DOI QR코드

DOI QR Code

Detection of Fracture Signals of Low Prestressed Steel Wires in a 10 m PSC Beam by Continuous Acoustic Monitoring Techniques

연속음향감지기법을 이용한 긴장력이 감소된 10 m PSC보의 PS 강선 파단음파 감지

  • Youn, Seok-Goo (School of Civil Engineering, Seoul National University of Technology) ;
  • Lee, Chang-No (School of Civil Engineering, Seoul National University of Technology)
  • 윤석구 (서울산업대학교 건설공학부) ;
  • 이창노 (서울산업대학교 건설공학부)
  • Published : 2010.02.28

Abstract

Corrosion of prestressing tendons and wire fractures in grouted post-tensioned prestressed concrete bridges have been considered as a serious safety problem. In bridge evaluation the condition of prestressing tendons should be inspected, and if corroded tendons are found, the loss of tendon area should be included when we calculate the ultimate strength. In the previous study, it was evaluated that continuous acoustic monitoring techniques could be considered as a reliable non-destructive method for detecting wire fractures of fully grouted post-tensioned prestressing tendons. In the present study, an experimental test was performed for detecting wire fractures of post-tensioned prestressing tendons which are prestressed lower than current design level. A 10 m prestressed concrete beam was fabricated, which included two tendons prestressed 66 percentage and 40 percentage of tensile strength, respectively. The corrosion of two tendons was induced by an accelerated corrosion equipment and the test beam was monitored by using seven acoustic sensors and a continuous acoustic monitoring system. From each prestressing tendon, two acoustic signals of wire fractures were successfully detected and source locations were estimated within 20 mm error. Based on the test results, it is considered that continuous acoustic monitoring techniques can be applied to detect low-prestressed wire fracture in fully grouted post-tensioned prestressed concrete beams.

후 긴장된 PS 강재의 부식과 파단은 프리스트레스 콘크리트 교량의 안전에 매우 심각한 문제를 발생시키고 있다. 따라서 교량의 내하력 평가시 PS 강재의 부식 상태를 조사해야 하며, 부식된 PS 강재가 발견되는 경우, 부식에 의한 강재의 단면적 감소량을 극한강도 평가시 고려해야만 한다. 선행 연구에서는 연속음향감지기법을 그라우팅되고 후 긴장된 PS 강연선의 부식과 파단을 감지할 수 있는 신뢰할 만한 비파괴검사방법으로 평가하였다. 이 연구에서는 긴장재에 도입된 응력 수준이 현행 설계기준에 제시된 수준보다 낮게 도입된 PS 강연선에 대해 부식에 의한 강선 파단을 감지하기 위한 실험적 연구를 수행하였다. 이를 위해 프리스트레스의 크기가 각각 인장강도의 66%와 40%로 도입된 PS 강연선이 포함된 길이 10 m의 PSC 보를 제작하였다. 부식 촉진 장비를 이용하여 긴장재를 인위적으로 부식시켰으며, 7개의 음향센서와 연속음향감지장치를 이용하여 실험부재를 모니터링하였다. 부식 촉진 실험 동안 각 PS 강연선으로부터 2번의 강선 파단음파를 성공적으로 감지하였으며, 또한 오차범위 20 mm 이하로 음원 위치를 표정할 수 있었다. 이상의 실험 결과를 토대로 그라우팅되고 후 긴장된 PSC 보에서 발생되는 PS 강선 파단을 감지하는데 연속음향감지기법을 적용할 수 있다고 판단된다.

Keywords

References

  1. The Concrete Society, "Durable Bonded Post-tensioned Concrete Bridges," Concrete Society Technical Report 47, TR047, 1996, 64 pp.
  2. Woodward, R. J. and Williams, F. W., "Collapse of Ynys-s-Gwas Bridge," Proceedings of Institute of Civil Engineers, Part 1, Vol. 84, 1988, pp. 635-669. https://doi.org/10.1680/iicep.1988.179
  3. Mathy, B., Demars, P., Roisin, F., and Wouters, M., "Investigation and Strengthening Study of Twenty Damaged Bridges: A Belgium Case History," Bridge Management : Inspection, Maintenance and Repair, Proceedings of the 3rd International Conference, University of Surrey, 1996, pp. 658-666.
  4. Halsall, A. P., Welch, W. E., and Trepanier, S. M., "Acoustic Monitoring Technology for Post-tensioned Concrete Structures," FIP Symposium 1996 on Post-tensioned Concrete Structures, The Concrete Society, 1996, pp. 483-491.
  5. Cullington, D. W., MacNeil, D., Paulson, P., and Elliot, J., "Continuous Acoustic Monitoring of Grouted Post-tensioned Concrete Bridges," NDT&E International, Vol. 34, 2001, pp. 95-105. https://doi.org/10.1016/S0963-8695(00)00034-7
  6. Youn, S. G., Cho, S. K., and Kim, E. K., "Acoustic Emission Technique for Detection of Corrosion-induced Wire Fracture," Key Engineering Materials, Vols. 297-300, 2005, pp. 2040-2045. https://doi.org/10.4028/www.scientific.net/KEM.297-300.2040
  7. Fricker, S. and Vogel, T., "Site Installation and Testing of a Continuous Acoustic Monitoring," Construction and Building Materials, Vol. 21, Issue 3, 2007, pp. 501-510. https://doi.org/10.1016/j.conbuildmat.2006.04.008
  8. Yuyama, S., Yokoyama, K., Niitani, K., Ohtsu, M., and Uomoto, T., "Detection and Evaluation of Failure in Highstrength Tendon of Prestressed Concrete Bridges by Acoustic Emission," Construction and Building Materials, Vol. 21, Issue 3, 2007, pp. 491-500. https://doi.org/10.1016/j.conbuildmat.2006.04.010
  9. 윤석구, 이창노, 김은겸, "AE기법을 이용한 PSC 보의 음파속도와 음원 위치 산정 방법," 대한토목학회논문집, 26권, 5A호, 2006, pp. 917-925.
  10. Mikhail, E. M., Observations and Least Squares, University Press of America, New York, 1976, 497 pp.

Cited by

  1. Experimental Tests for the Evaluation of One-dimensional and Two-dimensional Acoustic Source Locations with 50m length of a PSC Box Girder vol.33, pp.2, 2013, https://doi.org/10.12652/Ksce.2013.33.2.433