Deformation monitoring and analysis of a long-span cable-stayed bridge during strong typhoons

Deformation monitoring of the girders and towers during strong winds or typhoons is vitally important for serviceability and safety assessment of in-service long-span bridges. Although some field measurements were carried out, our understanding on the features of the bridge deformation during high-speed winds is still limited; therefore, more monitoring-based studies are still required. In this study, the displacements of a long-span cable-stayed bridge during three typhoons are recorded by the Global Positioning System (GPS) in its Structural Health Monitoring (SHM) system. The monitored displacements are decomposed into static and dynamic components using the autoregressive moving average model. The outliers and the low-frequency colored noise in the dynamic components are then analyzed and eliminated. On that basis, the relationship between the static displacements and environmental factors, in terms of wind and temperature, is investigated. Afterwards, the variation of dynamic displacements of the bridge is analyzed with respect to the surrounding environments. Results show that the structural temperature is the major reason that changes the static deformation of the bridge. The dynamic deformation of the girder is mainly controlled by the in-situ wind speed. Nevertheless, the influence of structural temperature on dynamic deformation is mildly. Conclusions are aimed to provide a reference for wind resistant design and assessment of similar long-span bridges.