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

Korea Institute for Structural Maintenance Inspection (한국구조물진단유지관리공학회)
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Evaluation of In-plane Shear Strength of CFRP Rebar-Concrete Member Using Modified Compression Field Theory

수정압축장이론에 의한 탄소보강근-콘크리트 부재의 면내전단강도 평가

  • Su-Tae Kang (Department of Architectural Engineering, Daegu University) ;
  • Eun-Ik Yang ;
  • Myung-Sung Choi
  • 강수태 (대구대학교 건축공학과) ;
  • 양은익 (강릉원주대학교 건설환경공학과) ;
  • 최명성 (단국대학교 토목환경공학과)
  • Received : 2024.05.29
  • Accepted : 2024.06.24
  • Published : 2024.08.31
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Abstract

In this study, when subjected to in-plane shear such as a shear wall, the behavior characteristics of a concrete member using CFRP rebars were investigated when the longitudinal reinforcement ratio was kept constant at 2.96% and the transverse reinforcement ratio was changed from 0.30 to 2.98%. The evaluation was conducted based on MCFT theory and analyzed by comparison with the case of concrete members using steel rebars. When the reinforcement ratio ranged from 0.30 to 1.19%, concrete members employing CFRP rebars exhibited higher shear strength compared to those using steel rebars. In contrast, at high reinforcement ratios of 1.79 and 2.98%, it was observed that the shear strength of the member with CFRP rebar was lower compared to the member with steel rebar. Maximum shear strain was observed to be higher for members reinforced with steel rebars at lower reinforcing bar ratios, while for ratios of 0.97% and above, CFRP rebars resulted in higher maximum shear strain. As the reinforcement ratio increases, the use of CFRP rebar instead of steel rebar results in a greater increase in maximum shear strain. By analyzing the difference in strain in the reinforcing bar as well as the difference in principal strain in the element caused by differences in the mechanical properties of the steel rebar and CFRP rebar, the shear strength and shear strain when using steel rebar and CFRP rebar with different reinforcement ratios can be compared and analyzed.

이 연구에서는 전단벽과 같은 면내 전단을 받는 경우에 대해, 종방향 보강근비를 2.96%로 일정하게 하고, 횡방향 보강근비를 0.30에서 2.98%까지 변화시켰을 때, CFRP 보강근을 사용한 콘크리트 부재의 거동특성을 MCFT 이론에 기반하여 평가하고, 철근을 사용한 콘크리트 부재의 경우와 비교하여 분석하고자 하였다. 보강근비 0.30에서 1.19% 사이에서는 CFRP 보강근을 사용한 경우가 철근을 사용한 경우보다 높은 전단강도를 보였으며, 그 이상의 1.79% 및 2.98%에서는 상대적으로 낮은 전단강도를 나타내었다. 최대전단변형률은 낮은 보강근비에서 철근을 사용한 경우가 더 크게 나타났으며, 0.97% 이상에서는 CFRP 보강근을 사용한 경우에 더 크게 나타났으며 보강근비가 커질수록 철근 대비 전단변형률 증가율이 더 크게 나타났다. 철근 및 CFRP 보강근의 기계적 성질 차이로 인해 발생하는 보강근에서의 변형률 차이 및 요소에서의 주변형률 차이 분석을 통해 보강근비 변화에 따른 철근 및 CFRP 보강근을 사용한 경우의 전단강도 및 전단변형률 변화를 비교하여 분석할 수 있었다.

Keywords

Acknowledgement

이 연구는 국토교통부/국토교통과학기술진흥원의 지원으로 수행되었음(과제번호 RS-2021-KA163381).

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