• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.743-749
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• 1999

Recently new rehabilitation techniques have been proposed with advanced composite materials like carbon fiber, aramid, glass fiber sheet and so forth. The purpose of this paper is to investigate the mechanical characteristics of reinforced concrete columns confined with carbon fiber sheet and evaluate the degree of their strengthening effect. For the test, the specimen size of column is 15cm$\times$15cm$\times$90cm reinforced with 4 number of main bars of 10 mm diameter, tied bars of 6 mm diameter and slenderness ratio 20. Columns were wrapped with carbon fiber sheet along the column length. It is necessary to make some assumption regarding the confinement of carbon fiber sheet to apply to reinforced concrete columns under concentric loads. The strength gain effect of columns confined with carbon fiber sheet could be predicted using the proposed equation.

• 한국구조물진단유지관리공학회 논문집
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• 제7권3호
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• pp.157-165
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• 2003

섬유시트들로 보강된 철근 콘크리트보에서 섬유시트들의 정당한 파단변형률을 평가하기 위해 적층수를 달리한 120개의 섬유시트 인장시험편과 72개의 섬유보강 콘크리트보들에 대한 실험적 연구를 수행하였다. 철근콘크리트보는 세 종류의 인장철근비를 선택하였다. 인장시험에 의한 섬유시트 파단변형률은 섬유시트 적층수에 관계없이 기술자료에서 주어진 값보다 다소 낮게 나타났으며, 보에 부착된 섬유시트들의 파단변형률은 적층수가 증가할 때 감소하는 경향을 보여주었다. 본 연구에서는 이들 결과를 바탕으로 섬유시트들의 파단변형률을 평가하였다.

• Journal of Mechanical Science and Technology
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• 제17권3호
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• pp.343-349
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• 2003

The fuselage-wing intersection suffers from the cyclic bending moment of variable amplitude. Therefore, the influence of cyclic bending moment on the delamination and the fatigue crack propagation behavior in AFRP/Al laminate of fuselage-wing was investigated in this study. The cyclic bending moment fatigue test in AFRP/Al laminate was performed with five levels of bending moment. The shape and size of the delamination Lone formed along the fatigue crack between aluminum sheet and aramid fiber-adhesive layer were measured by an ultrasonic C-scan. The relationships between da/dN and ΔK, between the cyclic bending moment and the delamination zone size, and between the fiber bridging behavior and the delamination zone were studied. As results, fiber failures were not observed in the delamination zone in this study, the fiber bridging modification factor increases and the fatigue crack growth rate decrease and the shape of delamination zone is semi-elliptic with the contour decreasing non-linearly toward the crack tip.

• 한국지진공학회논문집
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• 제27권4호
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• pp.171-180
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• 2023

This study proposed a seismic reinforcement of RC columns with non-seismic details, a fiber reinforcement method of aramid sheets and MLCP (high elasticity aromatic polyester fiber material) with different characteristics, and 4 full-size column specimens and conducted experiments. The results show that a non-seismic specimen (RC-Orig) rapidly lost its load-bearing capacity after reaching the maximum load, and shear failure occurred. The RC column reinforced with three types of aramid did not show an apparent increase in strength compared to the unreinforced specimen but showed a ductile behavior supporting the load while receiving a lateral displacement at least 1.57 to 1.95 times higher than the unreinforced specimen. The fracture mode of the specimen, according to the application of lateral load, also changed from shear to ductile fracture through aramid-based reinforcement. In addition, when examining the energy dissipation ability of the reinforced specimens, a ductile behavior dissipating seismic energy performed 4 times greater and more stably than the existing specimens.

• 한국구조물진단유지관리공학회 논문집
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• 제19권5호
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• pp.112-119
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• 2015

본 논문에서는 기둥이 취약한 골조의 내진성능을 향상시키기 위한 공법을 제안하였다. 이를 위하여 기둥을 아라미드 시트로 횡구속하여 취성적인 특성을 개선하였으며, S형 스트럿을 가지는 강재 댐퍼를 설치하여 에너지 소산 능력을 증진시켰다. 비보강 실험체 및 보강 실험체를 실물크기로 제작하여 수평하중 저항 능력을 평가하였다. 파괴 양상, 강도, 강성 저하 및 에너지 소산 능력 등에서 보강 실험체의 효과를 확인할 수 있었다. 또한 ABAQUS를 이용한 FE 해석으로부터, 대상 실험체의 이력 거동을 예측 및 평가하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.495-500
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• 1996

In this paper, it is the effect of using fiber sheet (Carbon Fiber Sheet & Aramid Fiber Sheet) and Steel Plate for reinforced concrete beam, 25 specimens are tested, 16 specimens for bending capacity and the other are for shear capacity. In the case of bending testing, the kind and quantity of the reinforcement materials, the bondage and the existence of crack were selected as experimental variables. And in the case of shear testing, it is testified the effect of reinforcement with the variables of the method of reinforcement (side type and U type). As a result, using the reinforcement meterials can increase the capacity of bending stress.

• 한국구조물진단유지관리공학회 논문집
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• 제5권2호
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• pp.121-128
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• 2001

Reinforced concrete frame buildings in regions of low to moderate seismicity are typically designed only for gravity loads with non-seismic detailing provisions of the code. These buildings possess strong beam-weak column, which brings about the brittle structural performance like the column sidesway failure mechanism during the strong lateral load. The objective of this paper is to enhance the column strength and deformation capacity for reconfiguring the structural failure mode by averting a column soft-story collapse and moving to a more ductile beam-sides way mechanism suing new reinforcing materials. Aramid fiber sheet and reinforcing rod-composite materials was used for this purpose. The column was modeled by the 2/3 scale experimental specimen retested. According to the concept of the capacity design, the damaged column was strengthened by the column jacketing using new reinfocing materials such as rod-composite materials. In conclusion, the improvement of the flexural strength is observed and the capacity of the energy dissipation and the ductility is enhanced, too.

• 한국공간구조학회논문집
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• 제23권1호
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• pp.77-84
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• 2023

In this study, the performance evaluation of the RC frame specimen (RV2) which was strengthened by a steel frame and a steel damper with the lateral deformation prevention details proceeded. The comparison objects are bare frame specimen (BF), RV2 and AWD, where AWD is a specimen reinforced with steel damper and aramid fiber sheets. In the evaluation of envelope curve, stiffness degradation, and energy dissipation capacity, RV2 was evaluated to have excellent capacity as a whole. To evaluate the strengthening effect of the steel frame based on the maximum strength and energy dissipation capacity, it was evaluated to have a 38% of the RV2's capacity.

• 대한기계학회논문집A
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• 제25권8호
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• pp.1277-1286
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• 2001

Aluminum 5052/Aramid Fiber Reinforced Plastic(Al5052/AFRP) laminates are applied to the fuselage-wing intersection. The Al5052/AFRP laminates suffer from the cyclic bending moment of variable amplitude during the service. Therefore, the influence of cyclic bending moment on the delamination and the fatigue crack propagation behavior in Al5052/AFRP laminate was investigated in this study. Al5052/AFRP laminate composite consists of three thin sheets of Al5052 and two layers of unidirectional aramid fibers. The cyclic bending moment fatigue tests were performed with five different levels of bending moment. The shape and size of the delamination zone formed along the fatigue crack between Al5052 sheet and aramid fiber-adhesive layer were measured by an ultrasonic C-scan. The relationships between da/dN and ΔK, between the cyclic bending moment and the delamination zone size, and between the fiber bridging mechanism and the delamination zone were studied. Fiber failures were not observed in the delamination zone in this study. It represents that the fiber bridging modification factor should turn out to increase and that the fatigue crack growth rate should decrease. The shape of delamination zone turns out to be semi-elliptic with the contour decreased non-linearly toward the crack tip.

• 한국안전학회지
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• 제14권1호
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• pp.129-140
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• 1999

This study presents test results of RC beams strengthened by steel plates, carbon fiber sheets(CFS) and aramid fiber sheets(AFS) for increasing flexural and shear resistance. The test was performed with different parameters including the type of strengthening materials, flexural-strengthening methods and shear-strengthening methods. In case of flexural test, RC beams are initially loaded to 70% of the ultimate flexural capacity and in case of shear test loaded to 60 or 80 percent of the ultimate shear capacity and subsequently reinforced with steel plates, CFS and AFS. Experimental data on strength, steel strain, deflection, and mode of failure of the reinforced beams were obtained, and comparisons between the different shear reinforced schemes and the non-strengthened control beams were made. The test results showed that damaged RC beams strengthened by steel plates, CFS and AFS have more improved the flexural and shear capacity. For the beams with external reinforcement by steel plates, aramid fiber sheets and carbon fiber sheets increases in ultimate strength of 4 to 21, 17 to 43 and 26 to 36 percent were respectively achieved. Initial load had small effect on strength after reinforcement, but an important influence on deflection. One sheet reinforced was stronger than two sheets reinforced but less deflected than two sheets reinforced.