• Title, Summary, Keyword: 강섬유

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Evaluation of Shear Strength in SFRC Beam without Stirrups Considering Steel Fiber Strengthening Factor (강섬유 보강계수를 고려한 전단보강 되지 않은 SFRC 보의 전단내력 평가)

  • Lee, Hyun-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.2
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    • pp.213-220
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    • 2004
  • The purpose of this study is to evaluate the shear strength of SFRC beam that has no stirrups by steel fiber strengthening factor. To achieve the goal of this study, two stage investigation, which is material and member level, is studied with literature and experimental side. From the reviewing of previous researches and analyzing of material and member test results, strengthening parameter of SFRC is defined as steel fiber coefficient. Based on above results, steel fiber strengthening factor is proposed. And by reviewing the proposed equation of shear strength estimation, equation of Shin was well estimated the shear strength of SFRC beams. Therefore, shear strength equation of SFRC, which is composed by Shin's Eq. and steel fiber strengthening factor, is proposed by regression analysis of test results.

Compressive Behavior of Hybrid Steel Fiber Reinforced Ultra-High Performance Concrete (하이브리드 강섬유 보강 초고성능 콘크리트의 압축거동)

  • Lim, Woo-Young;Hong, Sung-Gul
    • Journal of the Korea Concrete Institute
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    • v.28 no.2
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    • pp.213-221
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    • 2016
  • Uniaxial compression tests for ultra-high performance hybrid steel fiber reinforced concrete (UHPC) were performed to evaluate the compressive behavior of UHPC. The UHPC for testing contains hybrid steel fibers with a predetermined ratio using a length of 19 mm and 16 mm straight typed steel fibers. Test parameter was determined as a fiber volume ratio to investigate the effect of fiber volume ratio on the strength and secant modulus of elasticity. Test results showed that the compressive strength and elastic modulus of UHPC increased with increasing the fiber volume ratio. Based on the test results, the compressive strength and modulus of elasticity equations were proposed as function of the compressive strength of unreinforced and fiber reinforced UHPC, respectively. The simplified equations for predicting the mechanical properties of the UHPC were a good agreement with the test data. The proposed equations are expected to be applied to the SFRC and UHPC with steel fibers.

An Experimental Study on the Fracture Energy of Steel Fiber Reinforced Concrete Structures by the Effects of Fiber Contents (강섬유 혼입량에 의한 강섬유보강콘크리트의 파괴에너지에 관한 실험적 연구)

  • 장동일;채원규;정원우;손영환
    • Magazine of the Korea Concrete Institute
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    • v.3 no.4
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    • pp.79-88
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    • 1991
  • In this study, fracture tests were carried out in order to investigate the fracture behavior of SFRC(Steel Fiber Peinforced Concrete) with initial cracks. The relationships between loading. strain, mld-span deflections and CMOD(Crack Mouth Opening Displacement) of the beams were observed under the three point loading system. The effect of the fiber content and the initial crack ratio on the concrete fracture behavior were studied and the fracture toughness, the critical energy release ratio and the fracture energy were also calcul ated from the test results. From the test results, it was known that when the fiber contents are between 0.5% and 1.0%, and 1.5% the average fracture energy of SFRC specimens is about 7~10 times. and about 15 times better than that of the plam concrete specimens respectively.ively.

Properties of Advanced Synthetic Fiber Reinforced Concrete for Improvement of Tunnel Shotcrete Performance (터널 숏크리트 성능 향상을 위한 고기능성 합성섬유 보강 콘크리트의 물성 평가)

  • Jeon, Chanki;Jeon, Joongkyu
    • Journal of the Society of Disaster Information
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    • v.7 no.1
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    • pp.43-50
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    • 2011
  • The Application of Steel Fiber Shotcrete in tunneling construction has become part of tunneling practice at least since the 1970s because of its high bending and tensile properties. Over the past 3 decades, researcher from all over the world have been significantly developing the associated technologies for improved performance of SFRS. But still it has some major drawbacks in terms of durability, damage of pumping hose, wastage due to rebound concrete, corrosion and it costs high. To overcome this situation researcher has to look for some alternative material. Therefore, this part study deals with the three types of fiber in order to find good alternative for steel fiber. Polyamide and Polypropylene fiber were used in this study with 0.6, 0.5% mixing ratio. To evaluate its fresh and harden properties air content, slump, compressive, split tensile and bending strength were measured. After comparing the results of all three types of fiber reinforced concrete with its different mixing proportion this study propose that polyamide fiber with addition ratio of 0.6 % for field use.

Flexural Performance Characteristics of Amorphous Steel Fiber-Reinforced Concrete (비정질 강섬유보강콘크리트의 휨성능 특성)

  • Ku, Dong-Oh;Kim, Seon-Du;Kim, Hee-Seung;Choi, Kyoung-Kyu
    • Journal of the Korea Concrete Institute
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    • v.26 no.4
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    • pp.483-489
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    • 2014
  • In this study, the flexural test of amorphous steel fiber-reinforced concrete was performed according to ASTM C 1609 to investigate its flexural performances. The amorphous steel fibers have different configurations from conventional steel fibers : thinner sections and coarser surfaces. Primary test parameters are fiber type (amorphous and conventional steel fibers), concrete compressive strength (27 and 50 MPa), and fiber volume fraction (0.25, 0.50, and 0.75%). Based on the test results, flexural strength and flexural toughness of the amorphous and conventional steel fiber-reinforced concrete were investigated. The results showed that the addition of the amorphous steel fibers into concrete could enhance both flexural strength and toughness while the addition of the conventional steel fibers into concrete was mainly effective to increase the flexural toughness.

Evaluation of Mechanical Properties and Crack Resistant Performance in Concrete with Steel Fiber Reinforcement and CSA Expansive Admixture (CSA 팽창재를 혼입한 강섬유 보강 콘크리트의 역학적 성능 및 균열 저항성능 평가)

  • Choi, Se-Jin;Park, Ki-Tae;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.1
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    • pp.75-83
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    • 2014
  • In order to prevent brittle failure of concrete, steel fiber reinforcement is effective composite material. However ductility of steel fiber reinforced concrete may be limited due to shrinkage caused by large content of cement binder. Chemical prestressing for steel fiber reinforcement in cement matrix can be induced through expansive admixture and this can increase reinforcing effect of steel fiber. In this study, mechanical performances in concrete with CSA (Calcium sulfoaluminate) expansive admixture and steel fiber reinforcement are evaluated. For this work, steel fiber reinforcement of 1 and 2% of volume ratio and CSA expansive admixture of 10% weight ratio of cement are added in concrete. Mechanical and fracture properties are evaluated in concrete with steel fiber reinforcement and CSA expansive admixture. CSA concrete with steel fiber reinforcement shows increase in tensile strength, initial cracking load, and ductility performance like enlarged fracture energy after cracking. With appropriate using expansive admixture and optimum ratio of steel fiber reinforcement, their interactive action can effectively improve brittle behavior in concrete.

Evaluation on Shear Contribution of Steel Fiber Reinforced Concrete in Place of Minimum Shear Reinforcement (최소 전단철근 대용으로의 강섬유 콘크리트의 전단기여도 평가)

  • Kim, Chul-Goo;Park, Hong-Gun;Hong, Geon-Ho;Kang, Su-Min
    • Journal of the Korea Concrete Institute
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    • v.27 no.6
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    • pp.603-613
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    • 2015
  • In current design codes, minimum shear reinforcement is required for reinforced concrete flexural members, and the use of steel fiber reinforced concrete is permitted to replace the minimum shear reinforcements. In the present study, to estimate the effects of shear reinforcements and fibers on shear strength, simply supported beams were tested under transverse loading. The test results showed that the shear strength was significantly increased by the use of fibers. Particularly, the effect of fiber reinforced concrete was pronounced when high-strength concrete was used. The performance of fiber reinforced concrete for minimum shear reinforcement was evaluated using results of the present study and existing tests.

A study on pull-out behaviours of shotcrete steel fibers according to different shapes (숏크리트 강섬유 형상에 따른 인발 거동에 대한 연구)

  • Kim, Sang-Hwan;Kim, Ji-Tae
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.13 no.1
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    • pp.71-82
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    • 2011
  • This paper presents the tensile strength of shotcrete steel fibers depending on the shape of steel fiber. The experimental and numerical analyses are performed in this study. In experimental study, a series of laboratory pullout tests are carried out by changing both the angle and the length of the embedded steel fiber according to the corresponding type of steel fiber in order to derive the optimal type of steel fiber. Results obtained from the experimental work are evaluated and compared with the numerical analysis results. The results clearly show that the pull-out strength of the steel fiber are increased with increasing the hook angle and embedded angle of steel fiber. It is also found that the pull-out strength of the steel fiber is larger in case of the short steel fiber body length.

Flexural Behavior Evaluation of Two Types Fiber Reinforced Shotcrete using Round Panel Test (원형패널 시험을 활용한 두 종류 섬유 보강 숏크리트의 휨거동 평가)

  • Jeon, Chanki;Jeon, Joongkyu
    • Journal of the Society of Disaster Information
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    • v.11 no.4
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    • pp.607-614
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    • 2015
  • This study evaluated the flexural performance of steel and PP fiber reinfroced shotcrete using round panel test according to ASTM that can consider the actual stress of fiber reinforced shotcrete in tunnel and under ground structures. The results of round panel test are converted to the square panel test results according to the EFNARC. The energy absorptions of each fiber reinforced shotcrete were classified according to the EFNARC toughness classification. Test results show that the PP fiber reinforced shotcrete has better flexural performance compared with the steel fiber reinforced shotcrete.

Shear Behavior and Shear Analysis of Reinforced Concrete Members Containing Steel Fibers (강섬유를 혼입한 철근 콘크리트 부재의 전단거동 및 전단해석에 관한 연구)

  • 오병환;임동환;이형준
    • Magazine of the Korea Concrete Institute
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    • v.5 no.2
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    • pp.171-180
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    • 1993
  • 본 논문에서는 강섬유를 혼입한 철근콘크리트 부재의 전단거동에 관한 실험 및 이론적 연구를 수행하였다. 이를 위하여 강섬유가 혼입된 구조부재를 제작하여 실험을 수행하여 강섬유의 전단보강 효과를 규명하였으며, 부재의 연성, 극한전단강도 및 초기균열 전단강도 등을 모두 만족하는 최적의 강섬유 혼입량 및 전단 철근 배근량을 제안하였다. 본 실험으로부터 강섬유의 혼입으로 인하여 연성의 증가뿐 아니라, 초기균열강도는 크게 향상되었으며, 극한전단강도 역시 만족할만큼 증가함을 알수 있었다. 위의 실험결과로부터 강섬유 혼입량(체적비)1%, 시방서에서 규정하는 전단철근 필요량의 75%가 가장 만족스러운 조합임을 알 수 있었다. 본 논문에서는 강섬유가 혼입된 철근 콘크리트부재가 극한 전단강도 예측기법이 제시되었으며, 앞으로 강섬유 콘크리트는 연성을 필요로 한는 내진구조물등에 효율적으로 이용될 것으로 사료된다.