• Title/Summary/Keyword: FRP 피복

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Analytical Study on Concrete Cover Thickness of Anisotropic FRP Bar (이방성 섬유강화폴리머 보강근의 콘크리트 피복두께에 대한 해석적 연구)

  • Yi, Seong-Tae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.26 no.1
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    • pp.58-66
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    • 2022
  • In this study, to examine the effect of the transverse thermal expansion behavior of FRP reinforcing bars and concrete on the concrete cover thickness, based on 20℃, when the temperature changes from -70℃ to 80℃, the behavior of concrete was studied theoretically and numerically. Theoretical elastic analysis and nonlinear finite element analysis were performed on FRP reinforced concrete with different diameters and cover thicknesses of FRP reinforcement. As a result, at a negative temperature difference, concrete was compressed, and the theoretical strain result and the finite element result were similar, but at a positive temperature difference, tensile stress and further cracks occurred in the concrete, which was 1.2 to 1.4 times larger than the theoretical result. The ratio of the diameter of the FRP reinforcing bar to the thickness of the concrete cover (c/db) is closely related to the occurrence of cracks. Since the transverse thermal expansion coefficient of FRP reinforcing bars is three times greater than that of concrete, it is necessary to consider this in design.

Development of Performance-Based Seismic Design of RC Column Using FRP Jacket by Displacement Coefficient Method (FRP 보강 철근콘크리트기둥의 변위계수법에 의한 내진성능설계기법 개발)

  • Cho, Chang-Geun;Ha, Gee-Joo;Bae, Su-Ho
    • Journal of the Korea Concrete Institute
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    • v.19 no.4
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    • pp.491-497
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    • 2007
  • In the current research, the scheme of displacement-based seismic design for seismic retrofit of concrete structures using FRP composite materials has been proposed. An algorithm of the nonlinear flexural analysis of FRP composite concrete members has been presented under multiaxial constitutive laws of concrete and composite materials. An algorithm for performance-based seismic retrofit design of reinforced concrete columns with FRP jacket has been newly introduced to modify the displacement coefficient method used in reinforced concrete structures. From applications of retrofit design, the method are easy to apply in the practice of retrofit design and give practical prediction of nonlinear seismic performance evaluation of retrofitted structures.

Development of Performance-Based Seismic Design of RC Column Retrofitted By FRP Jacket using Direct Displacement-Based Design (직접변위기반설계법에 의한 철근콘크리트 기둥의 FRP 피복보강 내진성능설계법의 개발)

  • Cho, Chang-Geun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.2 s.54
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    • pp.105-113
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    • 2007
  • In the current research, an algorithm of performance-based seismic retrofit design of reinforced concrete columns using FRP jacket has been proposed. For exact prediction of the nonlinear flexural analysis or FRP composite RC members, multiaxial constitutive laws of concrete and composite materials have been presented. For seismic retrofit design, an algorithm of direct displacement-based design method (DDM) proposed by Chopra and Goel (2001) has been newly applied to determine the design thickness of FRP jacket in seismic retrofit of reinforced concrete columns. To compare with the displacement coefficient method (DCM), the DDM gives an accurate prediction of the target displacement in highly nonlinear region, since the DCM uses the elastic stiffness before reaching the yield load as the effective stiffness but the DDM uses the secant stiffness.

Behaviors of RC Beams Repaired with FRP-Rod by Use of Anchoring Pin (정착 앵커를 이용한 FRP-Rod 보수 RC 보의 거동)

  • Kim, Chung Ho;Jang, Hee Suk;Ko, Sin Woong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.1
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    • pp.151-157
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    • 2008
  • It is difficult for existing beams to ensure the sufficient embedding depth due to constructional cause. Owing to these problems, currently FRP-Rod embedding repair method run parallel with a section increasing method in many case. In this study, anchor pin was adopted to solving the problems of the sliding of FRP-Rod and the unified behaviors of the repaired beam without increasing the section. In the experiments, split failure of covering concrete and slippage of the FRP-Rod were not occurred. it was confirmed that FRP-Rod shown the integrate behaviors with RC beam till the repaired beams destroyed.

A Study on the Behavior Evaluation & Box Shape Designs of FRP Stiffeners (FRP 보강재의 Box 형상 설계 및 거동 평가에 관한 연구)

  • Jung, Woo-Young;Song, Young-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.165-168
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    • 2008
  • This paper presents the design, fabrication and performance of a reinforced concrete beam strengthened by GFRP box plate and its possibility for structural rehabilitations. The load capacity, ductility and failure mode of reinforced concrete structures strengthened by FRP box plate were investigated and compared with traditional FRP plate strengthening method. This is intended to assess the feasibility of using FRP box plate for repair and strengthening of damaged RC beams. A series of four-point bending tests were conducted on RC beams with or without strengthening FRP systems the influence of concrete cover thickness on the performance of overall stiffness of the structure. The parameters obtained by the experimental studies were the stiffness, strength, crack width and pattern, failure mode, respectively. The test yielded complete load-deflection curves from which the increase in load capacity and the failure mode was evaluated.

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An Experimental Study on the Application of FRP Tube to the Struts of PSC Box Girder Bridge (스트럿을 가진 PSC 박스거더교의 FRP 외양관 적용성 평가를 위한 실험연구)

  • Song, Jae-Joon;Hwang, Yoon-Koog;Lee, Young-Ho;Lee, Seung-Hye
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.1 s.53
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    • pp.179-185
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    • 2009
  • In recent, the investigations related to the FRP(Fiber Reinforced Polymers) have been increased due to their superior material and mechanical properties such as environmental resistance, high specific strength and stiffness. Considering these advantages, the FRP tube may be proper for strut on the PSC box girder bridge that can maximize the efficiency of cross section and are effective on economics and aesthetics of bridges. In this research, the specimen tests of the FRP tube and compression tests of the concrete member enclosed with the FRP were performed in order to evaluate the suitability of the FRP tubes, which are applied to the PSC box girder bridge with strut. The specific strength of concrete and the energy absorbing capacity as well as ductility were increased according to the experimental results, and it was found that FRP tubes have sufficient safety as strut member.

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.

Evaluation of Structural Performance of Reinforced Concrete Beams Retrofitted by Embedded FRP Rod and Metal Fittings (매입형 FRP봉과 보강철물을 보강한 철근콘크리트 보의 구조성능 평가)

  • Ha, Gee-Joo;Shin, Jong-Hack;Ha, Young-Joo;Kang, Hyun-Wook
    • Journal of the Korea Concrete Institute
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    • v.24 no.4
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    • pp.445-452
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    • 2012
  • In this study, experimental research was carried out to evaluate the structural performance of the reinforced concrete beam using strengthening materials (embedded FRP rod, metal fittings) in existing reinforced concrete buildings. Seven reinforced concrete beams comprised of retrofitted embedded FRP rod (BCR series), embedded FRP rod with metal fittings (BCR-AC series), and standard specimen (BSS) were constructed and tested under monotonic loading. Design parameters of test specimens were amount of embedded FRP rod and metal fittings. The test results showed that the maximum load carrying capacity of specimens with embedded FRP rod (BCR series) and embedded FRP rod with metal fittings (BCR-AC series) increased by 21~55% and 21~63%, respectively, in comparison with the standard specimen BSS. BCR series test specimens failed by the adhesion slip and concrete cover separation. BCR-AC series test specimens failed by the adhesion slip due to the confining effect of metal fittings.

Analytical Studies for Predicting Behaviors of RC Beams Retrofitted with Hybrid FRPs (하이브리드 FRP로 보강된 콘크리트 보의 거동 예측을 위한 해석연구)

  • Utui, Nadia;Kim, Hee-Sun
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.2 no.2
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    • pp.1-6
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    • 2011
  • This study aims at predicting structural behaviors of RC (Reinforced Concrete) beams retrofitted with hybrid FRPs (Fiber Reinforced Polymers). Toward this goal, structural analysis for the RC beams retrofitted with hybrid FRPs are performed and validated using existing experimental data. For the analysis, failure models due to debonding of FRPs and concrete separation are implemented within FE (Finite Element) model, based on Smith and Teng, model, and Teng and Yao model, respectively. Nonlinear material and geometrical effects are also included in the analysis. The suggested modeling approaches are able to predict structural behaviors of RC beams retrofitted with hybrid FRPs similar to the experimental data, however, a numerical model needs to be developed in order to predict failure strength of RC beams retrofitted with hybrid FRPs accurately.