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전단철근비와 보의 단면크기에 따른 고강도 철근콘크리트보의 전단강도 특성 연구
박나정(Park, Na-Jeong),노형진(Noh, Hyung-Jin),유인근(Yu, In-Geun),백승민(Baek, Seung-Min),김우석(Kim, Woo-Suk),곽윤근(Kwak, Yoon-Keun) 대한건축학회 2020 대한건축학회논문집 Vol.36 No.8
The purpose of this study is to investigate the shear strength of high strength reinforced concrete beams according to shear reinforcement ratio and beam section size. A total of twelve specimens were tested and designed concrete compressive strength is 50 MPa. The main variables are shear reinforcement ratio and beam section size fixed with shear span to depth ratio (a/d = 2.5), the tensile reinforcement ratio (ρ = 0.013) and width to depth ratio (h/b = 1.5). The test specimens were divided into three series of H1 (225×338 mm), H2 (270×405 mm) and H3 (315×473mm) respectively. The experimental results show that specimens represent various failure modes such as diagonal tensile failure (DTF), bond failure (BF), shear compression failure (SCF) and flexural compression failure (FCF). In the H1 series, the shear strength increased by 92.0%, 94.1% and 128.4% respectively as the shear reinforcement ratio increased, 103.8%, 138% and 143% respectively in the H2 series, 131.1%, 168.7% and 151.7% respectively in the H3 series. The decreasing rate of shear strength increased as the beam’s effective width increased, which is considered to be due to the size effect. Then, it is shown that the decreasing rate of shear strength increases as d/s increases, and it can be seen that the effect of the size effect increases as the spacing between shear reinforcing bars decreases. As compared to the standard and the proposed equations, theoretical values by proposed equation of Zsutty, Bazant, and Lee has compared relatively well with experimental values.
보의 크기와 전단철근간격비에 따른 고강도 철근콘크리트보의 전단강도 특성 연구
유인근(Yu, In-Geun),박나정(Park, Na-Jeong),백승민(Baek, Seung-Min),김우석(Kim, Woo-Suk),곽윤근(Kwak, Yoon-Keun) 대한건축학회 2021 대한건축학회논문집 Vol.37 No.9
This study conducted an experiment on the shear strength of high-strength reinforced concrete beams depending on the effects of shear reinforcement spacing and beam size. Through experiments, experimental values were compared with the theoretical values based on standard equations such as KDS 14 20 22, ACI 318-19, CEB-FIP, and existing proposal equations which are Zsutty, Bazant, and Lee’s equations. It will be compared and analyzed to be used as basic data for shear design of reinforced concrete beams with fck = 50 ㎫, ρ = 0.025 and the width-to-depth ratio (h/b) were constant, and the beam size (b×d) and shear reinforcement spacing (d/s) were variables. The test specimens were divided into three series, SHR1, SHR2, and SHR3, according to the size of the cross section. As a result of comparing the experimental value and the theoretical value according to the standard equations and the proposed equations, the average value was 1.15 to 1.61 and the standard deviation was 0.16 to 0.20. Among the comparisons between the standard and proposed equations, the Zsutty, Bazant, and Lee’s equations predict experimental values relatively well. The mean of the Zsutty’s equation was 1.29, the standard deviation was 0.18, the mean of the Bazant’s equation was 1.15, the standard deviation was 0.19, the mean of the Lee’s equation was 1.17, and the standard deviation was 0.20, respectively.
유인근 ( In-geun Yu ),박나정 ( Na-jeong Park ),이호경 ( Ho-kyung Lee ),백승민 ( Seung-min Beak ),김우석 ( Woo-suk Kim ),곽윤근 ( Yoon-keun Kwak ),김성기 ( Sung-ki Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2021 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2021 No.-
고강도 철근콘크리트 부재의 경우 일반콘크리트에 비해 시공성이 낮으며, 품질관리의 어려움, 화재시 고온으로 인한 내화성능 저하로 인해 구조 안전성이 요구되는 실정이다. 이것은 고강도 콘크리트의 파괴양상이 매우 취성적이며, 국부적인 파괴를 일으키기 때문이다. 콘크리트의 파괴를 일으키는 원인으로서는 전단철근비, 인장 철근비, 전단경간비, 콘크리트 압축강도, 보의 폭 대 깊이 비 등이 있으며, 이들은 서로 상호복합작용으로 인하여, 콘크리트 전단강도의 정확한 전단설계값 및 파괴를 예측하지 못하므로 기존의 전단강도 식들은 충분한 안전율을 확보하기 위하여 보수적인 값을 제시하고 있다. 본 연구에서는 고강도 철근콘크리트보의 전단강도 특성을 연구하기 위해 콘크리트압축강도( = 50 MPa), 인장철근비(ρ=0.025) 및 폭 대 깊이비(h/b)를 일정하게 하였으며, 보의 크기(b×d)와 전단철근간격(d/s)을 변수로 한 12개의 시험체를 제작하여 실험을 하였다. 시험체는 단면의 크기에 따라 SHR1, SHR2, SHR3으로 된 총 3개의 시리즈로 나누었으며, 각 시리즈 당 전단철근의 간격에 따라 4개씩 총 12개의 시험체를 제작하였고, 시험체의 전단파괴를 유도하기 위하여 전단경간비는 2.5로 하였다. 실험값에 대한 여러 기준식 및 제안식과의 비교를 한 결과, 평균값은 1.15 ~ 1.60, 표준 편차는 0.13 ~ 0.18로 나타났다. 여러 기준식 및 제안식들 중 실험값을 비교적 잘 예측하고 있는 것은 Zsutty, Bazant, Lee 식이다. Zsutty 방정식의 평균은 1.29, 표준 편차 0.16, Bazant 방정식의 평균은 1.15, 표준 편차는 0.17, Lee 방정식의 평균은 1.17, 표준 편차는 0.18로 나타났다.