Fast Bayesian Ambient Modal Identification Incorporating Multiple Setups
Publication: Journal of Engineering Mechanics
Volume 138, Issue 7
Abstract
In full-scale ambient vibration tests, many situations exist where it is required to obtain a detailed mode shape of a structure with a limited number of sensors. A common feasible strategy is to perform multiple setups with each one covering a different part of the structure while sharing some reference degrees of freedom (DOF) in common. Methods exist that assemble the mode shapes identified in individual setups to form a global one covering all measured DOF. This paper presents a fast Bayesian method for modal identification capable of incorporating the fast Fourier transform information in different setups consistent with probability logic. The method allows the global mode shape to be determined, taking into account the quality of data in different setups. A fast iterative algorithm is developed that allows practical implementation even for a large number of DOF. The method is illustrated with synthetic and field test data. Challenges of the mode shape assembly problem arising in field applications are investigated through a critical appraisal.
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Acknowledgments
This paper was funded by the Hong Kong Research Grant Council through General Research Fund (Project No. CityU 110210; 9041550). The financial support is gratefully acknowledged. The writers also would like to thank the following persons who participated in the field test: Dr Ching-Tai Ng, lecturer at the University of Adelaide; Ms. Yan-Chun Ni, graduate student at the City University of Hong Kong (CityU);, and Dr Xiu-Kai Yuan, senior research associate at CityU.
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© 2012. American Society of Civil Engineers.
History
Received: Feb 24, 2011
Accepted: Dec 13, 2011
Published online: Jun 15, 2012
Published in print: Jul 1, 2012
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