Monitoring System with a High Number of Accelerometers: Optimization of Installation and OMA

The presented case study refers to the dynamic monitoring system with only triaxial accelerometers - just installed on the Serra Cazzola viaduct (province of Agrigento, Sicily). The bridge has total length of 980 m and includes 12 spans. The monitoring system involves all spans - with each span being instrumented with 6 accelerometers - and the top of piers. It should be noticed that the monitoring system is in principle quite simple and consists of 6 autonomous and interconnected networks, each reporting to a slave PC and connected in synchrony with a master PC that can be managed remotely. The peculiar architecture - obtained by using DEWESoft MEMS accelerometers, serial connections with an open loop arrangement, and normal Ethernet cable in a LAN configuration - has allowed a significant reduction in installation times. The initial dynamic characterization - aimed at identifying the modal behaviour of the bridge and verifying the synchrony of the individual branches as well as the overall synchrony was carried out in a single solution, with all the triaxial accelerometers present on the deck. Once verified the overall operating condition of the monitoring system, preliminary identification of modal parameters from collected data was carried out by using the LSCE technique.