• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.891-896
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• 2002

Flat plate is susceptible to punching shear failure at the slab-column connection, which may cause catastrophic structural collapse. To prevent such brittle failure, strength and ductility of the connection should be ensured. However, since it is very difficult to experimentally simulate the actual load and boundary conditions of the flat plate system, it is not easy to obtain reliable information and data regarding to the strength and ductility of the flat plate-column connection. In the present study, numerical studies were performed for interior connections of continuous flat plate. The results were compared with the existing experiments, and the variations of bending moment, shear, torsional moment around the connection were investigated. Based on the findings of the numerical studies, the disadvantages of current design methods were discussed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.421-426
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• 2003

For the replacement of deteriorated concrete decks or wider-span slab, composite slab could be very attactive due to higher stiffness and strength. Based on the previous research, a modified I-beam composite hollow slab was suggested. In order to investigate the static flexural behavior of the proposed composite slab and to suggest its flexural design method, experiments were performed. Judging from the tests, a composite slab with I-beam having a semi-circle hole showed better structural performance. The effect of web details on the flexural stiffness was negligible. Flexural stiffness, ultimate strength, and ductility of the composite slabs were significantly greater than the RC slab due to composite action. While the failure of the RC slab was punching shear failure, the composite hollow slab showed flexural cracking and failure by yielding of the I-beams and crushing of concrete. Therefore, the current one-way design concept is appropriate for the design of I-beam composite hollow slab.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.285-288
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• 2007

In the recent years the using of low-density material such as high-strength Al alloy on the various industries is becoming light-weight. High strength and hollow Al alloy is good material for stiffness and recycling. Therefore the advanced manufacturing technology with Al alloy is continuously required in many industrial fields. In this study simplified hallow rectangular section of Al alloy is analyzed by FE analysis. Bending stress is affected punching and rotating of wing-die. The analysis of press bending is preformed at first. The elastic recovery value of component and stress distribution acting from the result of the bending angle of three types were obtained. The designed precesses were analyzed by the commercial FE code, Deform-3D. Forming dies for each process were designed and prototypes were manufactured by the verified forming process. Some of the important features of design parameters in the press bending were reviewed.

• 한국기계가공학회지
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• 제11권6호
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• pp.115-122
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• 2012

The purpose of this study is to optimize the design of the jack-up platform for 5MW offshore wind turbine system. Considering all the environmental loads such as currents, waves, winds and so on, the members of structures have been designed and optimized based on the AISC and API-RP-2A to be within the allowable stress even in the most critical and severe condition. In addition to the above strength check of structural members, the joint punching shear check and the hydrostatic collapse check are also performed where they are required for the design. The design life of the jack-up platform is 50 years for the static strength check and the fatigue design life is 100 years including to the DFF(Design Fatigue Factor) of 2.0 to have enough stability and workability for the design optimization.

• 한국공작기계학회논문집
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• 제12권1호
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• pp.58-64
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• 2003

A mechanical press joining was investigated in ender for joining A1-5052 sheets for automobile body weight reduction. Static tensile and fatigue tests were conducted using tensile-shear specimens for evaluation of fatigue strength of the joint. During Tox joining process for A1-5052 plates, using the current sheet thickness and punch diameter, the optimal applied punching force was found to be 32 kN under the current joining condition. For the static tensile-shear experiment results, the fracture mode is classified into interface fracture mode, in which the neck area fractured due to influence of neck thickness, and pull-out fracture mode due to influence of plastic deformation of the joining area. And, during fatigue tests for the A1-5052 tensile shear specimens, interface failure mode occurred in the region of low cycle. The fatigue endurance limit approached to 6 percents of the maximum applied load, considering fatigue lifetime of $2.5\times10^6$ cycles.

• 한국구조물진단유지관리공학회 논문집
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• 제18권4호
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• pp.10-21
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• 2014

프리캐스트 방식에 의해 제작이 가능한 격자형 강합성 바닥판의 이음부는 콘크리트 전단키와 고장력볼트 체결로 구성될 수 있으며, 이와같은 이음부 자체에 대한 휨 및 전단성능은 부재요소에 대한 실험을 통해 분석된 바 있다. 본 연구에서는 실제 바닥판 구조시스템에서 이음부에 의한 횡방향 하중전달 거동을 분석하고자, 길이 2.5m 및 폭 1m의 단위 바닥판 모듈 한쌍에 이음부를 설치한 실험체를 제작하고 중심 및 편심가력 휨실험을 하였다. 이음부에 하중이 직접 가해지는 중심재하 조건에서 고장력볼트의 설치개수가 30cm 간격 9개에서 60cm 간격 4개로 줄어 들 경우, 재하단계에 따라 이음부의 회전이 비교적 더 크게 증가하고, 이에 따라 바닥판 횡방향으로의 하중전달 정도가 감소함을 알 수 있었다. 그러나, 한쪽 바닥판의 중심에 집중하중이 가해지는 편심재하 조건의 경우에는 횡방향 하중전달 거동에 큰 차이가 없었다. 하중 재하방법별로 이음부의 거동을 비교한 결과, 집중하중에 대한 바닥판 횡방향으로의 하중분배 및 전달량은 이음부 자체의 성능뿐만 아니라 바닥판 슬래브의 펀칭전단에 의해서도 제한되는 것으로 분석되었다. 또한, 펀칭 전단파괴가 발생할 때까지 이음부의 고장력볼트가 항복하지 않은 점을 고려할 때, 이음부 고장력볼트의 설치개수를 4개에서 9개로 증가시키는 것은 실질적으로 강도 보다는 이음부 및 바닥판의 휨강성 성능 증가에 더 큰 영향을 미치는 것으로 사료된다.

• 콘크리트학회논문집
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• 제16권2호
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• pp.213-220
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• 2004

본 논문은 신공법인 carbon fiber rod로 보강된 교량 바닥판의 정적 및 피로성능개선 효과에 대한 것이다. 이 연구의 실험에서 적용된 보강변수는 등방성 및 이방성 보강이며, 보강성능을 평가하기 위하여 보강된 바닥판 시험체에 대해 정적 및 피로실험을 실시하여 그에 따른 내하성능, 균열 및 파괴양상 등을 분석하였다. 실험결과, 보강된 모든 시험체가 증설된 모르타르와 콘크리트와의 계면이 조기에 탈락하여 펀칭전단 파괴되는 양상을 보였다. 보강성능을 살펴보면, CFR로 보강된 바닥판은 무보강 시험체에 비해 극한강도, 강성, 피로수명 등에서 우수한 것으로 나타났다 또한 보강형식 측면에서는, 이방성 보강(CR-UE)이 등방성 보강(CR-E)보다 우수한 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제76권1호
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• pp.83-99
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• 2020

Shear walls are structural members in buildings that are used extensively in reinforced concrete frame buildings, and almost exclusively in the UK, regardless of whether or not they are actually required. In recent years, the UK construction industry, led by the Concrete Centre, has questioned the need for such structural elements in low to mid-rise reinforced concrete frame buildings. In this context, a typical modern, 5-storey residential building is studied, and its existing shear walls are replaced with columns as used elsewhere in the building. The aim is to investigate the impact of several design variables, including concrete grade, column size, column shape and slab thickness, on the building's structural performance, considering two punching shear limits (V_Ed/V_Rd,c), lateral drift and accelerations, to evaluate its maximum possible height under wind actions without the inclusion of shear walls. To facilitate this study, a numerical model has been developed using the ETABS software. The results demonstrate that the building examined does not require shear walls in the design and has no lateral displacement or acceleration issues. In fact, with further analysis, it is shown that a similar building could be constructed up to 13 and 16 storeys high for 2 and 2.5 punching shear ratios (V_Ed/V_Rd,c), respectively, with adequate serviceability and strength, without the need for shear walls, albeit with thicker columns.

• 한국구조물진단유지관리공학회 논문집
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• 제12권5호
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• pp.74-80
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• 2008

본 논문은 기둥형상비를 실험 변수로 가지는 무량판 슬래브-기둥 접합부의 내진성능을 평가하는데 있다. 본 연구에서는 무량판 슬래브의 뚫림 전단파괴를 방지하기 위하여 본 연구와 병행하여 진행된 연구에서 개발된 연속 절곡된 전단보강근을 적용하였다. 기둥형상비에 따른 실험체는 각각 FIS1-05(0.5), FIS1- 10(1.0), FIS1-20(2.0) 이다. 실험체의 수평방향으로 정적 수평하중을 가력 하였으며, 중력하중비에 의한 일정 수직 하중을 적용하였다. 실험결과는 슬래브-기둥 접합부의 수평 변위 및 강도를 기준으로 평가하였다. 분석결과, FIS1-05, FIS1-20와 같은 장방형 기둥을 갖는 접합부의 성능이 FIS1-10와 같은 정방형 기둥을 갖는 접합부보다 우수한 것으로 평가되었다.

• 한국해양공학회지
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• 제30권6호
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• pp.474-483
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• 2016

Accidental events such as collisions, groundings, and hydrocarbon explosions in marine structures can cause catastrophic damage. Thus, it is extremely important to predict the extent of such damage, which determines the total amount of oil spills and the residual hull girder strength. Punching fracture tests were conducted by Choung (2009b), where various sizes of indenters and circular unstiffened steel plates with different thicknesses were used to quasi-statically realize damage extents. A three-dimensional fracture strain surface was developed based on a reference (Choung et al., 2015b), where the average stress triaxiality and average normalized Lode angle were used as the parameters governing the fracture of ductile steels. In this study, new numerical analyses were performed using very fine axisymmetric elements in combination with an Abaqus user-subroutine to implement the three-dimensional fracture strain surface. Conventional numerical analyses were also conducted for the tests to identify the best fit fracture strain values by changing the fracture strains. Based on the phenomenon of the average normalized Lode angle starting out positive and then becoming slightly negative, it was inferred that the shear stress primarily dominates in determining the fractures locations, with a partial contribution from the compressive stress. It should be stated that the three-dimensional fracture surface effectively predicted at least the shear stress-dominant fracture behavior of a mild steel.