Abstract
An effective identification method is developed for the determination of modal parameters of a structure from its measured ambient nonstationary vibration data. It has been shown in a previous paper of the authors that by assuming the ambient excitation to be nonstationary white noise in the form of a product model, the nonstationary response signals can be converted into free-vibration data via the correlation technique. In the present paper, if the ambient excitation can be modeled as a nonstationary white noise in the form of a product model, then the nonstationary cross random decrement signatures of structural response evaluated at any fixed time instant are shown theoretically to be proportional to the nonstationary cross-correlation functions. The practical problem of insufficient data samples available for evaluating nonstationary random decrement signatures can be approximately resolved by first extracting the amplitude-modulating function from the response and then transforming the nonstationary responses into stationary ones. Modal-parameter identification can then be performed using the Ibrahim time-domain technique, which is effective at identifying closely spaced modes. Numerical simulations confirm the validity of the proposed method for identification of modal parameters from nonstationary ambient response data.
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Acknowledgements
This research was supported in part by National Science Council of the Republic of China under the grant NSC-96-2221-E-006-188.
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© 2012 The Society for Experimental Mechanics, Inc. 2012
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Lin, CS., Chiang, DY. (2012). Modal Identification from Nonstationary Ambient Vibration Data Using Random Decrement Algorithm. In: Allemang, R., De Clerck, J., Niezrecki, C., Blough, J. (eds) Topics in Modal Analysis I, Volume 5. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-2425-3_20
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DOI: https://doi.org/10.1007/978-1-4614-2425-3_20
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