Estimation of Displacement Response from the Measured Dynamic Strain Signals Using Mode Decomposition Technique

모드분해기법을 이용한 동적 변형률신호로부터 변위응답추정

  • 장성진 (부산대학교 토목공학과) ;
  • 김남식 (부산대학교 사회환경시스템공학부)
  • Received : 2008.03.26
  • Accepted : 2008.06.13
  • Published : 2008.07.31

Abstract

In this study, a method predicting the displacement response of structures from the measured dynamic strain signal is proposed by using mode decomposition technique. Evaluation of bridge stability is normally focused on the bridge completed. However, dynamic loadings including wind and seismic loadings could be exerted to the bridge under construction. In order to examine the bridge stability against these dynamic loadings, the prediction of displacement response is very important to evaluate bridge stability. Because it may be not easy for the displacement response to be acquired directly on site, an indirect method to predict the displacement response is needed. Thus, as an alternative for predicting the displacement response indirectly, the conversion of the measured strain signal into the displacement response is suggested, while the measured strain signal can be obtained using fiber optic Bragg-grating (FBG) sensors. As previous studies on the prediction of displacement response by using the FBG sensors, the static displacement has been mainly predicted. For predicting the dynamic displacement, it has been known that the measured strain signal includes higher modes and then the predicted dynamic displacement can be inherently contaminated by broad-band noises. To overcome such problem, a mode decomposition technique was used. Mode decomposition technique estimates the displacement response of each mode with mode shape estimated to use POD from strain signal and with the measured strain signal decomposed into mode by EMD. This is a method estimating the total displacement response combined with the each displacement response about the major mode of the structure. In order to examine the mode decomposition technique suggested in this study model experiment was performed.

Acknowledgement

Supported by : 건설교통부

References

  1. 김남식, 조남소(2002) 광섬유 브래그 격자 센서를 이용한 교량의 수직처짐 추정, 대한토목학회논문집, 대한토목학회, 제22권, 제6-A호, pp. 1357-1366
  2. 신수봉, 윤병구(2008) 측정변형률에서 동적변위 식별, 한국구조물 진단유지관리공학회학술발표논문집, 한국구조물진단유지관리공학회, pp. 447-451
  3. 정범석, 김남식, 국승규(2006) 웨이블릿 분해신호를 이용한 변위 응답의 추정, 한국콘크리트학회논문집, 한국콘크리트학회, 제18권 제3호, pp. 347-354 https://doi.org/10.4334/JKCI.2006.18.3.347
  4. 최은수, 강동훈, 정원석, 김이현(2006) FBG센서 응답을 이용한 단순보의 변위 추정, 한국강구조학회학술발표논문집, 한국강구조학회, pp. 349-354
  5. 홍윤화, 박현우, 이성욱, 이해성(2006) 구조물의 계측가속도를 이용한 변위 재구성에서의 정규화 기법, 대한토목학회 정기학술대회논문집, 대한토목학회, pp. 338-341
  6. Lee, J.J. and Shinozuka, M. (2006) Real-time displacement measurement of a flexible bridge using digital image processing techniques, Experimental Mechanics, Vol. 46, pp. 105-114 https://doi.org/10.1007/s11340-006-6124-2
  7. Kang, L.-H., Kim, D.-K., and Han, J.-H. (2007) Estimation of dynamic structural displacements using fiber Bragg grating strain sensors, Journal of sound and vibration, Vol. 305, pp. 534-542 https://doi.org/10.1016/j.jsv.2007.04.037
  8. Huang, N.E., Shen, Z., Long, S.R., Wu, M.C., Shih, H.H., Zheng, Q., Yen, N.-C., Tung, C.C., and Liu, H.H. (1998) The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis, Proceedings of the Royal Society of London Series A, Vol. 454, pp. 903-995
  9. Cheng, J.S., Yu, D.J., and Yang, Y. (2006) Research on the intrinsic mode function (IMF) criterion in EMD method, Mechanical Systems and Signal Processing, Vol. 20, pp. 817-824 https://doi.org/10.1016/j.ymssp.2005.09.011
  10. Berkooz, G. Holms, P., and Lumley, J. (1993) The proper orthogonal decomposition in the analysis of turbulent flows, Annual Review of Fluid Mechanics, Vol. 25, pp. 539-575 https://doi.org/10.1146/annurev.fl.25.010193.002543