Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
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Flexural Strength and Deflection Evaluation for FRP Bar Reinforced HSC Beams with Different Types of Reinforcing Bar and Fiber

이질 보강근 및 섬유와 함께 보강된 FRP 보강근 보강 고강도 콘크리트 보의 휨 강도 및 처짐 평가

  • Yang, Jun-Mo (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Yoo, Doo-Yeol (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Shin, Hyun-Oh (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Yoon, Young-Soo (School of Civil, Environmental and Architectural Engineering, Korea University)
  • 양준모 (고려대학교 건축사회환경공학부) ;
  • 류두열 (고려대학교 건축사회환경공학부) ;
  • 신현오 (고려대학교 건축사회환경공학부) ;
  • 윤영수 (고려대학교 건축사회환경공학부)
  • Received : 2010.12.02
  • Accepted : 2011.02.15
  • Published : 2011.08.31
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Abstract

The test results of high-strength concrete beam specimens, which have various combinations of different types of flexural reinforcement and short fibers, were compared with the prediction results of codes, guidelines and models proposed by researchers. The theoretical calculation based on the ultimate strength method of the KCI and ACI Code underestimated the ultimate moments of FRP bar-reinforced beams without fibers. The models proposed by ACI 544.4R and Campione predicted the ultimate moment capacities inaccurately for the FRP bar-reinforced beam with steel fibers, because these models do not consider the increased ultimate compressive strain of fiber reinforced concrete. Bischoff's deflection model predicted the service load deflections reasonably well, while the deflection model of ACI Committee 440 underestimated the deflection of FRP bar-reinforced beams. Because the ACI 440 expression, used to predict member deflection, cannot directly apply to the beams reinforced with different types of reinforcing bars, an alternative method to estimate the deflections of beams with different types of reinforcing bars using the ACI 440 expression was proposed. In addition, Bischoff's approach for computing deflection was extended to include deflection after yielding of the steel reinforcement in the beams reinforced with steel and FRP bars simultaneously.

휨 보강근의 종류 및 조합, 섬유 혼입을 변수로 하는 고강도 콘크리트 보의 구조 실험 결과를 균열 모멘트, 극한 모멘트, 처짐 등에 대해 각종 설계기준 및 가이드라인, 여러 연구자들에 의한 예측식과 비교 검토하였다. 섬유를 혼입하지 않은 FRP 보강근 보강 보의 극한 모멘트 이론값은 실험값을 과소평가하였다. 강섬유가 혼입된 FRP 보강근보강보에 대한 ACI 544.4R, Campione의 모델은 섬유 보강 콘크리트의 증가된 극한 압축 변형률을 고려하지 않고 있어 극한 모멘트를 부정확하게 예측하였다. 섬유가 혼입되지 않은 부재에 대해 Bischoff의 처짐 모델은 섬유가 혼입되지 않은 부재들의 사용 하중 하에서의 처짐을 정확하게 예측한 반면, ACI 440 위원회 모델은 사용 하중 하에서의 처짐을 비보수적으로 예측하였다. 이질 보강근이 동시에 적용된 부재에 대해 Bischoff 모델과는 달리 ACI 440 위원회의 처짐 모델은 직접적인 적용이 불가능하기 때문에 ACI 440 위원회 식을 이용하여 이질 보강근이 동시에 적용된 부재의 처짐을 예측하는 방법을 제안하였다. 또한 철근과 FRP 보강근이 동시에 보강된 보에서 철근이 항복한 이후의 처짐을 예측할 수 있는 방법을 제안하였다.

Keywords

References

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