PSI - Issue 62

Fabio Micozzi et al. / Procedia Structural Integrity 62 (2024) 848–855 Author name / Structural Integrity Procedia 00 (2024) 000 – 000

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The experimental outcomes indicated a very good agreement between the displacements measured using the video camera and the displacement transducer, with differences below 0.15 mm (relative differences below 2%). Considering the simple operations required to work with this structural monitoring system (target placement and camera set-up and calibration), the adopted vision-based system could be a very convenient solution in expedite dynamic monitoring of bridge displacements where other alternatives are not possible (absence of stationary point to install displacement transducers) or are more complex and expensive (ground-based radars or laser vibrometers). The analysis of the frequency contents of the contact and vision-based displacement measurements as well as of the accelerations recorded by the accelerometer at bridge midspan, showed basically superimposed estimates of the first (vertical) modal frequency of the bridge. The analysis of the frequency contents of the accelerations recorded at the head of the tripod supporting the video camera, evidenced significant noise in the 12 to 32 Hz range because of the vibrations determined by the traffic traveling on the bridge and transmitted through abutments and piers to the ground and hence to the tripod. In the considered case study this noise had little impact on the quality of the measurements. However, this condition might be not always satisfied and countermeasures to overcome their negative influence should deserve the attention of future studies. Acknowledgements This study was supported by FABRE “Research consortium for the evaluation and monitoring of bridges, viaducts and other structures” (www.consorziofabre.i t/en). Any opinion expressed in the paper does not necessarily reflect the view of the funder. 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