Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
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Evaluation of Axial Strains of Reinforced Concrete Columns

철근콘크리트 기둥의 축방향 변형률 평가

  • Lee, Jung-Yoon (Dept. of Architectural Engineering, Sungkyunkwan University) ;
  • Kim, Min-Ok (Dept. of Architectural Engineering, Sungkyunkwan University) ;
  • Kim, Hyung-Beom (Dept. of Architectural Engineering, Sungkyunkwan University)
  • 이정윤 (성균관대학교 건축공학과) ;
  • 김민옥 (성균관대학교 건축공학과) ;
  • 김형범 (성균관대학교 건축공학과)
  • Received : 2012.07.06
  • Accepted : 2012.11.19
  • Published : 2013.02.28
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Abstract

The longitudinal axial strain in the plastic hinge region of reinforced concrete (RC) columns influences on the structural behavior of RC structures subjected to reversed cyclic loading. This strain decreases the effective compressive strength of concrete and increases the lateral displacements between stories by causing the elongation of member length. This paper investigated the effects of the axial force on the elongation of a RC member by using a sectional analysis of RC members. The analytical and experimental results indicated that the axial force decreased the axial strain in the plastic hinge region of RC columns. In this study, a model was proposed to predict the axial strain of RC columns. The proposed model considering the effects of axial force ratio consisted of three path types ; Path 1-loading region, Path 2-unloading region, and Path 3-reversing cyclic loading region. The axal strains predicted by the proposed model were compared with the test results of RC columns with various axial force ratios, and agreed reasonably with the observed longitudinal strains.

소성힌지 구역의 축방향변형률의 예측은 지진하중을 받는 철근콘크리트 기둥의 합리적인 연성 평가를 위하여 필요한 항목이다. 축방향변형률은 콘크리트의 유효압축강도를 저하시키고 층간 변위를 크게 할 수 있다. 기존 연구는 주로 소성힌지가 발생하는 보의 축방향변형률 예측에 국한되었지만 횡력을 받는 구조물에서는 저층부 기둥도 소성힌지가 발생한다. 이 논문에서는 기둥 부재에 작용하는 축력의 크기에 따라 변화하는 축방향변형률을 예측할 수 있는 모델과 평가식이 제안되었다. 단면 해석법을 이용하여 하중이력에 따른 축방향변형률의 변화와 철근의 변형률 변화를 고찰한 후, 해석과 실험 결과를 근거로 축방향변형률 예측 모델을 제안하였다. 제안된 모델은 부재 축방향변형률을 3가지 경로(재하, 재하 후 반대하중이 하중이 가해지는 구간, 동일한 부재 회전각에서 반복하중을 받을 구간)로 구분하였다. 이 연구에서 제안된 기둥 부재의 축방향변형률의 계산식은 축력비가 다른 철근콘크리트 기둥의 실제 축방향변형률을 추적하였고, 축력비의 영향을 반영하였다.

Keywords

References

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