is =3.60 s.

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Figure 1. (a) Main façade and structural section; (b) typical floor plan; (c) isolation layout of the ChIP building (pictures from Dall’Asta et al., 2022).