• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.16 no.1
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• pp.37-41
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• 2020

The Nuclear containment building is a main safety-related structure that performs shielding and conservation functions to prevent highly radioactive materials from leakage to the outside environment in the case of various environmental conditions and postulated accidents. The containment building contains a reactor, steam generator, pressurizer, tank, reactor coolant system, auxiliary system and engineering safety system, and is designed so that highly radioactive materials above the limits specified in 10 CFR 100 do not escape to the outside environment in the case of LOCA(Loss of Coolant Accident) for instance. The containment metal liner plate(CLP) is a carbon steel plate with a nominal plate thickness of 6 mm, which functions as a mold for the wall and dome of the containment building when concrete is filled, fulfills airtightness to prevent leakage of seriously radioactive materials. In recent years, backside corrosion was found on the liner plate in some domestic nuclear power plants. The main cause of backside corrosion was unfilled concrete. In this paper, an inspection technique of assessing filling suitability for CLP backside concrete is developed. Results show that the validity of inspection technique for CLP backside concrete using vibration sensor is successfully verified.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.2 s.54
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• pp.95-104
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• 2007

Three types of high-rise RC building structures having irregularity in the lower two stories were selected as prototypes and were performed nonlinear static analysis by using OpenSees to verify the analysis technique and to investigate the seismic capacity of those buildings. The first one has a symmetrical moment resisting frame (Model 1), the second has an infilled shear wall in the central frame (Model 2), and the third has an infilled shear wall only in one of exterior frames (Model 3). Fiber model, which consists of concrete and reinforcing bar represented from stress-strain relationship, is adapted used for simulate the nonlinearity of members, and MVLEM(Multi vertical linear element model) is used for simulate the behavior of wall. The analytical results are simulate the behavior of piloti stories well, for example, the stiffness and yield farce of piloti stories, the up-lift of wall and the variation of lateral stiffness of column due to the variation of axial forces. Overstrength of Model 2 and Model 3 are about 2 times larger than that of Model 1. The reason of the high oversttrength and ductility of Model 2 and Model 3 is that the conservative design of Model 2 and Model 3, whose beam and column sections are the same as those of Model 1. The ductilities of Model 1 and Model 3 are slightly larger than that of Model 1 and Model 3. Model 1 and Model 3 reached mechanism condition, whereas Model 2 failed to the shear failure of shear wall and the large axial forces in columns due to large overturning moment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.243-253
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• 2011

This paper describes an analytical study on seismic performance of domestic reinforced concrete (RC) school building not designed by seismic provision. The seismic index and the seismic performance of the building were evaluated through Japanese standard and Midas Gen, respectively. Seismic index (Is) of the RC school buildings in the X-direction is below 0.4. Based on the seismic index, for seismic-strengthening the building, infill shear wall or steel brace with a capacity of 1,300 kN was used. According to nonlinear static analysis results, the contribution of the seismic-strengthening to the shear resistance of the school building was measured to be greater than 30%. However, as expected, shear strength of school building strengthened with infill wall dropt rapidly after peak load and much narrower ductile behavior range was observed compared to steel brace strengthened building. Also, the building strengthened with steel brace showed 30% larger spectral displacement than that strengthened with infill shear wall. In nonlinear dynamic analysis, for the time history analysis, the maximum displacement showed tendency to decrease as amount of reinforcement increased, regardless of strengthening method. It was recommended that variable soil properties and earthquake record should be considered for improving seismic performance of buildings in seismic zone.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.6
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• pp.293-299
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• 2018

Steel truss outriggers can be replaced by reinforced concrete walls to control the lateral drift of tall buildings. When reinforced concrete outrigger walls are connected to perimeter columns, not only axial forces but also shear forces and moments can be induced on the perimeter columns. In this study, the shear force of the perimeter column due to the rotation of the outer edge of the outrigger wall is derived as analytic equations and the result is compared with the finite element analysis result. In the finite element analysis, the effects of connecting beams at each floor and the effect of modeling shear walls and outriggers with beam element and plane stress element was analyzed. The effect of the connecting beam was almost negligible and the plane stress element was determined to have greater stiffness than the beam element. The inter-story rotation and the shear force of the perimeter column due to the rotation of the outer edge of the outrigger wall was considerably smaller than the allowable value. Therefore, even if the outrigger wall made of reinforced concrete is applied to a tall building, it is considered that there is no need to study the shear force and moment induced in the perimeter columns.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.219-224
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• 1993

본 연구는 철근콘크리트 격납구조물에서 가상의 냉각제 유출사고에 의한 온도하중과 압력에 따른 거동을 알아보기 위한 비선형 해석을 수행하였다. 시간에 따른 온도하중을 결정하기 위하여 과도온도해석을 통해 격납구조물 단면내의 온도분포를 구하였다. 구조물은 기하학적 비선형성과 재료비선형성을 고려한 판 및 쉘요소로 이상화되며, 쉘요소는 두께방향에 따라 변하는 응력을 고려하기 위해 몇 개의 층으로 이루어진 모델을 사용하였다. 열응력은 인접한 두시간 단계에서의 온도차를 하나의 하중증가로 고려하여 초기변형 문제로 변환하여 결정되었다. 본연구에서의 수치실험에 의하여 과도온도해석에 근거한 비선형온도경사를 고려할 때의 변위가 고려하지 않을 때의 변위에 비해 크게 나타남을 알 수 있다.

• Magazine of the Korea Concrete Institute
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• v.14 no.2
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• pp.77-82
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• 2002

일반적으로 공동주택 지하주차장과 같이 구조물이 대형화되거나 복잡할 경우 구조물의 응력취약 부위에서 균열, 누수 등의 문제가 발생할 확률이 크다. 이에 대한 대책으로 설계자들은 신축줄눈을 선호하고 있으나 신축줄눈은 시공상의 어려움과 사용 중 잦은 하자 발생이라는 문제점을 안고 있다. 이 때문에 근래에 들어 대형 건물을 한 단위로 처리하고 철근으로 보강하려는 경향이 있으나 구속도 차이에 따라 균열, 누수 등의 문제가 여전히 발생하고 있다. 이를 해결하기 위하여 수축대를 설치하여 일정 요구량의 초기 수축량을 수축대에서 흡수하고 이후 수축대 부위에 콘크리트를 메워 일체화시킴으로써 초기 수축에 의한 균열을 상당부분 방지할 수 있다.(중략)

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.99-100
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• 2009

In this paper, wish to achieve an experimental study to investigate enhanced performance of the masonry walls strengthened in shear and ductility using Aramid fiber strip.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.105-108
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• 2005

In damage investigation of building structures suffering from earthquake, estimation of residual seismic capacity is essential in order to access the safety of the building against aftershocks and to judge the necessity of repair and restoration. It has been proposed that an evaluation method for post-earthquake seismic capacity of reinforced concrete buildings based. on the residual energy dissipation capacity (the residual seismic capacity ratio )in lateral force-displacement curve of structural members. The proposed method was adopted in the Japanese 'Damage Level Classification Standard' revised in 200l. To evaluate the residual seismic capacity of RC column, experimental tests with positive and negative cyclic loading was carried out using RC building column specimen. Parameters used by the experiment are deformability and member proportion. From the test results, it is appropriated that the residual seismic capacity of RC buildings damaged by earthquakes is evaluated using the method in the Guideline.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.556-561
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• 1995

원자력발전소 중대사고시 격납건물의 건전성을 위협할 수 있는 현상들 중의 하나인 MCCI에 대한 분석을 목적으로 MCCI 관련 실험인 SWISS 및 SURC 실험에 대하여 MELCOR 1.8.2 를 이용하여 계산을 수행하였다. 에어로졸 생성량을 제외한 MCCI 진행과정의 주요 예측대상에 대하여 실험결과와의 비교를 통하여 콘크리트 침식 진행과정 및 침식을, 노심용융물의 온도분포 및 열유속, 반응에 의해 유출되는 각종 가스 생성을, 그리고 노심용융물의 냉각에 따른 각질층 형성 등을 파악하였다. 콘크리트 침식과정 및 노심용융물의 온도 예측은 적절하며 콘크리트 분해에 따른 각종 방출가스는 열수력 조건에 따라 큰 불확실성을 보여주는 것으로 나타났다. 아울러 노심용융물의 냉각에 따른 각질층의 동적 거동해석은 MELCOR 1.8.2의 모델로서는 불가능하였다. 보다 많은 검증계산을 통하여 적절한 해석방법의 도출 및 새로운 모델 제시의 필요성이 있다고 판단된다.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.95-100
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• 1996

Creep, drying shrinkage, modulus of elasiticity and Poisson's ratio of concrete are influenced by a number of factors such as mix type, member thickness, curing condition and loading cases. Particularly, creep and shrinkage in concrete have yet to be studied due to its complicated time-dependent properties. In this study, the concrete creep tests were carried out at varous ages of loading-7, 28, 90, 180 and 365 days in order to investigate and quantify its long-term properties. The test procedures and analysis of the test results were also described herein. The results of this study will enable A/E to calculate effective prestressing forces considering time-dependent prestressing loss and evaluate the structural integrity of the prestressing system using the representative values derived from this property test.