Journal of the Korea institute for structural maintenance and inspection (한국구조물진단유지관리공학회 논문집)

Korea Institute for Structural Maintenance Inspection (한국구조물진단유지관리공학회)
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A Study on Static and Fatigue Behavior of Restrained Concrete Decks without Rebar by Steel Strap

Steel Strap으로 횡구속된 무철근 바닥판의 정적 및 피로거동 특성 연구

  • 조병완 (한양대학교 건설환경공학과) ;
  • 김철환 (포스코건설, 한양대학교 건설환경공학과)
  • Received : 2012.06.18
  • Accepted : 2012.08.16
  • Published : 2012.09.30
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Abstract

In the steel-free bridge concrete deck, steel straps are generally used instead of conventional steel rebar while laterally restrained in the perpendicular direction to the traffic in order fir the arching effect of concrete deck. In this paper, the minimum amount of FRP bar is to be suggested based on the structural strength, crack propagation, stress level and others in order to control cracks. As a result of laboratory tests, the structural strength of deck with 0.15 percentage of steel strap showed improved structural strength including ductility. The long-term serviceability of steel strap deck with FRP bar proved to satisfy the requirements and to be structurally stable while showing the amount of crack and residual vertical displacement within the allowable limits after two million cyclic loadings. The structural failure of RC bridge deck is generally caused from the punching shear rather than moment. Therefore, the ultimate load at failure could be estimated using the shear strength formula in the two-way slab based on ACI and AASHTO criteria. However the design criteria tend to underestimate the shear strength since they don't consider the arching effects and nonlinear fracture in bridge deck with lateral confinement. In this paper, an equation to estimate the punching shear strength of steel strap deck is to be developed considering the actual failure geometries and effect of lateral confinement by strap while the results are verified in accordance with laboratory tests.

무철근 교량 바닥판은 콘크리트 내부의 철근을 없애고 거더를 Strap으로 횡구속시켜 Arching action을 극대화시킨 교량 바닥판이다. 본 연구에서는 무철근 바닥판의 균열제어를 목적으로 FRP bar의 배치량을 변수로 하여 내하력과 균열, 연성도, 파괴시 응력수준 등을 판단하여 FRP bar 최소 배치량을 제시하였다. 실험결과 Steel strap 무철근 바닥판은 최소 0.15% FRP 보강근만 배치하여도 내하력과 연성이 확연히 향상됨을 확인하였다. FRP bar를 보강한 무철근 바닥판에 대하여 피로실험을 수행하였으며 200만회 반복하중 재하후 균열, 잔류 처짐 등에서 장기 사용성에 문제가 없음을 확인하였다. 교량 바닥판은 대체로 펀칭전단 파괴를 하며 2방향 슬래브의 전단강도식을 적용할 수 있으나 ACI, AASHTO 등에서는 바닥판의 비선형 파괴형상과 횡구속에 의한 Arching 효과를 명확히 고려하지 못하기 때문에 실제 파괴강도보다 과소평가 한다. 본 연구에서는 Steel strap 바닥판의 실제 파괴형상과 Strap에 의한 횡구속도를 고려한 펀칭전단강도식을 제안하였으며 이는 실험결과와도 비교적 잘 일치하는 결과를 보여주었다.

Keywords

References

  1. 국토해양부, 도로교설계기준, 한국도로교통협회, 2010.
  2. 이용우, 황훈희, "단순트러스 모델에의한 철근콘크리트 교량 바닥판의 펀칭전단강도", 대한토목학회논문집, 제28권 2A호, 2008, pp.187-196.
  3. 조창빈, 김병석, 황훈희, 최경규, 최석환, "UHPC 바닥판 슬래브의 뚫림전단강도", 구조물진단학회지, 제15권 4호, 2011, pp.221-231.
  4. 한국콘크리트학회, 콘크리트구조설계기준, Sect. 5.7.2, 2007.
  5. ACI Innovation Task Group 3, "Report on Bridge Decks Free of Steel Reinforcement", ACI, ITG-3-10, 2004.
  6. Azad, A. K., Baluch, M. H., Abbasi, M. S. and Kaiser, K., "Punching Capacity of Deck Slabs in Girder-Slab Bridges", ACI Structural Journal, vol. 91, No. 6, 1994, pp.656-662.
  7. Bakht, B. and Mufti, A., "FRC Deck Slabs Without Tensile Reinforcement", Concrete International, 1996, pp.50-55.
  8. Canadian Highway Bridge Design Code(CHBDC), Section 16, Fibre-Reinforced Structures, 1998, pp.688-706.
  9. Graddy, J. C., Kim, J., James, H., Whitt, N., Burns, N. H. and Klingner, R. E., "Punching Shear Behavior of Bridge Decks under Fatigue Loading", ACI Structural Journal, vol. 99, No. 3, 2002, pp.257-266.
  10. Hassan, T. K., Rizkalla, S. H., "Punching Shear strength of GFRP Reinforcing Deck Slabs in Slab-Girder Bridges", 4th International Conference on Advanced Composite Materials in Bridges and Structures, 2004.
  11. Khanna, O. S., Mufti, A. A. and Bakht, B., "Experimental Investigation of the Role of Reinforcement in the Strength of Concrete Deck Slabs", Canadian Journal of Civil Engineering, vol. 27, No. 3, 2000, pp.475-480. https://doi.org/10.1139/l99-094
  12. Kinnunen, S. and Nylander, H., "Punching of Concrete Slabs without Shear Reinforcement", Transactions 158, Royal Institution of Technology, Stockholm, No. 158, 1960.
  13. Maeda, Y. & Matsui, S., "Punching Shear Equation of Reinforced Concrete Slabs", Journal of JSCE, No. 348/V-1, 1984, pp.133-141 (in Japanese).
  14. Mufti, A. A., Bakht, B. and Newhook J. P., "Precast Concrete Decks for Slab-on-Girder System : A New Approach", ACI Structural Journal, vol. 101, No. 3, May-June, 2004, pp.395-402.
  15. Mufti, A. A., Newhook, J. P., "Punching Shear Strength of Restrained Concrete Bridge Deck Slabs", ACI Structural Journal, vol. 95, No. 4, July-August, 1998, pp.375-p381.
  16. Muttoni, A., "Punching Shear Strength of Reinforced Concrete Slabs without Transverse Reinforcement", ACI Structural Journal, vol. 105, No. 4, 2008, pp.440-450.
  17. Salem, A. H., El-Aghoury, M., A., Moustafa, T. S. and Ezzeldin Y., "Finite Element Modelling of Composite Steelree Deck Bridges", Development in Sort and Medium Span Bridge Engineering, 2002, pp.57-64.
  18. Sukrawa, M., "Retrofitting Bridge Decks Using Additional Lateral Restraints(An Experimental Investigation)", Symposium ke-4 FSTPT, Udayana Bail, 2 November, 2001, pp.1-11.
  19. Youn, S. G., Chang, S. P., "Behavior of Composite Bridge Decks Subjected to Static and Fatigue Loading", ACI Structural Journal, vol. 95, No. 3, 1998, pp.249-258.

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  1. Design Equation Suggestion through Parametric Study of Laterally Restrained Concrete Decks with Steel Strap vol.18, pp.3, 2014, https://doi.org/10.11112/jksmi.2014.18.3.049