PSI - Issue 84

Francesco Nigro et al. / Procedia Structural Integrity 84 (2026) 183–190

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(a)

(b)

Fig. 4. Depiction of the interventions for the elimination of the Gerber saddles: longitudinal view on the left (a) and right (b) of the retained joint

2.3. The monitoring system As a part of the SHM program implemented by ANAS spa, the infrastructure management company, the bridge has been recently equipped with the aim to perform long-term dynamic monitoring with the aim to assess the structural response over time and evaluate the effectiveness of the performed interventions. The SHM system is composed of a network of 28 MEMS accelerometers, strategically deployed to characterize the bridge's dynamic behaviour. The sensing array is organized into two main measurement chains. To ensure a detailed assessment of both global and local responses, sensors are installed at critical locations: a biaxial accelerometer on each pier top (longitudinal and transversal directions), 2 uniaxial accelerometers (gravity direction) at two sides of the the mid-span of the cantilever girders and of the drop-in spans and one uniaxial accelerometer in the middle of the Gerber saddle, as depicted in Figure 5. The sensors are wired connected to a board computer, recording 60 minutes long time histories every 4 hours for a total of 6 recordings per day. This configuration enables continuous OMA, allowing for the real-time identification of natural frequencies and mode shapes, as well as the detection of potential structural anomalies through modal shift analysis.