• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.363-366
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• 2003

This study is to develop a strengthening method for RC slab bridges and rigid-frame bridges with external prestressing. In this study, we design the slab specimen that have a strengthening of the DB-13 and set up the longitudinal tendons placed on both side of slab strengthens the whole bridge, and lateral tendons placed under the slab strengthens the middle of slab, and conveys the load at middle slab to both sides. Structural analysis for the tensile force for strengthening were analysed and we know that displacement and strain was improved from this test. This method has no upward roof work, so it is very convenient for installing. And no spaces under the slab are need, so it is good for shallow slabs which has less space inder the slab.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.283-288
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• 2007

This paper presents an analytical prediction of Nonlinear characteristics of prestressed concrete bridges by strengthened of externally tendon considering the work sequence, using beam-column element based on flexibility method and tendon element. The beam-column element was developed with reinforced concrete material nonlinearities which are based on the smeared crack concept. The fiber hysteresis rule of beam-column element is derived from the uniaxial constitutive relations of concrete and reinforcing steel fibers. The tendon element represent the bonded tendon and unbonded tendon behaviors. Beam-column element and tendon element was be subroutine A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of RC and PSC structures was used. The proposed numerical method for prestressed concrete structures by strengthened of externally tendon is verified by comparison with reliable experimental results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.117-120
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• 2006

This study is for the strengthening method of continuous bridge through external tendon strengthening that is the most general and effective among concrete bridge's strengthening method. Recently, it is numerous that slab's parts between spans have continuity for improving trafficable ability. However, in this case, slab would have a crack; bridge's durability would be damaged, and also it is too difficult to manage and maintain bridge due to the tensile strength of negative moment. Therefore, the purpose of this study is to demonstrate load-carrying through experiments and develop new external pre-stressing strengthening method for reinforcing continuous bridge.

• 한국구조물진단유지관리공학회 논문집
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• 제14권3호
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• pp.91-99
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• 2010

RC 구조물의 보강에는 여러 가지 보강공법이 사용되고 있으며 특히 외부강선 보강공법은 손상된 구조물을 보강하는 대표적인 공법이며 효율성, 용이성, 경제성의 면에서도 우수하다. 본 연구에서는 PSC 및 RC 거더에서 추가 손상 없이 충분한 보강효과를 얻을 수 있는 보강공법으로써 개선된 인양홀을 이용한 정착장치를 제안하였다. 2가지 유형의 새롭게 제안된 정착장치를 6개의 실험체의 적용하였고 기존의 정착장치를 3개의 실험체에 적용하였다. 한 개의 실험체는 보강효율을 판단하기 위하여 보강공법을 적용하지 않았다. 이들 정착장치의 거동을 분석하기 위하여 정적 재하 시험을 수행하였고 실험변수들은 정착장치의 형상, 강봉의 긴장정도와 강선의 설치형태이다. 각 실험체의 보강 효과를 조사하기 위해 처짐, 변형률 그리고 파괴양상을 기록하였으며 균열하중, 항복하중, 극한하중, 연성지수 그리고 강선의 응력을 분석하였다. 그 결과 제안된 인양홀을 이용한 정착장치는 기존의 정착장치보다 높은 보강효율을 보였으며, 에너지 개념을 이용한 연성도 평가에 따르면 충분한 연성을 확보하고 있음을 알 수 있었다.

• 한국안전학회지
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• 제25권5호
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• pp.44-53
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• 2010

Recently, the external prestressed concrete structures are increasingly being built. The mechanical behavior of prestressed concrete beams with unbonded tendon is different from that of normal bonded PSC beams in that the increment of tendon stress was derived by whole member behavior. By this reason, the ultimate stress of external tendon is smaller than that of bonded tendon or internal unbonded tendon. However, in the domestic and abroad code, the equation of ultimate stress of external tendon is not suggested yet, and the equation of ultimate stress of internal unbonded tendon is used instead of that of external tendon. Therefore, in this paper, after effective variables of ultimate stress of external tendon were analyzed, the analytical equation of ultimate stress of external tendon was proposed. And the reasonable coefficients were proposed by statistical work of test results of 25 beam with external tendon. Finally, the practical proposed equation of ultimate stress of external tendon was proposed with analytical and statistical model. The equation of ACI-318 and AASHTO 1994 were not matched with test results and had no correlations, and the proposed equation was well matched with test results. So the proposed equation in this paper will be a effective basis for the evaluation of external tendons in analysis and design.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.93-98
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• 2001

This study is to develop the end anchorage of external steel reinforcement of RC slab bridges. External prestress method using the existing steel is that When the anchorage is installed in slab end, a plenty of anchor bolts were required because the only tangential stress of anchor bolt received a tendon force. Then, for this reason, the wide end anchorage was required and the shape was complicate. But this reinforcement method using method that inserts anchor key at concrete surface cut a groove gets big internal force comparing to the anchorage using existing anchor bolt. Furthermore, the number of anchor bolt for installing apparently will be reduced, and the operation will be convenient because a small anchorage of a simple shape will be received a great tendon force

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.411-416
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• 2002

With a rapid industrialization, repair and strengthening methods for a damaged bridges are raised a head in face of safety and reduction of physical distribution costs of bridges. Above all, external prestressing method has the high adaptability for concrete structures and the reliable effect of strengthening. Innovative ideas for bridges strengthening were considered along with established methods. That methods are identified, described. However there is not a systematic and categorized manual for external prestressing method. This study will provide a systematic and reliable manual with investigating the arrangement shape of cable and characteristics of brackets. And the key result of this study is an extensive compilation, which can be used by practicing engineers, of the most effective techniques for strengthening existing bridges.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1619-1620
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• 2015

KS C IEC 62561-2 표준은 피뢰시스템 구성요소로서의 도체 및 접지극에 관한 요구사항 및 시험에 대하여 규정되어 있다. 외부 피뢰 구성자재는 대기 중 혹은 대지에 직접 노출되어 있기 때문에 전기적 성능과 기계적 성능을 모두 만족해야 한다. 또한 피뢰도체와 접지극은 재질과 크기, 형태가 모두 다르기 때문에 각각의 요구사항에 부합할 수 있는 성능을 지녀야 한다. 본 논문에서는 일반적으로 많이 쓰이는 재질과 단면적을 가지는 접지봉으로 성능시험을 진행하였으며, 접지봉의 재료는 스테인레스강에 구리를 코팅한 동복강선으로 구성된다. 시험 결과 점착 시험 및 굽힘 시험에서 모두 크랙 및 코팅이 벗겨지는 것을 확인할 수 있었다. 코팅에 크랙 혹은 벗겨짐이 발생하면 지중에서 접지극의 부식이 진행되고, 접지저항이 높아져 전기적 성능을 저하시키는 결과를 야기한다. 때문에 스테인레스강에 구리 혹은 아연 등을 코팅하는 과정에서 벗겨짐이 없도록 점착 성능이 개선되어야 한다고 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.461-464
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• 2004

External prestressing method is the most papular method to strengthen concrete structures. The key parts of external prestressing method is an anchoring device which holds the prestressing cables. The most popular anchoring devices is an end bearing type, which has to be welded at site to assamble the anchor. The welding at site has a significant Quality problem. In this paper, new anchoring system has been developed, which needs no site welding. A design method for the new anchor has been proposed and developed to optimize the anchoring system. The developed anchors are very efficient, small, and compact, which have two types, one for abutment section and the other one for pier section. The anchors are expected to be used very widely, because of its convinience.

• 한국추진공학회지
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• 제24권3호
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• pp.59-70
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• 2020

본 논문에서는 기존 적층형 배관의 총 열전달 계수 경험식을 활용할 때 발생하는 한계점을 해결하고자, 외부 총 열전달 계수의 강제 대류 열전달 계수 항을 독립적으로 도출하는 간소화된 모델링을 제안하고, 이를 극저온 환경의 실험 결과로 확인하였다. 액체 산소 냉각 나선형 열교환기가 액체 질소와 열교환하는 실험 장치를 구성하고 열교환기의 열전달량을 계측하여, 외부 총 열전달 계수를 도출하였다. 측정된 외부 총 열전달 계수가 모델링으로 예측 곡선과 일치함을 확인하였다.