Enhanced Damping Estimation for Cable-Stayed Bridges Based on Operational Monitoring Data

Abstract

This study proposes an enhanced damping estimation procedure for flexible cable-supported bridges based on operational modal analysis (OMA). The OMA approach combines the natural excitation technique (NExT) with an eigensystem realization algorithm (ERA). An amplitude modulating (AM) function is introduced to stationarize the vehicle-induced responses. This study proposes guidelines for the selection of parameters for the NExT-ERA algorithm and AM-based stationarization. The proposed damping estimation procedure and parameter selection guidelines were applied to the data gathered from measuring an in-service cable-stayed bridge over a three-day period. The correlations between the identified damping ratios and environmental factors such as vibration level, temperature and wind velocity were investigated. The effect of aerodynamic damping during OMA is also discussed. The examined data identifies the amplitude-dependency of the damping ratios.