PSI - Issue 78

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

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b)

Figure 4. First three modal shapes (from left to right: first, second, and third modes) identified using (a) the permanent monitoring system and (b) the validation monitoring system.

Figure 5. Evolution of the first three vibration frequencies (F1, F2, F3) of the ChIP building identified using the SSI-UPCX estimator.

4. Seismic Event Analysis Through Permanent Monitoring System

This section presents the results obtained from the measurements recorded by the sensors of the permanent monitoring system installed on the ChIP building during a seismic event. The earthquake had a magnitude of 3.4, occurred on March 4, 2025, at 00:55:40 UTC, with its epicenter located 2 km southwest of Foligno (PG) at coordinates 42.9430 latitude and 12.6892 longitude, and a depth of 10 km. The distance from the ChIP building to the epicenter is 38.4 km. The seismic signal closest to the epicentral area (Figure 6a) was recorded by the station belonging to the Italian National Accelerometric Network (RAN), with NetCode: IT, Station: FLPC, Channel: HNN, located 3 km from the epicenter at latitude 42.9683 and longitude 12.7037, and recorded a Peak Ground Acceleration (PGA) of 0.1226g. The seismic signal nearest to the ChIP building (Figure 6b) was recorded by the station also part of the RAN, located 650 m away, with NetCode: IT, Station: CMRN, Channel: HNN, at latitude 43.1392 and longitude 13.0718, and recorded a PGA of 0.00126 g. Figure 7 presents a comparison between the seismic signal recorded at the IT-CMRN-HNN station and those recorded by the A1 accelerometer installed at Level 0 of the ChIP building, just above the isolation system, in both the X (Figure 7a) and Y (Figure 7b) directions. The seismic station is located approximately 650 meters from the building, and the signals are comparable. A PGA of 0.00126 g was recorded at the seismic station, while the A1 sensor measured 0.00098g in the X direction and 0.00116g in the Y direction. Figure 8 illustrates the comparison between the accelerometric signal recorded at the IT-CMRN-HNN station and the one recorded by the A2 accelerometer installed on the roof of the ChIP building. A PGA of 0.00237g was recorded in the X direction (Figure 8a) and 0.00134g in the Y direction (Figure 8b) by the A2 sensor. Figure 9 presents the shear force time history recorded by the SGB1 strain-gauge sensor installed on the steel vertical brace at Level 0, above the isolation system. The maximum shear force recorded is 4.61288 kN. Finally, Figure 10 provides the seismic response recorded by the LVDTs installed at Level 0, below the isolation system. The maximum deformation measured is 0.00755 µstrain in the X direction and 0.00256 µstrain in the Y direction.