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고온가열 및 하중재하에 따른 80, 130, 180 MPa 초고강도콘크리트의 역학적특성평가
최경철,윤민호,이태규,이승훈,김규용,Choe, Gyeong-Cheol,Yoon, Min-Ho,Lee, Tae-Gyu,Lee, Seong-Hun,Kim, Gyu-Yong 한국콘크리트학회 2013 콘크리트학회논문집 Vol.25 No.6
콘크리트는 고온에 강한재료로 인식되어 왔으나, 화재 등의 고온에 의해 내부조직의 물리 화학적 변화가 발생해 역학적 특성이 저하하게 된다. 이에, 고온시 콘크리트의 역학적 특성의 저하에 관한 연구보고 및 기준이 제시되고 있다. 그러나 고강도 콘크리트 및 하중을 재하한 상태에 관한 연구데이터는 적다. 따라서 이 연구에서는 고온 및 하중재하에 따른 고강도 콘크리트의 고온특성을 평가하였다. W/B 12.5%, 14.5%, 20%의 고강도 콘크리트를 대상으로 비재하상태 및 $0.25f_{cu}$의 하중조건을 설정하여, 고온시의 응력-변형, 최대하중에서의 변형, 압축강도, 탄성계수, 열팽창변형, 단기 고온크리프을 평가하였다. 실험 결과, 압축강도가 높아질수록 가열에 의한 압축강도의 저하가 크게 나타났고, $500^{\circ}C$이상의 온도에서 고온에 의한 열팽창변형과 하중재하에 의한 수축변형이 상쇄되어 압축강도 및 탄성계수의 잔존율이 높아지는 것을 확인할 수 있었다. Concrete has been recognized as a material which is resistant to high temperatures, but chemicophysical property of concrete is changed by the high temperature. So, mechanical properties of concrete may be reduced. Because of this, standards and researches on the degradation of the mechanical properties of concrete at high temperatures have been presented. However, research data about the state that considering the loading condition and high-strength concrete is not much. Therefore, this study evaluated the high-temperature properties of high-strength concrete by loading condition and elevated temperature. The stress-strain, strain at peak stress, compressive strength, elastic modulus, thermal strain and the transient creep are evaluated under the non-loading and $0.25f_{cu}$ loading conditions on high strength concrete of W/B 12.5%, 14.5% and 20%. Result of the experiment, decrease in compressive strength due to high temperature becomes larger as the compressive strength increases, and residual rate of elastic modulus and compressive strength is high by the shrinkage caused by loading and thermal expansion due to high temperature are offset from each other, at a temperature above $500^{\circ}C$.
가열속도에 따른 콘크리트 내부의 수분이동이 폭렬발생에 미치는 영향
최경철 ( Choe Gyeong-cheol ),김규용 ( Kim Gyu-yong ),남정수 ( Nam Jeong-soo ),김홍섭 ( Kim Hong-seop ),윤민호 ( Yoon Min-ho ),황의철 ( Hwang Ui-chul ) 한국건축시공학회 2017 한국건축시공학회 학술발표대회 논문집 Vol.17 No.1
In this study, it reviewed the effect of moisture migration in concrete with heating rate on concrete spalling. Concrete specimens with compressive strength 30MPa and 110MPa are used and its size is □100×100×h200mm. And, two kinds of heating rate are set such as IS0 834 and 1℃/min. As a result, in the concrete specimen exposed to ISO 834 standard heating condition, moisture could migrate through pore network and surface concrete pieces fall out by generating moisture clog near the surface in 110MPa concrete specimen. Meanwhile, In the case of concrete specimens exposed to 1℃/min. heating condition, it is appeared that moisture could not migrate because temperature is distributed uniformly. Therefore, surface spalling is not occurred with low heating rate. However, in the case of 110MPa concrete specimen is exploded even though it heated by low heating rate.
고출력펄스 레이저 기반 비접촉 콘크리트 열화깊이 추정 기법 검토
최경철 ( Choe Gyeong-cheol ),김홍섭 ( Kim Hong-seop ),전준서 ( Jeon Jun-seo ),김은영 ( Kim Eun-young ),이문환 ( Lee Mun-hwan ) 한국건축시공학회 2023 한국건축시공학회 학술발표대회 논문집 Vol.23 No.1
Out of an estimated 7 million buildings nationwide, approximately 38% of them have been standing for over 30 years, and this number is expected to continue to increase. Additionally, due to the Building Act, safety inspections will be mandatory for approximately 70,000 buildings annually, leading to an increase in demand for building safety inspections. However, the current building safety diagnosis heavily relies on manpower, making it difficult to diagnose locations that are hard to access, and requiring lengthy investigation periods. Therefore, this paper presents the basic research results of a non-contact concrete damage depth estimation technique using laser technology aimed at remote building safety diagnosis and shortening investigation periods.