Journal of the Architectural Institute of Korea Structure & Construction (대한건축학회논문집:구조계)

Architectural Institute of Korea (대한건축학회)
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Modified Development Design Equation Proposal on the Rib-Shape of Reinforcement

철근의 마디형상을 고려한 수정 정착설계식 제안

  • Received : 2012.04.02
  • Published : 2012.06.25
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Abstract

Continued efforts to improve the bond strength were continuously achieved in order to prevent the increase of development and splice length by the development of high strength reinforcement. High relative rib area reinforcing bars by increasing the relative rib area were developed to improve the bond strength, however there is a limit to increase the bond strength because the increase of the rib height can cause the pullout failure. A few domestic researcher suggested new deformation pattern of bars with high and low height tranverse ribs, and these alternating ribs are expected to help limiting local shear failure and increase the bond strength significantly. They verified its bond performance by various experimental research results. But it is very difficult to reflect the bond strength increase in the design equation because most development design equations did not include the variables which reflect the deformation pattern of the bars. This study suggested the modified development design equation to consider the bond strength increase of the new deformation pattern of bars. Previoue research results and proposed design equations were synthesized and analyzed to draw a applicable equation for it. Proposed equation was based on the equation of ACI 408 committee, and replaced the relative rib area $R_r$ to modified relative rib area ${R_r}^{\prime}$ using the weighted average of high and low rib height as 0.8 and 0.2 each. And the analysis of previous experimental results indicated that the restriction value of $(c{\omega}+K_{tr})/d_b$ was too conservative, and it is possible to extend it to 4.5.

Keywords

Acknowledgement

Supported by : 국토해양부

References

  1. Darwin, D., Zou, J., Tholen, m. L. and K.ldun, E., Splice strength of high relative rib area reinforcing bars, ACI Structural Journal, Jan.-Feb., 1996, pp. 95-106
  2. Darwin, D., Zou, J., Tholen, m. L. and K.ldun, E., Development length criteria for conventional and high relative rib area reinforcing bars, ACI Structural Journal, May-June, 1996, pp. 347-358
  3. Darwin, D., Graham E.K., Effect of deformation height and spacing on bond strength of reinforcing bars, ACI Structural Journal, Nov.-Dec., 1993, pp. 646-656
  4. Hamad, B. S., Bond strength improvement of reinforcing bars with specially designed rib geometries, ACI Structural Journal, Jan.-Feb., 1995, pp. 3-13
  5. ACI Committee 408, Splice and development length of high relative rib area reinforcing bars in tension and commentary(408.3-01), ACI Manual of Concrete Practice, 2008
  6. 홍건호, 김진아, 최완철, 철근 마디 형상에 따른 RC 휨부재의 부착강도 평가, 한국콘크리트학회 논문집, Vol.23, No.3, 2011. 6, pp. 393-400
  7. 김기성, "대형마디를 갖는 이형철근의 부착강도 연구", 숭실대학교 건축학과 석사학위 논문, 2007.
  8. 한국콘크리트학회, 콘크리트구조설계기준 해설, 한국콘크리트 학회, 2007, pp. 205-209
  9. 홍건호, 최동욱, 최완철, 홍기섭, "높은 마디면적 고강도 철근의 부착강도에 관한 실험적 연구", 한국콘크리트학회 논문집, 17권, 3호, 2005, pp. 375-384
  10. 홍건호, 최완철, "이형철근의 부착강도에 대한 마디형태의 영향", 한국콘크리트학회지, 16권, 4호, 2004, 95-99