• 한국전산구조공학회논문집
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• 제24권4호
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• pp.449-455
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• 2011

최근 가압중수형 원전 격납건물의 내압능력 및 비선형 거동에 관한 실증실험과 해석코드에 대한 검증을 위하여 인도의 BARC 주관으로 가압중수형 격납건물 1/4 축소모델을 건설하였고, 내압성능평가를 위한 국제공동연구가 수행되었다. 이 논문은 가압중수형 1/4 축소모델 격납건물에 대한 내압성능과 비선형 거동을 예측하기 위하여 유한요소해석을 수행하였고 그 결과를 도출하였다. 대상 격납건물은 기초매트와 원통형 벽체 및 돔으로 구성되어 있고, 수평 텐던의 정착을 위하여 4개의 부벽(buttress)을 가지고 있다. 유한요소해석을 위하여 ABAQUS를 이용하였고 콘크리트, 철근 및 텐던에 대한 유한요소 모델을 작성하여 극한내압해석을 수행하였다. 유한요소해석결과 콘크리트의 초기 균열은 $1.6P_d$(design pressure)에서 발생하였고, 철근의 항복은 $3.36P_d$ 그리고 극한내압능력은 $4.0P_d$ 수준으로 나타났다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.858-861
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• 2014

This paper presents a simplified finite element tire model for vehicle dynamics analysis. The classical finite element tire model was too big to simulate dynamic properties of the tire. In the simplified model, number of nodes of the tire model was dramatically reduced, and thus its simulation time was several times less than the classical model. Bead, carcass, belt which have an important role to the dynamic characteristics of tire were replaced by simple axis symmetric membrane elements. Also the rebar element was deleted. The tire model has been verified by comparing vertical stiffness data of the simulation model to the test data.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1519-1525
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• 2011

Construction of the coping of reinforced concrete piers is very complicated due to heavy density of rebars and usually exposed to negligent accident. To correct these problems, coping is pre-assembled at the ground in pier coping pre-assembly method and recently a new method of rebar assembling has proposed in this study. For safety assessment of proposed method, small scale model test of railway bridge(PSC U-GIRDER T-shaped pier) was carried out and it was verified that crack pattern, failure mechanism and load resistance capacity are similar between existing method and proposed method. And using analytical approach, linear and non-linear finite element analysis was performed. As a result, it was checked that proposed method has an acceptable structural safety.

• Nuclear Engineering and Technology
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• 제32권2호
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• pp.180-190
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• 2000

In this study, nonlinear analyses of prestressed concrete(PSC) test beams for inservice inspection of prestressed concrete containments for CANDU nuclear power plants are presented. In the analysis the material nonlinearities of concrete, rebar and prestressing steel are used. To reduce the numerical instability with respect to the used finite element mesh size, the tension stiffening effect has been considered. For concrete, the tensile stress-strain relationship derived from tests is modified and the stress-strain curve of rebar is assumed as a simple bilinear model. The stress-strain curve of prestressing steel is applied as a multilineal curve with the first straight line up to 0.8fpu. To prove the validity of the applied material models, the behavior and strength of the PSC test specimens tested to failure have been evaluated. A reasonable agreement between the experimental results and the predictions is obtained. Parametric studies on the tension stiffening effects, the impact of prestressing losses with time, and the compressive strength of concrete have been conducted.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.756-761
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• 1999

The objective of this study is to develop finite element analysis technique to predict the strength reduction of deteriorated reinforced concrete beams and their strengthening capacity. In order to consider the effect of rebar corrosion, a tension stiffening model is proposed and area reduction of rebars due to corrosion is considered. For the analysis of strengthened deteriorated RC beams, one dimensional truss element and an interface element are introduced for models of the strengthening composite and the interface between concrete and composite to simulate delamination or discontinuous behavior at the interface. Then, analyses for deteriorated RC beams strengthened with glass fiber reinforced epoxy panel (GFREP) are carried out to predict both flexural failure and plate-end delamination failure. Finally, analysis results are verified with experimental results.

• Computers and Concrete
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• 제3권1호
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• pp.65-77
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• 2006

This study reports the details of the finite element analysis of eleven shear critical partially prestressed concrete T-beams having steel fibers over partial or full depth. Prestressed concrete T-beams having a shear span to depth ratio of 2.65 and 1.59 and failing in the shear have been analyzed using 'ANSYS'. The 'ANSYS' model accounts for the nonlinear phenomenon, such as, bond-slip of longitudinal reinforcements, post-cracking tensile stiffness of the concrete, stress transfer across the cracked blocks of the concrete and load sustenance through the bridging of steel fibers at crack interface. The concrete is modeled using 'SOLID65'-eight-node brick element, which is capable of simulating the cracking and crushing behavior of brittle materials. The reinforcements such as deformed bars, prestressing wires and steel fibers have been modeled discretely using 'LINK8' - 3D spar element. The slip between the reinforcement (rebar, fibers) and the concrete has been modeled using a 'COMBIN39'-non-linear spring element connecting the nodes of the 'LINK8' element representing the reinforcement and nodes of the 'SOLID65' elements representing the concrete. The 'ANSYS' model correctly predicted the diagonal tension failure and shear compression failure of prestressed concrete beams observed in the experiment. The capability of the model to capture the critical crack regions, loads and deflections for various types of shear failures in prestressed concrete beam has been illustrated.

• 콘크리트학회논문집
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• 제22권6호
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• pp.753-760
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• 2010

초고성능 콘크리트(ultra high performance concrete, UHPC)는 종래의 보통 콘크리트와 다른 새로운 재료로써 높은 강도와 향상된 인성을 그 특징으로 한다. 이러한 새로운 재료의 활용을 위하여 이 연구에서 초고성능 콘크리트의 부착 성능을 평가하고자 하였다. 수정된 RILEM 방법을 사용하여 초고성능 콘크리트와 이형 철근의 인발실험(pull-out test)을 수행하였으며 보통 콘크리트와 비교하여 5~10배에 달하는 부착강도를 확인하여 기존의 설계 기준에 비하여 현저하게 감소한 정착길이와 피복 두께를 제안하였다. 700 MPa급 고장력 철근의 실험 결과의 비교로부터 초고성능 콘크리트에서 고강도 철근 활용의 유효성을 확인하였다. 강연선의 응력전달길이 측정실험을 통하여 현재 전달길이 기준이 UHPC의 경우 매우 보수적이라는 것을 확인하였다. 또한 유한요소해석을 통하여 실험 결과를 검증하였다.

• 한국안전학회지
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• 제34권2호
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• pp.40-47
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• 2019

The Half-depth precast deck is a structural system that utilizes pre-cast panels pre-built at the factory as formwork at the construction stage and as a major structural member at the same time after completion. These systems have joints between segments, and the detail and performance of the joints are factors that have a very large impact on the quality, such as the constructability and durability of the bridge decks. In this study, strength performance evaluation was performed for improved joints using connecting rebar by experimental method. Static loading tests were conducted on the test specimen with improved joint, those with existing joint and those without joint. The test results of the specimens were compared to each other, and the flexural strength required by the design was compared. The flexural strength required in the design was presented by finite element analysis. It has been shown that the flexural strength of the specimens with joints were more than twice that required by the design. But the flexural strength of the specimen with existing joint was about 84% of that without joint. The flexural strength of the specimen with improved joints was a nearly similar degree of that compared to the specimen without joint. And a comparison of the moment-deflection relationship curves of the two specimens also shows a very similar flexural behavior. It is confirmed that improved joint has sufficient flexural strength. In addition to strength, the bridge decks require serviceability, such as deflection and cracking, and in particular, fatigue resistance due to repetitive live loads is an important performance factor. Therefore, further verification studies are required.

• Steel and Composite Structures
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• 제37권2호
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• pp.117-136
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• 2020

Curved steel-concrete composite box girder has been widely adopted in urban overpasses and ramp bridges. In order to investigate its mechanical behavior under complicated and combined bending, shear and torsion load, two large-curvature composite box girders with interior angles of 25° and 45° were tested under static hogging moment. Based on the strain and deflection measurement on critical cross-sections during the static loading test, the failure mode, cracking behavior, load-displacement relationship, and strain distribution in the steel plate and rebar were investigated in detail. The test result showed the large-curvature composite box girders exhibited notable shear lag in the concrete slab and steel girder. Also, the constraint torsion and distortion effect caused the stress measured at the inner side of the composite beam to be notably higher than that of the outer side. The strain distribution in the steel web was approximately linear; therefore, the assumption that the plane section remains plane was approximately validated based on strain measurement at steel web. Furthermore, the full-process non-linear elaborate finite element (FE) models of the two specimens were developed based on commercial FE software MSC.MARC. The modeling scheme and constitutive model were illustrated in detail. Based on the comparison between the FE model and test results, the FE model effectively simulated the failure mode, the load-displacement curve, and the strain development of longitudinal rebar and steel girder with sufficient accuracy. The comparison between the FE model and the test result validated the accuracy of the developed FE model.

• Steel and Composite Structures
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• 제31권1호
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• pp.53-67
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• 2019

This study presents finite element analysis (FEA) on a Y-type perfobond rib shear connection using Abaqus software. The performance of a shear connection is evaluated by conducting a push-out test. However, in practice, it is inefficient to verify the performance by conducting a push-out test with regard to all design variables pertaining to a shear connector. To overcome this problem, FEA is conducted on various shear connectors to accurately estimate the shear strength of the Y-type perfobond rib shear connection. Previous push-out test results for 14 typical push-out test specimens and those obtained through FEA are compared to analyze the shear behavior including consideration of the design variables. The results show that the developed finite element model successfully reflects the effects of changes in the design variables. In addition, using the developed FEA model, the shear resistance of a stubby Y-type perfobond rib shear connector is evaluated based on the concrete strength and transverse rebar size variables. Then, the existing shear resistance formula is upgraded based on the FEA results.