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

Architectural Institute of Korea (대한건축학회)
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Shear Strengthening Effect by Deviator Location in Externally Post-tensioning Reinforcement

외적 포스트텐셔닝 보강에서 데비에이터의 위치에 따른 전단보강효과

  • 이수헌 (경북대학교 융복합시스템공학부) ;
  • 신경재 (경북대학교 건설환경에너지공학부) ;
  • 이희두 (경북대학교 건설환경에너지공학부)
  • Received : 2018.03.06
  • Accepted : 2018.05.23
  • Published : 2018.06.30
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Abstract

This paper described the shear strengthening effect by deviator location in pre-damaged reinforced concrete (RC) beams strengthened with externally post-tensioning steel rods. Three reinforced concrete beams as control beam and eight post-tensioned beams using external steel rods were tested to fail in shear. The externally post-tensioning material was a steel rod of 22 mm diameter, and it had a 655 MPa yield strength and an 805 MPa tensile strength. Specimens depend on multiple variables, such as the number of deviators, location of deviator, and load pattern. The pre-damaged loads up to about 2/3 of ultimate shear capacities were applied to specimens using displacement control and the diagonal shear crack just occurred at these loading levels. And then, the post-tensioning up to when a strain of steel rod reaches about $2000{\mu}{\varepsilon}$ was continuously applied to beam. A displacement control was changed to a load control during post-tensioning. The post-tensioning resulted in increase of load-carrying capacity and restoration of existing deflection. Also, it prevented the existing diagonal cracks from excessively growing. Two deviators effectively improved the load capacity when compared with in case of test which one deviator at mid-span installed. When deviators were located near region which the diagonal crack occurred on, the strengthening impact by post-tensioning was greater.

Keywords

Acknowledgement

Supported by : 한국연구재단

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