System identification analysis of the dynamic monitoring data of the Confederation Bridge (New Brunswick, Prince Edward Island)

The Confederation Bridge is one of the longest continuous bridges in the world built over seawater. Its construction represents a major engineering achievement in the design of long-span bridges. Since its completion in 1997, a comprehensive remote monitoring system installed in the bridge has been collecting data on the static and dynamic responses of the bridge. In this paper, a brief introduction of the dynamic monitoring system is presented. The system identification methods and modal analysis procedures in frequency domain and time domain employed in the analysis of the field monitoring data to extract the vibrational modal properties of the bridge are presented. Comparison of the frequency and time domain system identification methods shows that the Stochastic Subspace method in time domain is an effective tool for identification of the dynamic properties of full-scale bridges using the structural response data under ambient conditions. The system identification results obtained from the monitoring data can be used to calibrate and improve the FEM model of the bridge. System identification results show that the measured field data include noise and components of local vibration modes of the cross-section of the bridge, all of which tend to obscure the modal behavior of the bridge. Detailed noise reduction and data analysis of the field response data can lead to useful information on the modal properties of the structure.