• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.23-28
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• 2001

Since non-corrosive Fiber Reinforced Polymer(FRP) tendons have been in increasing use for underground and coastal structures constantly contacted with fresh water or sea water because of their superiority to metallic ones in corrosion-resistance, new non-metallic anchoring system for FRP tendons has been developed and investigated to verify the effectiveness of tendon force, which consist of mainly FRP pipes and Highly Expansive Mortar(HEM). The major factors considered in this experiment were expansive pressures of HEM during its hydration, sleeve lengths and types, and anchoring methods of tendon. New anchoring system were investigated from the pull-out tests. The pull-out procedures of the FRP tendons in the various pipe filled with HEM were analyzed and improved ideas were suggested to develop novel non-metallic anchoring system for FRP tendons The pull-out tests for the FRP tendon and new non-metallic anchoring system were conducted. The results show that non-metallic anchoring system for the FRP tendon has been more stablized due to the gradual expansive pressrure of HEM, as tims goes. Since tile lower stiffness of FRP pipes causes the weakness of anchoring force, it requires the increase of stiffness using a carbon fiber or an increased section area.

• 한국구조물진단유지관리공학회 논문집
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• 제18권5호
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• pp.51-58
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• 2014

본 연구에서는 철근콘크리트 구조의 FRP를 이용한 보강에서 낮은 내화성능을 개선하기 위한 방안을 찾기 위하여, 보강된 FRP의 외부를 내화보강하는 방법에 대한 내화실험을 실시하였다. 특히 철근콘크리트 부재의 피복에 홈을 형성하여 FRP를 매입하는 보강 즉, NSM 보강을 대상으로 하였다. 실험에서의 주요 변수는 보강방법과 사용 내화재료로서, Perlite계 재료를 표면에 분사하여 보강하는 방법, Calcium silicate계 보드로 표면에 부착하는 방법, 그리고 추가로 홈내부에 Polymer mortar 또는 Calcium silicate조각을 삽입하여 보강하는 방법으로 보강한 뒤 가열로 내부의 온도변화에 따른 열전달을 관찰하였다. 실험결과, Perlite계 내화뿜칠로 표면을 보강하는 경우보다 Calcium Silicate계 내화보드로 표면을 보강하는 방법이 효과적인 것으로 나타났다. 홈 내부의 에폭시가 유리전이온도에 도달할 때의 외부 표면온도 $820^{\circ}C$까지 내화단열성능을 확보할 수 있는 것으로 나타났다.

• 콘크리트학회논문집
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• 제23권3호
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• pp.257-264
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• 2011

이 연구는 부착형 정착 장치를 갖는 CFRP(carbon fiber reinforced polymer) 긴장재의 정착에 관한 실험 연구이다. 적절한 채움재를 도출하기 위해 예비 실험을 수행하였고, 에폭시 또는 콘크리트 모르타르와 같은 5종의 재료가 채움재로 사용되었다. 실험 결과 무수축 모르타르를 사용한 시편에서 최대 인장강도를 보이므로 이 연구에서는 CFRP 긴장재용 강관 몰드의 채움재로써 무수축 모르타르를 결정하였다. 예비 실험으로 도출된 채움재를 이용하여 강관 몰드의 적정 제원을 도출하기 위해 외경, 두께 및 길에 대한 추가 실험을 수행하였다. 이 실험을 통해 무수축 모르타르를 사용한 강관 몰드의 적정 제원이 도출되었고, 이러한 제원의 강관 몰드로 정착된 CFRP 긴장재는 안정적인 인장 성능을 보였다.

• 한국공간구조학회논문집
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• 제14권4호
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• pp.73-80
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• 2014

For the last decade many bridges and buildings have experienced flexural strengthening with the fiber reinforced polymer(FRP) bonding system, demands for increasing heavy traffic loads and the changing of the code application. Of the many strengthening systems, NSM(near surface mounted) system with FRP has become attractive and popular way of strengthening for the existed RC structures and many studies and applications of this technique have significantly increased all over the world. Meanwhile, polymer mortar that contains much of the same ingredients as cement but includes the addition of certain polymer resins for enhancing desired physical properties, has been used as an alternative adhesive. This paper focuses on flexural behaviour of CFRP-bar NSM system with variables such as kinds of adhesive, anchorage, sectional aspect ratio. Based on the test results and test-to-predicted ratio, this paper provides researchers and practical engineers a fundamental knowledge and intuition.

• 폴리머
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• 제34권5호
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• pp.410-414
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• 2010

재활용 PET와 fly-ash를 이용하여 두 가지 종류의 고분자 몰타르(PMM)를 제조하였다. 재활용 PET의 조성을 변화시켜 경성(rigid) polymer-modified mortar(PMM)와 연성(flexible) PMM을 제조하였다. 마찰계수 측정을 포함하는 기계적 특성과 흡음 특성을 조사하였고 상업적 PMM인 에폭시 PMM과 PET PMM을 비교하였다. 기계적 특성들의 결과로부터 경성 PMM이 상업적인 PET PMM에 비하여 우수함을 알 수 있었다. 흡음계수 측정에서 경성 PMM과 연성 PMM 모두 상업적인 PMM에 비하여 매우 우수한 흡음 특성을 보여주었다. 또한, 마찰계수 측정결과는 경성 PMM이 바닥재의 활용에 적절하다는 것을 보여주었다.

• 콘크리트학회논문집
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• 제15권4호
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• pp.549-556
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• 2003

시멘트 모르타르의 내마모성, 여러 피착체에 대한 부착성능, 내화학성, 내수성 등의 많은 성능을 개선시키는 데 폴리머 디스퍼젼은 매우 유용한 재료로서 본 실험에 사용한 SBR은 상업적으로 국내에서 생산되고 있는 시멘트 적용성이 우수한 재료이다. 본 실험에서는 시멘트 모르타르에 높은 유동성을 유도하여 자기 평활성을 가지도록 고유동화제와 SBR을 사용하여 시험체를 제작하였으며 SBR에 의한 시험체의 부착강도의 발현 특성을 파악하고자 하였으며 SBR에 의해 개질된 자기 평활성을 가지는 시멘트 모르타르는 재령의 증가에 따라 부착강도는 증가하는 현상을 보여주었으며 파괴형상을 보면 재령이 증가함에 따라 시험체에서 보다는 계면과 피착체에서 외부 인장력에 대하여 파괴가 일어났다. 현재 사무실, 공장, 주차장 등의 바닥 마감재로 널리 사용되고 있는 합성 고분자계 재료인 에폭시 수지나 폴리우레탄 제품은 연도변화가 심하여 가사시간이 상당히 짧다는 것을 확인할 수 있었으며 이에 반하여 본 연구의 시험체는 충분한 가사시간을 확보할 수 있는 이점을 가진 재료로 여겨진다.

• Steel and Composite Structures
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• 제13권2호
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• pp.123-137
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• 2012

Steel plate-masonry composite structure is a newly-developed type of structural technique applicable to existing masonry buildings by which the load-bearing walls can be removed for large spaces. This kind of structure has been used in practice for its several advantages, but experimental investigation on its elements is nearly unavailable in existing literature. This paper presents an experimental study on the flexural behaviour of four steel plate-masonry composite beams loaded by four-point bending. Test results indicate that failure of the tested beams always starts from the local buckling of steel plate, and that the tested beams can satisfy the requirement of service limit state. In addition, the assumption of plane section is still remained for steel plate prior to local buckling or steel yielding. By comparative analyses, it was also verified that the working performance of the beam is influenced by the cross-section of steel plate, which can be efficiently enhanced by epoxy adhesive rather than cement mortar or nothing at all. Besides, it was also found that the contribution of the encased masonry to the flexural capacity of the composite beam cannot be ignored when the beam is injected with epoxy adhesive.

• 대한건축학회논문집:구조계
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• 제34권4호
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• pp.35-42
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• 2018

This study evaluated the fire resisting capacity and post-fire serviceability of the concrete beams retrofitted by near surface mounted method(NSM) using GFRP plates. Main parameters in the test are grout materials and fire exposure. For the test, two types of grout materials between concrete substrate and GFRP plate were used; flame resisting epoxy and filling mortar. Four RC beam specimens were made and two of them were exposed to fire according to real scale fire curve proposed KS F 2257. After the fire exposure test, flexural test were performed to investigate the flexural performance of concrete beams including strength and deformation. From the test results, it was found that the beam retrofitted by NSM-GFRP presented higher flexural strength than that of the beam without retrofit, which indicates NSM-GFRP retrofit technologies is effective to maintain flexural strength even after fire exposure. In addition, the specimens grouted by epoxy showed good performance in strength but bad performance in ductility.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.607-612
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• 1998

In this study, the behavior of R/C beam strengthened with carbon fiber laminate(C.F.L) is analyzed from the test results. Test parameters are the width, the thickness and the length of C.F.L. and method of construction. The failure mode and ultimate load are analyzed from these measured data. Test results shows that the peak moment of specimens strengthened with C.F.L is increased to 1.43~1.90 times of that of non-rehabilitation specimen. The wider lap width, larger amount of rehabilitation materials, the larger strength is obtained.

• Structural Engineering and Mechanics
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• 제56권1호
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• pp.1-25
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• 2015

The main goal of this study was to develop a convenient strengthening technique for retrofitting of reinforced concrete members. For this purpose a new retrofitting material so-called prefabricated-HSPRCC (high performance steel plate reinforced cementitious composite) panel was developed by using high performance concrete and perforated steel plate. Prefabricated-HSPRCC composes advantages of steel and high performance concrete. The prefabricated-HSPRCC panels were either only bonded on the specimens using epoxy mortar or anchored to the specimen by steel bolts as well as bonding. Effect of different variations such as prefabricated-HSPRCC panel thicknesses, steel plate thicknesses, puncture orientation of perforated steel plate, existence of anchorage etc. were studied through a simple experimental work. The behaviour of the specimens under vertical point load was also studied by using simple mechanics. The retrofitted specimens were found to exhibit much better performance both in terms of strength and deformation capability. The anchorage application was found to positively affect this improved performance. Furthermore, as a result of the tests the best parameters of prefabricated-HSPRCC plate for improving strength and deformation capacities were determined.