Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
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Compression Lap Splice Length in Concrete of Compressive Strength from 40 to 70 MPa

40-70 MPa 콘크리트에서의 철근 압축이음 길이

  • Chun, Sung-Chul (Architectural Technology Research Team, Daewoo Institute of onstruction Technology, Daewoo E&C Co., Ltd) ;
  • Lee, Sung-Ho (Architectural Technology Research Team, Daewoo Institute of onstruction Technology, Daewoo E&C Co., Ltd) ;
  • Oh, Bo-Hwan (Architectural Technology Research Team, Daewoo Institute of onstruction Technology, Daewoo E&C Co., Ltd)
  • 천성철 ((주)대우건설기술연구원 건축연구팀) ;
  • 이성호 ((주)대우건설기술연구원 건축연구팀) ;
  • 오보환 ((주)대우건설기술연구원 건축연구팀)
  • Published : 2009.08.31
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Abstract

A compression lap splice becomes an important issue due to development of ultra-high strength concrete. Current design codes regarding compression lap splice do not utilize merits of the improved strength of ultra-high strength concrete. Especially, a compression lap splice can be calculated longer than a tension lap splice according to the codes because they do not consider effects of compressive strength of concrete and transverse reinforcement. This anomaly confuses engineers in practice. Design equation is proposed for compression lap splice in 40 to 70 MPa of compressive strength of concrete. The proposed equation is based on 51 specimens conducted by authors. Basic form of the equation includes main parameters which are derived from investigating test results. Through two-variable non-linear regression analysis of measured splice strengths, a strength equation of compression lap splices is then derived. A specified splice strength is defined using a 5% fractile coefficient and a lap length equation is constructed. By the proposed equation, the anomaly of lap lengths in tension and compression is got rid of. In addition, the equation has a reliability equivalent to those of the specified strengths of materials.

초고강도콘크리트의 개발에 따라 철근 압축이음에 대한 연구 필요성이 높아지고 있다. 40여년 전의 연구를 바탕으로 한 현재의 압축이음 설계기준으로는 향상된 강도를 제대로 활용할 수 없으며, 특히 압축이음길이가 인장이음 길이보다 길어지는 기현상(奇現象)이 발생되어 실무의 혼란을 초래하기도 한다. 이러한 현상은 현행 설계기준에서 콘크 리트 강도와 횡보강근의 영향을 고려하지 않기 때문이다. 본 연구에서는 51개 실험체의 결과를 바탕으로 40부터 70MPa 까지 콘크리트에 대한 압축이음길이 설계식을 제안하였다. 실험 결과를 통해 도출된 압축이음의 영향 인자들을 분석하 여 이음강도식의 기본형을 만들었다. 실험 결과에 대한 비선형 회귀분석을 통해 압축이음강도 평가식을 마련하고, 5% 분위수 개념을 통해 설계기준이음강도를 설정하고 압축이음길이 설계식을 도출하였다. 이 연구에서 제안된 압축이음길 이 설계식을 이용하여 고강도콘크리트에서 압축이음길이가 인장이음길이보다 길어지는 이상 현상을 해소할 수 있다. 더 불어 제안된 압축이음길이 설계식은 통계적 기법에 기반을 두어 재료강도와 동일한 수준의 신뢰성을 확보할 수 있다.

Keywords

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