Application of HHT method to system identification of Di Wang Building during Typhoon York

Abstract

This chapter examines the application of the newly emerged Hilbert–Huang transform (HHT) method together with the random decrement technique (RDT) to the measured data of the Di Wang Building to identify its dynamic characteristics. The basic procedure of using the HHT method to identify the natural frequencies and modal damping ratios from the measured response time histories can be followed in three steps. First, the measured structural response time history is decomposed into the intrinsic mode functions using the empirical mode decomposition method with the intermittency check to obtain modal response. Second, the RDT is applied to each of the modal response to extract the free modal response. Finally, the Hilbert transform is applied to each of the free modal response lime histories to obtain the corresponding natural frequency and modal damping ratio. A series of natural frequencies and modal damping ratios of the building under different wind speeds in different directions are identified and compared with those from the fast Fourier transform (FFT)-based method. The results show that the natural frequencies identified by the HHT method and the FFT method are almost the same, but the modal damping ratios identified by the two methods are different to some extent.