• Title/Summary/Keyword: 탄소섬유판

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Flexural Behavior of Reinforced Concrete Beams Strengthened by CFRP Plates (탄소섬유판으로 보강된 철근콘크리트 보의 휨거동해석)

  • Yang, Dong-Suk;Koh, Byung-Soon;Park, Sun-Kyu;You, Young-Chan;Choi, Ki-Sun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.243-246
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    • 2005
  • This paper focuses on the flexural behavior of RC beams externally reinforced using Carbon Fiber Reinforced Plastics plates (CFRP). A non-linear finite element (FE) analysis is proposed in order to complete the experimental analysis of the flexural behaviour of the beams. This paper is a part of a complete program aiming to set up design formulate to predict the strength of CFRP strengthened beams, particularly when premature failure through plates-end shear or concrete cover delamination occurs. An elasto-plastic behaviour is assumed for reinforced concrete and interface elements are used to model the bond and slip.

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Flexural Behavior of RC beams Strengthened with Externally Bonded Prestressed CFRP Strips (외부 부착형 프리스트레스트 탄소섬유판으로 보강된 RC보의 휨 거동)

  • You Young Chan;Choi Ki Sun;Park Young-Hwan;Park Jong-Sup;Kim Keung Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.255-258
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    • 2005
  • Experimental study has been performed in order to investigate the behavior of RC beams strengthened with externally bonded prestressed CFRP (Carbon Fiber Reinforced Polymer) strips. A total of 7 specimens have been manufactured of which specimens strengthened with bonded CFRP strips considering the level of prestress as experimental variable, and a specimen with simply bonded CFRP strips. The following phenomena have been observed through the experimental results. The specimen with simply bonded CFRP strips failed below 50$\%$ of its tensile strength due to premature debonding. On the other hand, all the specimens strengthened with prestressed CFRP strips showed sufficient strengthening performance up to the ultimate rupture load of the CFRP strips. Also, it was observed that the cracking loads and yield loads of the strengthened beams were increased proportionally to the prestress level, but the maximum loads were nearly equal regardless of the prestress level.

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Flexural Behavior of RC Beams Strengthened with CFRP Strips (탄소섬유판으로 보강된 RC보의 휨 거동)

  • Choi, Ki-Sun;You, Young-Chan;Park, Young-Hwan;Park, Jong-Sup;Kim, Keung-Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.287-290
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    • 2005
  • CFRP strips manufactured in factory are produced normally with smaller width and larger thickness than CFRP sheets. By this reason, bonding force between CFRP strips and concrete substrate is not sufficient to sustain tensile force in CFRP strips. Therefore premature debonding failure cannot be avoided when strengthening is done by simply bonding the CFRP strips. The flexural strength of RC beam strengthened with CFRP strips must be calculated based on the effective strain considering debonding failure. This paper presents test results of an experimental study conducted to evaluate the flexural strength on RC beams strengthened with CFRP strips. 7 specimens were tested with respect to bond length and amount of CFRP strips. From the test results, it was indicated that the strain of the CFRP strips achieved at debonding failure can be decreased less than 6,000$\mu$ depending on the amount of CFRP strips.

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Shear Behavior of Reinforced Concrete Beams Strengthened with CFRP Strips (탄소섬유판(CFRP Strip)으로 보강된 철근콘크리트 부재의 전단거동)

  • Lim, Dong-Hwan;Park, Sung-Hwan;Kim, Yong-Il
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.161-164
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    • 2006
  • Carbon fiber reinforced polymer(CFRP) strips have superior mechanical and chemical properties in comparison with conventional materials. The purpose of this study is to investigate the mechanical shear behavior of concrete structures strengthened by CFRP strips A total of 15 concrete members were made and tested. Shear span to depth ratio(a/d) and the spacing of CFRP stripswere selected as major test variables. From test results, it isshown that shear strengthening with CFRP strips can increase the first shear strength and ultimate shear strength of concrete members significantly. And the brittle shear failure mode can be changed to a ductile failure mode by CFRP strips.

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Strengthening of Concrete Structures with External Post-Tensioning and CFRP Strips (외부 프리스트레싱과 탄소섬유판을 결합한 콘크리트 구조물 보강)

  • Lim, Dong-Hwan;Park, Sung-Hwan;Kim, Yong-Il
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.165-168
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    • 2006
  • Carbon fiber reinforced polymer(CFRP) have superior mechanical and chemical properties in comparison with conventional materials. And post-tensioning method has been used for structural reinforcement of RC structures due to easy installation and good effect of resisting capacity of structures. But the higher cost of CFRP and the loss of prestressing force with time are considered the major problems to use it. In this study, CFRP Strips and external post tensioning for rehabilitation of old concrete structures were adapted and optimal combination of these methods is considered. A total of 17 concrete members were made and tested. The types and numbers of CFRP strips and post-tensioning types were selected as major test variables. From test results, it is shown that the concrete members that post tensioned and bonded CFRP strips has a pronounced effect on the strength and deformational behavior. This present study indicates that external temporally post tensioning can reduce the amount of CFRP strips required and the combination of temporally post tensioning and CFRP strips may meet the strength and ductility requirements of old structures.

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Failure Mode and Flexural Performance of RC Beams Strengthened with Different Bond Length of CFRP Strips (탄소섬유판으로 보강된 RC부재의 부착길이 변화에 따른 파괴모드 및 휨 보강성능)

  • Choi, Ki-Sun;You, Young-Chan;Kim, Keung-Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.173-176
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    • 2006
  • The one of the commonly reported failure mode of the RC beam strengthened with FRP was caused by the separation of the concrete cover, so called delamination. Therefore, ACI440 recommended that concrete cover delamination can be prevented in strengthened beams if bond length of FRP composite be exteneded over a point of cracking moment. In this study, the failure mode and the flexural performance of RC beam with different bond length of FRP are estimated. Each bonded length is calculated based on the point of cracking moment with addition or subtraction of specific length(=150mm). The results of this study show that mid-span debonding occurs in the specimen strengthened with CFRP strips which are bonded over the point of cracking moment, while concrete cover deliamination occurs at the termination point of CFRP in the specimen with less bonded length than the point of cracking moment region.

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Flexural Rehabilitation Performance of Reinforced Concrete Beams Strengthened with Carbon Fiber Laminate (탄소섬유판을 이용한 철근콘크리트 보의 휨 보강 성능)

  • Chung, Lan;Kim, Sung-Chul;Lee, Hee-Kyoung;Yoo, Seong-Hoon;Kim, Joong-Koo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.3 no.1
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    • pp.121-128
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    • 1999
  • In this study, the behavior of R/C beams strengthened with carbon fiber laminate (CFL) is analyzed from the test results. CFL is attractive for this application due to its good tensile strength and low weight. Test parameters are the width and the thickness of CFL and repair of damaged specimen. The failure mode and ultimate load are analyzed from these measured data. Test results show that the peak load of specimens strengthened with CFL is increased to 1.27~2.04 times that of non-rehabilitation specimen. The wider lap width, larger amount of CFL, the larger strength is obtained. But the ductile behavior of the rehabilitated specimens is inversely proportional to the CFL thickness.

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A Study on Characteristics of Impact Fracture in CFRP Laminate Plates (탄소섬유강화 복합재 적층판의 충격파괴 특성에 관한 연구)

  • Yang, I.Y.;Jung, J.A.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.5
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    • pp.38-46
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    • 1995
  • In this paper, an experimental study on the effects of the impact damage and the perforation characteristic of CFRP laminates with different fiber stacking orientation and ply number was done through an observation of interrelations between the impact energy vs. transmitted energy and the impact energy vs. absorbed energy per unit volume. The velocities of the ball before or after impact are measured by the high-speed camera. And when CFRP laminates are subjected to tranverse impact by a steel ball(${\phi}10$), the delamination shapes generated by impact damage are observed by using SAM (Scanning acoustic Microscope).

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Structural Behavior of Pre-loaded RC Beams Strengthened by SP, CFS, and CFL (재하상태에서 보강된 철근 콘크리트보의 보강 재료에 따른 구조적 거동)

  • Chung, Lan;Lee, Young-Jea;Moon, Heui-Jeung;Lee, Kyung-Un;Jung, Sang-Jin
    • Magazine of the Korea Concrete Institute
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    • v.11 no.1
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    • pp.201-208
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    • 1999
  • In recent years, strengthening by steel plate, carbon fiber sheets, and carbon fiber laminate is spotlighted in order to repair and rehabilitation of R/C structures. In this study, 3 methods of rehabilitation technique were analyzed from the test results. Test parameters were the width of cracks, the method of repair and rehabilitation, the magnitude of pre-load. Deflections, failure loads, strains of reinforcing bar, strains of carbon fiber sheet, carbon fiber laminate and steel plate were measured during the tests. The primary purpose of this research was to analyze the failure mode and structural behavior of strengthened RC beams with/without superimposed pre-load. Test results should that no significant difference was observed between with pre-loaded specimens and no-loaded specimens during rehabilitation.

An Experimental Study on Flexural Performance Evaluation of RC Beams Strengthened with Anchored CFRP Plates (CFRP판을 단부정착한 RC보의 휨성능 개선에 관한 실험적 연구)

  • Kim, Hyung-Jin;Hong, Ki-Nam;Han, Sang-Hoon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.4
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    • pp.167-174
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    • 2006
  • The purpose of this paper is to analyse and compare experimentally flexural behavior of RC beams strengthened with CFRP plates by different methods, which are divided into three classes: externally-bonded without end anchorage, externally-bonded with end anchorages, and anchored after prestressing of CFRP plates. Test results show that the RC beams strengthened with end anchorages have the improvement of ductility and flexural performance evaluation including ultimate strength and deflection, compared with only external bonding. Especially, RC beams with prestressed and anchored CFRP plates increase ultimate strength and ductility significantly.