• 한국구조물진단유지관리공학회 논문집
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• 제17권3호
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• pp.40-47
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• 2013

외부강선으로 보강된 철근콘크리트 보에 대한 기존 연구 대상은 과보강 철근콘크리트 보가 대부분이다. 그러나 이러한 저보강 철근콘크리트 보에 대한 외부 강선 보강은 보강 텐던의 양이 아주 적어서 외부 강선의 보강 효과를 명확하게 분석할 수 없다는 문제점이 있다. 이러한 이유로 본 연구에서는 손상된 저보강 철근콘크리트 보를 외부강선으로 보강한 경우를 선택하여 연구를 수행하고자 하였다. 따라서 본 연구에서는 실험을 통하여 보강 효과를 평가하고 적절한 보강방법을 찾기 위해서 7개의 실험 부재를 제작하여 휨거동 실험을 실시하였다. 실험 결과에 의하면, 강선량이 증가할수록 보강효과는 증가하는 것으로 나타났으며, 특히 에폭시 레진으로 균열을 보수하면 그 효과는 더욱 커지는 것으로 나타났다. 또한 외부 강선의 극한응력에 대한 AASHTO 1994와 ACI-318 설계식은 실험결과와 잘 일치하지 않는 것으로 나타났다. 이러한 본 연구의 결과는 향후 손상된 철근콘크리트 보의 적정 보강 방법을 제시하는 데 효과적일 것으로 예상된다.

• 한국구조물진단유지관리공학회 논문집
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• 제13권6호통권58호
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• pp.204-211
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• 2009

본 연구에서는 RC 중공슬래브 교량의 내하력을 향상시키기 위해 외부 프리스트레싱을 이용한 보강방법을 제시하였다. 효과적인 보강을 위해 Queen-post 형식과 King-post 형식이 고려되었으며, 축차무제 약 최소화 기법(SUMT)를 이용하여 목표 내하율을 달성하기 위한 최적의 형상과 긴장력을 구하였다. 최적보강을 위한 목적함수는 재료비용을 무차원화한 비용함수로 구성하였으며, 제약조건은 시방서 규정과 내하율을 고려하여 형성하였다. RC 중공슬래브 교량의 보강을 실행한 후 그 결과를 분석하여 제안된 방법의 타당성을 제시하였다.

• 한국철도학회논문집
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• 제9권2호
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• pp.151-159
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• 2006

It analyzed the mechanical behaviors of non-ballasted railway bridge (steel plate girder type) with ballast reinforced on the finite element analysis, field test and laboratory test far the static and dynamic responses. The major objective of this study is to investigate the effects and application of reinforcement for steel plate girder railway bridge by the external post-tensioning method. The reinforcement of non-ballast railway bridge had obviously stable dynamic behaviors due to the additional dead force which was ballast. But in case of static behaviors, static displacements and stresses had increased nearly the allowable values. Therefore we analyzed the mechanical behaviors of non-ballasted railway bridge with ballast reinforced and external post-tensioning reinforced on the finite element analysis and laboratory test for the static and dynamic behavior. As a result, the reinforcement of ballasted railway bridge the external post-tensioning method are obviously effective for the additional dead force which is ballast. The analytical and experimental study are carried out to investigate the post-tension force decrease bending behavior and deflection in composite bridge for serviceability. The servicing railway bridge with ballast reinforced has need of the reasonable reinforcement measures which could be reducing the effect of additional dead load that degradation phenomenon of structure by an unusual. stresses and a drop durability.

• 한국구조물진단유지관리공학회 논문집
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• 제5권4호
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• pp.147-153
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• 2001

The major objectives of this study are to investigate experimental and analytical behavior of composite steel plate strengthened by external post prestressing method and to study the increasing magnitude of load carrying capacity by the external post prestressing method. With installed strain gauges and LVDT, the change of structural behaviors according to the amount of prestressing force is measured and the effects of shear strengthening according to the degree of angle in tendon are studied. The analytical structural behavior according to the amount of prestressing force is also investigated using finite element method. The effectiveness of strengthening of external post prestressing method is proved and an efficient FEM model is suggested by comparing the test results and analyzing results.

• 한국철도학회논문집
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• 제10권2호
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• pp.186-194
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• 2007

This study was performed to compare the load-carrying capacities of the reinforced concrete structure between the carbon fiber adhesion reinforcement method and the external post-tensioning method and further estimate the effective stress of the reinforced material by analyzing the experimental reinforcing effect of each method and the behavior resulting from each method. As a result, it was found out that the effective stress of the carbon fiber reinforcement according to the carbon fiber adhesion reinforcement method had an unexpected value, and also, bearing of the stress was found to be far from sharing thereof. That is to say, while the carbon fiber was bearing the whole stress to some limits, it got to be momentarily ruptured as soon as it went beyond such limits. On the other hand, the external post-tensioning method has the advantage of inducing an initial effective stress by introducing a strain, and thus, it was found that behavior or bearing of the stress was also found to be a solid behavior of the steel wire. This method was also found to be more efficient and excellent than the carbon fiber adhesion reinforcement method in the reinforcing effect or securing the effective stress. Accordingly, we were to discuss the effective stress as comparatively examined, focusing on deriving of the more enhanced reinforcing effect on the basis of the experiment to which the field characteristic is added.

• 콘크리트학회논문집
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• 제18권2호
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• pp.283-290
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• 2006

본 연구는 와이어 로프를 이용한 비부착 보의 전단보강에 대한 실험에 대한 것이다. 전단보강 방법은 와이어 로프를 보 단면의 외부에 노출시킨 형태로 볼트와 너트로 기계적 정착을 하는 폐쇄형과 U자형이 있다. 폐쇄형 전단보강방법은 슬래브를 관통하여 와이어 로프로 보 단면을 둘러싼 후 슬래브 상부면에서 와이어 로프를 긴장 고정시키는 방법이곤 U자형 전단보강방법은 슬래브 하부면과 접하는 보 옆면의 정착장치에 U자형으로 와이어 로프를 설치하는 방법이다. 콘크리트 압축강도가 24MPa이고 전단스팬비(a/d)가 4인 실험체의 주요변수로 폐쇄형과 U자형에 대해서 보강 간격을 각각 150, 200, 250mm로 하였다. 실험 결과, 와이어 로프를 이용한 전단보강방법은 무보강 실험체에 대해서 폐쇄형과 U자형 보강실험체의 내력의 최대 증가비가 각각 2.88, 1.91배로 증가하였으며, 복부의 초기 사인장균열시의 처짐에 대한 최대전단강도에서의 처짐의 비로 정의한 연성도 크게 증가하였으며, 특히 폐쇄형의 전단보강의 경우 U자형 전단보강방법에 비해 내력 및 연성의 증가가 두드러졌다. 따라서 본 연구는 와이어 로프를 이용한 전단보강방법의 타당성을 평가하기 위한 실험으로서 중요한 가능성을 제시하며, 전단보강 설계 및 시공에 유용한 기초 자료로서 의의가 있다.

• 한국구조물진단유지관리공학회 논문집
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• 제7권1호
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• pp.157-163
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• 2003

Recently, the number of Prestressed Concrete(PSC) bridges needed repair and retrofit because of the increase of heavy traffic loads and aging of concrete materials. But there are a few related researches about strengthening PSC bridges. In this study, the practicability of strengthening methods for PSC beam were studied by the static experimental method. PSC beams in length of 6m were made with concrete slabs. Glass fiber sheeting and external post-tensioning methods were used for strengthening PSC beams. Some beams were strengthened after cracks to investigate the applicability for cracked bridges. As a result, there strengthening methods were efficient at increasing the cracking loads and the failure load, to decrease deflection and prevent cracks. In the case of using glass fiber retrofit methods, it should be careful in the anchorage problems for preventing the bonding failure.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1034-1039
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• 2004

The major objective of this study is to investigate the effects and application of reinforcement for steel plate girder railway bridge by the external prestressing method. It analyzed the mechanical behaviors of non-ballasted railway bridge with ballast reinforced and external post-tensioning reinforced on the finite clement analysis for the static and dynamic behavior. As a result, the reinforcement of ballasted railway bridge the external prestressing method are obviously effective for the additional dead force which is ballast. The analytical study are carried out to investigate the post-tension force decrease bending behavior and deflection in composite bridge for serviceability. To develop two type FEM model which reflect well the post-tension force transverse distribution behavior of servicing bridge. With the comparing the results of railway bridge with ballast which carried out before the post-tensioning with the results of railway bridge with ballast which carried out after post-tensioning, It is investigated that the additional dead load decrease effect and bending behavior of servicing bridge is effect by the post-tensioning. The reinforcement by using the external tendon can be reducing that structure of a degradation phenomenon by unusual stresses due to additional dead load and other problems.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.514-521
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• 2006

In strengthening structure, the external post-tensioning method which secure clearness in the structure analysis process is adopted to bridge as well as architecture structure. Therefore, the major objective of this study is to investigate the effects and application of external post-tensioning method for steel plate girder bridge. It analyzed the mechanical behaviors of steel plate girder bridge with applying external post-tensioning on the finite element analysis and laboratory test for the dynamic characteristics. As a result, the reinforcement of steel plate girder bridge the external post-tensioning method are obviously effective for the response which is non-reinforced. The analytical and experimental study are carried out to investigate the post-tension force decrease stress and deflection on steel plate girder bridge for serviceability. It is investigated that the change degree of natural frequency is very low with applying the external post-tensioning method. The servicing steel plate girder bridge with external post-tensioning is the reasonable reinforcement measures which could be secured the stability of dynamic behavior and increase a dropped durability.