• Title/Summary/Keyword: FRP 강도특성

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Simulation and Evaluation of Compressive Strength of FRP According to the Winding Orientation of Glass Fiber (FRP에서 와인딩 각도에 따른 압축강도의 시뮬레이션과 특성평가)

  • Park, Hoy-Yul;Kang, Dong-Pil;Han, Dong-Hee;Kim, In-Sung;Pyo, Hyun-Dong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.05b
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    • pp.250-253
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    • 2000
  • The fiber orientation in FRP has a great effect on the strength of FRP because the strength of FRP mainly depends on the strength of fiber. Unidirectional FRP made by pultrusion method has comparatively lower compressive strength than tensile strength. Compressive strength of unidirectional FRP may be increased by filament winding layer which has tensile stress when compressive stress was loaded. In this study, compressive strength and stresses of FRP rods were simulated according to the winding orientation of glass fiber. Inner part of FRP was made unidirectionally by pultrusion method and outer part of FRP was made by filament winding method. Simulated value and real evaluated compressive strength were compared to investigate stresses which is prominent to the fracture of FRP. The shear stresses had a great effect on the strength of FRP although the stress of parallel direction of FRP was much higher.

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Mechanical Properties of Insulator FRP Rod According to the Winding Orientation of Glass Fiber (유리섬유의 배향에 따른 전기절연용 FRP의 강도특성)

  • Park, Hyo-Yeol;Gang, Dong-Pil;Han, Dong-Hui;Pyo, Hyeon-Dong;Kim, Tae-Ok
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.6
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    • pp.321-327
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    • 2000
  • FRP has been used very much as high strength and electrical insulation materials. The fiber contributes the high strength and modulus to the composite. The main roles of the matrix in composite materials like FRP are to transmit and distribute stresses among the individual fibers. The fiber orientation in FRP has a great effect on the strength of FRP because the strength of FRP mainly depends on the strength of fiber. In this study, compressive and bending stresses of FRP rods were simulated and measured according to the winding orientation of glass fiber. Inner part of FRP was made unidirectionally by pultrusion method and outer part of FRP was made by filament winding method to give fiber orientation to the FRP. The shear stresses had great effect on the strength of FRP although the stress of parallel direction of FRP was much higher. The tendency of compressive and bending strengths with glass fiber orientation was different each other.

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Bond Behavior between Near-Surface-Mounted Fiber Reinforced Polymer Plates and Concrete in Structural Strengthening (표면매입보강방법으로 콘크리트내에 매입된 FRP판과 콘크리트 사이의 부착거동)

  • Seo, Soo-Yeon;Yoon, Seoung-Jo;Kwon, Yeong-Soon;Choi, Ki-Bong
    • Journal of the Korea Concrete Institute
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    • v.23 no.5
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    • pp.675-682
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    • 2011
  • Recently, in retrofit of RC structures using FRP (Fiber Reinforced Polymer), researches about Near-Surface-Mounted Rertofit (NSMR) method have been widely performed. In NSMR, FRP bar is normally inserted in the slit formed in the cover concrete and then bonded by using epoxy mortar. In this paper, the bond characteristic of NSMR using FRP plate instead of bar was studied experimentally. Fracture behavior is observed from bond test using the parameters of embedment length, shear key, and FRP plate layer. In addition, an equation to predict the splitting strength of NSMR using FRP is proposed using the test result. The results showed that when the longer embedment length and more layers of FRP are used, the higher bond strength is achieved. There was a good co-relationship between the test and calculated results using the proposed equation.

Composite Hollow Bushing의 변위 특성 해석에 관한 연구

  • Jo, Han-Gu;Kim, Gwang-Yong;Seong, Yun-Gi;Lee, Cheol-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.113-113
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    • 2010
  • 본 논문에서는 composite hollow bushing에 사용되는 FRP tube의 winding 각도 및 장력 변화에 의한 변위 특성을 해석하였다. Winding 각도 및 장력에 따라 FRP tube의 인장 및 굽힘강도 특성이 변화되므로 최적의 composite bushing의 설계하기 위해서는 이에 대한 해석 및 시험이 요구된다. 따라서, 본 논문에서는 와인딩 각도 및 와인딩 장력에 따른 굽힘강도와 변위에 대하여 고찰하였으며, 와인딩 장력에 따른 각각의 특성에 대해서도 검토하였다.

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Stress-Strain Behavior Characteristics of Concrete Cylinders Confined with FRP Wrap (FRP로 횡구속된 콘크리트의 응력-변형률 거동 특성)

  • Lee, Dae-Hyoung;Kim, Young-Sub;Chung, Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.19 no.2
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    • pp.135-144
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    • 2007
  • Recently, fiber-reinforced plastic(FRP) wraps are blown as an effective material for the enhancement and rehabilitation of aged concrete structures. The purpose of this investigation is to experimentally investigate behavior of concrete cylinder wrapped with FRP materials. Experimental parameters include compressive strength of concrete cylinder, FRP material, and confinement ratio. This paper presents the results of experimental studies on the performance of concrete cylinder specimens externally wrapped with aramid, carbon and glass fiber reinforced Polymer sheets. Test specimens were loaded in uniaxial compression. Axial load, axial and lateral strains were investigated to evaluate the stress-strain behavior, ultimate strength ultimate strain etc. Test results showed that the concrete strength and confinement ratio, defined as the ratio of transverse confinement stress and transverse strain were the most influential factors affecting the stress-strain behavior of confined concrete. More FRP layers showed the better confinement by increasing the compressive strength of test cylinders. In case of test cylinders with higher compressive strength, FRP wraps increased the compressive strength but decreased the compressive sham of concrete test cylinders, that resulted in prominent brittle failure mode. The failure of confined concrete was induced by the rupture of FRP material at the stain, being much smaller than the ultimate strain of FRP material.

Concrete Shear Strength of Light Weight Concrete Beams Reinforced with GFRP bar (GFRP bar 경량콘크리트 보의 콘크리트 전단강도)

  • Jin, Min-Ho;Jang, Hee-Suk;Kim, Chung-Ho;Baek, Dong-Il
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.177-180
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    • 2008
  • Recently, the research of FRP bar as an alternative reinforcing material in reinforced concrete structures has increased to get an innovative solution to the corrosion problem. In addition to the noncorrosive nature of FRP materials, they also have a high strength-to-weight ratio. Therefore, when light weight concrete reinforced with FRP bar is used in marine environment, for instance floating structures, some advantages can be expected. But researches for the light weight concrete structure using FRP bar as a flexural reinforcement are limited to date. In this paper, the concrete shear contribution of the light weight concrete beam reinforced with GFRP bar was studied. Experiment for beams varying concrete compressive strengths and flexural reinforcement ratios was conducted and analysed. The test results showed that 75% of values obtained from proposed equation in preceding research were well agreed with the test results and were better results than the one predicted by the ACI 440.1R-06 code.

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A Study on the Evaluation of Shear Resisting Capacity for the Various Perforated Shape Shear Connector (합성거동을 위한 유공판형 전단연결재의 강도평가에 관한 연구)

  • Kim, Young-Ho
    • Composites Research
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    • v.21 no.5
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    • pp.1-8
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    • 2008
  • In recent years, the reversed L-shaped perforated shear connector has been developed to mitigate the problem associated with headed stud and Perforbond shear connector and to simulate the simultaneous failure of concrete and shear connector. And FRP perforated shear connector has been applied to composite concrete and FRP module in the FRP-concrete composite bridge deck. The design criterion of the reversed L-shaped and FRP perforated shear connector has not been established yet since the lack of experimental and analytical study results. In this paper, the existing design equations for the Perforated were briefly discussed and the equation fur the prediction of shear resisting capacity of the reversed L-shaped and FRP perforated shear connector was suggested based on the experimental test, FEM analysis. and the existing equation for the Perfobond. The predict results obtained by the suggested equation arc compared with the experimental results, the applicability and effectiveness of suggested equation was verified.

Development and Splice Lengths of FRP Bars with Splitting Failures (쪼갬파괴에 의한 FRP 보강근의 정착길이와 이음길이)

  • Chun, Sung-Chul;Choi, Dong-Uk
    • Journal of the Korea Concrete Institute
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    • v.22 no.4
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    • pp.519-525
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    • 2010
  • Data from beam-based bond tests for FRP bars in the literature were collected and regression analyses were conducted for the data of splitting failure. Average bond strengths obtained from splice tests were found to be lower and more affected by C/$d_b$ values than average bond strengths from anchorage tests, indicating needs of new design equation for the splice length of FRP bars based on the data of splice tests only. In addition, the variation of bond strengths was greater than that of tensile strengths of FRP bars and, therefore, a new safety factor should be involved for the design equation. Five percent fractile coefficients were used to develop the design equations based on the assumption that load and resistance factors for FRP reinforced concrete structures are same to the factors for steel reinforced concrete structures. The proposed design equations give economical and reliable lengths for development and splice of FRP bars. The proposed equation for splice provides shorter lengths than the ACI 440 equation in case of C/$d_b$ of 3.0 or greater. Because FRP bars are expected to be used in slabs and walls exposed to weather with thick cover and large spacing between bars, the proposed equation gives optimal splice lengths.

An Experimental Study on the Static Behavior in Weak Axis of FRP Bridge Deck Filled with a Foam (폼 충전 FRP 바닥판의 약축방향 정적거동 특성에 관한 실험적 연구)

  • Kim, Byeong Min;Zi, Goang Seup;Hwang, Yoon Koog;Lee, Young Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.6A
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    • pp.943-953
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    • 2006
  • We investigated experimentally the static behavior of an orthotropic bridge deck which is made from glass fiber reinforced polymer (GFRP) and polyurethane foam. The bridge deck consists of many unit cells with rectangular holes which are filled with the foam to improve its structural behavior in its weak axis. It is found that although the elastic modulus of the foam compared to that of the GFRP is about the order of, the structural behaviors in the weak axis such as nominal strength, stiffness, etc. are greatly improved. Owing to the low mass density of the foam used in this study, the bridge deck is still light enough with the improved structural properties. Webs of the cells filled with the foam did not significantly contribute to the strength development of the deck. However, the propagation of a crack initiated in a cell is caught by the webs and limited to the inside of that cell only, which makes the load-displacement behavior of the foam-filled GFRP deck less brittle.

Appraisal Study on Tensile Test Method of Mechanical Properties of FRP Composite Used in Strengthening RC Members (구조보강용 FRP 복합체의 역학적 특성치 분석을 위한 인장시험방법 평가 연구)

  • You, Young-Chan;Choi, Ki-Sun;Kang, In-Seok;Kim, Keung-Hwan
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.1
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    • pp.73-80
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    • 2008
  • Experimental study has been performed in order to construct the standard test methods and appraisal criteria by investigating the influence of specimen types(property, width, layers) and loading rate on the tensile characteristics of FRP used in strengthening RC structures. The FRP composite tested in this study are the unidirectional CFRP sheet/strip and the bidirectional GFRP sheet. Test variables consist of the various width ranging from 10mm to 25mm and number of CFRP sheets plied up to 5 layers. Test results indicated that maximum tensile strength and minimum coefficient of variation are recorded at each different width according to the fiber types and weaving directions. Also, the average tensile strengths of CFRP sheets are decreased as the number of layer of CFRP sheet are increased.