Modal Parameter Estimation for Jacket-Type Platforms Using Free-Vibration Data
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 137, Issue 5
Abstract
An accurate estimation of the modal parameters of a structure, including modal frequency and damping ratio, is crucial for many practical engineering problems. This article introduces Prony’s method for identifying multiple modal parameters of a jacket-type platform from the measured free-vibration data. In contrast to the Fourier analysis for the decomposition of a periodic signal, Prony’s method involves the decomposition of a transient signal into a number of damped sinusoidal components. By using a finite-element model of a realistic offshore jacket-type platform, free-vibration data, corresponding to two different initial displacement patterns, were extracted and used in a numerical study. From the sampled response acceleration signals associated with each of the initial displacement patterns, the modal parameters of different participating modes were accurately determined. This numerical study demonstrates that the modal parameters, of at least the first nine modes of the jacket-type platform, including six translation modes and three torsion modes, can be accurately estimated by using the proposed method.
Get full access to this article
View all available purchase options and get full access to this article.
References
Allemang, R. J., and Brown, D. L. (1998). “A unified matrix polynomial approach to modal identification.” J. Sound Vib., 211(3), 301–322.
ANSYS Release 9.0 [Computer software]. ANSYS, Canonsburg, PA.
Clough, R. W., and Penzien, J. (1993). Dynamics of strutures, 2nd Ed., McGraw-Hill, New York.
Craig, R. R., and Kurdila, A. J. (2006). Fundamentals of structural dynamics, 2nd Ed., Wiley, New York.
de Prony, G. C. F. M. R. (1795). “Essai experimental et analytique: Sur les lois de la dilatabilite des fluids elastiques et sur celles de la force expansive de la vapeur del’eau et de la vapeur de l’alkool, a differentes temperatures.” J. Ec. Polytech., 1(2), 24–76 (in French).
Ewins, D. J. (2000). Modal testing: Theory, practice and applications, 2nd Ed., Research Studies, Baldock, Hertfordshire, England.
Friswell, M. I., and Mottershead, J. E. (1995). Finite element model updating in structural dynamics, 1st Ed., Kluwer Academic, Dordrecht, Netherlands.
Golub, G., and van Loan, C. (1996). Matrix computations, 3rd Ed., Johns Hopkins University Press, Baltimore.
Heylen, W., Lammens, S., and Sas, P. (1997). Modal analysis theory and testing, 2nd Ed., Departement Werktuigkunde, Katholieke Universteit Leuven, Leuven, Belgium.
Kannan, N., and Kundu, D. (2001). “Estimating parameters in the damped exponential model.” Signal Processing, 81(11), 2343–2351.
Maia, N. M. M., et al. (1997). Theoretical and experimental modal analysis, Research Studies, Taunton, Somerset, England.
Mangal, L., Idichandy, V. G., and Ganapathy, C. (2001). “Structural monitoring of offshore platforms using impulse and relaxation response.” Ocean Eng., 28(6), 689–705.
Markovsky, I., and van Huffel, S. (2007). “Overview of total least squares methods.” Signal Processing, 87(10), 2283–2302.
Marple, L. S. (1987). Digital spectral analysis with applications, Prentice-Hall, Upper Saddle River, NJ.
McConnell, K. G., and Varoto, P. S. (2008). Vibration testing: Theory and practice, 2nd Ed., Wiley, Englewood Cliffs, NJ.
Information & Authors
Information
Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 137 • Issue 5 • September 2011
Pages: 234 - 245
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Apr 16, 2010
Accepted: Feb 9, 2011
Published online: Feb 11, 2011
Published in print: Sep 1, 2011
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.