Monitoring abnormal vibration and structural health conditions of an in-service structure from its SHM data

• Published in: Journal of sound and vibration Vol. 537; p. 117185
• Main Authors: Li, X.Y., Guan, Y.H., Law, S.S., Zhao, W.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 27.10.2022
• Subjects: Abnormal vibration; Long-term monitoring; Novelty detection; Power spectral density; Vibration power; Long-term monitoring; Power spectral density; Vibration power; Abnormal vibration; Novelty detection
• ISSN: 0022-460X; 1095-8568
• DOI: 10.1016/j.jsv.2022.117185

•3D PSD plot and novelty detection are combined to automatically identify structural abnormality.•Two structural state vectors are defined.•Novelty score of the structural state is defined.•The vibration power of each frequency is used for abnormal vibration.•Analysis of field measurement data is made. Vortex-induced vibration occurred recently in several important engineering structures in China. Very large mono-frequency periodic vibration was noted. This study reports on the analysis of recorded data from the structural health monitoring (SHM) system of a suspension bridge with the aim to develop some indicators that may be useful to evaluate if there is any abnormal vibration or change of health conditions of a structure in future. The power spectrum of measured acceleration responses is plotted in three-dimensions of time, frequency and power. Acceleration responses from 16 sensors on the target bridge deck in 233 days are analyzed. The evolution of different dynamic parameters in the period encompassing the occurrences of large vortex-induced vibration are reported. The changes in these parameters are identified to be closely associated with some temporary installations on the deck and temporary measures for vibration suppression. The changes in vibration power at different natural frequencies of the structure can be used to demonstrate the evolution of the unexpected event. The trend and abrupt changes of natural frequencies and modal components show the flow of vibration energy between different vibration modes. In addition to the intuitive three-dimension power spectral plot, two state vectors are also developed from the power spectrum. The identification of abnormal vibration and structural state can then be carried out automatically with the novelty detection method and a threshold. The analysis of the SHM acceleration responses of the bridge deck demonstrates the implementation procedure and the effectiveness of the proposed method.