Signal stationarization in damping estimation for bridges from traffic loadings

This study focuses on the enhancement in damping estimation of cable-stayed bridges from traffic loadings by a signal stationarization. Since the response of bridge in a sensing position is represented by an envelope-like function as traffic loading moves over the deck, the operational monitoring data can be nonstationary when the number of lanes of the bridge is limited one or two for one direction with small volume of traffic. In this case, the estimation of damping from operational modal analysis becomes more challenging. An amplitude-modulating (AM) function was proposed for minimizing this sort of nonstationarity. The AM function was obtained from temporal root-mean-square function of measured response. An approximated stationary signal was extracted from dividing the original signal by the AM function. This process reduced nonstationarity in traffic-induced response significantly. Using these stabilized damping ratio, a correlation analysis was performed with the representative environmental factors.