• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.5-8
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• 2005

The purpose of this study is to investigate the mechanical characteristics of plain and steel fiber high strength concrete under uniaxial and biaxial loading condition. A number of plain and steel fiber high strength concrete cubes having 28 days compressive strength of 82.7Mpa (12,000psi) were made and tested. Four principal compression stress ratios, and four fiber concentrations were selected as major test variables. From test results, it is shown that confinement stress in minor stress direction has pronounced effect on the strength and deformational behavior. Both of the stiffness and ultimate strength of the plain and fiber high strength concrete increased. The maximum increase of ultimate strength occurred at biaxial stress ratio of 0.5 in the plain high strength concrete and the value were recorded 30 percent over than the strength under uniaxial condition. The failure modes of plain high strength concrete under uniaxial compression were shown as splitting type of failure but steel fiber concrete specimens under biaxial condition showed shear type failure.

• 한국구조물진단유지관리공학회 논문집
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• 제20권3호
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• pp.93-102
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• 2016

이 논문의 목적은 압축강도 130 MPa급의 고강도 강섬유 보강 콘크리트 보의 휨거동 특성을 파악하는데 있다. 부피비 1.0%의 강섬유와 철근비 0.02 이하의 철근으로 보강된 고강도 강섬유 보강 콘크리트의 휨거동 특성 실험결과를 제시하였다. 일반강도철근과 고강도철근을 실험 부재에 사용하였다. 강섬유 보강 콘크리트의 압축 및 인장거동 재료 실험과 모델링을 수행하였다. 강섬유 보강 콘크리트의 하중-균열개구변위 실험결과를 반영하여 가상균열모델에 근거한 역해석을 통해 인장거동모델링을 제시하였다. 실험결과는 강섬유 보강 콘크리트와 고강도철근의 사용은 균열제어 및 연성 거동에 유리한 것을 나타낸다. 일반강도철근을 사용한 보의 휨강도 실험값에 대한 수치해석에 의한 예측값의 비는 0.81~1.42를 나타내고, 고강도철근을 사용한 보의 휨강도 실험값에 대한 수치해석에 의한 예측값의 비는 0.92~1.07을 나타낸다. 수치해석에 의한 휨강도는 실험결과를 합리적으로 예측하고 있는 것으로 판단된다.

• Advances in concrete construction
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• 제10권3호
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• pp.195-209
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• 2020

This study investigates the behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) with hybrid macro-micro steel and macro steel-polypropylene (PP) fibers. Compression, direct and indirect tension tests were carried out on cubic and cylindrical, dogbone and prismatic specimens, respectively. Three types of macro steel fibers, i.e., round crimped (RC), crimped (C), and hooked (H) were combined with micro steel (MS) and PP fibers in overall ratios of 2% by volume. Additionally, numerical analyses were performed to validate the test results. Parameters studied included, fracture energy, tensile strength, compressive strength, flexural strength, and residual strength. Tests showed that replacing PP fibers with MS significantly improves all parameters particularly flexural strength (17.38 MPa compared to 37.71 MPa). Additionally, the adopted numerical approach successfully captured the flexural load-deflection response of experimental beams. Lastly, the proposed regression model for the flexural load-deflection curve compared very well with experimental results, as evidenced by its coefficient of correlation (R²) of over 0.90.

• Computers and Concrete
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• 제26권6호
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• pp.515-531
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• 2020

Due to the construction difficulties of steel reinforced concrete (SRC), a new composite structure of steel and steel fiber reinforced concrete (SSFRC) is proposed for solving construction problems of SRC. This paper aims to investigate the bond properties and composition of interfacial bond stress between steel and steel fiber reinforced concrete. Considering the design parameters of section type, steel fiber ratio, interface embedded length and concrete cover thickness, a total of 36 specimens were fabricated. The bond properties of specimens were studied, and three different methods of calculating interfacial bond stress were analyzed. The results show: relative slip first occurs at the free end; Bearing capacity of specimens increases with the increase of interface embedded length. While the larger interface embedded length is, the smaller the average bond strength is. The average bond strength increases with the increase of concrete cover thickness and steel fiber ratio. And calculation method 3 proposed in this paper can not only reasonably explain the hardening stage after the loading end curve yielding, but also can be applied to steel reinforced high-strength concrete (SRHC) and steel reinforced recycled coarse aggregate concrete (SRRAC).

• Computers and Concrete
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• 제3권6호
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• pp.389-400
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• 2006

This paper presents the investigations towards developing a better understanding on the contribution of steel fibers on the tensile strength of high-performance fiber reinforced concrete (HPFRC). An extensive experimentation was carried out with w/cm ratios ranging from 0.25 to 0.40 and fiber content ranging from zero to 1.5 percent with an aspect ratio of 80. For 32 concrete mixes, flexural and splitting tensile strengths were determined at 28 days. The influence of fiber content in terms of fiber reinforcing index on the flexural and splitting tensile strengths of HPFRC is presented. Based on the test results, mathematical models were developed using statistical methods to predict 28-day flexural and splitting tensile strengths of HPFRC for a wide range of w/cm ratios. The expressions, being developed with strength ratios and not with absolute values of strengths and are applicable to wide range of w/cm ratio and different sizes/shapes of specimens. Relationship between flexural and splitting tensile strengths has been developed using regression analysis and absolute variation of strength values obtained was within 3.85 percent. To examine the validity of the proposed model, the experimental results of previous researchers were compared with the values predicted by the model.

• 한국건축시공학회지
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• 제12권2호
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• pp.183-193
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• 2012

Compressive property of high strength concrete with amorphous metal fibers subject to high temperature has been investigated. The measure of this investigation includes explosive spalling, weight loss, residual compressive strength, strain at peak stress, elastic modulus, and residual energy absorption capacity after exposure to $400^{\circ}C$, $600^{\circ}C$and $800^{\circ}C$. In addition to the amorphous metal fiber, two other types of fibers (polypropylene fiber and hooked-end steel fiber) were also included in this investigation for comparison. The experimental program was conducted with high strength concrete using several combinations of the fiber types. The testing result shows that the concrete with amorphous metal fibers plus polypropylene fibers shows a superior behavior than those using other combination or single fiber type ingredient.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.421-424
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• 2008

초고강도 강섬유 보강 콘크리트의 역학특성은 높은 인장강도와 균열 이후의 높은 연성발현을 들 수있다. 본 연구에서는 섬유혼입률의 변화에 따른 초고강도 강섬유 보강 콘크리트의 인장연화 특성을 시험적으로 규명하고, 시험결과를 토대로 FEM 해석을 통해 변형성능을 정확하게 추정할 수 있는 인장 연화모델을 구축하고자 하였다. 초고강도 강섬유 보강 콘크리트의 인장거동은 강섬유의 혼입률에 관계없이 일정한 값의 초기강성을 나타내었으며, 강섬유의 혼입률이 증가할수록 초고강도 강섬유 보강 콘크리트의 휨인장강도는 증가하고 연화거동은 취성적인 것으로 나타났다. 노치낸 보에 대한 3점 휨실험 결과를 토대로 초고강도 강섬유 보강 콘크리트의 인장연화곡선을 얻기 위해 Uchida 등이 제안한 역해석법을 사용하였으며, 섬유혼입률과 임계균열폭의 함수로서 인장연화모델을 제안하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.491-496
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• 2001

In recent years, the research and development about the new material proceed rapidly and actively in the building industry. As building structures become bigger, higher and more specialized, so does the demand for material with higher strength. In the future, we will need to research repair and rehabilitation to make high strength concrete mixed steel fibrous building safe. The carbon fiber reinforced plastic bonding method is widely used in reinforcing the existing concrete structure among the various methods. The repair of initiate loaded reinforced high-strength concrete beams mixed steel fibrous with epoxy bonded Carbon Fiber Sheets(CFS) was investigated experimentally. The CFS thickness and length were varied to assess the peel failure at the curtailment of CFS, The behaviour of the repaired beams was represented by load-longitudinal steel strain relation and failure modes were discussed. The test results indicate that CFS is very effective for strengthening the demand beams and controlling deflections of reinforced high strength concrete beams mixed steel fibrous happen diagonal crack, the increase in the number of CFS layers over two layers didn't effect the increase in the strength of beams.

• 한국해양환경ㆍ에너지학회지
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• 제17권1호
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• pp.46-51
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• 2014

폐 FRP 양의 증가는 환경적 문제를 일으키고 있다. 최근 폐 FRP로부터 콘크리트를 보강시킬 수 있는 섬유를 만들 수 있는 기술이 개발되었으며, 재활용 섬유로 강화된 콘크리트 제품의 구조적 성능을 연구하기 위한 시험도 수행되었다. 본 연구의 목적은 폐 FRP에서 생성되는 재활용 섬유 분진이 고강도 콘크리트의 압축강도와 내화성능에 주는 영향을 연구하는 것이다. 실험적 강도 측정 결과 재활용 섬유 분진의 부피 분율이 0.7%보다 작으면 그 분진을 사용하더라도 고강도 콘크리트의 압축강도가 감소하지 않았다. 전기로 시험 결과 역시 재활용 섬유 분진의 사용으로 고강도 콘크리트의 내화성이 크게 향상될 수 있음을 보였다.

• 한국농공학회논문집
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• 제46권5호
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• pp.79-85
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• 2004

This study was performed to evalute mechanical and drying shrinkage properties of polypropylene fiber reinforced high flow concrete. The compressive strength and drying shrinkage ratio were increased with increasing the binder volume ratio and decreased with increasing the content of polypropylene fiber. The splitting tensile strength was increased with increasing the binder volume ratio and the content of polypropylene fiber. The flexural strength was increased with increasing the binder volume ratio and increased by the polypropylene fiber content 0.4%, but above the polypropylene fiber content 0.6% was decreased. This concrete can be used for high flow concrete.