한국구조물진단유지관리공학회 논문집 (Journal of the Korea institute for structural maintenance and inspection)

  • 제19권5호
  • /
  • Pages.67-74
  • /
  • 2015
  • /
  • 2234-6937(pISSN)
  • /
  • 2287-6979(eISSN)
한국구조물진단유지관리공학회 (Korea Institute for Structural Maintenance Inspection)
권호 표지
DOI QR코드

DOI QR Code

염해 실태조사를 통한 철근 콘크리트 교각의 내구수명 평가 - 결정론적 및 확률론적 해석방법

Evaluation of Service Life in RC Column under Chloride Attack through Field Investigation: Deterministic and Probabilistic Approaches

  • 권성준 (한남대학교 건설시스템 공학과)
  • 투고 : 2015.04.24
  • 심사 : 2015.06.10
  • 발행 : 2015.09.01
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

콘크리트 구조물은 경제적이고 내구적인 구조물이지만 철근부식에 따라 성능이 내구적, 구조적 저하하게 된다. 최근들어 내구성설계가 도입되고 있는데, 콘크리트 구조물의 내구수명은 해수에 같이 노출되더라도, 국부적인 노출환경과 설계방법에 따라 다르게 평가된다. 본 연구는 3.5년~4.5년 해수에 노출된 4개의 RC 교각을 대상으로 실태조사를 수행하여 25개의 콘크리트 코어를 채취하였으며, 전염화물을 평가하여 표면염화물량 및 겉보기 확산계수를 도출하였다. Fick's $2^{nd}$ Law를 기본으로 한 결정론적 방법과 임계확률을 고려한 확률론적인 방법을 수행하여 내구수명을 각각 평가하고 분석하였다. 확률론적인 방법은 보수적으로 평가되었으며, 같은 구조물이라 하더라도 간만대 및 40.0 m 이상의 비말대에서는 비교적 낮은 내구수명이 평가되었다. 본 연구에서는 코어채취높이에 따른 염화물 거동 분석과 내구성 설계방법의 현시점에서의 한계성이 분석되었다.

RC (Reinforced Concrete) structures are considered as cost-benefit and durable however performances of structural safety and durability are degraded due to steel corrosion. Service life in RC structure is differently evaluated due to different local environmental conditions even if it is exposed to the same chloride attack. In the paper, 25 concrete cores from field investigation are obtained from 4 RC columns with duration of 3.5~4.5 years exposed to sea water. Through total chloride content measurement, surface chloride contents and apparent diffusion coefficients are evaluated. Service life of the target structure is estimated through deterministic method based on Fick's $2^{nd}$ Law and probabilistic method based on durability failure probability, respectively. Probability method is evaluated to be more conservative and relatively decreased service life is evaluated in tidal zone and splash zone over 40.0 m. Chloride penetration behavior with coring location from sea level and the present limitations of durability design method are investigated in the paper.

키워드

참고문헌

  1. Broomfield, J.P., Corrosion of Steel in Concrete: Understanding, Investigation and Repair, E&FN, 1977, pp.1-15.
  2. RILEM, Durability Design of Concrete Structures, Report of RILEM Technical Committee 130-CSL, E&FN, 1994, pp.28-52.
  3. CEB-FIP, Model Code for Service Life Design, The International Federation for Structural Concrete (fib), Task Group 5.6, 2006, pp.16-33.
  4. Thomas MDA, Bentz EC, $life-365^{TM}$ Service Life Prediction $Model^{TM}$ and Computer program for predicting the service life and life-cycle costs of reinforced concrete exposed to chlorides, SFA, 2002.
  5. ACI Committee 201, Guide to durable concrete, Manual of Concrete Practice Part 1. Detroit USA: American Concrete Institute, 1994.
  6. Korea Concrete Institute, Concrete standard specification durability part, 2004.
  7. JSCE-Concrete committee, Standard specification for concrete structures, 2002.
  8. Park, S.S., Kwon, S.-J., Jung, S.H., Lee, S.W., "Modeling of water permeability in early aged concrete with cracks based on micro pore structure," Construction and Building Materials, 27(1), 2012, pp.597-604. https://doi.org/10.1016/j.conbuildmat.2011.07.002
  9. Park, S.S., Kwon, S.-J., Jung, S. H., "Analysis technique for chloride penetration in cracked concrete using equivalent diffusion and permeation", Construction and Building Materials, 29(2), 2012, pp.183-192. https://doi.org/10.1016/j.conbuildmat.2011.09.019
  10. Song, H.-W., Kwon, S.-J., "Evaluation of chloride penetration in high performance concrete using neural network algorithm and micro pore structure,"Cement and Concrete Research, 39(9), 2009, pp.814-824. https://doi.org/10.1016/j.cemconres.2009.05.013
  11. Kwon, S.-J., Kim, S.C., "Concrete mix design for service life of RC structures exposed to chloride attack," Computers and Concrete, 10(6), 2012, pp.587-607. https://doi.org/10.12989/cac.2012.10.6.587
  12. Maekawa, K., Ishida, T., Kishi, T., "Multi-Scale Modeling of Concrete Performance," Journal of Advanced Concrete Technology, 1(2), 2003, pp.91-126. https://doi.org/10.3151/jact.1.91
  13. Maekawa, K., Ishida, T., Kishi, T., "Multi-Scale Modeling of Structural Concrete," Tylor&Francis, London and Newyork, 1st Edition, 2003, pp.291-352.
  14. Song, H.-W., Pack, S.W., Lee, C.H., Kwon, S.-J., Service life prediction of concrete structures under marine environment considering coupled deterioration," Journal of Restoration Buildings and Monuments, 1(2), 2006, pp.265-284.
  15. Yokozeki, K., Okada, K., Tutsumi, T., Watanabe, K., "Prediction of the service life of RC with crack exposed to chloride attack," Journal of Symposium: Rehabilitation of Concrete Structure, 10, 1998, pp.1-6.
  16. DuraCrete Final Report, DuraCrete Probabilistic Performance based Durability Design of Concrete Structures, 2000.
  17. Kwon, S.-J., Na, U.J., Park, S.S., Jung, S.H., "Service life prediction of concrete wharves with early-aged crack: probabilistic approach for chloride diffusion,"Structural Safety, 31(1), 2009, pp.75-83. https://doi.org/10.1016/j.strusafe.2008.03.004
  18. Kwon, S.-J., Park, S.S., "A study on estimation for chloride diffusivity in cracked concrete in harbor structures through field survey," Journal of KSCE, 27(5A), 2007, pp.745-752.
  19. AASHTO T260, Standard Method of Test for Sampling and Testing for Chloride Ion in Concrete and Concrete Raw Materials, 1997, pp.25-32.
  20. EN 1991, Eurocode 1: Basis of design and actins on structures, CEN, 2000, pp.12-18.
  21. Song, H.-W., Pack, S.W., Ann, K.Y.,"Probabilistic assessment to predict the time to corrosion of steel in reinforced concrete tunnel box exposed to sea water," Construction and Building Materials, 23(10), 2009, pp.3270-3278. https://doi.org/10.1016/j.conbuildmat.2009.05.007