LAUSR

Time-varying parameter identification of bridges subject to moving vehicles using ridge extraction based on empirical wavelet transform Jiantao Lia,b , Jian Guoa,* and Xinqun Zhub a Institute of Bridge Engineering, Zhejiang University of Technology, Hangzhou 310000, Zhejiang, China. Email: [email protected] b School of Civil and Environmental Engineering, University of Technology Sydney, Broadway, NSW 2007, Australia Abstract When a vehicle moves over the bridge, the vehicle-bridge interaction(VBI) leads to the time-varying modal parameters of the system. The identification of non-stationary characteristics of bridge responses due to moving vehicle load is important and remains a challenging task. A new method based on the improved empirical wavelet transform (EWT) along with ridge detection of signals in time-frequency representation (TFR) is proposed to estimate the instantaneous frequencies (IFs). Numerical studies are conducted using a vehicle-bridge interaction model to investigate the time-varying characteristics of the system. The effects of the measurement noise, road surface roughness and structural damage, on the bridge IFs are investigated. Finally, the dynamic responses of an in-situ cable-stayed bridge subjected to a passing vehicle are analyzed to further explore the time varying characteristics of the VBI system. Numerical and experimental studies demonstrate the feasibility and effectiveness of the proposed method on the IF estimation. The identified IFs reveal important time-varying characteristics of the bridge dynamic that is significant to evaluate the actual performance of operational bridge and may be used for the structural health assessment.