Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
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Experiment of Flexural Behavior of Composite Beam with Steel Fiber Reinforced Ultra High Performance Concrete Deck and Inverted-T Steel Girder

강섬유로 보강된 초고성능 콘크리트 바닥판과 역T형 강거더 합성보의 휨거동 실험

  • Yoo, Sung-Won (Department of Civil and Environmental Engineering, Woosuk University) ;
  • Ahn, Young-Sun (Department of Civil and Environmental Engineering, Woosuk University) ;
  • Cha, Yeong-Dal (Department of Civil and Environmental Engineering, Woosuk University) ;
  • Joh, Chang-Bin (Structural Engineering Research Division, Korea Institute of Construction Technology)
  • 유성원 (우석대학교 토목환경공학과) ;
  • 안영선 (우석대학교 토목환경공학과) ;
  • 차영달 (우석대학교 토목환경공학과) ;
  • 조창빈 (한국건설기술연구원 인프라구조연구실)
  • Received : 2014.08.18
  • Accepted : 2014.09.03
  • Published : 2014.12.31
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Abstract

Ultra high performance concrete (UHPC) has been developed to overcome the low strengths and brittleness of conventional concrete. Considering that UHPC, owing to its composition and the use of steel fibers, develops a compressive strength of 180 MPa as well as high stiffness, the top flange of the steel girder may be superfluous in the composite beam combining a slab made of UHPC and the steel girder. In such composite beam, the steel girder takes the form of an inverted-T shaped structure without top flange in which the studs needed for the composition of the steel girder with the UHPC slab are disposed in the web of the steel girder. This study investigates experimentally and analytically the flexural behavior of this new type of composite beam to propose details like stud spacing and slab thickness for further design recommendations. To that goal, eight composite beams with varying stud spacing and slab thickness were fabricated and tested. The test results indicated that stud spacing running from 100 mm to 2 to 3 times the slab thickness can be recommended. In view of the relative characteristic slip limit of Eurocode-4, the results showed that the composite beam developed ductile behavior. Moreover, except for the members with thin slab and large stud spacing, most of the specimens exhibited results different to those predicted by AASHTO LRFD and Eurocode-4 because of the high performance developed by UHPC.

인장강도 및 휨강도가 낮고 취성파괴의 특성을 가지는 일반적인 콘크리트의 단점을 극복하기 위하여 최근에는 압축강도가 180 MPa이상인 고성능 콘크리트에 강섬유를 혼입한 강섬유 보강 초고성능 콘크리트(UHPC)에 대한 연구가 활발히 진행되고 있다. UHPC 바닥판과 강재 거더를 이용하여 합성보를 구성할 때, UHPC 바닥판의 높은 강도와 강성으로 인하여 강재거더 상부 플랜지의 역할이 거의 불필요할 것으로 예상된다. 이러한 점을 착안하여 본 논문에서는 합성보 구성 시에 강재 거더의 상부플랜지를 없앤 역T형 거더를 적용하였다. 역T형 거더에 UHPC바닥판을 합성하여 합성보를 구성할 경우, 상부플랜지가 없는 이유로 전단연결재의 설치 위치가 상부플랜지 대신에 강재 거더 복부에 설치해야하는 문제점이 발생되며, 강재 복부에 설치되는 전단연결재에 대한 거동, 역T형 강거더 합성보의 휨거동 특성 등은 현재까지 실험 및 이론적으로 평가된 적이 거의 없는 실정인 이유로 이에 대한 연구가 절실하다. 이를 위하여 본 논문에서는 전단연결재 간격, 바닥판 두께 등을 변수로 하여 역T형 거더와 UHPC바닥판을 합성한 합성보를 8개 제작하여 전단연결재의 거동, 휨거동 특성 등을 파악하고자 하였다. 실험결과를 기준으로 볼 때, 향후 UHPC의 경우 스터의 간격은 100 mm에서 바닥판 두께의 2~3 배 사이로 규정함이 적절할 것으로 예상된다. 또한 실험 부재의 특성 상대변위는 Eurocode-4의 연성거동 기준에 의하면 충분한 연성 거동을 하는 것으로 판정되었으며, 바닥판이 지나치게 얇고 전단연결재의 간격이 지나치게 넓은 경우를 제외한 대부분의 부재들은 일반 콘크리트보다 UHPC의 성능이 우수하여 기존의 AASHTO LRFD 및 Eurocode-4의 식과 실험결과간의 차이가 있음을 알 수 있다.

Keywords

References

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Cited by

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  2. A Study on the Experiment of Flexural Behavior of Composite Beam with Steel Fiber Reinforced UHPC and Inverted-T Steel Considering Compressive Strength Level vol.27, pp.6, 2015, https://doi.org/10.4334/JKCI.2015.27.6.677
  3. Structural Design of Ultra High-Strength Concrete Non-Uniform Truss Using Strut-Tie Approach vol.18, pp.2, 2018, https://doi.org/10.9712/KASS.2018.18.2.69