• Title/Summary/Keyword: 섬유길이

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Analysis of the Flowability for Organic·Inorganic Fiber with the Variation of Length (유·무기 섬유 길이조합변화에 따른 섬유 보강 모르타르의 유동성 분석)

  • Park, Yong-Jun;Kang, Byung-Hoi;Lee, Hong-Kyu;Jo, Man-Ki;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2014.05a
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    • pp.128-129
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    • 2014
  • In this study, flowability of the mortar added with length change and combination of steel and inorganic fiber has been tested to evaluate the performance of fiber-reinforced mortar. The following results could be made as the conclusion. Early age flow of the mortar has been decreased when fibers added. Slump also decreased with the adding of fibers. For the air content, comparing with Plain, all the specimens with fibers showed higher air content than Plain., Addition of every kinds fibers showed the similar EIS test results.

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Engineering characteristics of the Fiber Reinforced Floor Finishing Concrete According to the changes of Nylon Fiber Length (나일론 섬유의 길이변화에 따른 섬유보강 바닥마감용 콘크리트의 공학적 특성)

  • Jeon, Kyu-Nam;Baek, Dae-Hyun;Jung, Woo-Tai;Park, Jong-Sup;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2009.11a
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    • pp.153-156
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    • 2009
  • This study investigated the fundamental properties corresponding to various length changes on NY fiber reinforced concrete. For results of fresh concrete, the slump and air content were declined, but the unit volume weight and vebe time were increased. For the hardened concrete properties, the compressive strength showed increasing tendency according to the NY fiber length. The dry and autogenous shrinkage also decreased compared with Plain. Generally, the caes that 19 mm NY fiber was used was better than any other cases.

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The Effects of Reinforcing of Steel Fiber on the Strength Properties of the High-Strength Concrete (강섬유의 보강이 고강도 콘크리트의 강도 특성에 미치는 영향)

  • 구봉근;정경섭;김태봉
    • Magazine of the Korea Concrete Institute
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    • v.4 no.2
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    • pp.93-101
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    • 1992
  • 강섬유를 혼입한 고강도 콘크리트의 강도 특성에 관한 연구를 수행하였다. 이를 위하여 고성능 감수제를 이용하여 제조한 고강도 콘크리트에 강섬유를 0, 0.5, 1.0, 1.5%로 변화시키면서 실험을 실시하였고, 또한 강섬유의 길이와 휨 시험편의 크기에 따른 강도의 변화에 대하여도 연구하였다. 연구결과 강섬유 보강 고강도 콘크리트의 압축강도는 강섬유의 혼입률에 따라 크게 영향을 받지 않으나, 할열인장강도와 휨강도는 강섬유 혼입률과 길이에 따라 크게 증가하였고, 특히 최대하중을 지나서도 응력의 감소가 작아 연성이 크게 증가하는 것으로 나타났다.

Evaluation of Fire Resistance Performance of Polymer Modified Cement Mortar Using Polypropylene Fiber (폴리프로필렌 섬유를 혼입한 폴리머 시멘트 모르타르의 내화성능 평가)

  • Jeon, Ki-Soo;Sim, Sang-Rak;Lee, Young-Do
    • Journal of the Korea Institute of Building Construction
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    • v.23 no.2
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    • pp.133-142
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    • 2023
  • In this study, the fire resistance capabilities of polypropylene fiber-reinforced polymer-modified cement mortar were assessed to guarantee the fire resistance fo this materials, commonly employed in the repair of concrete structures. Experimental outcomes revealed that an increased water and polymer content heightened the likelihood of spalling, while longer polypropylene fibers and elevated polymer concentrations proved more effective in mitigating spalling.

Fracture Characteristics of Polypropylene Fiber Reinforced Concrete (폴리프로필렌 섬유보강 콘크리트의 파괴특성 연구)

  • Shin-Won Paik
    • Journal of the Korean Society of Safety
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    • v.12 no.4
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    • pp.230-240
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    • 1997
  • An experimental research investigation of the fracture properties of polypropylene fiber reinforced concrete is reported. Fibers used in this experiment were two types, monofilament and fibrillated polypropylene fibers. Fiber length was 19 mm, and volume fractions were 0, 1, 2, and 3%. Also, as initial notch depths influence the fracture properties of fiber reinforced concrete, the notch depth ratios by specimen height were 0.15, 0.30 and 0.45. The main objective of this experimental program is to obtain the load-deflection and the load-CMOD curves, to investigate the fracture properties of the polypropylene fiber reinforced concretes. Therefore, the flexural specimen testings on the four-point bending were conducted. Then, the load-load point displacement and the load-crack mouth opening displacement curves were measured. The effects of different volume fractions of the monofilament and the fibrillated polypropylene fiber reinforced concrete on the compressive strength, flexural strength and toughness, stress intensity factor, and fracture energy were investigated through the experimental results.

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길이가 유한한 선접촉의 탄섬유체윤활

  • 박태조;김경웅
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1986.11a
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    • pp.47-51
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    • 1986
  • 로울러 베어링의 로울러는 길이방향으로 적당하게 Profiling하여 양단부에서 발생하는 응력집중을 줄이고 있다. 로울러와 레이스간의 접촉을 단순한 탄성접촉문제로 해석하는 경우에는 유막의 개념이 없어서 로울러와 레이스 사이의 압력분포와 유막형상을 정확하게 나타내기가 어려우므로 탄성변형과 압력에 따른 윤활유의 점도 변화를 고려한 탄성유체윤활(EHL)해석이 필요하다. 대부분의 해석은 무한장 로울러로 취급하는 것이 보통이며 실제의 로울러에 해당하는 유한한 길이의 선접촉 EHL 해석은 Mostofi & Gohar 및 Kuroda & Arai의 해석 정도이나 각각은 수렴하중이 작거나 로울러의 길이가 아주 짧은 경우에 해당한다. 본 연구에서는 FDM과 Newton-Raphson method를 이용하여 길이가 유한한 실제 크기의 Profiled 로울러에 대한 EHL상태에서의 압력분포와 유막형상을 보다 하중이 온 경우에 대해서 구하고자 한다.

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An Experimental Study on the Flexural Strength of Lap Spliced Ultra High Strength Fiber Reinforced Concrete Beams (이음된 초고강도 강섬유보강콘크리트 보의 휨강도에 관한 실험적 연구)

  • Bae, Baek-Il;Son, Dong-Hee;Choi, Hyun-Ki;Jung, Hyung-Suk;Choi, Chang-Sik
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.6
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    • pp.76-83
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    • 2021
  • This study examines the bending behavior of lap-spliced ultra-high-strength fiber-reinforced concrete members and evaluates the safety of the design codes for ultra-high-strength fiber-reinforced concrete structures. An experiment on a total of six beams was performed. The main variables were the fiber-inclusion and the lap-spliced length at the center of the beams. The steel fibers in a volume fraction of 2% were used, and the lap-splice lengths were determined to be 8db and 16db. As a result of the test, the specimens not reinforced with fiber lost abrupt load-bearing capacity at the lap region and did not experience yielding of the reinforcing bar. In the case of fiber-reinforced concrete, if a lap-splice length of 16db is secured, the yielding of the main reinforcing bar can be experienced, and appropriate flexural strength can be expressed. Based on the experimental results of this study, as a result of reviewing the lap-splice length calculation formulas of the current design standards and the ultra-high-strength concrete structural design recommendations, it was found that all of them were evaluated conservatively.

Bond Capacity of Pseudo-Ductile FRP Hybrid Sheet to Strengthen RC Members (철근콘크리트 부재 보강용 유사연성 FRP 하이브리드 시트의 부착 특성)

  • Yoon, Hye-Sun;Lee, Jung-Mi;Lee, Chin-Yong;Choi, Dong-Uk;Kim, Kil-Hee
    • Journal of the Korea Concrete Institute
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    • v.21 no.1
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    • pp.47-53
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    • 2009
  • 12 concrete blocks, on which hybrid fibrous sheets (carbon fiber and glass fiber) had been bonded, were subjected to tensile load in order to estimate properties of the bonded interface. the sheet length was varied by 100mm, 200mm and 400mm. It was found that more than 150mm bond length is required to achieve the maximum bearing capacity of the interface. In this study, maximum bond stress $\tau_{F,max}$, ultimate slip $S_{FU}$ of the interface were estimated $\tau_{F,max}$=3.0MPa and $S_{FU}$= 0.175mm, respectively.

Tensile Stress-Crack Opening Relationship of Ultra High Performance Cementitious Composites(UHPCC) Used for Bridge Decks (바닥판 적용 초고성능 시멘트 복합체의 인장응력-균열개구 관계)

  • Kwon, Seung Hee;Lee, Seung Kook;Park, Sung Yong;Cho, Keun Hee;Cho, Jeong Rae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.1
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    • pp.46-54
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    • 2013
  • Two different UHPCCs having different fiber lengths and volume fractions are considered to be applied to bridge decks. The objective of this study is to estimate cracking resistance of the two UHPCCs. The notched beam tests were performed with the UHPCCs, and the relationships between load and CMOD(Crack Mouth Opening Displacement) were obtained from the tests. The tensile stress and crack opening relationships optimally fitting the measured load-CMOD curves were found through the inverse analyses. The UHPCC with 2% volume fraction of 13 mm long fiber has lower fracture energy than the UHPCC with 0.5% and 1.0% volume fractions of 16.3 mm and 19.5 mm long fibers, respectively. It indicates that the latter UHPCC is more effective in uniformly distributing crack formation and reducing crack width.