Condition assessment of a supertall structure by an improved Hilbert-Huang transform and empirical mode decomposition method

Structural condition assessment using structural health monitoring (SHM) real-time data is performed in this research for the Canton Tower in China by three different approaches. Firstly, by evaluating frequency and phase angle relations with time during typhoon event using Hilbert-Huang transform (HHT) combined with empirical mode decomposition (EMD) technique. Secondly, by evaluating mode shape dependent indexes, considering mode shapes obtained by an improved-HHT approach applied on decomposed signals by EMD after another typhoon, then verifying these indexes by those evaluated based on mode shapes obtained by the frequency domain decomposition method. Thirdly, a new formulation of an index based on the energy of the intrinsic modal functions produced by the EMD technique is proposed and verified. The results of the three approaches confirmed the tower did not suffer any damage caused by the considered extreme events. Nevertheless, their benefits varied from one desired assessment to the other.