콘크리트학회논문집 (Journal of the Korea Concrete Institute)

  • 제24권5호
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  • Pages.525-533
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  • 2012
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  • 1229-5515(pISSN)
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  • 2234-2842(eISSN)
한국콘크리트학회 (Korea Concrete Institute)
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노치 유무와 섬유혼입률에 따른 UHPCC의 휨인장강도 비교

Comparison of Flexural Tensile Strength according to the Presence of Notch and Fiber Content in Ultra High Performance Cementitious Composites

  • 투고 : 2012.02.20
  • 심사 : 2012.07.27
  • 발행 : 2012.10.31
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초록

이 연구에서는 UHPCC에서 섬유혼입률에 따른 초기균열강도 및 휨인장강도의 변화를 0~5 vol.% 범위에서 조사하였으며, 노치의 여부에 따른 영향을 파악하기 위해 노치가 없는 보에 대한 4점 재하실험 및 노치 낸 보에 대한 3점 재하실험을 같이 실시하였다. 실험 결과로부터 섬유혼입률이 증가함에 따라 휨인장강도는 선형적으로 강도가 향상됨을 확인할 수 있었고, 초기균열강도의 경우에는 1 vol.% 이상에서는 강도향상을 나타내었으나 그 이하의 섬유혼입에서는 강도향상 효과가 거의 없는 것으로 나타났다. 노치 유무에 따른 휨 실험으로부터 구한 UHPCC의 초기균열발생강도 및 휨 인장강도를 비교했을 때, 섬유혼입률에 따라 노치의 영향이 변하는 것으로 나타났다. 섬유혼입률이 증가함에 따라 노치에서의 응력집중의 영향이 감소하여 강도 차이가 점차 줄어들었으며, 높은 섬유혼입률에서는 노치에 의한 응력집중효과는 없어지고 균열면의 상태 및 크기효과의 영향이 지배적으로 작용하여 노치낸 보의 강도가 좀 더 크게 나타났다.

In this study, bending tests were performed on beam specimens made of UHPCC with the fiber content range of 0~5 vol% to investigate the contribution of fiber content to first cracking strength and flexural tensile strength. Also, four-point bending tests for unnotched beam as well as three-point bending test for notched beam were performed to estimate the effect of the presence of notch on the strengths. The experiment result showed that the increase in fiber content made linear improvement in the flexural tensile strength; whereas first cracking strength was enhanced only when at least 1 vol% of fibers was incorporated. Comparison of the bending test results with and without notch showed that the notch effect varied with the fiber content. The increase in fiber content diminished the effect of stress concentration on the notch tip, reducing the difference in the strengths. With much higher fiber content, the effect of stress concentration almost disappeared and the defection on cracking plane or the size effect dominated the strengths, consequently resulting in higher strengths in the notched beams than the unnotched ones.

키워드

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피인용 문헌

  1. Performance of Fresh and Hardened Ultra High Performance Concrete without Heat Treatment vol.26, pp.1, 2014, https://doi.org/10.4334/JKCI.2014.26.1.023
  2. Compressive Behavior of Hybrid Steel Fiber Reinforced Ultra-High Performance Concrete vol.28, pp.2, 2016, https://doi.org/10.4334/JKCI.2016.28.2.213
  3. Fracture Behavior of UHPC Reinforced with Hybrid Steel Fibers vol.28, pp.2, 2016, https://doi.org/10.4334/JKCI.2016.28.2.223