Modal-parameter identification from nonstationary ambient vibration data

Dar Yun Chiang, Chang Sheng Lin

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Identification of modal parameters from response data only is studied for structural systems under nonstationary ambient vibration. By assuming the ambient excitation to be nonstationary white noise in the form of a product model, the modal parameters of a system could be identified through the correlation method in conjunction with a technique of curve-fitting. However, the error involved in the approximate free-decay response would generally lead to a distortion in the modal parameters of identification. It is shown that, under appropriate conditions, the ambient response corresponding to nonstationary input of various types can be approximately expressed as a sum of exponential functions, so that we can use the Ibrahim time-domain method in conjunction with a channel-expansion technique to directly identify the major modes of a structural system without any additional treatment of converting the original data into the form of free vibration. To further distinguish the structural modes from non-structural modes, the concept of mode-shape coherence and confidence factor is employed. Numerical simulations, including one example of using practical excitation data, confirm the validity and robustness of the proposed method for identification of modal parameters from general nonstationary ambient response.

Original languageEnglish
Title of host publicationExperimental and Applied Mechanics - Proceedings of the 2011 Annual Conference on Experimental and Applied Mechanics
PublisherSpringer New York LLC
Number of pages13
ISBN (Print)9781461402213
Publication statusPublished - 2011 Jan 1
Event2011 SEM Annual Conference on Experimental and Applied Mechanics - Uncasville, CT, United States
Duration: 2011 Jun 132011 Jun 16

Publication series

NameConference Proceedings of the Society for Experimental Mechanics Series
ISSN (Print)2191-5644
ISSN (Electronic)2191-5652


Other2011 SEM Annual Conference on Experimental and Applied Mechanics
Country/TerritoryUnited States
CityUncasville, CT

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Computational Mechanics
  • Mechanical Engineering


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