• Title/Summary/Keyword: Carbon fiber polymer plate

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Stress intensity factors for double-edged cracked steel beams strengthened with CFRP plates

  • Wang, Hai-Tao;Wu, Gang;Pan, Yu-Yang;Zakari, Habeeb M.
    • Steel and Composite Structures
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    • v.33 no.5
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    • pp.629-640
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    • 2019
  • This paper presents a theoretical and finite element (FE) study on the stress intensity factors of double-edged cracked steel beams strengthened with carbon fiber reinforced polymer (CFRP) plates. By simplifying the tension flange of the steel beam using a steel plate in tension, the solutions obtained for the stress intensity factors of the double-edged cracked steel plate strengthened with CFRP plates were used to evaluate those of the steel beam specimens. The correction factor α1 was modified based on the transformed section method, and an additional correction factor φ was introduced into the expressions. Three-dimensional FE modeling was conducted to calculate the stress intensity factors. Numerous combinations of the specimen geometry, crack length, CFRP thickness and Young's modulus, adhesive thickness and shear modulus were analyzed. The numerical results were used to investigate the variations in the stress intensity factor and the additional correction factor φ. The proposed expressions are a function of applied stress, crack length, the ratio between the crack length and half the width of the tension flange, the stiffness ratio between the CFRP plate and tension flange, adhesive shear modulus and thickness. Finally, the proposed expressions were verified by comparing the theoretical and numerical results.

Bond Capacity of Near-Surface-Mounted CFRP Plate to Concrete Under Various Temperatures (콘크리트에 표면매입 보강된 탄소섬유 판의 온도에 따른 부착성능)

  • Seo, Soo-Yeon;Kim, Jeong-Hun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.4
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    • pp.75-83
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    • 2013
  • This paper presents a series of test result in order to study fire resistance capacity of the Near-Surface-Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) plate, which are tensile test of CFRP under various temperature loading, temperature loading test of epoxy and bond test of NSM CFRP to concrete under various temperature loading. From the tests, it was found that NSM retrofit method had high efficiency in strengthening concrete under ordinary temperature. However, the strength of the system was able to be drastically decreased even a little increase of surrounding temperature. Especially, bond capacity begins to disappear when the surrounding temperature approaches the glass transition temperature of epoxy. Therefore, it is necessary to improve the fire resistance capacity of both fiber reinforced polymer reinforcement and epoxy for bonding in order to develop safe fire resistance design of structure.

Parametric study of shear strength of CFRP strengthened end-web panels

  • Shalaby, Haitham A.;Hassan, Maha M.;Safar, Sherif S.
    • Steel and Composite Structures
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    • v.31 no.2
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    • pp.159-172
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    • 2019
  • Strengthening of civil infrastructure with advanced composites have recently become one of the most popular methods. The use of Fiber Reinforced Polymer (FRP) strips plates and fabric for strengthening of reinforced concrete structures has well established design guidelines and standards. Research on the application of FRP composites to steel structures compared to concrete structures is limited, especially for shear strengthening applications. Whereas, there is a need for cost-effective system that could be used to strengthen steel high-way bridge girders to cope with losses due to corrosion in addition to continuous demands for increasing traffic loads. In this study, a parametric finite element study is performed to investigate the effect of applying thick CFRP strips diagonally on webs of plate girders on the shear strength of end-web panels. The study focuses on illustrating the effect of several geometric parameters on nominal shear strength. Hence, a formula is developed to determine the enhancement of shear strength gained upon the application of CFRP strips.

Experimental Study by Single and Double Face Shear Test of Bond Ability between Carbon Fiber Reinforced Plate and Concrete. (1면과 2면 인장전단 실험 방법에 따른 부착성능에 관한 실험적 연구)

  • Kang Dae Eon;Woo Hyun Su;Choi Ki Sun;Yang Won Jik;You Young Chan;Yi Waon Ho
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.315-318
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    • 2005
  • The objective of this study is to find out discrepancy in ability of bond behavior between Carbon fiber-reinforced polymer(CFRP Plate) and concrete by method of experiment. For the objective, single and double face shear test were tested. From the experimental results, it was analyzed bond strength of FRP to concrete, distribution of stress and strain of FRP. The bond strength and the effective bond length was evaluated by the theory of existing studies. Effective bond length of single face test was smaller than it of double face test.

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Behavior Prediction of Strengthened! Reinforced! Concrete Beam using Nonlinear Analysis (비선형 해석을 통한 보강된 RC 보의 거동 예측)

  • 박중열;황선일;조홍동;한상훈
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.05a
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    • pp.561-566
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    • 2003
  • In this study, to predict the behavior of RC beam strengthened with Carbon fiber reinforced polymer(CFRP) plate, analytical program considering material non-linearity is developed. Strain compatibility and force equilibrium are applied and internal forces of constitutive material are calculated using nonlinear stress-strain relationship. Also, to certainty the reliability of analytical program, deflection, strain of CFRP plate, change of neutral axis on cross section and crack distribution at failure are compared with those of experiment, and each results are almost coincident.

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The Analysis for Reinforced Concrete Beams Strengthened with Externally Unbonded Prestressed CFRP Plates (비부착 탄소섬유판 긴장재로 외부 긴장 보강된 철근콘크리트 보의 해석)

  • Park, Jong Sup;Jung, Woo Tai;Park, Young Hwan;Kim, Chul Young
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.4A
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    • pp.439-445
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    • 2008
  • This paper suggests a modified bond reduction coefficient considering the average CFRP (Carbon Fiber Reinforced Polymer) strain concept for the unbonded prestressed CFRP plate strengthening system. The strengthened length and the pure bending length were seen to influence the variation of the strain of unbonded CFRP plate. Therefore, a new bond reduction coefficient considering such effect was suggested. Comparison with the experimental data revealed that the analytic results obtained by considering the proposed bond reduction coefficient were effective in estimating the strain of the unbonded CFRP plate in the CFRP plate prestressing system.

A study on the electrical and mechanical properties of PEMFC bipolar plate by thermoplastic composite injection molding process (열가소성 복합소재를 이용하여 사출성형 한 PEMFC용 bipolar plate의 전기전도도 및 기계적 특성 연구)

  • Yoon, Yong-Hun;Kim, Dong-Hak
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.4
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    • pp.1999-2004
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    • 2011
  • This research aims to develop polymer composites which can be used for PEMFC bipolar plate by injection molding process. Considering the moldability and stiffness, we used LCP(Liquid crystal polymer) as base resin. In order to improve electrical conductivity and mechanical properties, we chose carbon black, and both synthetic graphite and expanded graphite. The composites with different recipe are prepared for injection molding of PEMFC bipolar plate and CAE(Computer Aided Engineering) analysis was performed to predict melt flow and fiber orientation We did successfully fabricate the ASTM specimens by injection molding, and measure the electrical conductivity of the samples by using four point probe device. We measured mechanical properties such as flexural strength, flexural modulus and Izod impact strength. Conclusively, the electrical conductivity increased with increasing additive concentration, but both flexural strength and Izod impact strength decreased due to the brittle nature of carbon-based additives.

A Study on Strength Effect of Timber Beam with Inserting CFRP Plate (탄소섬유판 삽입공법에 의한 목재보 보강효과에 관한 연구)

  • Yu, Hye-Ran;Jung, Won-Chul;Choi, Min-Seok;Kwon, Ki-Hyuk
    • 한국방재학회:학술대회논문집
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    • 2007.02a
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    • pp.41-44
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    • 2007
  • In repairing and reinforcing modem architecture, altering the features must be minimized. We concluded that inserting CFRP(Carbon Fiber Reinforcement Polymer) plate method is the most appropriate reinforcing method that minimize altering the features. This study focuses on the effect of reinforcement by inserting CFRP plate in the timber beam of the modem architecture's roof truss. We concluded that inserting CFRP plate method is highly influenced by its parent material, however, it is obvious that materials had reinforced by this method in general. We guess that this method is applicable to reinforcement in the modern architecture's roof truss in various ways.

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The Study on Improvement of Flexural Performance of RC Beam Strengthened with CFRP Plate (탄소섬유보강판으로 보강된 철근콘크리트 보의 휨성능 개선에 관한 연구)

  • 한상훈;최만용;조홍동;박중열;황선일;김경식
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.399-404
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    • 2002
  • This paper presents the results cf research on improved flexural performance cf reinforced concrete beams strengthened with bonded carbon fiber reinforced polymer plate. Recently, strengthening technique with CFRP plate were almost carried out by external bonding. But current external bonding technique cf CFRP plates may result in debonding CFRP plate. Therefore, this study proposes a strengthening method that prevents or delays debonding between CFRP plates and concrete and at the same time improves the strength. For this test, there were only 14 test beams manufactured and failure load, deflection, strains and modes cf failure have been examined Test variables included the type cf strengthening, steel ratio and strengthening length, and the effects according to each test variables were analyzed. The experimental results show that the strength and stiffness cf the beam significantly increased between 34.55 and 116.51% and the increase cf the more lead-carrying capacity than the control beams.

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Development of Thermoplastic Carbon Composite Bipolar Plates for High-temperature PEM Fuel Cells (고온 양성자 교환막 연료전지용 열가소성 탄소 복합재료 분리판 개발)

  • Lim, Jun Woo;Kim, Minkook;Lee, Dai Gil
    • Composites Research
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    • v.29 no.5
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    • pp.243-248
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    • 2016
  • Although thermoset carbon fiber composite bipolar plates not only have high mechanical properties but also high corrosion resistance in acid environment, high manufacturing cost and low bulk electrical conductivity are the biggest obstacle to overcome. In this research, thermoplastic polymer is employed for the matrix of carbon composite bipolar plate to increase both the manufacturing productivity and bulk electric conductivity of the bipolar plate. In order to increase the electrical conductivity and strength, plain type carbon fabric rather than chopped or unidirectional fibers is used. Also nano particles are embedded in the thermoplastic matrix to increase the bulk resistance of the bipolar plate. The area specific resistance and the mechanical strength of the developed bipolar plate are measured with respect to the environmental temperature and stack compaction pressure.