Mode Shape Reconstruction Using Operational Modal Analysis of Stay Cables Load Cells Data

This paper shows the possibility of using load cells on stay cables for monitoring the modal properties of cable-stayed bridges. This strategy allows reducing the number of sensors to be placed on the infrastructure to develop a comprehensive structural health monitoring system since load cells substitute the use of accelerometers over the deck. The use of load cells measuring with a high sampling frequency has a twofold purpose: (i) to monitor the axial force on cables and (ii) to identify the deck modal properties by using operational modal analysis techniques. The work is developed by considering as case study a newly built cable-stayed bridge located in Central Italy. The bridge has been equipped with a complete static and dynamic monitoring system and measures of about 2-year period are used to assess the feasibility of the proposed strategy. The dynamics of the deck identified by using load cell recordings is compared with that identified through accelerometers installed over the deck, as well as with results of a comprehensive operational modal analysis performed during the proof load test of the bridge. Results are promising, demonstrating the potential of the proposed strategy.