Conditions for occurrence of vortex shedding on a large cable stayed bridge: Full scale data from monitoring system

Monitoring systems are nowadays usually provided on large bridges, the decision being taken as early as the initial design process. After completion they are very valuable for providing data about the actual behavior of the structure under real wind, which can usefully be compared with design models. The Charilaos Trikoupis Bridge, between Rion and Antirion in Greece, was equipped with a very complete monitoring system including accelerometers on the deck, pylons and cables along the four spans as well as anemometers. This system is perfectly maintained by permanent staff of the bridge owner, and gives information about the bridge׳s structural health which is regularly used for maintenance purposes. This smart system continuously records only sparse data, with a complete dynamic check being performed every 2 h. This monitoring system was also designed to trigger detailed recording following specific events. From recorded data, cable vibration has been observed after bridge completion and the bridge owner suppressed this within several months by installing dampers between the deck and the cables. Limited-amplitude vertical vibration of the deck in the third mode was also observed on some occasions. The bridge owner asked a foreign laboratory to process two years of monitoring data in order to fully understand the origin of this vibration and evaluate whether treatment would be necessary.