Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
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An Experimental Study on the Shear Behavior of RC Beams Strengthened with Near Surface Mounted and Externally Bonded CFRP Strips

표면매입 및 외부부착 탄소섬유판으로 보강된 철근콘크리트 부재의 전단 거동에 관한 실험적연구

  • 임동환 (동서대학교 건축토목공학부 토목공학) ;
  • 권영순 (재신건설(주))
  • Published : 2009.06.30
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Abstract

The purpose of this study is to investigate the shear strengthening effectiveness of the beams strengthened with near surface mounted (NSM) and external bonded (EB) CFRP strips. A total of nine concrete beams were made and tested. From this study, it was found that the shear stiffness and strength of the beams strengthened with NSM and EB strips were significantly improved compared to the control beam. Failure of the beam strengthened with NSM and EB strips was initiated by shear cracks, propagated diagonally to the adjacent epoxy grooves without crossing the epoxy and finally sudden diagonal crack connecting the point of application of load and flexural crack was occurred. For the beam strengthened combined with NSM and EB CFRP strips, the tensile strains in the NSM CFRP strips were observed in the range of 0.35% to 0.45% and strains with EB strips were measured about 0.3%.

본 연구에서는 탄소섬유판이 외부 부착, 표면 매입 그리고 외부부착 및 표면매입이 혼합된 보강 방식의 철근콘크리트 부재의 전단 거동 및 전단 보강 효과를 구명하고자 하였다. 본 연구 결과, 표면매입 탄소섬유판 및 외부부착과 표면매입으로 혼용된 탄소섬유판으로 보강된 철근콘크리트 보의 전단 강성 및 극한 전단강도는 섬유판으로 보강되지 않은 보에 비하여 크게 증진되는 것으로 나타났다. 표면매입 탄소섬유판 및 외부부착과 표면매입으로 혼용된 탄소섬유판으로 보강된 철근콘크리트 보의 파괴는 전단균열로 시작되었으며, 하중이 증가함에 따라 하중 재하점과 가장 인접한 매입 탄소섬유판 하단 모서리에서 발생한 휨 균열은 하중재하점 방향으로 급격하게 진행되었고, 하중 재하점과 휨 균열을 연결하는 압축파괴가 발생되었다. 이러한 사실은 매입 섬유판의 전단보강 효과가 매우 우수하여 보가 전단으로 파괴되지 않고 섬유판이 매입 보강되지 않은 휨 구역에서 압축파괴가 발생하고 있음을 설명하고 있다. 매입 탄소섬유판 보강부재 및 탄소섬유판 부착 및 매입을 혼용한 부재에서는 매입 탄소섬유판의 변형률이 각각 0.45% 및 0.35%로 나타났으며, 외부 부착 탄소섬유판의 변형률이 약 0.3%로 나타났다.

Keywords

References

  1. De Lorenzis, L. and Teng, J. G., “Near-Surface Mounted FRP Reinforcement: An Emerging Technique for Strengthening Structures,” ELSEVIER, Composite Part B, Vol. 38, 2007, pp. 119-143 https://doi.org/10.1016/j.compositesb.2006.08.003
  2. Novidis, D., Pantazopoilou, S. J., and Tentoluris, E., “Experimental study of bond of NSM-FRP reinforcement,” ELSEVIER, Construction Building Materials, Vol. 27, 2007, pp. 1760-1770 https://doi.org/10.1016/j.conbuildmat.2006.05.054
  3. Oehlers, D. J., Rashid, R., and Seracino, R., “IC Debonding Resistance of Group of FRP NSM Strips in Reinforced Concrete Beams,” ELSEVIER, Construction and Building Materials, Vol. 22, 2008, pp. 1574-1582 https://doi.org/10.1016/j.conbuildmat.2007.03.021
  4. Oehlers, D. J., Liu, I., and Seracino, R., “A Generic Design Approach for EB and NSM Longitudinally Plated RC Beams,” ELSEVIER, Construction and Building Materials, Vol. 27, 2007, pp. 697-708 https://doi.org/10.1016/j.conbuildmat.2006.06.018
  5. Liu, I., Oehlers, D. J., and Seracino, R., “Test on the Ductility of Reinforced Concrete Beams Retrofitted with FRP and Steel Near Surface Mounted Plates,” ASCE, Composite Construction Journal, Vol. 10, No. 2, 2006, pp. 106-114 https://doi.org/10.1061/(ASCE)1090-0268(2006)10:2(106)
  6. Mohamed Ali, M. S., Oehlers, D. J., Giffith, M. C., and Seracino, R., “Interfacial Stress Transfer of Near Surface Mounted FRP-to-Concrete Joints,” ELSEVIER, Engineering Structure, In Press
  7. Raizal Saifulnaz, M. R., Oehlers, D. J., and Seracino, R., “IC Debonding of FRP NSM and EB Retrofitted Concrete: Plate and Cover Interactions Tests,” ASCE, Composite, In Press
  8. Seracino, R., Raizal Saifulnaz, M. R., and Oehlers, D. J., “Generic Intermediate Crack Debonding Resistance of EB and NSM Plate-to-Concrete Joints,” ASCE, Composite Construction Journal, Vol. 11, No. 1, 2007, pp. 62-70 https://doi.org/10.1061/(ASCE)1090-0268(2007)11:1(62)
  9. 임동환, 남민희, “탄소섬유판 (CFRP strip)으로 보강된 철근콘크리트 부재의 전단거동,” 콘크리트학회 논문집, 20권, 3호, 2008, pp. 299-305 https://doi.org/10.4334/JKCI.2008.20.3.299
  10. 임동환, “ 표면매입 및 외부부착 탄소섬유판으로 보강된 RC보의 휨 거동에 관한 실험연구,” 콘크리트학회 논문집, 20권, 5호, 2008, pp. 601-610 https://doi.org/10.4334/JKCI.2008.20.5.601
  11. 정우태, 박종섭, 박영환, 강재윤, “표면매립보강재를 이용한 철근콘크리트보의 휨보강에 대한 연구,” 대한토목학회논문집, 27권, 1A호, 2007, pp. 27-33
  12. 정우태,박종섭, 박영환, “탄소섬유보강재료 표면매립 보강된 철근콘크리트보의 파괴모드 예측,” 대한토목학회논문집, 28권, 3A호, 2008, pp. 349-356
  13. Barros, J. A. O. and Dias, S. J. E., “Surface Mounted CFRP Laminates for Shear Strengthening of Concrete Beams,” ELSEVIER, Cement & Concrete Composites, Vol. 28, 2006, pp. 276-292 https://doi.org/10.1016/j.cemconcomp.2005.11.003
  14. Nanni, A., Di Ludovico, M., and Parretti, R., “Shear Strengthening of PC Bridge with NSM CFRP Rectangular Bars,” Adv Struct Engr., Vol. 7, No. 4, 2004, pp. 97-109. https://doi.org/10.1260/1369433041653570
  15. Rizzo, A. and De Lolenzis, L., “Behavior and Capacity of RC Beams Strengthened in Shear with NSM FRP Reinforcement,” ELSEVIER, Construction and Building Materials, In Press
  16. ACI Committee 440, Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures, American Concrete Institute, 2005
  17. Fib-Bulletin 14, “Externally Bonded FRP Reinforcement for RC Structures,” Technical Report by Task Group 9.3 FRP (Fiber Reinforced Polymer) Reinforcement for Concrete Structures, Federation Incternationale du Beton-FIB, July, 2001
  18. Sena-Cruz, J. M. and Barros, J. A. O., “Modeling of Bond between Near-Surface Mounted CFRP Laminate Strips and Concrete,” Comput Sturct J, Vol. 82, No. 17, 2004, pp. 1513-1521 https://doi.org/10.1016/j.compstruc.2004.03.047

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