Magazine of the Korea Concrete Institute (콘크리트학회지)

Korea Concrete Institute (한국콘크리트학회)
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Prediction of Deflection of Reinforced Concrete Beams due to Creep

크리프에 의한 철근콘크리트 보의 처짐 예측

  • 이상순 (한국과학기술원 토목공학과박사과정) ;
  • 김용빈 (한려대학교) ;
  • 김진근 (한국과학기술원 토목공학과교수) ;
  • 이수곤 (전남대학교 건축공학과)
  • Published : 1998.12.01
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Abstract

An approximate method for the calculation of creep deflections of reinforced concrete beams under sustained service loads is proposed. The position of neutral axis and strain and stress distribution of fully cracked section after creep is determined from the requirements of strain compatibility and equilibruim of a section and then the long-term flexural rigidity of fully cracked section is determined based on the new neutral axis. The long-term flexural rigidity of uncracked section at the level of the reinforcenment. The approach of calculating long-term effective flexural rigidity and defections is similar to the current American Concrete Institue procedure for calculating effecitve moment of inertia and short-term deflections. The accuracy of the analysis is verified by comparison with several experimental mesurements of beam deflectons. The result is good between the theotetical values and mesured valus.

본 논문에서는 장기지속하중을 받는 철근콘크리트 보의 처짐을 계산하는 방법을 제안하였다. 균열단면에 대하여 적합조건 및 평형조건을 적용하여 크리프에 의한 중립축의 변화를 계산하는 효율적인 알고리즘을 제시하였으며, 이 값을 이용하여 임의의 시간에서의 휨강성을 유도하였다. 그리고 유사한 방법으로 비균열단면에서의 휨강성을 계산하고 균열단면과 비균열단면에서 각각 계산된 휨강성을 사용하여 ACI규준식의 유효단면 2차모멘트를 계산하는 것과 유사한 방법으로 휨강성을 계산하여 지속하중을 받는 철근콘크리트 보의 처짐을 예측하는 방법을 제시하였다. 제안된 방법과 기존의 실험결과를 비교하여 볼 때, 제안된 방법이 장기지속하중을 받는 철근콘크리트보의 처짐을 잘 예측하였다.

Keywords

References

  1. Building Code Requirement for Reinforced Concrete (ACI 318-95) ACI Committee 318
  2. Deformation of Concrete Structure Branson, D. E.
  3. Creep of Plain and Structural Concrete Neville, A. M.;Digler, W. H.;Brooks, J. J.
  4. ACI Journal v.82 no.6 Deflections of Reinforced Concrete Members : A Simple Approach Pretorius, P. C.
  5. Journal of Structural Engineering v.115 no.5 Predicting Deflections of Reinforced Concrete Beams Analytically Samra, R. M.
  6. ACI Structural Journal v.94 no.6 Renewed Assessment of Creep and Shrinkage Effects in Reinforced Concrete Beams Samra, R. M.
  7. Journal of the American Concrete Institute v.63 no.3 Time-dependent deflections of Reinforced concrete Beams Corley, W. G.;Sozen, M. A.
  8. Magazine of Concrete Research v.34 no.121 Long-term Deflections of Reinforced Concrete Beams Bakoss, S. L.;Gilbert, R. I.;Faultkes, K. A.;Pulmano V. A.
  9. Journal of the American Concrete Institute v.49 no.2 Effect of Compressive Reinforcement on the Plastic Flow of Reinforced Concrete Beams Washa, G. W.;Fluck, P. G.
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  11. ACI Material Journal v.85 no.2 New Method to Predict the Creep Deflection of Cracked Reinforced Concrete Flexural Members Clarke, G.;Scholz, H.;Alexander, M.
  12. Journal of the American Concrete Institute v.68 no.8 Compression Steel Effects on Long-time Deflections Branson, D. E.
  13. Concrete Structures: Stresses and Deformations Ghali, A.;Favre, R.