• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.1003-1006
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• 2003

In recent years, FRP plates have been studied for flexural reinforcement of RC structures due to easy installation and good Quality control. This study presents experimental field test results for the effectiveness of flexural reinforcement of the RC slab using external prestressing with thin CFRP strips made by the pultrusion process. It was demonstrated that flexural strength was considerably increased with relatively easy installation when compared to the other methods used for the composite reinforcement.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.17-24
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• 2002

인발성형 적층 FRP 복합소재의 재료상수는 일반적으로 시편실험을 통해 구해지고 있으나, 본 논문에서는, 실험에서 구한 탄성계수가 부재일 경우를 위해, Micromechanics와 Classical Laminate Theory (CLT)를 이용한 적층 FRP 복합재료의 탄성계수(E/sub L/과 E/sup b//sub L/) 예측모델을 제시하였다 또한 예측모델로부터 구한 값과 실험으로부터 얻은 실측값을 비교하여 그 적정성을 검증하였고, 예측모델의 민감도 및 확률적인 특성을 구성소재 (Constituents)의 재료특성에 근거해 평가하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.241-248
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• 2002

Due to many advantages such as light weight, fast installation, high durability, composite bridge deck is considered to be one of the promissing alternatives to concrete bridge deck. The paper presents procedures of finite element analysis and laminate design for composite bridge deck of triangular shape for DB24 load. After design of the section glass reinforced composite deck tube of double triangular section with 200mm profile was fabricated with pultrusion and the procedure are presented.

• Composites Research
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• 제14권6호
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• pp.16-23
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• 2001

인발 와인딩에 의한 섬유강화 복합재료 중공 봉의 기계적 거동해석을 수행하였다. 이 목적의 수행을 위해 새롭게 제작된 와인더를 전통적 인발 시스템에 부탁하여 시편을 제작하였다. 또한 인발-와인딩된 시편을 제작할 수 있는 새로운 공법을 개발하였다. 이 연구를 위해 유한요소 해석 프로그램 POSTII를 확장 개발하였다. 비선형유한요소 수식화에는 2차 피올라-키르히호프 응력 텐서와 그린 변형률 텐서에 기초한 업데이트된 라그란지언 표현법이 사용되었다. 복합재료 중공봉의 유한요소 모델링을 위해 8절점 응축쉘요소를 사용하였다. 파손평가를 위해 모든 유한요소의 각 단층에서의 평균응력을 최대음력 판정법에 대입하였다. 수치해석 예로서 불포화 섬유강화 복합재료 중공 봉의 기계적 거동을 초기 하중상태에서 최종 붕괴가지 조사하였다. 파손에 따른 강성저하와 응력제하를 고려한 유한요소해석 결과는 극만 하중과 파손 및 변형에서 실험치와 잘 일치하였다.

• 복합신소재구조학회 논문집
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• 제5권3호
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• pp.17-22
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• 2014

Fiber reinforced plastic (FRP) structural shapes are readily available in civil engineering applications. Among many manufacturing techniques used for FRP structural shapes, pultrusion process is one of the most widely used techniques in civil engineering applications. Pultrusion is a manufacturing process for producing continuous lengths of reinforced polymeric plastic structural shapes with constant cross-section. Pultruded composites are attractive for structural applications because of their continuous mass production with excellent mechanical properties. This paper presents the results of investigations pertaining to the bolted connection with two bolts for the pultruded FRP (PFRP) structural members. PFRP bolted connection tests were conducted with end distance to bolt diameter ratio ($e_1/d_b$) and two types of bolt pattern such as horizontal (Pattern A) and vertical arrangement (Pattern B). As a result, it is found that the $e_1/d_b$ is recommended as the ratio of 4. In addition, it is also found that the bearing strengths at failure of the Pattern A and Pattern B have a similar value.

• 복합신소재구조학회 논문집
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• 제1권2호
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• pp.20-28
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• 2010

이 논문에서는 기존의 CFFT(Concrete Filled FRP Tube) 복합재 말뚝의 휨강성을 확보하기 위한 새로운 복합재 말뚝형식을 제안하였다. 기존의 CFFT 복합재 말뚝은 필라멘트와인딩 공정으로 제작한 FRP를 사용하기 때문에, 압축력이 편심재하될 경우 휨거동에 대한 안전성을 확보하기 위해 철근 등 별도의 보강재를 필요로 한다. 이 연구에서는 별도의 보강재 없이 휨거동에 대한 저항성을 확보하기 위하여 펄트루젼 방식으로 제작된 FRP를 CFFT 외부에 원주방향으로 부착시킨 FRP-콘크리트 합성말뚝(Hybrid CFFT, HCFFT)을 제안하였다. 이 논문은 HCFFT의 구조적 거동을 검토하기 위한 연구의 일부로서, HCFFT에 사용되는 필라멘트와인딩 FRP의 역학적 특성을 알기 위한 실험을 실시하였다. 또한, 기존 연구 결과를 참조하여 HCFFT의 압축강도를 추정하였으며, 유한요소해석을 통해 얻은 결과와 비교분석하였다.

• 대한치과교정학회지
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• 제45권3호
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• pp.130-135
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• 2015

Objective: In our previous study, glass-fiber-reinforced plastics (GFRPs) made from polycarbonate and glass fibers were prepared for esthetic orthodontic wires using pultrusion. These laboratory GFRP wires are more transparent than the commercially available nickel-titanium wire; however, an investigation of the color stability of GFRP during orthodontic treatment is needed. Accordingly, in the present study, the color stability of GFRP was assessed using colorimetry. Methods: Preparation of GFRP esthetic round wires (diameter: 0.45 mm [0.018 inch]) using pultrusion was described previously. Here, to investigate how the diameter of fiber reinforcement affects color stability, GFRPs were prepared by incorporating either $13-{\mu}m$ (GFRP-13) or $7-{\mu}m$ glass (GFRP-7) fibers. The color changes of GFRPs after 24 h, and following 1, 2, and 4 weeks of coffee immersion at $37^{\circ}C$, were measured by colorimetry. We evaluated the color stability of GFRPs by two evaluating units: the color difference (${\Delta}E^*$) and National Bureau of Standards (NBS). Results: After immersion, both GFRPs showed almost no visible color change. According to the colorimetry measurements, the ${\Delta}E^*$ values of GFRP-13 and GFRP-7 were 0.73-1.16, and 0.62-1.10, respectively. In accordance with NBS units, both GFRPs showed "slight" color changes. As a result, there were no significant differences in the ${\Delta}E^*$ values or NBS units for GFRP-13 or GFRP-7. Moreover, for both GFRPs, no significant differences were observed in any of the immersion periods. Conclusions: Our findings suggest that the GFRPs will maintain high color stability during orthodontic treatment, and are an attractive prospect as esthetic orthodontic wires.

• 한국재난정보학회 논문집
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• 제8권4호
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• pp.391-400
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• 2012

최근 건설 산업에서 FRP는 재료적 장점들 때문에 구조물의 보강 재료로서 많이 사용되어지고 있다. FRP 외부부착보강은 중량에 비하여 높은 강도 및 강성, 우수한 내구성과 시공성 등 여러 가지 장점을 가지는 공법이다. 그러나 외부부착보강은 구조물이 투수성이 낮은 보강재로 밀폐되고 수분이 외부로 배출되지 못함으로 인하여, 장기적인 구조물의 손상을 발생시키는 문제점이 있다. 본 연구에서는 인발성형으로 제작되었으며, 기존의 FRP와 재료역학적 성질은 동등하면서 투수성을 지녀 구조물의 내구성, 부착성능에 유리한 유리섬유패널(GP)에 대해서 정적실험을 통해 실험체의 반복하중 하에서의 하중-처짐 선도, 파괴형태, 하중-변형율 관계 등을 조사하였다. 실험결과 2,000,000회 피로실험 후에도 파괴에 도달하지 않았으며, 보의 처짐이나 콘크리트 압축변형률이 기준 콘크리트 시험체보다 현저히 낮은 것으로 측정되어 장기 부착력 및 장기 내구성능이 우수함을 알수 있었다.

• 한국도로학회논문집
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• 제15권1호
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• pp.23-36
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• 2013

PURPOSES: The problem under this circumstance is that the erosion not only drops strength of the steel dowel bar but also comes with volume expansion of the steel dowel bar which can reduce load transferring efficiency of the steel dowel bar. To avoid this erosion problem, alternative dowers bars are developed. METHODS: In this study, the bearing stresses between the FRP tube dowel bar and concrete slab are calculated and compared with its allowable bearing stress to check its structural stability in the concrete pavement. These comparisons are conducted with several cross-sections of FRP tube dowel bars. Comprehensive laboratory tests including the shear load-deflection test on a full-scale specimen and the full-scale accelerated joint concrete pavement test are conducted and the results were compared with those from the steel dowel bar. RESULTS: In all cross-sections of FRP tube dowel bars, computed bearing stresses between the FRP tube dowel bar and concrete slab are less than their allowable stress levels. The pultrusion FRP-tube dowel bar show better performance on direct shear tests on full-scale specimen and static compression tests at full-scale concrete pavement joints than prepreg and filament-winding FRP-tube dowel bar. CONCLUSIONS: The FRP tube dowel bars as alternative dowel bar are invulnerable to erosion that may be caused by moisture from masonry joint or bottom of the pavement system. Also, the pultrusion FRP-tube dowel bar performed very well on the laboratory evaluation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1572-1574
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• 1999

FRP has been used very much as high strength core materials for insulators because of its high strength and good insulation properties. The fiber orientation of FRP has a great effect on FRP strength because the strength of FRP mainly depends on the strength of fiber. In this study, compression and bending stress were simulated along to the orientation of glass fiber. In addition, FRP was made by pultrusion and filament winding method. The compression and flexural strength were measured. The tendency of compression and flexural strength according to the fiber orientation of practical measured value of FRP was similar to simulated results.