Modal identification of tsing Ma bridge by using the frequency domain method

This paper presents results of researches on modal identification of the long span bridge, Tsing Ma bridge, by using the frequency domain method on the basis of ambient testing data, and researches on mean square estimate value error of auto-power spectrum caused by the statistical sampling. In this paper, first use the phase information of cross-power spectrum between responses at the reference point and responses at Other points to distinguish output spectral peaks which are due to structural vibration modes from peaks in the input spectrum. Then the mode shape coefficient is made by the ratio of the square root values between the response auto-power density spectrum at the reference point and responses at other points. At last, the damping ratio is calculated by using the half power band method. The lateral bending modal identification results of Tsing Ma bridge with different relative mean root errors are also compared in this paper.