| description abstract | Chongqi Bridge is part of an important route over the Yangtze River connecting Chongming City in Shanghai with Qidong City in Jiangsu. The steel box-girder bridge consists of separate but adjacent twin six-span bridges, and each is 16 m wide and 944 m long. During construction of the bridge, vortex-induced vibration (VIV) was observed, which caused concern about the performance of the bridge. A vibration test was conducted and an eigensystem realization algorithm (ERA) was performed to identify mode properties of the bridge. A wind tunnel test showed that VIV could occur in the first vertical mode, and tuned mass dampers (TMDs) were installed in the four middle spans of the bridge to control large vibrations. A structural health monitoring (SHM) system was also deployed on the bridge and the TMDs, which includes anemometers, accelerometers, displacement transducers, and so on. On July 10–12, 2015, Typhoon Chan-hom passed through the area near Chongqi Bridge. Wind characteristics were calculated with monitoring data, and the response of the bridges and the TMDs were evaluated under Typhoon Chan-hom. The results indicate effectiveness of the TMDs and their functioning under different wind conditions. An effectiveness factor is proposed to describe the functioning of TMD to mitigate deck vibration, which is illustrated with the acceleration measurements of the deck and the TMDs. | |
