Abstract
An automatic estimation system for bridge dynamic characteristics (frequency, damping ratio, and vibration mode) under ambient vibration by ERA, ERA/DC and PHCA method is presented in this paper. The Hankel matrix was derived from block covariance of ambient vibration data. The experiments were conducted under (a) strong wind, (b) weak wind and (c) under traffic condition to estimate the dynamiccharacteristics of existing steel langer girder bridge. As a result of this study, the better result is realized from the strong wind data. In contrast, the inducement of high frequency by the data under traffic condition leads to frequent estimation of higher mode with inconsistent level of accuracy. In the various method of analysis, ERA/DC method has the advantages for its simple algorithm and ability to provide accurate estimation with fast calculation speed.
