• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.463-468
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• 2002

For the Externally bonded FRP systems, flexural design method is studied focusing on the reinforcement layer of the carbon fiber sheets. As the FRP layer is added, strengthening rate increases, but not proportionally as the FRP layer increases. This is reflected in the design formula appropriately by the bond cofficients from the added layers. As the number of FRP layer increases, the stress reinforcement and FRP sheet decreases, and it generally corresponds to the decrease rate of member flexural strength. This phenomenon is appearing indentically in a design formula and experimental result. The rate of $M_{test}$ and $M_n$ is 1.19 and it is estimated as safety factor which is the reduction factor, ${\psi}_f = 0.85$.

• International Journal of Concrete Structures and Materials
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• 제8권2호
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• pp.117-128
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• 2014

Numerous investigations of RC beams strengthened in shear with externally-bonded (EB) fibre-reinforced polymer (FRP) sheets, plates and strips have been successfully conducted in recent years. These valuable studies have highlighted a number of influencing parameters that are not captured by the design guidelines. The objective of this study was: (1) to highlight experimentally and analytically the influential parameters on the shear contribution of FRP to RC beams strengthened in shear using EB FRP sheets and strips; and (2) to develop a set of transparent, coherent, and evolutionary design equations to calculate the shear resistance of RC beams strengthened in shear. In the experimental part of this study, 12 tests were performed on 4,520-mm-long T-beams. The specimens were strengthened in shear using carbon FRP (CFRP) strips and sheets. The test variables were: (1) the presence or absence of internal transverse-steel reinforcement; (2) use of FRP sheets versus FRP strips; and (3) the axial rigidity of the EB FRP reinforcement. In the analytical part of this study, new design equations were proposed to consider the effect of transverse-steel in addition to other influential parameters on the shear contribution of FRP. The accuracy of the proposed equations has been verified in this study by predicting the FRP shear contribution of experimentally tested RC beams.

• 한국농공학회논문집
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• 제46권1호
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• pp.41-51
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• 2004

FRP re-bar in concrete structures could be used as a substitute of steel re-bars for that cases in which aggressive environment produce high steel corrosion, or lightweight is an important design factor, or transportation cost increase significantly with the weight of the materials. But FRP fibers have only linearly elastic stress-strain behavior; whereas, steel re-bar has linear elastic behavior up to the yield point followed by large plastic deformation and strain hardening. Thus, the current FRP re-bars are not suitable concrete reinforcement where a large amount of plastic deformation prior to collapse is required. The main objectives of this study in to evaluate the tensile behavior and the fracture mode of hybrid FRP re-bar. Fracture mode of hybrid FRP re-bar is unique. The only feature common to the failure of the hybrid FRP re-bars and the composite is the random fiber fracture and multilevel fracture of sleeve fibers, and the resin laceration behavior in both the sleeve and the core areas. Also, the result of the tensile and interlaminar shear stress test results of hybrid FRP re-bar can provide its excellent tensile strength-strain and interlaminar stress-strain behavior.

• 콘크리트학회논문집
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• 제20권3호
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• pp.357-367
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• 2008

본 연구에서는 FRP 보강근으로 보강된 콘크리트보의 설계변수들에 대한 영향을 고찰하기 위하여 유한요소 해석을 수행하여 휨거동 특성을 해석적으로 분석하였다. 유한요소해석은 범용구조해석 프로그램인 ABAQUS를 사용하여 해석 모델을 구성하였으며, 기 실험된 실험 결과와 거동과 응력등에 대하여 비교 분석함으로서 모델의 적절성을 검증하였다. 검증된 모델을 기준으로 설계변수인 보강비, FRP 보강근의 탄성계수 및 콘크리트 압축강도 등의 변화에 따른 부재의 휨-변위 관계와 휨강성의 영향을 ACI 440에 제시된 이론적인 강성과 비교하였다. 고찰 결과, FRP 보강 콘크리트 보의 거동은 보강비의 영향이 가장 큰 것으로 나타났으며, 콘크리트의 압축강도가 증가할수록 FRP 보강근의 보강비의 영향이 크게 증가하는 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 사면안정 설계 및 시공 특별강연회
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• pp.60-76
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• 2001

The grout-effect evaluation of the ground reinforcement technique, which has been widely applied to civil engineering and construction fields, is not established for the guidelines of choosing the efficient evaluation method, and in fact the expects have little effort to determine the reinforcement effect quantitively. This paper presents some results a field test performance of FRP pressure grouting method at a collapsed slope were carried out to verify the improving effect.

• 해양환경안전학회지
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• 제19권4호
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• pp.403-409
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• 2013

철근 및 FRP Bar를 보강재로 사용한 콘크리트 보의 전단 거동을 실험적으로 평가하였다. 실험 변수는 특성이 다른 보강근을 휨 및 전단 보강한 것과 전단보강근비이다. 콘크리트 보의 전단강도 산정에 일반적으로 널리 이용되는 수정트러스 이론의 타당성을 실험 결과의 분석을 통하여 평가하였다. CFRP 및 GFRP를 휨 및 전단 보강한 콘크리트 보에 그대로 적용하는 것은 적절하지 않음을 알 수 있었다. 실험결과는 FRP Bar를 보강근으로 사용한 콘크리트 보의 전단 문제에 수정트러스 이론을 그대로 적용하는 것은 타당하지 않다는 것을 알 수 있었다.

• 한국전산구조공학회논문집
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• 제24권1호
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• pp.23-31
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• 2011

본 연구는 섬유 보강 폴리머(Fiber Reinforced Polymers, 이하 FRP) bar로 보강된 콘크리트 깊은보의 전단강도을 평가하기 위하여 전단경간비, 보강비, 유효깊이, 주근의 종류를 변수로 총 15개의 시험체에 대한 전단 실험을 수행하였다. 전단 실험을 토대로 FRP bar로 보강된 콘크리트 깊은보의 균열 및 처짐에 대한 거동 조사를 수행하였으며, ACI 318-08의 스트럿-타이 모델(이하 STM)을 이용한 전단강도와 아치작용을 고려한 기존 제안식에 의한 전단강도를 비교 평가하였다. 그 결과 FRP bar로 보강한 경우가 Steel bar로 보강한 경우보다 전단강도가 증가하는 것으로 나타났으며, 전단강도 산정에 있어 ACI 318-08 STM을 이용한 방법이 경험식에 의한 방법보다 상대적으로 정확했다.

• Computers and Concrete
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• 제23권1호
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• pp.49-60
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• 2019

In recent years, multiple experimental studies have been performed on using fiber reinforced polymer (FRP) bars in reinforced concrete (RC) structural members. FRP bars provide a new type of reinforcement that avoids the corrosion of traditional steel reinforcement. In this study, predicting the shear strength of RC beams with FRP longitudinal bars using artificial neural networks (ANNs) is investigated as a different approach from the current specific codes. An ANN model was developed using the experimental data of 104 FRP-RC specimens from an existing database in the literature. Seven different input parameters affecting the shear strength of FRP bar reinforced RC beams were selected to create the ANN structure. The most convenient ANN algorithm was determined as traingdx. The results from current codes (ACI440.1R-15 and JSCE) and existing literature in predicting the shear strength of FRP-RC beams were investigated using the identical test data. The study shows that the ANN model produces acceptable predictions for the ultimate shear strength of FRP-RC beams (maximum $R^2{\approx}0.97$). Additionally, the ANN model provides more accurate predictions for the shear capacity than the other computed methods in the ACI440.1R-15, JSCE codes and existing literature for considering different performance parameters.

• Structural Engineering and Mechanics
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• 제5권4호
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• pp.339-353
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• 1997

Fiber reinforced plastic (FRP) rods provide certain benefits over steel as concrete reinforcement, such as corrosion resistance, magnetic and electrical insulation, light weight, and high strength. FRP composites can be combined with a steel core to form hybrid reinforcing rods that take advantage of properties of both materials. The objective of this study was to characterize the bond behavior of hybrid FRP rods made with braided epoxy-impregnated aramid or poly-vinyl alcohol FRP skins. Eleven rod types were tested using two concrete strengths. Specific topics examined were bond strength, slip, and type of failure in concentric pull-out tests from concrete cubes. From analysis of identical pull-out tests on both hybrid and steel rods, information on relative bond strength and behavior were obtained. It is concluded that strength is similar but slip in hybrid rods is much higher. Hybrid rods failed either by pull-out or splitting the concrete block (with or without yielding of the steel core). Experimental data showed consistency with similar test results presented in the literature.

• 콘크리트학회논문집
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• 제19권6호
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• pp.727-734
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• 2007

철근과 fiber-reinforced polymer (FRP)의 물리적, 역학적 특성의 차이 및 슬래브 상부 보강재의 기둥 인접부 집중 배근, 그리고 기둥 인접부 슬래브에 강섬유 콘크리트 (SFRC)의 타설 등에 따른 2방향 슬래브의 펀칭 전단 거동에 대한 효과를 평가하였다. 펀칭 전단강도, 강성, 연성, 변형률 분포 그리고 균열 제어 성능 등을 파악하였다. 실험 결과 기둥 인접부의 슬래브에 집중 배근을 하거나 SFRC를 타설하는 것은 glass fiber-reinforced polymer (GFRP) 바로 보강된 슬래브의 펀칭 전단 거동을 향상시켰다. 기둥 인접 구역에 집중 배근된 슬래브의 실험 결과를 다양한 설계기준과 타 연구자에 의해 제안된 예측식과 비교하였으며, 집중 배근으로 인한 이점을 예측식에 반영할 수 있도록 집중 배근된 슬래브의 철근비를 산정하는 합리적인 방법도 제안하였다.