Repeated Loading Tests of Reinforced Concrete Beams Containing Headed Shear Reinforcement

Headed Shear Bar를 사용한 콘크리트 보의 반복 하중 실험

  • 김영훈 (고려대학교 방재과학기술연구센터) ;
  • 윤영수 (고려대학교 토목환경공학과) ;
  • 데니스미첼 (카나다 맥길대학교 토목공학과)
  • Published : 2003.05.01

Abstract

The repeated loading responses of four shear-critical reinforced concrete beams, with two different shear span-to-depth ratios, were studied. One series of beams was reinforced using pairs of bundled stirrups with $90^{\circ}C$ standard hooks, having free end extensions of $6d_b$. The companion beams contained shear reinforcement made with larger diameter headed bars anchored with 50mm diameter circular heads. A single headed bar had the same area as a pair of bundled stirrups and hence the two series were comparable. The test results indicate that beams containing headed bar stirrups have a superior performance to companion beams containing bundled standard stirrups, with improved ductility, larger energy adsorption and enhanced post-peak load carrying capability. Due to splitting of the concrete cover and local crushing, the hooks of the standard stirrups opened, resulting in loss of anchorage. In contrast, the headed bar stirrups did not lose their anchorage and hence were able to develop strain hardening and also served to delay buckling of the flexural compression steel. Excellent load-deflection predictions were obtained by reducing the tension stiffening to account for repeated load effects.

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