Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
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Shear Behavior of Reinforced Concrete Beams Strengthened with Unbonded-Type Wire Rope Units

비 부착형 와이어로프로 보강된 철근콘크리트 보의 전단 거동

  • Published : 2007.02.28
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Abstract

The present study reports a simple unbonded-type shear strengthening technique for reinforced concrete beams using wire rope units. Fifteen beams failed in shear were repaired and strengthened with wire rope units, and then retested to failure. Influence of the prestressing force, orientation and spacing of wire rope units on the shear behavior of strengthened beams having shear span-to-depth ratios of 1.5, 2.5, or 3.25 were investigated. Test results showed that beams strengthened with wire rope units exhibited a higher shear strength and a larger post-failure deformation than the corresponding original beams. Inclined wire rope units was more effective for shear strength enhancement than vertical wire rope units. The increase of the prestressing force in wire rope units causes the decrease of the principal tensile stress in concrete, as a result, the diagonal tensile cracking strength of strengthened beams was higher than that of the corresponding original beams. Shear capacity of strengthened beams is compared with predictions obtained from ACI 318-05 and EC 2. Shear capacity of strengthened beams having shear span-to-depth ratio below 2.5 is reasonably predicted using ACI 318-05 formula. On the other hand, EC 2 overestimates the shear transfer capacity of wire rope units for beams having shear span-to-depth ratio above 2.5.

본 연구에서는 와이어로프 단위를 이용한 철근콘크리트 보의 비 부착형 보강 공법을 제시하였다. 전단에서 파괴된 15개의 보가 제시된 보강 공법에 의해 보수, 보강 된 후 재 실험되었다. 주요 변수는 전단경간비, 와이어로프 단위의 초기 프리스트레스력, 배근 방법 및 간격이다. 실험 결과 제시된 와이어로프로 보강된 보들의 전단강도와 파괴 후 연성 거동이 원래 보의 것들에 비해 매우 향상되었다. 또한 수직 와이어로프보다는 경사 와이어로프가 내력 향상에 유리하였으며 와이어로프에 작용된 초기 프리스트레스의 증가는 콘크리트 스트럿에서 주 인장응력의 크기를 감소시킴으로서 사인장 균열내력을 향상시켰다. 보강된 보의 전단내력과 ACI 318-05 및 EC 2 설계기준과의 비교로부터 전단경간비 2.5 이하의 보강된 보들의 전단내력은 ACI 318-05 기준에 의해 적절히 평가될 수 있었다. 한편 EC 2는 전단경간비 2.5 이상인 보강된 보들에서 와이어로프의 전단 전달 능력을 과대평가하였다.

Keywords

References

  1. AI-Sulaimani, Gf., Sharif, A., Basunbul, LA., Baluch, M.H., and Ghaleb, B.N., 'Shear Repair of Reinforced Concrete by Fiberglass Plate Bonding', ACI Structural Journal, VoI.91, No.3, 1994, pp.458-464
  2. BasunbuI. LA., Sharif, A.M., Al-Sulaimani, GJ., and BaIuch, M.H., 'Repair of Shear Cracked RC Beams with Bonded External Steel Plates', Proceedings of the ICSF 93, Fourth International Conference on Structural Failure and Retrofitting, Singapore, July 1993, pp.629-634
  3. Islam, M.R., Mansur, M.A., and Maalej, M., 'Shear Strengthening of RC Deep Beams using Externally Bonded FRP System', Cement & Concrete Composites, Vol.27, 2005, pp.413-420 https://doi.org/10.1016/j.cemconcomp.2004.04.002
  4. Malek, M. and Saadatmanesh, H., 'Ultimate Shear Capacity of Reinforced Concrete Beams Strengthened with WebBonded Fiber-Reinforced Plastic Plates', ACI Structural Journal, VoI.95, No.4, 1998, pp.391-399
  5. Paramasivam, P., Ong. K.C.G, and Lim, C.T.E., 'Repair of Damaged RC Beams using Ferroccment Laminates', Proceedings of ICSF 93, Fourth International Conference on Structural Failure and Retrofitting, Singapore, July 1993, pp.613-620
  6. Triantafillou, T.C., 'Shear Strengthening of Reinforced Concrete Beams Using Epoxy-Bonded FRP Composites', ACI Structural Journal, Vol.95, No.2, 1998, pp.107-115
  7. Teng, S., Kong, F. K., Poh, S. P., Guan, L. W., and Tan, K. H., 'Performance of Strengthened Concrete Deep Beams Predamaged in Shear', ACI Structural Journal, Vol.93, No.2, 1996, pp.159-171
  8. 양근혁, 김선영, 변항용, 정헌수, '전단파괴 된 개구부를 갖는 연속 깊은 보의 외부 강연선 보강에 의한 역학적 거동', 대한건축학회논문집, 22권 2호, 2006, pp.67-74
  9. ACI Committee 318: Building Code Requirements for Structural Concrete(ACI 318-05) and Commentary(ACI 318R-05), American Concrete Institute, 2005
  10. The European Standard EN 1992-1-1 :2004, Eurocode 2: Design of Concrete Structures, British Standards Institution, 2004
  11. Bickford, J. H., An Introduction to the Design and Behavior of Bolt Joints, Marcel Dekker INC., 1990
  12. Raoof, M. and Kraincanic, I., 'Analysis of Large Diameter Steel Ropes', Journal of Engineering Mechanics, ASCE, Vol.121, No.6, 1995, pp.667-675 https://doi.org/10.1061/(ASCE)0733-9399(1995)121:6(667)