• Title/Summary/Keyword: FRP hybrid bar

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Evaluation of Tension Behavior in FRP Hybrid Bar Affected by UV Exposure and Freezing/Thawing Tests (UV 폭로 및 동결융해 시험을 거친 FRP Hybrid Bar의 인장거동 평가)

  • Yoon, Yong-Sik;Park, Jae-Sung;Park, Ki-Tae;Kwon, Seung-Jun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.2
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    • pp.130-136
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    • 2017
  • The present work is for an evaluation of tension behavior and surface deterioration of FRP Hybrid Bar due to UV exposure and freezing/thawing(F/T) actions. For the work, FRP Hybrid Bar is subjected to UV exposure test, then F/T test is performed successively to 180 cycles. In FRP Hybrid Bar, no significant surface deterioration is evaluated after UV exposure. Tension hardening performance, a unique engineering advantage of FRP Hybrid Bar, is still maintained after F/T test. The performance in FRP Hybrid Bar exposed to UV is still effective. FRP Hybrid Bar exposed to UV have almost similar tension behavior of FRP Hybrid Bar without UV exposure. Although F/T cycles increase to 180, steel rebar, FRP Hybrid Bar, and FRP Hybrid Bar exposed to UV show no significant changes in tension behavior. In the work, UV exposure and F/T actions are evaluated to have little negative effect on surface deterioration and tensile performance in FRP Hybrid Bar, however spalling of silica coating due to impact should be considered since it affects bonding strength to outer concrete.

Evaluation of Bond Strength in FRP Hybrid Bar Affected by Freezing/thawing Test and UV Rays (동결융해 및 UV 폭로시험을 거친 FRP Hybrid Bar의 인발거동특성 평가)

  • Park, Jae-Sung;Yoon, Yong-Sik;Park, Ki-Tae;Kwon, Sung-Jun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.1
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    • pp.53-58
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    • 2017
  • FRP Hybrid Bar, composed of an embedded steel and the coated composites with epoxy and glass fiber, is an effective construction material with tension-hardening performance and lightweight. The epoxy exposed to UV(Ultra Violet Rays) and FT(Freezing and Thawing) action easily shows a surface deterioration, which can cause degradation of bonding strength between inside-steel and outside-concrete. In the present work, surface inspection for 3 different samples of normal steel, FRP Hybrid Bar before UV, and FRP Hybrid Bar after UV test was performed, then concrete samples with 3 reinforcement types were prepared for accelerated FT test. Through visual inspection on 3 typed reinforcement, no significant deterioration like chalking was evaluated. The results from FT test to 120 and 180 cycles showed FRP Hybrid Bar exposed to UV test has higher bonding strength than normal steel by 106.3% due to enlarged bond area by silica coating. The 3 cases showed a similar bond strength tendency with increasing FT cycles, however a relatively big deviations of bond strength were evaluated in FRP Hybrid Bar after UV test due to loss of silica coating.

Evaluation of Bond Strength for FRP Hybrid Bar According to Coating Methods using Silica Sands (규사 코팅 방법에 따른 FRP Hybrid Bar의 부착강도 평가)

  • Jung, Kyu-San;Park, Ki-Tae;You, Young-Jun;Seo, Dong-Woo;Kim, Byeong-Cheol;Park, Joon-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.12
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    • pp.118-125
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    • 2017
  • In this study, we examined the bond performance of FRP Hybrid Bars. FRP Hybrid Bars are developed by wrapping glass fibers on the outside of deformed steel rebars to solve the corrosion problem. The surface of the FRP Hybrid Bars was coated with resin and silica sand to enhance its adhesion bonding performance with concrete. Various parameters, such as the resin type, viscosity, and size of the silica sand, were selected in order to find the optimal surface condition of the FRP Hybrid Bars. For the bonding test, FRP Hybrid Bars were embedded in a concrete block with a size of 200 mm3 and the maximum load and slip were measured at the interface between the FRP Hybrid Bar and concrete through the pull-out test. From the experimental results, the maximum load and bond strength were calculated as a function of each experimental variable and the resin type, viscosity and size of the silica sand giving rise to the optimal bond performance were evaluated. The maximum bond strength of the specimen using epoxy resin and No. 5 silica sand was about 35% higher than that of the deformed rebar.

Characteristics of Flexural Capacity and Ultrasonic in RC member with Corroded Steel and FRP Hybrid Bar (부식된 FRP Hybrid Bar의 휨 내력 및 초음파 속도 특성)

  • Choi, Se-Jin;Mun, Jin-Man;Park, Ki-Tae;Park, Cheol-Woo;Kwon, Seung-Jun
    • The Journal of the Korea Contents Association
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    • v.15 no.8
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    • pp.397-407
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    • 2015
  • Concrete is a attractive construction material, however durability problem occur due to steel corrosion, which leads propagation to structural safety problem. The recently developed FRP (Fiber Reinforced Plastic) Hybrid Bar has an engineering merit of both structural steel and FRP. Accelerated corrosion test for RC (Reinforced Concrete) samples with normal steel and FRP Hybriud Bar are performed and their flexural capacity is evaluated. Furthermore UV(Ultrasonic Velocity) measurement is attempted for analysis of variation of UV due to corrosion condition. After corrosion test, there is no significant reduction in RC beam with FRP hybrid bar but 11.5% of reduction in the case of normal steel is evaluated with 3.3% of UV reduction. For commercial production of FRP hybrid bar, bond strength evaluation through long-term submerged corrosion is required.

Tensile Behavior and Fracture Properties of Ductile Hybrid FRP Reinforcing Bar for Concrete Reinforcement (콘크리트 보강용 고연성 하이브리드 FRP 보강근의 인장 및 파괴 특성)

  • Park, Chan-Gi;Won, Jong-Pil
    • Journal of The Korean Society of Agricultural Engineers
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    • v.46 no.1
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    • pp.41-51
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    • 2004
  • FRP re-bar in concrete structures could be used as a substitute of steel re-bars for that cases in which aggressive environment produce high steel corrosion, or lightweight is an important design factor, or transportation cost increase significantly with the weight of the materials. But FRP fibers have only linearly elastic stress-strain behavior; whereas, steel re-bar has linear elastic behavior up to the yield point followed by large plastic deformation and strain hardening. Thus, the current FRP re-bars are not suitable concrete reinforcement where a large amount of plastic deformation prior to collapse is required. The main objectives of this study in to evaluate the tensile behavior and the fracture mode of hybrid FRP re-bar. Fracture mode of hybrid FRP re-bar is unique. The only feature common to the failure of the hybrid FRP re-bars and the composite is the random fiber fracture and multilevel fracture of sleeve fibers, and the resin laceration behavior in both the sleeve and the core areas. Also, the result of the tensile and interlaminar shear stress test results of hybrid FRP re-bar can provide its excellent tensile strength-strain and interlaminar stress-strain behavior.

Resistance to Chloride Attack of FRP Hybrid Bar After Freezing and Thawing Action (동결융해 이후의 FRP Hybrid Bar의 부식 저항성)

  • Ryu, Hwa-Sung;Park, Ki-Tae;Yoon, Yong-Sik;Kwon, Seung-Jun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.1
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    • pp.59-65
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    • 2018
  • RC(Reinforced Concrete) structures are exposed to various exterior conditions, and the performances of both chloride resistance and freezing/thawing action are evaluated for those exposed to corrosive environment-sea shore. Recently developed FRP Hybrid Bars which is coated with glass fiber and epoxy with core steel has an engineering advantage of higher Elasticity than FRP rod. In this work, corrosion resistance, weight loss, and bond strength are evaluated for the FRP Hybrid Bar tested through freezing/thawing action for 300cycles. The double coated FRP Hybrid Bar shows the least weight loss without defection due to freezing/thawing action. Bond strength in FRP Hybrid Bar increases to 120% of normal steel through torturity effect with Si-coating. Bond strength in normal steel shows 0.86~0.89times in 3-day corrosion acceleration and 0.35~0.38times in 5-day corrosion acceleration, however, that in FRP Hybrid Bar shows little changes in bond strength before and after freezing/thawing action.

A Study on the Application of FRP Hybrid Bar to Prevent Corrosion of Reinforcing Bar in Concrete Structure (콘크리트구조물 중의 철근 부식 저감을 위한 FRP Hybrid Bar의 적용성 연구)

  • Lee, Seung-Tae;Park, Kwang-Pil;Park, Ki-Tae;You, Young-Jun;Seo, Dong-Woo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.5
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    • pp.559-568
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    • 2019
  • Recently, the infrastructure of the marine environment has been increasing. Therefore, there has been increasing interest in increasing the durability of structures. The FRP Hybrid Bar with improved durability against corrosion was developed in recent years. On the other hand, studies that evaluate the corrosion resistance are insufficient. In this study, the corrosion resistance according to the type of rebar in concrete was assessed and analyzed. The experiment used steel bars and FRP Hybrid Bar. The corrosion test method was a galvanic current and half-cell potential method. The accelerated corrosion test was carried out by four levels (0%, 1.5%, 3%, and 6%) of chloride added to the concrete. The galvanic current measurements revealed no corrosion current in the FRP Hybrid Bar. The half-cell measurement also showed the corrosion resistance of the FRP Hybrid Bar. Therefore. FHB can be used as an alternative steel for structures where a marine environment and steel corrosion are predicted.

Evaluation of Load Capacity Reduction in RC Beam with Corroded FRP Hybrid Bar and Steel (철근부식을 고려한 FRP Hybrid Bar 및 일반 철근을 가진 RC 보의 내력저하 평가)

  • Oh, Kyung-Suk;Moon, Jin-Man;Park, Ki-Tae;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.2
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    • pp.10-17
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    • 2016
  • Steel corrosion is a very significant problem both to durability and structural safety since reinforcement has to support loads in tensile region in RC(Reinforced Concrete) member. In the paper, newly invented FRP Hybrid Bar and normal steel are embedded in RC beam member, and ICM (Impressed Current Method) is adopted for corrosion acceleration. Utilizing the previous theory of Faraday's Law, corrosion amount is calculated and flexural tests are performed for RC beam with FRP Hybrid Bar and steel, respectively. Corrosion amount level of 4.9~7.8% is measured in normal RC member and the related reduction of flexural capacity is measured to be -25.4~-50.8%, however there are no significant reduction of flexural capacity and corrosion initiation in RC samples with FRP Hybrid Bar due to high resistance of epoxy-coated steel to corrosion initiation. In the accelerated corrosion test, excellent performance of anti-corrosion and bonding with concrete are evaluated but durability evaluation through long-term submerged test is required for actual utilization.

Evaluation of Anti-Corrosion Performance of FRP Hybrid Bar with Notch in GGBFS Concrete (GGBFS 콘크리트에 매립된 Notch를 가진 FRP Hybrid Bar의 부식저항성 평가)

  • Oh, Kyeong-Seok;Park, Ki-Tae;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.4
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    • pp.51-58
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    • 2016
  • Concrete structure is a construction material with durability and cost-benefit, however the corrosion in embedded steel causes a critical problem in structural safety. This paper presents an evaluation of chloride resistance and pull-off performance with various corrosion level. For the work, OPC(Ordinary Portland Cement) concrete and GGBFS(Ground Granulated Blast Furnace Slag) concrete are prepared with normal steel. Artificially notch induced FRP Hybrid Bar is also prepared and embedded in OPC concrete and accelerated corrosion test is performed. Through the test, FRP Hybrid Bar with notch is evaluated to have insignificant effect on pull-off capacity when corroded steel shows only 21% level of pull-off capacity. Furthermore GGBFS concrete with normal steel shows over 70% level of pull-off capacity due to reduced corrosion currency.

An Experimental Study on the Mechanical Properties of Hybrid Fiber Reinforced Plastic(FRP) Rebar for Concrete Structure (콘크리트 구조물용 하이브리드 섬유강화 복합재료 리바 물성에 관한 실험적연구)

  • 배시연;신용욱;한길영;이동기;심재기
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.04a
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    • pp.63-66
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    • 2000
  • This paper describes the need for a ductile Fiber Reinforced Plastic(FRP) reinforcement for concrete structures. Using the material hybrid and geometric hybrid, it is demonstrated that the pseudo-ductility characteristic can be generated in FRP rebar. Ductile hybrid FRP bars were successfully fabricated at 4mm and l0mm nominal diameters using an hand lay up method. Tensile specimens from these bars were tested and compared with behavior of FRP rebar and steel bar

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