PSI - Issue 84

Donato Fiore et al. / Procedia Structural Integrity 84 (2026) 417–424

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have a user-configurable sampling rate (40, 80, 160, 320 or 640 Hz). The sensitivity of the instruments enables measurements even in the absence of vibrations, where only environmental noise occurs. These devices are also equipped with a temperature sensor, used for correlations with accelerometric readings (Maccanti et al. 2023).

3. Preliminary Modelling A preliminary Finite Element Model (FEM) of the bridge was developed utilizing the data from the interferometric measurement. Several models were developed, two of which were utilized for the Bisantis Bridge: Model 1 (Fig. 7a), which includes only the main arch, and Model 4 (Fig. 7b), which considers the complete geometry of the bridge. Therefore, a theoretical FEM was developed (Fig. 8). The objective was to evaluate how elements such as the piers, the Gerber-type deck, and the lateral trestles influence the structural response of the arch. Both models incorporate detailed structural features and assume elastic material properties similar to those of concrete. The identified natural modes exhibit predominantly horizontal or vertical deformation patterns, while the complete model also reveals interaction modes between the deck and the arch.

Fig. 7. Theorical model 1 (a) and theoretical model 4 (b) for the Bisantis bridge. Comparing the natural frequencies reveals that the full model exhibits lower frequencies due to increased mass, rather than decreased stiffness. For example, the first three horizontal modes shift from 0.79–2.48 Hz in the arch-only model to 0.55–0.94 Hz in the full model. Vertical frequencies also shift due to the interaction between mass and stiffness changes. Local modes associated to deck piers appear at higher frequencies, making them harder to detect using global dynamic analysis. Structural Health Monitoring (SHM) continuously assesses structural integrity by detecting changes from damage, geometric shifts, or material degradation. It integrates material testing with static and dynamic monitoring systems. Dynamic monitoring, while complex and costly, provides rapid results and relies on prior structural knowledge for accurate interpretation. Modern SHM systems set threshold values for triggering alerts, guided by standards like DIN 4150 and ISO 9916. 4. Results Following the modelling activities and considering the site logistics, a monitoring system for the Bisantis Bridge was designed and implemented with an online platform (movedeck.herokuapp.com), allowing real-time consultation of displacement and acceleration data. Analysis of data from accelerometers placed on the deck, arch, and piers enabled the identification of experimental natural frequencies, which partially matched those from the FEM model and radar interferometry. However, the FEM model tends to underestimate the frequencies, likely due to inaccuracies in representing the bridge’s mass and stiffness. Radar interferometry identified a subset of the primary modal shapes (Table 1).