PSI - Issue 64

Filippo Andreose et al. / Procedia Structural Integrity 64 (2024) 40–47

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such a way as to define a limited training period (from 10 January to 31 January 2023) and using the remaining time window as data to be analyzed in the continuous monitoring process.

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Fig. 6. Modal Identification of first section of Molo VII Bridge in P3P. (a) Stabilization diagram and (b) MAC diagram.

Fig. 7b shows the control chart, where the green area is relative to the training period. The anomalies, represented by the red dots, in this context must be interpreted as the result of the definition of a training period that is too limited and therefore not statistically robust.

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Fig. 7. (a) Frequency tracking and (b) Control Chart obtained with P3P software.

3.3. San Faustino bridge The San Faustino bridge is a post-tensioned box-girder bridge located along a motorway connection in the municipality of Perugia, Italy (Fig. 8a). The deck is composed by 9 spans, the first and ninth ones are 33.6 m each, while the internal spans measure 42.6 m, for a total length of 365.4 m. It is characterized by 10 half-joints, one for each span, except for the third one which has two. Fig. 8b shows the geometry of the structure, with indication of half joints (Fig. 8c). The dynamic monitoring system installed on the bridge is composed by 66 MEMS-based accelerometers covering 114 measurement channels. Each span is equipped by 2 biaxial accelerometers in the transversal and vertical directions, and 2 additional uniaxial sensors in vertical direction. Each pile is equipped with a biaxial accelerometer on the top, with the first and last piles featuring a triaxial sensor at the base. Furthermore, on half joints there are a triaxial accelerometer and a uniaxial sensor in vertical direction. The monitoring system continuously stores 12 data files per day, each with a two-hour duration and a sampling acquisition frequency of 125 Hz.