DOI QR코드

DOI QR Code

Theoretical research on the identification method of bridge dynamic parameters using free decay response

  • 투고 : 2009.08.12
  • 심사 : 2011.01.15
  • 발행 : 2011.05.10

초록

Input excitation and output response of structure are needed in conventional modal analysis methods. However, input excitation is often difficult to be obtained in the dynamic load test of bridge structures. Therefore, what attracts engineers' attention is how to get dynamic parameters from the output response. In this paper, a structural experimental modal analysis method is introduced, which can be used to conveniently obtain dynamic parameters of the structure from the free decay response. With known damping coefficients, this analysis method can be used to identify the natural frequencies and the mode shapes of MDOF structures. Based on the modal analysis theory, the mathematical relationship of damping ratio and frequency is obtained. By using this mathematical relationship to improve the previous method, an improved experimental modal analysis method is proposed in this paper. This improved method can overcome the deficiencies of the previous method, which can not identify damping ratios and requires damping coefficients in advance. Additionally, this improved method can also identify the natural frequencies, mode shapes and damping ratios of the bridge only from the free decay response, and ensure the stability of identification process by using modern mathematical means. Finally, the feasibility and effectiveness of this method are demonstrated by a numerical example of a simply supported reinforced concrete beam.

키워드

참고문헌

  1. Arunasis, C., Biswajit, B. and Mira, M. (2006), "Identification of modal parameters of a mdof system by modified L-P wavelet packets", J. Sound Vib., 295(2-5), 827-837. https://doi.org/10.1016/j.jsv.2006.01.037
  2. Brincker, R., Zhang, L. and Andersen, P. (2000), "Modal identification from ambient responses using frequency domain decomposition", Proceeding of 18th International Modal Analysis Conference, San Antonio, 625-630.
  3. Feeny, B.F. and Kappagantu, R. (1998), "On the physical interpretation of proper orthogonal modes in vibrations", J. Sound Vib., 211(4), 607-616. https://doi.org/10.1006/jsvi.1997.1386
  4. Formenti, D. and Richardson, M. (2002), "Parameter estimation from frequency response measurements using rational fraction polynomials (Twenty Years of Progress)", Proceedings of the International Society for Optical Engineering, Los Angeles, CA, 373-382.
  5. Kerschen, G. and Golinval, J.C. (2004), "Comments on interpreting proper orthogonal modes of randomly excited linear vibration systems", J. Sound Vib., 274(2-5), 1091-1092. https://doi.org/10.1016/j.jsv.2004.01.001
  6. Lardies, J. and Larbi, N. (2001), "A new method for modal order selection and modal parameter estimation in time domain", J. Sound Vib., 245(2), 187-203. https://doi.org/10.1006/jsvi.2000.3593
  7. Li, D.B. and Lu, Q.H. (2001), Experimental Modal Analysis and Application, Science Press, Beijin.
  8. Qin, X.R., Kwok, K.C.S., Fok, C.H., Hitchcock, P.A. and Xu, Y.L. (2007), "Wind-induced self-excited vibrations of a twin-deck bridge and the effects of gap-width", Wind Struct., 10(2), 463-479. https://doi.org/10.12989/was.2007.10.5.463
  9. Qin, X.R., Kwok, K.C.S., Fok, C.H. and Hitchcock, P.A. (2009), "Effects of frequency ratio on bridge aerodynamics determined by free-decay sectional model tests", Wind Struct., 12(5), 413-424. https://doi.org/10.12989/was.2009.12.5.413
  10. Ren, W.X. and Harik, I.E. (2002), "Modal analysis of the cumberland river bridge on I-24 highway in west Kentucky", Proceedings of IMAC-XIX: A Conference on Structural Dynamics, Los Angeles, California, 21-27.
  11. Yu, D.J. and Ren, W.X. (2005), "EMD-based stochastic subspace identification of structures from operational vibration measurements", Eng. Struct., 27(12), 1741-1751. https://doi.org/10.1016/j.engstruct.2005.04.016
  12. Wang, B.T. and Cheng, D.K. (2008), "Modal analysis of mdof system by using free vibration response data only", J. Sound Vib., 311(3-5), 737-755. https://doi.org/10.1016/j.jsv.2007.09.030

피인용 문헌

  1. Dynamic response analysis of generally damped linear system with repeated eigenvalues vol.42, pp.4, 2012, https://doi.org/10.12989/sem.2012.42.4.449