Application of Hilbert-Huang Transform to theVibration Analysis of Bridges

The signal processing method of Hilbert-Huang transform is applied in the vibration analysis of bridges. The complicated original data set is decomposed into a series of intrinsic mode functions(IMF)and a residue by the empirical mode decomposition(EMD). Each IMF is transformed into signal amplitudes and instantaneous frequencies as the functions of time by the Hilbert transform method. Thus, the frequency-time distribution of the amplitude designated as the Hilbert-Huang amplitude spectrum H(ω,t) and accordingly the marginal Hilbert spectrum H(ω,t) are obtained. The measured acceleration responses of the Nanjing Yangtze River Bridge under train passing are processed by Hilbert-Huang transform. Results show the method is effective and practicable.