PSI - Issue 84

Giorgia Ghirelli et al. / Procedia Structural Integrity 84 (2026) 1047–1054

1050

The characteristics of the bridge, such as its idealized isostatic behavior and the predominance of vertical deformation modes under operational loads, offer an advantageous context for validating the proposed methodology and comparing the measured displacements with numerical predictions obtained from the finite element model. 4. Monitoring campaign framework The monitoring campaign is designed to investigate the dynamic response of the bridge during train passages by measuring displacements at selected points of the structure. Owing to the structural configuration of the bridge, the experimental activity is focused on a single representative span. Specifically, the first span in the direction of Vignola is selected as the target of monitoring operations, as it offers unobstructed visibility from the riverbed and provides a suitable reference for validating the proposed vision-based methodology. To capture the structural response with sufficient spatial resolution, a set of high-contrast checkerboard targets is installed at selected sections of interest. The installation is carried out during nighttime hours to ensure safe access and avoid disturbance to railway operations. As shown in Fig. 2, the monitored locations correspond to key structural components, such as transverse beams and vertical ties reached using a mobile elevated platform equipped with a telescopic arm. The monitoring equipment consists of a Lumix GH6 and a Canon Eos R10 digital cameras, recording video in 4K resolution at a frame rate of 25 frames per second. To avoid disturbances caused by manual camera handling, the initial and final seconds of each recording, associated with the start and stop operations, are removed during pre processing. The cameras are mounted on tripods on the dry riverbed to capture the structural response during train crossings. With reference to Fig. 2, the first camera is oriented to frame the longitudinal elevation of the span (Fig. 2a), enabling the measurement of global deformation patterns and vertical displacements at multiple points along the arch-deck system. The second camera is installed beneath the bridge to record the underside of the deck and the transverse beams (Fig. 2b), providing additional insight into any torsion induced by train passages as a result of imperfect mass or stiffness distribution.

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Fig. 2. (a) Lateral and (b) transverse camera position, with checkerboard targets mounted on the structure (outlined in red).