PSI - Issue 64

Donato Fiore et al. / Procedia Structural Integrity 64 (2024) 740–748 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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• in addition, we have verified that the length of the structure included several intervals along the line of sight of IBIS-FS • in order to obtain a measurable movement of that point, it was verified that the angle between the IBIS-FS line of sight and the farthest measurement point was greater than 5 degrees and that the expected line of sight displacement of the farthest measurement point was greater than 0.05 mm

Figure 5 – (a) satellite position of the IBIS System, (b) boxes pointing the Cannavino bridge

• to ensure that the system is able to resolve the scenario only in the range direction and not in the transverse direction, were installed corner reflectors on both sides of the viaduct: twelve to the east and sixteen to the west, corresponding to the optical targets installed for the preliminary and control surveys carried out with the total station. In this way, each range bin corresponds to a single measurement point (Fig. 6 a&b)

Figure 6 – range bins measured from both side of the Cannavino bridge: (a) East side; (b) West side

• with a view to remove the atmospheric effects (temperature, humidity and pressure) from the measurement results, in long term monitoring tests the illuminated scenario must contain at least one still point (not moving) to be used as reference point (GCP - Ground Control Point). In this specific case, in addition to the GCP, a weather station was use to eliminate any discrepancies caused by instrumental drift 3.2. Live monitoring static acquisition Static monitoring consists of overseeing the elastoplastic characteristics of structures during the loading and unloading cycles of the viaduct subjected to normal vehicular traffic. Maximum deformations (under load) and residual deformations (after load removal) were measured every 24 hours. (Fig. 7).