• Title/Summary/Keyword: 고강도 강섬유

Search Result 144, Processing Time 0.024 seconds

Anchorage Strength of High Strength Headed Bar Embedded Vertically on SFRC Members (SFRC 부재에 수직 배근된 고강도 확대머리철근의 정착강도)

  • Lee, Chang-Yong;Kim, Seung-Hun
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.24 no.1
    • /
    • pp.148-156
    • /
    • 2020
  • The paper is a summary of the results of the basic pullout test which is conducted to evaluate the anchorage capacity of high strength headed bars that is mechanical anchored vertically on steel fiber reinforced concrete members. The main experimental parameters are volume fraction of steel fiber, concrete strength, anchorage length, yield strength of headed bars, and shear reinforcement bar. Both sides of covering depth of the specimen are planned to double the diameter of the headed bars. The hinged point is placed at the position of each 1.5𝑙dt and 0.7𝑙dt around the headed bars, and the headed bars are drawn directly. As a result of pullout test experiment, concrete fracture and steel tensile rupture appear by experimental parameters. The compressive strength of concrete is 2.7~5.4% higher than that of steel fiber with the same parameters, while the pullout strength is 20.9~63.1% higher than that of steel fiber without the same parameters, which is evaluated to contribute greatly to the improvement of the anchorage capacity. The reinforcements of shear reinforcements parallel to the headed bars increased 1.7~7.7% pullout strength for steel fiber reinforced concrete, but the effect on the improvement of the anchorage capacity was not significant considering the increase in concrete strength. As with the details of this experiment, it is believed that the design formula for the anchorage length of KCI2017and KCI2012 are suitable for the mechanical development design of SD600 head bar that is perpendicular to the steel fiber reinforced concrete members.

Fracture Properties of High Strength Steel Fiber Concrete (강섬유를 혼입한 고강도 콘크리트의 파괴 특성)

  • Kim, Wha-Jung;Lee, Jun-Cheol;Lee, Jae-Min;Kwak, Min-Seok
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2010.05a
    • /
    • pp.415-416
    • /
    • 2010
  • This study presents the fracture properties of steel fiber concrete. The volume ratio of steel fiber in the concrete specimen was changed from 0%, 0.5%, 0.75%, and to 1%. The notch length was changed from 0, 15, 30, to 45mm. By applying 3-point bending tests, J-integral($J_{Ic}$), $K_{Ic}$, $G_F$ deflection strength, and fracture energy was obtained. The test results showed that the fiber content increases the concrete fracture energy.

  • PDF

Effets of Steel Fiber Contents on Flexural Creep Behavior of High-Strength Concrete (강섬유 혼입률에 따른 고강도 콘크리트의 휨 크리프 특성)

  • Lim, Seong-Hoon;Kim, Dong-Hwi;Yun, Hyun-Do
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.24 no.2
    • /
    • pp.111-118
    • /
    • 2020
  • In this paper, the flexural creep behavior of hooked-end steel fiber reinforced high-strength concrete was evaluated to investigate the steel fiber content influence on long-term behavior of flexural members. An experimental program consisted of nine prismatic beam specimens with dimensions of 150 × 150 × 600mm reinforced with different contents of steel fiber (0, 0.75 and 1.5% at the volume fraction). To introduce flexural creep loading to notched prismatic beam specimens, a four-point bending test setup was used. The sustained load with 40% of the flexural strength was applied by means of a lever system and controlled by a load cell for 90 days. During sustained loading, crack mouth opening displacement (CMOD) was monitored. Conventional flexural test after creep tests were carried out to evaluate the residual capacity of each specimen. Test results showed that steel fiber content has a significant effect on the flexural creep behavior of high-strength concrete and long-term flexural load with 40% of flexural strength doesn't generate negative effects on the residual capacity of steel fiber reinforced high-strength concrete.

Shear Strenhth and Ductility of Steel-Fiber Reinforced High Strength Concrete Beams with Shear Confinement (전단보강이 있는 강섬유 보강 고강도 철근콘크리트 보의 전단 및 연상에 관한 연구)

  • 오정근;이광수;권영호;신성우
    • Magazine of the Korea Concrete Institute
    • /
    • v.2 no.4
    • /
    • pp.53-60
    • /
    • 1990
  • Investigations on the behavior of steel fiber reinforced high strength concrete beams with shear confinement are accomplished to determine their ultimate shear strength including diagonal tension strength. The parameters varied were the shear confinement ratio(Ps), and fiber volume fraction(Vs). Ultimate shear strength increased significantly in steel fiber reinforced concrete beam without shear confinement. In steel- fiber reinforced high strength concrete beams with shear confinement, there is no increase of ultimate shear strength but shows much beneficial effects of Ductility Capacity.

Effects of Aggregate Size and Steel Fiber Volume Fraction on Compressive Behaviors of High-Strength Concrete (골재크기 및 섬유혼입률에 따른 강섬유 보강 고강도 콘크리트의 압축거동)

  • Ahn, Kyung-Lim;Jang, Seok-Joon;Jang, Sang-Hyeok;Yun, Hyun-Do
    • Journal of the Korea Concrete Institute
    • /
    • v.27 no.3
    • /
    • pp.229-236
    • /
    • 2015
  • This paper describes the effect of aggregate size on compressive behavior of high-strength steel fiber reinforced concrete. The Specified compression strength is 60 MPa and the range of fiber volume fraction is 0~2%. The main variable is the aggregate size, which was used for the aggregate size of 8 and 20 mm. So, ten concrete mixtures were prepared and tested to evaluate the fresh and hardened properties of SFRC at curing ages (7, 14, 28, 56 and 91 days), respectively. Items estimated in this study are the fresh properties (air contents, slump), hardened properties (compressive strength, modulus of elasticity, post-peak response and compressive toughness). As a result, the aggregate size has little effect on the compressive strength and modulus of elasticity. On the other hand, the ductile behavior was shown after post peak and the compressive toughness was increasing as decreasing the aggregate size. These effects are clearly represented in the fiber volume fraction 2%, which are the point appeared fiber ball. It is considered that the decreasing the aggregate size has effect on the fiber dispersibility.

Performance Evaluation of High Strength Concrete with Composite Fibers in Accordance with High Temperature (복합섬유가 혼입된 고강도 콘크리트의 고온가열에 따른 성능 평가)

  • Kim, Seung-Ki;Kim, Woo-Suk
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.19 no.6
    • /
    • pp.63-71
    • /
    • 2015
  • The objective of the present study is to investigate how elevated temperature ranging from $100^{\circ}C$ to $800^{\circ}C$ as well as room temperature affects the variation of mechanical properties of high strength concrete ($over\;f_{ck}=60MPa\;grade$). In this experiment, specimens were exposed for a period of $2^{\circ}C/min$ to temperatures of $20^{\circ}C$, $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$ $400^{\circ}C$, $500^{\circ}C$, $600^{\circ}C$, $700^{\circ}C$ and $800^{\circ}C$, respectively. Accordingly, the study investigated the fire resistance performance of high strength concrete mixed with composite fibers which composed with hybrid fibers and steel fibers. After cooling down to ambient temperature, the following basic mechanical properties were then evaluated and compared with reference values obtained prior to thermal exposure: (i) compressive strength in room temperature; (ii) residual compressive strength; (iii) Poisson's ratio; (iv) weight change; (v) SEM analysis & XRD analysis In addition, XRD and SEM Images analyses were performed to investigate chemical and physical characteristics of high strength concrete with composite fibers according to high temperature.

Strength and Mechanical Characteristics of Fiber-Reinforced Polymer Concrete (섬유보강 폴리머 콘크리트의 강도 및 역학적 특성)

  • 오병환
    • Magazine of the Korea Concrete Institute
    • /
    • v.4 no.3
    • /
    • pp.147-155
    • /
    • 1992
  • 최근들어 성능이 우수하고 품질이 높은 새로운 건설소재를 개발하려는 노력이 계속되고 있다. 본 논문에서는 고강도화 및 연성확보를 위하여 폴리머 콘크리트에 섬유를 혼입한 섬유보강 폴리머 콘크리트를 제조하여 강도 및 역학적 특성을 규명하고자 하였다. 이를 위하여 포괄적인 실험연구를 수행하였으며 주요실험변수로는 강섬유의 혼입량과 채움재(filler)의 혼입량, 그리고 양생온도를 주요변수로 선정하였다. 강섬유의 혼입량은 체적비로 0%, 1%, 2%로 변화시켰으며, 채움재와 수지의 비는 1.0과 1.5로 하였다. 본 연구결과 섬유의 혼입으로 인하여 압축강도, 휨강도, 인장강도 모두 증가하였으며, 특히 인장강도의 증가가 더 크게 나타났다. 양생온도가 증가한 경우 폴리머의 중합반응이 좋아져 강도가 증가하였다. 또한 본 논문에서는 섬유보강 폴리머 콘크리트의 응력-변형도 관계곡선을 도축하였으며, 이것은 구조설계시 중요한 기초가 될 것으로 사료된다.

An Experimental Study on The Fire Resistance Performance and Spalling of 100 MPa HSC Column Mixed Fiber-Cocktail (Fiber-Cocktail 섬유를 혼입한 100 MPa 고강도 콘크리트의 단면크기에 따른 폭렬 및 내화성능에 관한 실험적 연구)

  • Kim, Hyung-Jun;Kim, Heung-Yonl;Park, Kyung-Hoon;Yeo, In-Hwan;Kwon, Ki-Hyuck
    • Fire Science and Engineering
    • /
    • v.25 no.5
    • /
    • pp.85-92
    • /
    • 2011
  • Along the fire resisting capacity of high strength concrete has been brought up as a social issue, and the Ministry of Land also had notified the control standard about it, the researches for improving the fire resisting capacity have been considerably activated these days. In this study, we performed a research for developing a high strength concrete, contains the fiber cocktail, which is a hybrid of polypropylene fiber as organic matter, and steel fiber. As we analyzed the temperature of the steel part during the fire test with 100 MPa high strength concrete, there was a tendency that the lower temperature comes out with the larger cross section, and the $600{\times}600mm$, $800{\times}800mm$ cross sectioned can secure the fire resistance capability, so the $600{\times}600mm$ is deducted as the optimal size if we consider the double economic feasibility. As well, among them the best qualified $600{\times}600mm$ shapes, the fiber cocktail hybrid of $1.5kg/m^3$ PP fiber and $40kg/m^3$ of steel, comes out the best ratio.

An Experimental Study on the Freeze-Thaw Resistance of High-Strength Light Weight Aggregate Concrete (고강도 경량골재콘크리트의 동결융해 저항성에 대한 실험적 연구)

  • 한상묵;최세규;김생빈
    • Magazine of the Korea Concrete Institute
    • /
    • v.10 no.1
    • /
    • pp.125-132
    • /
    • 1998
  • 경량골재 콘크리트의 내구성과 경제성에 대한 인식 부족으로 조경재료나 인공토양 둥 구조부재 이외의 분야에 사용되고 있는 국내 실정에 비해서, 구미 여러나라에서는 고강도 경량골재를 장지간 교량과 고충건물에 사용하고 있다. 경량골재 콘크리트는 구조물의 재료비 단순비교에 있어서도 경제성이 있을 뿐만 아니라, 자중감소로 인한 구조적, 기하학적 장점도 있으며, 또한 고강도 경량골재의 개발로 경량골재가 가지고 있는 여러 문제점을 해소하여 사용성과 내구성에 있어서 보통골재 콘크리트와 큰 차이가 없는 상황이다. 그러나국내에서 생산된 경량골재는 닫힌 공극보다 열린 공극을 많이 내포하고 있어 수분흡수가 많고, 특히, 동결융해에 대한 내구성에 취약한 문제점을 가지고 있다. 본 논문에서는 내동해성 향상을 위해 10종류의 고강도 경량골재 콘크리트 공시체를 제작하여 실리카 흄, 물.시멘트비, AE제, 강섬유 등을 실험 변수로 하여동결융해 실험을 수행하였다. 연구결과 실리카흄, 물.시멘트 비는 어느 정도 내동해성을 향상시키지만 근본적인 해결방안이 되지 못하며, AE제를 첨가한 공시체와 강섬유를 사용한 공시체는 동결융해 내구성 지수가 90%이상으로 측정되어 내동해성을 개선시킬 수 있는 요소로 나타났다.

Compressive Strength and Fire Resistance Performance of High Strength Concrete with Recycled Fiber Power from Fiber-Reinforced Plastics (재활용 FRP 미분말을 혼입한 고강도 콘크리트의 압축강도 및 내화성능)

  • Lee, Seung Hee;Park, Jong Won;Yoon, Koo Young
    • Journal of the Korean Society for Marine Environment & Energy
    • /
    • v.17 no.1
    • /
    • pp.46-51
    • /
    • 2014
  • Increasing of waste FRP (fiber reinforced plastics) has caused environmental problems. Recently, the technology of making fibers from waste FRP, which can be used to reinforce the concrete, was developed and the reinforced concretes were tested to study the structural performance. The purpose of this study is to investigate the effect of the powder, obtained together with F-fiber from the waste FRP, on the compressive strength and the fire resistance performance as in the high strength concrete. Strength tests show that the use of recycled FRP powder does not reduce the compressive strength of high strength concrete if the volume fraction of FRP powder is less than 0.7%. Electric furnace test results also show that the use of recycled FRP powder may increase the fire resistance performance of high strength concrete significantly.