| Titre : | Fast bayesian FFT method for ambient modal identification with separated modes (2011) |
| Auteurs : | Siu-Kui Au, Auteur |
| Type de document : | Article : texte imprimé |
| Dans : | Journal of engineering mechanics (Vol. 137 N° 3, Mars 2011) |
| Article en page(s) : | pp.214-226 |
| Note générale : | Mécanique appliquée |
| Langues : | Anglais |
| Tags : | Bayesian analysis Field tests Modal Spectral analysis. |
| Résumé : | Previously a Bayesian theory for modal identification using the fast Fourier transform (FFT) of ambient data was formulated. That method provides a rigorous way for obtaining modal properties as well as their uncertainties by operating in the frequency domain. This allows a natural partition of information according to frequencies so that well-separated modes can be identified independently. Determining the posterior most probable modal parameters and their covariance matrix, however, requires solving a numerical optimization problem. The dimension of this problem grows with the number of measured channels; and its objective function involves the inverse of an ill-conditioned matrix, which makes the approach impractical for realistic applications. This paper analyzes the mathematical structure of the problem and develops efficient methods for computations, focusing on well-separated modes. A method is developed that allows fast computation of the posterior most probable values and covariance matrix. The analysis reveals a scientific definition of signal-to-noise ratio that governs the behavior of the solution in a characteristic manner. Asymptotic behavior of the modal identification problem is investigated for high signal-to-noise ratios. The proposed method is applied to modal identification of two field buildings. Using the proposed algorithm, Bayesian modal identification can now be performed in a few seconds even for a moderate to large number of measurement channels. |
| DEWEY : | 620.1 |
| ISSN : | 0733-9399 |
| En ligne : | http://ascelibrary.org/emo/resource/1/jenmdt/v137/i3/p214_s1?isAuthorized=no |
