• 도시과학
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• 제11권2호
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• pp.25-30
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• 2022

Resin Transfer Molding FRP (RTM FRP) is a fiber reinforced polymeric plastic which is manufactured by applying pressure to fibers, injecting resin into a mold, and then impregnating it. RTM FRP is a new construction material suitable for producing non-continuum structural elements such as sole plate because it has excellent strength and can produce many members in a short time. In this study, experiments were conducted to estimate the capacity of the bolted connection of RTM FRP. First, a tensile test was conducted to confirm the mechanical properties such as the tensile strength of the RTM FRP to be used for the bolted connection experiments. In addition, experiments were conducted on the bolted connection with the thickness of the RTM FRP and the edge distance of the bolt as variables. In the first experiment, F4.8 bolts were used, and shear failure of the bolt occurred before the RTM FRPs were failed. The F4.8 bolt is a general structural bolts used for the sole plate of a bridge bearing, and it was confirmed that the RTM FRP has a higher bold bearing strength than the shear strength of a F4.8 bolt. In the second experiment, G12.9 bolts were used, and shear failure of the bolt and bearing failure of the RTM FRP occurred simultaneously. In addition, as the thickness of the RTM FRP and the edge length of the bolt increased, the strength of the joint increased. When analogized with the bearing fracture equation of steel plate, the bolted connection of RTM FRP showed a bearing strength coefficient of 0.420 to 0.549 compared to the tensile strength, and it is considered that further research is needed.

• 한국해양환경ㆍ에너지학회지
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• 제10권2호
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• pp.102-106
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• 2007

선박 제조에 사용되고 있는 FRP(Fiber-reinforced plastic)를 재활용하기 위한 노력이 지속되고 있는 가운데 보다 친환경적이며 가치를 재창출할 수 있는 방법들이 연구되고 있다. 본 연구진들은 선박용 FRP에 쓰이는 유리섬유의 구조가 그 짜임새의 형태에 따라 로빙층과 매트층으로 구분된다는 사실에 착안하여 FRP를 분쇄하지 않고 층을 분리할 수 있었다. 그 중 로빙층을 적절한 크기로 잘라 장섬유(약 50 mm, 이후 'F섬유')를 만들었다. F섬유의 인장강도 증가와 화학적 내식성 증가는 잔재하는 수지(전체 섬유의 무게비 25% 정도)의 영향인 것으로 보인다. 본 연구에서는 F 섬유의 재활용의 한 방법으로 섬유강화 모르타르를 제조한 결과 2%(v/v)의 F섬유를 포함한 모르타르는 28일 양생 후 휨 강도가 34.6% 증가함을 보였다. 수입 합성섬유 P-54를 사용한 모르타르와 유사한 정도의 휨 강도를 얻을 수 있었다. 이는 F섬유가 골재로 사용이 가능하며 수입품을 대체할 수 있음을 의미한다.

• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2004년도 춘계 학술발표회 논문집 제1권1호(통권1호)
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• pp.206-211
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• 2004

This paper deals with the flexural strengthening of reinforced concrete beams by means of thin fiber reinforced plastic(FRP) laminas. This study focuses on modeling of structural of concrete bonded FRP laminate in flexural bending members. Used computational equation is derived by relation of stress and strain. The section analysis is based on experimental observations of a linear strain distribution in the cross section until failure, and a multi-linear moment-deflection curve that is divided into four regions, each terminated by a similarly numbered point. The load-deflection relationship in each region is assumed to be linear. The present model is validated to compare wit the experiment of 4-point bending tests of R/C rectangular beams strengthened with CFRP laminates, and has well predicted the moment-displacement relationships of members.

• 복합신소재구조학회 논문집
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• 제4권4호
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• pp.1-8
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• 2013

Pile foundations constructed by the fiber reinforced polymer plastic piles have been used in coastal and oceanic regions in many countries. Generally, fiber reinforced polymer plastic piles are consisted of filament winding FRP which is used to wrap the outside of concrete pile to increase the axial load carrying capacity or pultruded FRP which is located in the core concrete to resist the bending moment arising due to eccentric loading. In this paper, the analytical procedures of hybrid concrete filled FRP tube flexural members are suggested based on the CFT design method. Moreover, the analytical results are compared with the experimental results to obtained by the previous researches. The results of comparison analyses are performed to estimate the accuracy of the analytical procedure for hybrid FRP-concrete composite compression test, members under eccentrical loading.

• Wind and Structures
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• 제3권2호
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• pp.83-96
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• 2000

Due to their high corrosion and chemical resistance, fiber reinforced plastics (FRP) are becoming widely used as the main structural material for industrial chimneys. However, no national code currently exists for the design of such type of chimneys. The purpose of this study is to investigate analytically the response of FRP chimneys to wind loads. The classical lamination theory is used to substitute the angle-ply laminate of a FRP chimney with an equivalent orthotropic material that provides the same stiffness. Dynamic wind loads are applied to the equivalent chimney to evaluate its response to both along and across wind loads. A parametric study is then conducted to identify the material and geometric parameters affecting the response of FRP chimneys to wind loads. Unlike the across-wind response, the along-wind tip deflection is found to be highly dependent on the angle of orientation of the fibers. In general, the analysis shows that FRP chimneys are very vulnerable to across-wind oscillations resulting from the vortex shedding phenomenon.

• 콘크리트학회논문집
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• 제18권2호
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• pp.293-298
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• 2006

The reinforced concrete(RC) structures strengthened with fiber reinforced plastic(FRP) has been accepted by the construction engineering community for rehabilitation. FRP composites can present many advantages like a corrosion resistance, strength-weight ratio, relatively short application time, and cost effectiveness. The beams under design load, however, are cracked and result in degrading the strength. It is difficult to recognize cracks and deflections on the surface of the concrete members retrofitted with FRP through the life cycle. For these reasons, if they result in the effects, which were below the expected strength, we must monitor the state of concrete structures all the time in order to take an appropriate measure. Fiber Bragg Grating(FBG) sensor excel as monitoring of investigating the stress state of the retrofitted beams with FRP. The main objective of this study is to measure strain by experiment and analyze the behavior of RC beams retrofitted with FRP using FBG sensor. The kinds of FRP which were used in research are carbon, glass and improved hybrid FRP(IFRP) that has capacity than any other FRP. Other variables are the length of FRP, the number of sheet.

• 한국터널지하공간학회 논문집
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• 제3권1호
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• pp.11-19
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• 2001

이 연구는 강관 보강형 다단 그라우팅공법의 설치 및 절단 시 어려움, 부식에 취약한 문제점 등을 개선하는데 목적이 있으며, 강관 대신에 고강도 유리섬유(fiberglass)를 이용한 FRP(Fiberglass Reinforced Plastic)의 적용성에 대한 연구를 수행하였다. 연구결과는 강관에 비하여 FRP 보강재의 가격이 높긴 하지만 시공성 및 내구성 등에서 우수한 것으로 파악되었다. 그리고 FRP 보강재의 형상에 따른 수치해석 결과에서는 국외에서 상용화 된 판상형 보강재 보다 등각곡선형 보강재가 더 구조적 측면에서 효율적임을 알 수 있었고, 그라우트 복합체에 대한 굴곡강도시험 결과에서는 강관과 FRP 보강재의 지보효과가 유사한 것으로 평가되었다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.112-116
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• 2003

This paper describes the need for a ductile of Fiber Reinforced Plastic(FRP) reinforcement for concrete structures. The criteria to be met by the FRP, which are based on the properties of the steel rebar it is to replace, are threefold: high initial modulus, a definite yield point and a high level of ultimate strain. It is shown that the use of a fiber architecture based design methodology facilitates the optimization of the performance of FRP through material and geometric hybrid. Ductile hybrid FRP bars were successfully fabricated at 3mm and 5mm nominal diameters using an in-line braiding and pultrusion process.

• Computers and Concrete
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• 제33권2호
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• pp.163-173
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• 2024

Fiber-reinforced polymers (FRP) have a proven strength enhancement capability when installed into Reinforced Concrete (RC) beams. The brittle failure of traditional FRP strengthening systems has attracted researchers to develop novel materials with improved strength and ductility properties. One such material is that known as polyethylene terephthalate (PET). This study presents a numerical investigation of the flexural behavior of reinforced concrete beams externally strengthened with PET-FRP systems. This material is distinguished by its large rupture strain, leading to an improvement in the ductility of the strengthened structural members compared to conventional FRPs. A three-dimensional (3-D) finite element (FE) model is developed in this study to predict the load-deflection response of a series of experimentally tested beams published in the literature. The numerical model incorporates constitutive material laws and bond-slip behavior between concrete and the strengthening system. Moreover, the validated model was applied in a parametric study to inspect the effect of concrete compressive strength, PET-FRP sheet length, and reinforcing steel bar diameter on the overall performance of concrete beams externally strengthened with PET-FRP.

• 복합신소재구조학회 논문집
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• 제2권1호
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• pp.30-39
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• 2011

이 논문에서는, CFT 감재-콘크리트 합성말뚝과 FRP를 원주방향으로 보강한 FRP-콘크리트 합성말뚝 (CFFT)과 관련하여 발생하는 문제점들을 완하시키기 위해 새롭게 제안된 콘크리트 채움 원형 FRP 말뚝 (HCFFT)의 구조적 거동에 대한 실험적 연구결과를 발표하였다. 연구를 통해 기존의 CFT와 CFFT 말뚝과 비교하여 새로 제안한 HCFFT 말뚝이 말뚝 기초의 시공에서 축하중과 휨모멘트를 포함하는 상부하중을 지반에 효과적으로 전달할 수 있음을 알 수 있었다.