• Title/Summary/Keyword: 고강도 강섬유

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Enhancing the Performance of High-Strength Concrete Corbels Using Hybrid Reinforcing Technique (하이브리드 보강기법을 활용한 고강도 콘크리트 내민받침의 성능 향상)

  • Yang, Jun-Mo;Lee, Joo-Ha;Min, Kyung-Hwan;Yoon, Young-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.13-16
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    • 2008
  • Corbels are short cantilevers that project from the faces of a column and are a type of stress disturbed member, resisting both the ultimate shear force applied to them by the beam, and the ultimate horizontal force caused by shrinkage, temperature changes, and creep of the supported elements. Recently, as there have been an increase in the use of high-strength concrete and the concern about corrosion problems, lots of researches about hybrid reinforcing technique, applying strategically high performance reinforcements to the concrete elements, are performed. In this study, fiber reinforced high strength concrete corbels were constructed and tested for applying hybrid reinforcing technique to the corbels using steel fibers and headed bars. The results showed that the performance in terms of load carrying capacities, stiffness, ductility, and crack width was improved, as the steel fibers were added and the percentage of steel fibers was increased. In addition, the corbel specimens used headed bars as main tension ties showed superior load carrying capacities, stiffness, and ductility to the corbel specimens anchored main tension ties by welding to the transverse bars.

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Effects of Steel Fiber Properties on Compressive and Flexural Toughness of Steel Fiber-Reinforced Concrete (강섬유의 특성이 강섬유보강 콘크리트의 압축 및 휨 인성에 미치는 영향)

  • Lim, Dong-Gyun;Jang, Seok-Joon;Jeong, Gwon-Young;Youn, Da-Ae;Yun, Hyun-Do
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.3
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    • pp.43-50
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    • 2019
  • Effects of tensile strength and aspect ratio of steel fiber on compressive and flexural behavior of steel fiber-reinforced concrete (SFRC) with high- and normal-strength were investigated. Also, this study explores compressive behavior of SFRC with different loading rate. For this purpose, four types of steel fiber were used for SFRC with specified compressive strength of 35 and 60 MPa, respectively. Cylindrical specimens with a diameter of 150 mm and height of 300 mm were made for compression test, and prismatic specimens with a $150{\times}150mm$ cross-section and 450 mm span length were made for flexural test. Test results from compression and flexural tests indicated that the toughness of concrete significant increased with steel fibers. Especially, using steel fiber with high tensile strength and aspect ratio can be lead to performance improvement of high-strength SFRC. In this study, equations are suggested to predict compressive toughness ratio of SFRC from flexural toughness ratio.

Development of Fire-resistant Concrete using Fibre Cocktail (섬유혼입공법을 적용한 고내화 콘크리트의 개발)

  • Youm, Kwang-Soo;Jeon, Hyun-Kyu;Won, Cheol;Kim, Heung-Youl
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.949-952
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    • 2008
  • 화재안전 신뢰성이 확보된 고강도 콘크리트 구조물의 시장 공급을 위하여 GS건설에서는 2005년 부터 고강도 콘크리트 구조물의 강도 영역별 폭렬 저감 및 거동 안전성 평가와 수치해석 방법을 통한 경제적인 설계방법를 최종 연구목표로 하여 현재까지 콘크리트 재료의 열적 특성 확보와 구조부재 화재 특성 연구를 수행해 왔다. 강도발현, 시공성, 내화성능과 경제성에 대한 분석을 해외연구 기관에 의뢰하여 섬유혼입공법을 선정한 후 이에 대한 재료의 물리적 특성과 역학적 특성 실험결과를 바탕으로 고강도 콘크리트 구조부재의 내화성능을 예측 분석할 수 있도록 비열 모델, 열전도율모델, 압축강도 모델, 탄성계수 모델을 구축하였다. 또한 기둥과 보에 대한 내화실험을 실시하여 내화성능을 평가하였으며, 이에 대한 열적 해석을 병행하여 진행하였다.

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Fire Resistance Performance of Fiber-Cocktail Reinforced 50 MPa High Strength Concrete (섬유혼입된 50 MPa 고강도 콘크리트의 내화성능)

  • Youm, Kwang-Soo;Jeon, Hun-Kyu;Park, Jong-Heon
    • Journal of Korean Society of societal Security
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    • v.2 no.3
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    • pp.55-60
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    • 2009
  • After applying the fiber cocktail(polypropylene and steel fibers) into the mixture of high strength concrete with a compressive strength of 50 MP, the fire test was carried out on specimens in order to evaluate the fire resistance performance, such as possible explosive spalling, temperature distributions of concrete and rebar. According to an enforcement ordinance, four column specimens were exposed to the fire for 180 minutes based on the standard curve of ISO-834. No explosive spalling has been observed. The required minimum quantity of polypropylene to prevent explosive spalling is more than 0.57 kg per unit concrete volume. The comparing test results from temperature distributions of concrete and rebar has found that the difference of fiber quantity is insignificant.

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Seismic Performance Assessment of Roof-Level Joints with Steel Fiber-Reinforced High-Strength Concrete (강섬유보강 고강도콘크리트를 적용한 최상층 접합부의 내진성능 평가)

  • Kim, Sang-Hee;Kwon, Byung-Un;Kang, Thomas H.-K.
    • Journal of the Korea Concrete Institute
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    • v.28 no.2
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    • pp.235-244
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    • 2016
  • This study was conducted to verify seismic performance of special moment frame's joints at roof-level with high-strength concrete and SD600 bars. K-RC-H was designed according to the seismic code and K-HPFRC-H had 150% of the original hoop spacing and 1.0% steel fiber volume fraction compared with K-RC-H. Both specimens had remarkable seismic performance without noticeable decrease in moment, but with very good energy dissipation before rebar failure. The U-bars in the joint sufficiently constrained rebar's action that pushed the cover upward. SD600 bars with $1.25l_{dt}$ had minimum slip in the joint. It was considered that the steel fiber contributed to improvement of the bending moment and joint shear distortion, and the result showed that it would be possible to increase the hoop spacing to 150% of the regular spacing.

A Study on the Structural Strength Assessment of FRP Composites Boat (FRP 복합재료 선박의 구조강도 평가에 관한 연구)

  • Choi, Han-Kyu;Kwon, Soo-Yeon
    • Journal of Korea Ship Safrty Technology Authority
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    • s.28
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    • pp.46-63
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    • 2010
  • 플레저보트의 고강도 및 경량화 추세에 따라 복합재료 등 관련 소재의 경량화가 요구되었고, 이에 부응하여 관련 신소재 개발과 진공성형 신건조공법 등이 출현하였으며, 이러한 신공법을 이용한 선박건조가 증가하고 있는 실정에 따라 선박의 구조강도 평가가 중요한 과제로 부각되고 있다. 또한 선박의 안전성 확보와 고객의 편리 도모를 위한 플레저보트 구조강도 확인을 위한 시험방법 등도 다양화할 필요가 있다. 따라서 진공적층 및 수적층 성형방법으로 건조한 플레저보트를 대상으로 선체구조 강도 시험 결과를 비교 분석하여 우리 실정에 적합하고 플레저보트의 안정성 평가를 위한 선체구조 강도 시험 기준안을 제시하고자 한다.

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A Study on Fire-proof Characteristics of Ultra High Strength Concrete Using Polyamide Fiber (폴리아미드섬유를 사용한 초고강도 콘크리트의 내화성능에 관한 연구)

  • Lee, Soo-Choul;Jeon, Joong-Kyu;Jeon, Chan-Ki
    • Journal of the Society of Disaster Information
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    • v.7 no.4
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    • pp.286-293
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    • 2011
  • Accordingly architectural structure is getting high-rise and bigger, a use of high strength and high performance concrete has been increased. High performance concrete has cons of explosion in a fire. This explosion in the fire can cause the loss of the sheath on a concrete surface, therefore it effects that increasing a rate of heat transmission between the steel bar and inner concrete. Preventing this explosion of high performance concrete in the fire, many kinds of researches are now in progressing. Typically, researches with using polypropylene-fiber and steel-fiber can prove controling the explosion, but the reduction of mobility was posed as a problem of workability. Consequently, to solve the problem as mentioned above, concrete cans secure fire resisting capacity through the using of coating liquid, including Ester-lubricant and non-ionic characteristic surfactant. This research has been drawn a ideal condition in compressive strength areas of concrete by an experiment. When applying 13mm of polyamide fiber, proper fiber mixing volume by compressive strength areas of concrete more than 2.5kg in 160MPa. These amount of a compound can control the explosion.

The Fundamental Property and Fire Resistance of the High Strength Concrete Corresponding to mixtures for the High Strength (고강도용 혼합재를 사용한 고강도 콘크리트의 기초물성 및 내화특성 검토)

  • Kim, Jong-Baek;Lee, Keon-Ho;Bae, Jun-Yeong;Jo, Sung-Hyun;Roh, Hyeon-Seung;Kim, Jung-Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.605-608
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    • 2008
  • This study investigated fundamental properties corresponding to mixtures for the high strength, and their properties of spalling prevention after a fire test. The results were summarized as following. For the flowability of using mixtures for the high strength, the target flow was satisfied with a small quantity of high performance reducing water agent to compare with silica fume. For the compressive strength in the case of using mixtures for the high strength, it was higher to compare with silica fume at 7 days, so it was proved that using mixtures for the high strength was profitable to prevent early frost damage. The compressive strength at the 28 days of silica fume and mixtures for the high strength were similar. There was no reduced tendency at the compressive strength according fiber contents, so it found out that the bonding strength between the fiber and concrete was hardly effective. For the spalling properties, the specimens without fibers were destroyed, however using over 0.05% of NY and PP fibers was effective to prevent spalling on the high strength concrete.

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Spalling Reduction Method of High Strength Reinforced Concrete Columns Using Fibers (섬유를 활용한 고강도 콘크리트기둥의 폭렬제어방안)

  • Yoo, Suk-Hyeong
    • Fire Science and Engineering
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    • v.23 no.4
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    • pp.7-12
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    • 2009
  • As the concrete strength increases the degree of damage caused by the spalling becomes more serious because of the permeability. It is reported that the polypropylene (PP) fiber has an important role in protecting concrete from spalling. However, the excessive usage of PP fiber would not useful in spalling control and would decrease the workability of ultra high strength concrete. The high-temperature behaviors of high-strength reinforced concrete columns with various dosage of PP fibers and three types of fire endurance fibers were observed this study. In results, the ratio of unstressed residual strength of columns, in case of concrete strength 60MPa, increases as the dosage of PP fiber increases from 0% to 0.2%, however, the effect of fiber dosage on residual strength of column barely changes above 0.2% and in case of concrete strength 120MPa, PVA fiber is the most suitable fire endurance fiber in accounting fire endurance performance and workability.

The Variations on The Fire Resistance of High Strength Concrete Column Incorporating Organic Fiber with Assessment Methods (유기 섬유 혼입 고강도 콘크리트 부재의 평가 방법에 따른 내화성능 변화에 관한 연구)

  • Lee, Seung-Hoon;Park, Chan-Kyu
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.945-948
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    • 2008
  • Fire resistance is a measure of the ability of building element to resist a fire. For concrete columns, the fire resistance depends on many factors, including strength, density, and moisture content of concrete, fire intensity, column size and shape, reinforcement detail, loading condition, and aggregate type etc. However, it is well-known that the high strength concrete (HSC) is more susceptible to spalling than normal strength concrete (NSC) and the behaviour of HSC column exposed to fire is significantly affected by the spalling. Recently, as one of the measures to reduce the spalling of HSC, incorporating polypropylene(PP) fiber has been investigated and successfully used in construction fields. However, the establishment of assessment method on the fire resistance of HSC column is very important as well as the improvement of fire performance of HSC. In this study, the variations on the fire resistance of HSC column with assessment methods was studied for the columns controlled the concrete spalling by PP fiber.

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