• 한국강구조학회 논문집
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• 제10권4호통권37호
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• pp.701-708
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• 1998

최근 2등급(DB18)으로 설계된 국도상의 일부 교량들은 교통량 수송능력 향상을 위해 외부후긴장 방법을 적용하여 보강하는 방법이 사용되고 있으나, 그러한 보강 작업의 대부분은 실험 및 해석적 검증없이 사용되고 있다. 본 논문에서는 DB18로 설계된 단순 합성보에 외부 후긴장을 적용하여 보강효과 및 거동을 실험적으로 연구하였으며 실험 결과로부터 외부 후긴장은 극한 및 항복에 대한 강성을 증가시키며 인장파괴 모드로 설계된 구조물의 인장보강에 특히 효과적임을 알 수 있었다.

• 대한토목학회논문집
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• 제29권6A호
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• pp.587-596
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• 2009

본 연구는 외부 후 긴장력 횡분배 거동을 연구하고 일부 거더 외부 후 긴장만 으로 공용중인 강합성형교 보강 가능성을 평가하기 위한 연구이다. 실험 및 해석적 연구로부터 부분 거더 긴장만으로도 강합성형교 보강이 가능한 것으로 나타났으며, 브레이싱에 의하여 긴장력 횡분배 거동이 개선되는 것으로 평가되었다. 강성비, 거더 간격, 경간장의 영향을 받는 긴장력 횡분배 거동은 교량 형태 및 긴장되는 거더 위치에 의해 변화하는 것으로 분석되었으며, 외부 후 긴장력 횡분배 거동을 예측하는 제안식을 도출하여 합리성을 평가 하였다.

• 대한건축학회논문집:구조계
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• 제34권1호
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• pp.3-10
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• 2018

This experimental investigation was conducted to observe the shear strengthening behavior of pre-damaged reinforced concrete (RC) beams strengthened with externally post-tensioning steel rods. A total of six simply supported beams - two control beams and four post-tensioned beams using external steel rods - were tested to failure in shear. The external steel rods of 18 mm or 28 mm diameter were respectively employed as post-tensioning material. The four post-tensioned beams have a V-shaped profile with a deviator (or saddle pin) located at mid-span, and the post-tensioning system increased the low load-carrying capacity and overcame a little bit of deflection caused by damage. Concretely, the load-carrying capacity and flexural stiffness were respectively increased by about 25~57% and 263~387% due to the post-tensioning when compared with the unstrengthened control beams.

• 한국강구조학회 논문집
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• 제12권5호통권48호
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• pp.549-558
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• 2000

외부 후 긴장 공법은 설계에 수반되는 구조해석이 비교적 명확하여 강교량 구조물뿐만 아니라 건축구조물 등 그 적용 범위가 매우 넓은 보강방법이다. 본 연구에서는 후 긴장 공법에 있어서 긴장력 도입 과정의 강합성보의 거동을 연구하기 위하여 긴장력 증가에 따른 긴장재, 경간 중앙부 하부 플랜지, 정착단 주형 하부 플랜지의 도입 변형율과 긴장재 절곡 각도에 따른 도입 전단력 및 압축력을 실험 및 해석적으로 분석하였다. 또한 긴장력 도입 후 정적 휨 재하 실험을 수행하여 긴장력 도입 정도에 따른 휨 보강 정도를 분석하였으며, 절곡 각도의 변화에 따른 전단보강 및 휨 보강 양상을 연구하였다. 그 결과 외부 후 긴장력 도입에 따른 휨 보강 효과가 매우 높은 것으로 분석되었으며, 긴장재의 절곡 배치에 의해서는 추가적으로 전단보강 효과까지 나타났다.

• 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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.165-168
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• 2006

Carbon fiber reinforced polymer(CFRP) have superior mechanical and chemical properties in comparison with conventional materials. And post-tensioning method has been used for structural reinforcement of RC structures due to easy installation and good effect of resisting capacity of structures. But the higher cost of CFRP and the loss of prestressing force with time are considered the major problems to use it. In this study, CFRP Strips and external post tensioning for rehabilitation of old concrete structures were adapted and optimal combination of these methods is considered. A total of 17 concrete members were made and tested. The types and numbers of CFRP strips and post-tensioning types were selected as major test variables. From test results, it is shown that the concrete members that post tensioned and bonded CFRP strips has a pronounced effect on the strength and deformational behavior. This present study indicates that external temporally post tensioning can reduce the amount of CFRP strips required and the combination of temporally post tensioning and CFRP strips may meet the strength and ductility requirements of old structures.

• 한국강구조학회 논문집
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• 제9권3호통권32호
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• pp.441-455
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• 1997

많은 나라에서 기 시공된 교량의 보수 보강에 대한 관심이 고조되고 있고 많은 보고서와 인쇄물에서 이에 대해 강조되고 있다. 국내의 1960년대와 1970년대 사이에 시공된 교량은 상대적으로 적은 차량크기, 속도, 중량으로 설계되어 현재의 교통조건에 부적절하다. 다소의 설계오류와 함께 이는 많은 교량의 여러 결함을 유발한다. 보수 보강의 한 방법으로 많은 잇점을 가진 external post-tension tendon을 사용하는 것이고 본 논문에서 external post-tension을 이용한 3경간 연속 합성교량의 보강방안에 대해 기술한다.

• 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.

• Computers and Concrete
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• 제17권1호
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• pp.67-86
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• 2016

Strengthening as well as correcting unsightly deflections of reinforced concrete (RC) beam may be accomplished by retrofitting. An innovative way to do this retrofitting that is proposed in this study utilizes turnbuckle to apply external post-tensioning. This Turnbuckle External Post-Tensioning (T-EPT) was experimentally proven to improve the serviceability and load carrying capacity of reinforced concrete beams. The T-EPT system comprises a braced steel frame and a turnbuckle mechanism to provide the prestressing force. To further develop the T-EPT, this research aims to develop a numerical scheme to analyze the structural performance of reinforced concrete beams with this kind of retrofitting. The fiber method analysis was used as the numerical scheme. The fiber method is a simplified finite element method that is used in this study to predict the elastic and inelastic behavior of a reinforced concrete beam. With this, parametric study was conducted so that the effective setup of doing the T-EPT retrofitting may be determined. Different T-EPT configurations were investigated and their effectiveness evaluated. Overall, the T-EPT was effective in improving the serviceability condition and load carrying capacity of reinforced concrete beam.

• 대한건축학회논문집:구조계
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• 제34권6호
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• pp.3-10
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• 2018

This paper described the shear strengthening effect by deviator location in pre-damaged reinforced concrete (RC) beams strengthened with externally post-tensioning steel rods. Three reinforced concrete beams as control beam and eight post-tensioned beams using external steel rods were tested to fail in shear. The externally post-tensioning material was a steel rod of 22 mm diameter, and it had a 655 MPa yield strength and an 805 MPa tensile strength. Specimens depend on multiple variables, such as the number of deviators, location of deviator, and load pattern. The pre-damaged loads up to about 2/3 of ultimate shear capacities were applied to specimens using displacement control and the diagonal shear crack just occurred at these loading levels. And then, the post-tensioning up to when a strain of steel rod reaches about $2000{\mu}{\varepsilon}$ was continuously applied to beam. A displacement control was changed to a load control during post-tensioning. The post-tensioning resulted in increase of load-carrying capacity and restoration of existing deflection. Also, it prevented the existing diagonal cracks from excessively growing. Two deviators effectively improved the load capacity when compared with in case of test which one deviator at mid-span installed. When deviators were located near region which the diagonal crack occurred on, the strengthening impact by post-tensioning was greater.