• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.345-348
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• 2004

In this study, an effect of fiber blending on material property of hybrid fiber reinforced concrete (HFRC) was evaluated. Also, optimized association and the mixing rate of fiber for HFRC was determined. Test result shows, in the case of mono fiber reinforced concrete, use of steel fiber in concrete caused increment in tensile and bending strength as the blended ratio increases, while use of carbon fiber and glass fiber caused increment in compressive strength. Use of hybrid fiber reinforcement in concrete caused a significant influence on its fracture behavior; consequently, caused increase by mixing rate of steel fiber and contributed by carbon fiber, glass fiber, celluloid fiber in reinforcement effect in order.

• 한국건축시공학회지
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• 제8권3호
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• pp.75-83
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• 2008

In this paper, concrete material tests were carried out to investigate influence of steel fiber volumn ratios on variations of workability and strength characteristics of steel fiber reinforced high-strength concrete, $50MPa{\sim}90MPa$ of compressive strength, according to increase of fiber volume. Test specimens were arranged with six levels of concrete compressive strength and fiber volumn ratios, 0.0%, 0.5%, 1.0%, 1.5%, 2.0%. The test results showed that steel fiber reinforced high-strength concrete($70MPa{\sim}90MPa$, 1.5% fiber volumn ratio) with good workability of slump 20cm could be used practically and effects of steel fiber reinforcement in improvement of concrete strength and toughness characteristics such as splitting tensile strength, flexural strength, and diagonal tensioned shear strength, were more distinguished in high-strength concrete than general strength concrete. And the test results indicated that splitting tensile strength of fiber reinforced concrete was proportioned to the product of steel fiber volumn ratios, $V_f(%)$ and sqare root of compressive strength, $\sqrt{f_{ck}}$, and the increasing rate was in contrast with that of flexural strength, and increase of diagonal tensioned shear strength was remarkable at steel fiber volumn ratio, 0.5%.

• 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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.453-456
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• 2008

섬유보강재는 부식에 대한 저항성이 높고, 고강도이며, 또한 강도에 대한 중량비(섬유보강재의 중량은 보강철근의 약 1/4정도)가 매우 낮아서 구조물 및 내하력이 저하된 콘크리트구조물의 보강에 따른 추가적인 중량의 증가 없이 보강을 할 수 있는 장점을 가지고 있다. 그러나 섬유보강재는 하중을 가하면, 최대 응력점까지 응력이 선형적으로 증가하다가 파괴되는 취성적 성질을 가지고 있다. 이러한 단점을 보완하기 위해 여러 섬유를 혼합하여 하이브리드화된 섬유보강재를 개발하였다. 개발된 하이브리드 섬유보강재는 유리섬유와 탄소섬유를 혼합하여 바 형태로 제작했으며, 유리섬유에 대한 탄소섬유의 체적비는 약 9 : 1로 구성이 된다. 하이브리드 섬유보강재를 타격식 앵커를 사용하여 시험체를 보수한 다음 인발 및 휨 시험을 실시하여 정착앵커의 수에 대한 시험체의 거동을 분석하였다. 본 연구에서는 타격식 앵커를 이용한 하이브리드 섬유보강재로 보강된 구조물의 보강특성을 알아보는데 목적이 있다.

• 콘크리트학회논문집
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• 제18권3호
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• pp.361-370
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• 2006

본 연구에서는 국내외 강섬유보강 콘크리트보의 실험값 및 이론식을 분석하여 강섬유의 보강효과 및 부재의 역학적 거동을 규명하였고, 기존의 휨강도식보다 더 정확하고 합리적인 휨강도식을 제안하였다. 제안된 휨강도식은 실험값과 좋은 일치를 보여주었고, 강섬유보강 콘크리트보의 휨강도식은 강섬유보강효과뿐만 아니라 철근의 변형률 경화효과도 함께 고려하는 것이 적절함을 알 수 있었다.

• Computers and Concrete
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• 제21권5호
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• pp.539-546
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• 2018

Making a transverse opening in concrete beams in order to accommodate utility services through the member instead of below or above of that, sometimes may be necessary. It is obvious that inclusions of an opening in a beam decreases its flexural and shear strengths. Fabricated steel bars are usually used to increase the capacity of the opening section, but details of reinforcements around the opening are dense and complex resulting in laborious pouring and setup process. The goal of this study was to investigate the possibility of using steel fibers in concrete mixture instead of complex reinforcement detailing order to strengthen opening section. Nonlinear finite element method was employed to investigate the behavior of steel fiber reinforced concrete beams. The numerical models were validated by comparison with experimental measurements tested by other investigators and then used to study the influence of fiber length, fiber aspect ratio and fiber content on the shear performance of SFRC slender beams with opening. Finally, it was concluded that the predicted shear strength enhancement is considerably influenced by use of steel fibers in concrete mixture but the effect of fiber length and fiber aspect ratio wasn't significant.

• 대한건축학회논문집:구조계
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• 제35권8호
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• pp.131-138
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• 2019

Since concrete has a low tensile strength compared to the compressive strength, reinforced concrete flexural members represent easy crack occurance under a small load. In order to overcome this problem, steel fiber reinforced concrete has been developed to compensate the tensile strength and brittleness of members. However, in the design formula of the domestic building code, it is not specified in the design formula reflecting the material characteristics. Therefore, the field application of the steel fiber reinforced concrete have had many restrictions. In this study, a flexural tensile strength model of steel fiber reinforced concrete is proposed by collecting and analyzing the material properties of material test results conducted by various researchers, and verified by the test results of cracking and stiffness evaluation of flexural members based on the proposed model. As a result of this study, the flexural tensile strength model of steel fiber reinforced concrete which can reflect the mixing ratio and aspect ratio of the steel fiber was proposed and the validity of the proposed material model equation was evaluated from the load-deflection relationship in the flexural test of the slab member.

• Computers and Concrete
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• 제28권5호
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• pp.451-463
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• 2021

Inorganic basalt fiber (BF) is a novel sort of commercial concrete fiber which is made with basalt rocks. Previous studies have not sufficiently handled the behavior of self-compacted concrete, at elevated temperature, containing basalt fiber. Present endeavor covers experimental work to examine the characteristics of this material at high temperature considering different fiber content and applied temperature. Different tests were carried out to measure the mechanical properties such as compressive strength (fc), modulus of elasticity (E), Poisson's ratio, splitting tensile strength (fsplit), flexural strength (fflex), and slant shear strength (fslant) of HSC and hybrid concrete. Gene expression programming (GEP) was employed to propose new constitutive relationships depending on experimental data. It was noticed from the testing records that there is no remarkable effect of BF on the Poisson's ratio and modulus of elasticity of self-compacted concrete. The flexural strength of basalt fiber self-compacted concrete was not sensitive to temperature in comparison to other mechanical properties of concrete. Fiber volume fraction of 0.25% was found to be the optimum to some extend according to degradation of strength. The proposed GEP models were in good matching with the experimental results.

• 자원리싸이클링
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• 제24권2호
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• pp.13-22
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• 2015

건설 분야 중 건설 재료와 건자재 산업에서 발생하는 $CO_2$는 약 6,700만톤으로 건설 분야에서 발생하는 $CO_2$의 약 30%를 점유하고 있다. 건설 분야에서 $CO_2$ 저감은 건자재 산업에서 $CO_2$를 발생시키는 2차, 3차 양생을 줄여 소비되는 화석연료 사용과 배출 가스 저감의 조절이 필수적이다. 따라서 본 연구는 저에너지양생용 혼합재(Low energy curing Admixture 이하 LA)를 압출성형패널에 적용한 후 그 혼입량, 섬유종류, 섬유 혼입율에 따른 물리적 특성을 관찰하였다. 섬유종류가 강도에 영향을 나타내는 주요한 인자는 아닌 것으로 나타났으며, LA 혼입율과 섬유 혼입량은 강도에 영향을 주는 주요한 인자인 것으로 나타났다. 특히 LA 혼입율 dl 40% 일 때 가장 높은 강도발현을 나타냈으며, 50% 인 시험체의 경우 강도가 하락하는 결과를 나타냈다, 또한 섬유 혼입율은 휨강도에 크게 영향을 주었으며 혼입율이 증가할수록 휨강도는 증가하는 것으로 나타났다.

• 한국공작기계학회논문집
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• 제17권3호
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• pp.101-107
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• 2008

A composite mechanics for discontinuous fiber reinforced polymer matrix composites(PMC) is analysed in order to predict fiber axial stresses. In continuum approach. frictional slip which usually takes place between fibers and polymers is accounted to derive PMC equations. The interfacial friction stress is treated by the product of the coefficient of friction and the compressive stress norma1 to the fiber/matrix interface. The residual stress and the Poisson's contraction implemented by the rule of mixture(ROM) are considered for the compressive stress normal to the fiber/matrix interface. In addition. the effects of fiber aspect ratio and fiber volume fraction on fiber axial stresses are evaluated using the derived equations. Results are illustrated numerically using the present equations with reasonable materials data. It is found that the fiber axial stress in the center region shows no great discrepancy for different fiber aspect ratios and fiber volume fractions while some discrepancies are shown in the fiber end region.