• 콘크리트학회논문집
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• 제17권4호
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• pp.521-526
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• 2005

원전 격납건물의 축대칭 모델은 해석상의 간편성으로 인하여 널리 사용된다. 하지만, 일반적인 돔 텐던의 배치는 축대칭 형상이 아니며 곡률을 가진 돔에 임의로 배치된 관계로 축대칭 근사화시 좀 더 엄밀한 수학적 유도가 요구된다. 본 연구에서는 국내의 CANDU형 및 한국형 격납건물 돔에 비축대칭으로 배치된 텐던을 축대칭 모델에 적용하기 위한 합리적인 변환 절차를 제안하였다. 텐던 강성의 모델링에서는 실제 3차원으로 배치된 돔 텐던의 자오선방향 및 원환방향으로의 강성 기여를 고려할 수 있도록 텐던을 등가의 층으로 근사화하였다. 프리스트레싱의 효과는 등가하중법 및 초기응력법 관점에서 고찰하였으며, 축대칭 모델의 방법론에 적합하도록 등가하중 및 초기응력을 유도하였다. 후속 논문에서는 제안된 모델을 적용한 수치 예제들을 범용구조해석 프로그램으로 해석하고 타당성을 검증하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.758-761
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• 2004

Prestressing tendons of the nuclear containment building dome are arranged in a non-axisymmetric manner. However, simple axisymmetric modeling of the containment building is often employed to estimate the structural behavior for, e.g. the ultimate pressure, which requires the axisymmetric approximation of the actual tendon arrangements of the dome. A procedure is proposed that can devise the actual 3-dimensional tendon stiffness and prestressing effect into the axisymmetric model. A numerical example of the CANDU type is presented to verify the procedure and to estimate the amount of approximation.

• 콘크리트학회논문집
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• 제15권5호
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• pp.679-688
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• 2003

종방향 텐던이 경사진 복부에 배치되는 박스 거더의 경우 프리스트레스 힘은 종방향 뿐만 아니라 횡방향 거동에도 영향을 미친다. 본 논문에서는 종방향 프리스트레싱에 의해 유발되는 횡방향 효과를 산정하는 기법을 제안하였다. 박스 거더의 유한요소 정식화 및 종방향 프리스트레싱 해석에 의해 프리스트레스 분포를 산정한 후, 이를 이용하여 횡방향 등가하중을 산정한다. 제안기법에 의한 수치해석결과와 기존의 접판법에 의한 수치해석결과는 유사하며, 이는 본 기법이 합리적임을 나타낸다. 제안기법을 이용하여 박스 거더 슬래브의 횡방향 거동을 분석하였다. 수치분석은 복부경사각, 텐던 편심에 대한 경간 길이비 등과 같은 주요 변수를 통해 수행되었다. 전형적인 단면 조건에서 종방향 프리스트레싱 효과만을 고려할 때, 박스 거더 슬래브의 횡방향 응력은 크지 않은 것으로 나타난다. 그러나, 복부 경사각이 50도 이하로 과도하게 작아지거나 텐던 편심에 대한 경간 길이비가 28이하로 작아지는 경우에는 교량 설계시 횡방향 응력의 크기를 고려할 필요가 있다고 사료된다.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.805-819
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• 2016

The numerical simulation methodologies to evaluate the structural behaviors of prestressed concrete containment vessels (PCCVs) have been substantially developed in recent decades. However, there remain several issues to be investigated more closely to narrow the gap between test results and numerical simulations. As one of those issues, the effects of no stiffness inside unbonded tendon ducts on the behavior of PCCVs are investigated in this study. Duct holes for prestressing cables' passing are provided inside the containment wall and dome in one to three directions for general PCCVs. The specific stress distribution along the periphery of the prestressing duct hole and the loss of stiffness inside the hole, especially in an unbonded tendon system, are usually neglected in the analysis of PCCVs with the assumption that the duct hole is filled with concrete. However, duct holes are not small enough to be neglected. In this study, the effects of no stiffness inside the unbonded tendon system on the behaviors of PCCVs are evaluated using both analytical and numerical approaches. From the results, the effects of no stiffness in unbonded tendons need to be considered in numerical simulations for PCCVs, especially under internal pressure loading.

• 콘크리트학회논문집
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• 제21권3호
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• pp.303-310
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• 2009

CFRP (carbon fiber reinforced polymer) 긴장재는 PC 강연선의 부식문제를 해결하기 위해 대안으로 사용될 수 있다. CFRP 긴장재를 콘크리트구조물에 적용하기 위해서는 부착강도, 전달길이, 정착길이와 같은 재료적 특성이 명확히 결정되어야 한다. 특히 프리텐션 콘크리트 부재에 CFRP 긴장재가 적용될 경우 전달길이는 긴장력 도입에 있어서 중요한 요소가 된다. 본 연구에서 개발된 CFRP 전달길이 및 정착길이를 산정하기 위해 프리텐션 보 9개를 제작하였다. 전달길이 실험결과, 긴장력 25%인 경우는 34D, 긴장력 50%인 경우는 55D로 측정되었고, 긴장력이 커지면 전달길이가 증가하는 것으로 나타났다. 시간경과에 따른 전달길이 변화를 살펴보면, 긴장력의 크기에 따라 시간경과가 전달길이에 영향을 주는 것으로 나타났다. 보강재 특성계수 산정 결과, 본 연구에서 개발된 CFRP 긴장재의 보강재-특성 계수 ${\alpha}_t$는 2.3으로 PS강연선 (${\alpha}_t=2.4$)과 비슷한 것으로 나타났다.

• 한국구조물진단유지관리공학회 논문집
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• 제7권1호
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• pp.227-238
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• 2003

Due to deterioration of bridge, usually be using the external prestressing method among repair reinforcement method. But, there is much to be desired about a detailed account, almost it has analysed by cambers of girders, deflections of middle span and upper, bottom stresses of girders. Also, it is not examined closely that effect of internal prestress by external prestressing. The purpose of this study is confirmed the effect of internal tendons by external prestressing, estimation of additional external prestressing force and look for exact external prestressing force.

• 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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.681-684
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• 1999

The development of external prestressing methods has been one of the major trends in the concrete bridge constructions over the past decades. One of the promising methods to enhance the flexural strength of a externally prestressed girder is to place the tendons with large eccentricities. The test results in this study showed that the external prestressing of a composite girder increased the range of the elastic behavior, reduced deflections, increased ultimate strength, and added to the redundancy by providing the multiple stress paths. This study was conducted on the concrete bridges reinforced by the continuous girders and the external prestressing.

• Computers and Concrete
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• 제17권2호
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• pp.241-253
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• 2016

Depending on the researcher, the effect of prestressing on the natural frequency of a PSC (prestressed concrete) structure appear to have been interpreted differently. Most laboratory tests on PSC beams available showed that the natural frequency is increased appreciably by prestressing. On the other hand, some other references based on field experience argued that the dynamic response of a PSC structure does not change regardless of the prestressing applied. Therefore, the deduced conclusions are inconsistent. Because an experiment with and without prestressing is a difficult task on a full size PSC bridge, the change in natural frequency of a PSC bridge due to prestressing may not be examined through field measurements. The study examined analytically the effects of prestressing on the natural frequency of PSC bridges. A finite element program for an undamped dynamic motion of a beam-tendon system was developed with additional geometric stiffness. The analytical results confirm that a key parameter in changing the natural frequency due to prestressing is the relative ratio of prestressing to the total weight of the structure rather than the prestressing itself.

• 한국재난정보학회 논문집
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• 제5권2호
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• pp.124-137
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• 2009

The research on the effect of the prestressing force on the frequency of PSC(Prestressed Concrete beam) has been conducted theoretically and experimentally, and a few theory has been presented. However, the presented theories show no agreement in predicting the effect of the prestressing force. In this paper, the theories on the effect of the prestressing force on the frequency of PSC beam are presented and evaluated using the experimental result. To obtain the experimental result, two PSC beam specimens were manufactured, and the modal test and analysis were performed. The modal analysis results revealed that the prestressing force increased the natural frequency of the PSC beam. Comparing predicted results using existing theories show that Kim's model, which substitutes the prestressing tendon with the equivalent beam, gives the best prediction result.