System identification of linear structures based on Hilbert-Huang spectral analysis. Part 1: Normal modes

Jann N. Yang, Ying Lei, Shuwen Pan, Norden Huang

Research output: Contribution to journalArticlepeer-review

393 Scopus citations

Abstract

Based on the Hilbert-Huang spectral analysis, a method is proposed to identify multi-degree-of-freedom (MDOF) linear systems using measured free vibration time histories. For MDOF systems, the normal modes have been assumed to exist. In this method, the measured response data, which are polluted by noises, are first decomposed into modal responses using the empirical mode decomposition (EMD) approach with intermittency criteria. Then, the Hilbert transform is applied to each modal response to obtain the instantaneous amplitude and phase angle time histories. A linear least-square fit procedure is proposed to identify the natural frequency and damping ratio from the instantaneous amplitude and phase angle for each modal response. Based on a single measurement of the free vibration time history at one appropriate location, natural frequencies and damping ratios can be identified. When the responses at all degrees of freedom are measured, the mode shapes and the physical mass, damping and stiffness matrices of the structure can be determined. The applications of the proposed method are illustrated using three linear systems with different dynamic characteristics. Numerical simulation results demonstrate that the proposed system identification method yields quite accurate results, and it offers a new and effective tool for the system identification of linear structures in which normal modes exist.

Original languageEnglish
Pages (from-to)1443-1467
Number of pages25
JournalEarthquake Engineering and Structural Dynamics
Volume32
Issue number9
DOIs
StatePublished - 25 Jul 2003

Keywords

  • Hilbert transform
  • Hilbert-Huang spectral analysis
  • Linear structures
  • Normal modes
  • System identification

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