Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
권호 표지
DOI QR코드

DOI QR Code

Development and Splice Lengths of FRP Bars with Splitting Failures

쪼갬파괴에 의한 FRP 보강근의 정착길이와 이음길이

  • Received : 2010.02.01
  • Accepted : 2010.04.07
  • Published : 2010.08.31
Download PDF
⟨ Previous Next ⟩

Abstract

Data from beam-based bond tests for FRP bars in the literature were collected and regression analyses were conducted for the data of splitting failure. Average bond strengths obtained from splice tests were found to be lower and more affected by C/$d_b$ values than average bond strengths from anchorage tests, indicating needs of new design equation for the splice length of FRP bars based on the data of splice tests only. In addition, the variation of bond strengths was greater than that of tensile strengths of FRP bars and, therefore, a new safety factor should be involved for the design equation. Five percent fractile coefficients were used to develop the design equations based on the assumption that load and resistance factors for FRP reinforced concrete structures are same to the factors for steel reinforced concrete structures. The proposed design equations give economical and reliable lengths for development and splice of FRP bars. The proposed equation for splice provides shorter lengths than the ACI 440 equation in case of C/$d_b$ of 3.0 or greater. Because FRP bars are expected to be used in slabs and walls exposed to weather with thick cover and large spacing between bars, the proposed equation gives optimal splice lengths.

FRP 보강근의 정착과 이음에 대한 국내외 실험을 수집하고, 정착과 이음실험을 분리한 회귀분석을 통해 쪼갬파괴에 의한 정착길이 설계식과 이음길이 설계식을 제안하였다. 이음실험에 의한 평균 부착강도는 정착실험에 의한 평균 부착강도에 비해 낮으며, C/$d_b$에 크게 영향을 받는 것으로 평가되었다. 따라서 합리적인 이음길이 설계를 위해 이음실험만으로 구성된 데이터에 근거한 이음길이 설계식을 개발할 필요가 있다. 또한 부착강도의 분산(分散)이 FRP 보강근의 인장강도 분산에 비해 크므로, 정착길이와 이음길이 설계식에 이를 반영한 안전율이 요구된다. 이 연구에서는 FRP 보강 콘크리트 구조물의 하중계수와 강도감소계수가 철근콘크리트구조와 동일하다는 조건에서, 철근 품질관리에 적용되는 5% 분위수를 이용하여 경제적이면서 신뢰성 높은 정착길이와 이음길이 설계식을 개발하였다. 제안된 이음길이 설계식은 정착실험을 중심으로 개발된 ACI 440 설계식보다 C/$d_b$의 영향을 정확하게 반영하여, C/$d_b$가 3.0 이상인 경우 ACI 440보다 짧은 이음길이가 산정된다. FRP 보강근이 주로 활용될 것으로 기대되는 외기에 노출된 슬래브와 벽체의 배근 특성을 고려하면 이 연구에서 제안된 설계식은 매우 경제적인 이음길이 설계를 가능하게 한다.

Keywords

References

  1. 최동욱, 천성철, 하상수, “RC부재 휨 실험에 의한 GFRP 보강근의 이음길이 제안,” 콘크리트학회 논문집, 21권, 1호, 2009년 2월, pp. 65-74. https://doi.org/10.4334/JKCI.2009.21.1.065
  2. 최동욱, 하상수, 이창호 “인발실험에 의한 GFRP 보강근의 정착길이 제안,” 콘크리트학회 논문집, 19권, 3호, 2007년 6월, pp. 323-331.
  3. 한국건설기술연구원, “FRP 복합재료 보강재 개발 및 이를 활용한 콘크리트 구조물 건설기술 개발,” 1차년도 최종 보고서, 2004, 19 pp.
  4. 한국건설기술연구원, “FRP 복합재료 보강재 개발 및 이를 활용한 콘크리트 구조물 건설기술 개발,” 2차년도 최종 보고서, 2005, 784 pp.
  5. fib, “FRP Reinforcement in RC Structures,” Bulletin 40, 2007, 147 pp.
  6. ACI Committee 440, “Guide for the Design and Construction of Structural Concrete Reinforced with FRP Bars (ACI 440.1R-06),” American Concrete Institute, Farmington Hills, Mich., USA, 2006, 44 pp.
  7. CAN/CSA S806-02, “Design and Construction of Building Components with Fibre-Reinforced Polymers,” Canadian Standard Association, Rexdale, Ontario, Canada, 2002, 177 pp.
  8. Japan Society of Civil Engineers (JSCE), “Recommendations for Design and Construction of Concrete Structures Using Continuous Fiber Reinforcing Materials,” Concrete Engineering Series 23, Japan, 1997, 311 pp.
  9. Wambeke B. W. and Shield C. K., “Development Length of Glass Fiber-Reinforced Polymer Bars in Concrete,” ACI Structural Journal, American Concrete Institute, Vol. 103, No. 1, 2006, pp. 11-17.
  10. ACI Committee 408, “Bond and Development of Straight Reinforcing Bars in Tension (ACI 408R-03),” American Concrete Institute, Farmington Hills, Mich., USA, 2003, 49 pp.
  11. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318M-08) and Commentary,” American Concrete Institute, Farmington Hills, Mich., USA, 2008, 465 pp.
  12. Orangun, C. O., Jirsa, J. O., and Breen, J. E., “A Reevaluation of Test Data on Developoment Length and Splices,” ACI Journal, Proceedings, Vol. 74, No. 3, 1977, pp. 114-122.
  13. 천성철, 최동욱, 하상수, 오보환, “인장 겹침이음에서 프라이 거동의 영향,” 한국콘크리트학회 봄학술대회 논문집, 2008, pp. 1085-1088.
  14. Wambeke, B. W., “Development Length of Glass Fiber Reinforced Polymer Bars in Concrete,” MS thesis, University of Minnesota, Minneapolis, Minn., USA, 2003, 85 pp.
  15. Ehsani, M. R., Saadatmanesh, H., and Tao, S., “Design Recommendations for Bond of GFRP Rebars to Concrete,” Journal of Structural Engineering, Vol. 122, No. 3, 1996, pp. 247-254. https://doi.org/10.1061/(ASCE)0733-9445(1996)122:3(247)
  16. Daniali, S., “Development Length for Fiber-Reinforced Plastic Bars,” Advanced Composite Materials in Bridges and Structures, K. W. Neale and P. Labossiere, Eds., Sherbrooke, Canada, 1992, pp. 179-188.
  17. Shield, C. K., French, C., and Retika, A., “Thermal and Mechanical Fatigue Effects on GFRP Rebar-Concrete Bond,” Non-metallic (FRP) Reinforcement for Concrete Structures, Proceedings of the Third International Symposium on Non-Metallic Reinforcement for Concrete Structures, Sapporo, Japan, 1997, pp. 381-388.
  18. Shield, C., French, C., and Hanus, J., “Bond of GFRP Rebar for Consideration in Bridge Decks,” Fiber Reinforced Polymer Reinforcement for Reinforced Concrete Structures, Fourth International Symposium, SP-188, C. W. Dolan, S. H. Rizkalla, and A. Nanni, eds., American Concrete Institute, Farmington Hills, Mich., USA 1999, pp. 393-406.
  19. Tighiouart, B., Benmokrane, B., and Mukhopadhyaya, P., “Bond Strength of Glass FRP Rebar Splices in Beam under Static Loading,” Construction and Building Material, Vol. 13, No. 7, 1999, pp. 383-92. https://doi.org/10.1016/S0950-0618(99)00037-9
  20. Mosley, C. P., Tureyen, A. K., and Frosch, R. J., “Bond Strength of Nonmetallic Reinforcing Bars,” ACI Structural Journal, Vol. 105, No. 5, 2008, pp. 634-642.
  21. 園部 泰寿, 藤沢 正視, 金久保利之, 米丸 啓介,“連続纖 維による補コンクリ一ト部材の付着性状(その4: 片持ばり部材の主筋鉄筋の場合の付着強度),” 日本建築學會 學術講演梗概集, 構造II, 1991, pp. 843-844.
  22. Aly, R., Benmokrane, B., and Ebead, U., “Tensile Lap Splicing of Fiber-Reinforced Polymer Reinforcing Bars in Concrete,” ACI Structural Journal, Vol. 103, No. 6, 2006, pp. 857-864.
  23. Hognestad, E., “A Study of Combined Bending and Axial Load in Reinforced Concrete Members,” Bulletin Series No. 399, University of Illinois Engineering Experiment Station, Urbana, Ill, USA, 1951, 128 pp.
  24. KS D 3504 : 2007, 철근 콘크리트용 봉강, 산업자원부 기술표준원, 2009, 30 pp.
  25. ISO 6935-2 Steel for the Reinforcement of Concrete - Part 2: Ribbed Bars-Second Edition, International Organization for Standardization, 2007, 20 pp.
  26. Natrella, M. G., Experimental Statistics, National Bureau of Standards Handbook 91. 1966.
  27. Thompson, M. K., Jirsa, J. O., and Breen, J. E., “Behavior and Capacity of Headed Reinforcement,” ACI Structural Journal, Vol. 103, No. 4, 2006, pp. 522-530.