Journal of the Korea Academia-Industrial cooperation Society (한국산학기술학회논문지)

The Korea Academia-Industrial cooperation Society (한국산학기술학회)
권호 표지
DOI QR코드

DOI QR Code

A Study on the Efficient Tension Estimation of Cables under Ambient Vibration using Minimized Measurement and Signal Processing System

최소화된 계측 및 신호 처리 시스템을 이용한 상시진동 케이블의 효율적인 장력 추정에 관한 연구

  • Lee, Hyeong-Jin (Department of Civil Engineering, Changwon National University)
  • Received : 2018.08.22
  • Accepted : 2018.11.02
  • Published : 2018.11.30
Download PDF
⟨ Previous Next ⟩

Abstract

Recently, according to the development of measurement techniques, it has become possible to take complicated and time-consuming field measurements in a simple and convenient manner. In this background, this study estimated the tension of cables under ambient vibration using minimized measurement and signal processing. The VBDM using video-only by low-cost equipment was used as a minimized measurement. An estimation of the natural frequency using the mirror frequency concept was also proposed to solve the shortage of frequency band in this case. Furthermore, the FDD method was adopted for a natural frequency estimation in the ambient vibration related to field application. Experimental studies using a cable-stayed bridge model were carried out to examine the properties of the mirror frequency and the applicability of FDD with the proposed minimized system. The results showed that FDD for ambient vibration also works properly in an estimation of the natural frequency using the minimized system. In addition, the mirror frequency concept can allow a high natural frequency estimation even in a distorted signal by low-speed recording, which can overcome the limit of the minimized system. Overall, the proposed minimized system can be effective for the tension estimations of a cable under ambient vibration.

최근 계측 기술의 발달에 따라 종래의 복잡하고 시간 소모적인 현장 계측분석 작업을 단순하고 편리하게 만드는 작업이 가능해지고 있다. 이런 배경에서 이 논문에서는 최소화된 계측 및 신호처리를 통해 상시진동 케이블의 장력을 추정하는 문제에 대해 연구하였다. 최소화 계측 방법으로는 저가 영상장비로 촬영된 동영상만을 이용하는 영상 변위 계측을 구상하였다. 또한 이로 인한 유효 주파수 대역 부족 문제의 해결을 위해 미러 주파수를 이용한 고유진동수 추정 방법을 제시하였다. 더불어 현장 사용 성능과 관련한 상시진동 문제를 처리하기 위해 신호처리 및 고유진동수 추정법으로 FDD 방법이 채택되었다. 제안된 최소화 계측 시스템과 미러 주파수 개념의 특성 및 FDD 방법의 적용성을 보기 위하여 사장교 모형을 이용한 실험적 연구가 수행되었다. 실험 결과는 상시진동을 위한 FDD 방법이 최소화 시스템을 이용한 고유 진동수 판별에서도 효과적으로 잘 작동됨을 보여 주었다. 또한 미러 주파수 개념은 저속촬영에 따라 왜곡된 신호에서도 고주파수 영역에 있는 고유진동수 추정이 가능함을 보여 최소화 시스템의 한계돌파에 효과적임을 보여 주었다. 결론적으로 실험결과는 제안된 최소화 계측 및 신호처리 시스템이 상시진동 케이블 장력 추정에 효과적인 방법이 될 수 있음을 보여주었다.

Keywords

SHGSCZ_2018_v19n11_594_f0001.png 이미지

Fig. 1. Procedure of tension estimation using vision-based displacement measurement

SHGSCZ_2018_v19n11_594_f0002.png 이미지

Fig. 2. Setup of vision-based displacement measurement

SHGSCZ_2018_v19n11_594_f0003.png 이미지

Fig. 3. Frequency function due to aliasing effect (a) Exact frequency function and mirror image (b) Actually estimated frequency function

SHGSCZ_2018_v19n11_594_f0004.png 이미지

Fig. 4. Basic concept of system identification method

SHGSCZ_2018_v19n11_594_f0005.png 이미지

Fig. 5. Grouping of time history for average

SHGSCZ_2018_v19n11_594_f0006.png 이미지

Fig. 6. Experimental setup (a) Model of cable-stayed bridge (b) Applied load (c) Target and cam-corder

SHGSCZ_2018_v19n11_594_f0007.png 이미지

Fig. 7. Measured time history, frequency and PSD functions (129cm 9kg, 60FPS) (a) Measured time history (b) Frequency function in DFA (No window) (c) PSD function in FDD (Hanning window)

SHGSCZ_2018_v19n11_594_f0008.png 이미지

Fig. 8. Measured time history, frequency and PSD functions (84cm 3kg, 60FPS) (a) Measured time history (b) Frequency function in DFA (No window) (c) PSD function in FDD (Hanning window)

SHGSCZ_2018_v19n11_594_f0009.png 이미지

Fig. 9. Exact and estimated natural frequencies (a) 1.29 m (b) 1.03 m (c) 0.84 m

SHGSCZ_2018_v19n11_594_f0010.png 이미지

Fig. 10. Exact and estimated cable tensions (a) 1.29 m (b) 1.03 m (c) 0.84 m

Table 1. Specification of cases

SHGSCZ_2018_v19n11_594_t0001.png 이미지

References

  1. S. K. Kim, H. M. Koh, J. W. Lee, I. H. Bae, "Signal Analysis from a Long-Term Bridge Monitoring System in Yongjong Bridge", Journal of Earthquake Engineering Society of Korea, Vol.10, No.6, pp.9-18, 2006. DOI: https://dx.doi.org/10.5000/EESK.2006.10.6.009
  2. S. Jo, H. Cho, S. Jang, J. Park, H. J. Jung, C. B. Yun, B. F. Jr. Spencer, J. W. Seo, "Structural health monitoring of a cable-stayed bridge using wireless smart sensor technology: data analyses", Smart Structures and Systems, Vol.6, No.5_6, pp.461-480, 2010. DOI: https://dx.doi.org/10.12989/sss.2010.6.5_6.461
  3. Z. Zhou, X. Zhao, C. Wang, Z. Zhang, Q. Hu, J. Ou, "A new kind of smart bridge cable based on FBG sensors", SPIE Proceedings, Vol.5502, pp.196-199, Spain, 2004. DOI: https://dx.doi.org/10.1117/12.566622
  4. J. Im, M. L. Wang, S. W. Shin, C. B. Yun, H. J. Jung, J. T. Kim, S. H. Eem, "Field application of elasto-magnetic stress sensors for monitoring of cable tension force in cable-stayed bridges", Smart Structures and Systems, Vol.12, No.3, pp.465-482, 2013. DOI: https://dx.doi.org/10.12989/sss.2013.12.3_4.465
  5. H. Zui, T. Shinke, Y. Namita, "Practical Formulas for Estimation of Cable Tension by Vibration Method", Journal of Structural Engineering, Vol.122, No.6, pp.651-656, 1996. DOI: https://dx.doi.org/10.1061/(ASCE)0733-9445(1996)122:6(651)
  6. S. Cho, C. B. Yun, S. H. Sim, "Evaluation of Cable Tension Forces Using Vibration Method for a Cable-stayed Bridge under Construction", Journal of the Korean Society of Safety, Vol.29, No.2, pp.38-44, 2014. DOI: https://dx.doi.org/10.14346/JKOSOS.2014.29.2.038
  7. J. J. Lee, M. Shinozuka, "A vision-based system for remote sensing of bridge displacement", NDT & E International, Vol.39, No.5, pp.425-431, 2006. DOI: https://dx.doi.org/10.1016/j.ndteint.2005.12.003
  8. S. W. Kim, N. S. Kim, "Multi-point Displacement Response Measurement of Civil Infrastructures Using Digital Image Processing", Procedia Engineering, Vol.14, pp.195-203, 2011. DOI: https://dx.doi.org/10.1016/j.proeng.2011.07.023
  9. D. Feng, T. Scarangello, M. Q. Feng, Q. Ye, "Cable tension force estimate using novel noncontact vision-based sensor", Measurement, Vol.99, pp.44-52, 2017. DOI: https://dx.doi.org/10.1016/j.measurement.2016.12.020
  10. R. Brincker, L. Zhang, P. Andersen, "Modal identification of output-only systems using frequency domain decomposition", Smart Materials and Structures, Vol.10, No.3, pp.411-445, 2001. DOI: https://dx.doi.org/10.1088/0964-1726/10/3/303
  11. J. H. Yi, C. B. Yun, "Comparative study on modal identification methods using output-only information", Structural Engineering and Mechanics, Vol.17, No.3_4, pp.445-466, 2004. DOI: https://dx.doi.org/10.12989/sem.2004.17.3_4.445
  12. D. Zenunovic, M. Topalovic, R. Folic, "Identification of Modal Parameters of Bridges Using Ambient Vibration Measurements", Shock and Vibration, Vol.2015, Article ID 957841, pp.1-21, 2015. DOI: https://dx.doi.org/10.1155/2015/957841
  13. K. K. Wijesundara, C. Negulescu, E. Foerster, "Estimation of Modal Properties of Low-Rise Buildings Using Ambient Excitation Measurements", Shock and Vibration, Vol.2015, Article ID 173450, pp.1-18, 2015. DOI: https://dx.doi.org/10.1155/2015/173450
  14. D. J. Erwins, Modal Testing: Theory, Practice and Application, 2nd Edition, Research Press Ltd, 2000.