• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.746-752
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• 2001

Design sensitivity analysis for nonlinear structural problems has been emerged in the last decade as a glowing area of engineering research. As a result, theoretical formulations and computational algorithms have already developed for design sensitivity of nonlinear structural problems. There is not enough research for practical nonlinear problems using multi-element, due to difficulties of implementation into FEA. Therefore, nonlinear response analysis for stiffened shell which consists of Mindlin plate and Timoshenko beam, was considered. Specially, it presents the backward-Euler method which is adopted to describe an exact yield state in the stress computation procedure. Then, design sensitivity analysis of nonlinear structures, particularly elasto-perfectly-plastic structure, is developed using direct differentiation method. The accuracy of the developed sensitivity analysis was compared with the central finite difference method. Finally, on the basis of above results, design improvement for stiffened shell is suggested.

• 한국해양공학회지
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• 제9권1호
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• pp.22-35
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• 1995

A simplified numerical procedure have proposed to trace the dynamic behaviour of offshore tubulars subjected to lateral collision impacts. The local denting and overall bending deformation of the struck tubular are represented by a non-linear spring and an elastic visco-plastic beam respectively. In this method a temporal finite difference method and a spacial finite element method are employed. Using this method various boundary conditions are able to considered and their effects on the extent of damage can be quantified. The extent of damage due to collision can be obtained as results of the dynamic analysis. The predictions using the proposed method have been correlated with existing test results and then the reliability of the procedure has been substantiated. The characteristics of the dynamic response of tubulars under lateral impacts are compared for simply supported roller and fixed end conditions and their effects on the extent of damage are specfied.

• Computers and Concrete
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• 제26권1호
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• pp.95-106
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• 2020

Castellated beams fabricated from standard I-sections are being used for several structural applications such as commercial and industrial buildings, multistory buildings, warehouses and portal frames in view of numerous advantages. The advantages include enhanced moment of inertia, stiffness, flexural resistance, reduction in weight of structure, by passing the used plate girders, the passage of service through the web openings etc. In the present study, experimental and numerical investigations were carried out on concrete encased steel castellated beams with hexagonal openings under flexural loading. Various positions of openings such as along the neutral axis, above the neutral axis and below the neutral axis were considered for the study. From the experimental findings, it has been observed that the load-carrying capacity of the castellated beam with web opening above neutral axis is found to be higher compared to other configurations. Nonlinear finite element analysis was performed by using general purpose finite element software ABAQUS considering the material nonlinearities. Concrete damage plasticity model was employed to model the nonlinearity of concrete and elasto-plastic model for steel. It has been observed that FE model could able to capture the behaviour of concrete encased steel castellated beams and the predicted values are in good agreement with the corresponding experimental values.

• Steel and Composite Structures
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• 제30권4호
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• pp.365-382
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• 2019

In steel frame-tube structures (SFTSs) the application of flexural beam is not suitable for the beam with span-to-depth ratio lower than five because the plastic hinges at beam-ends can not be developed properly. This can lead to lower ductility and energy dissipation capacity of the SFTS. To address this problem, a replaceable shear link, acting as a ductile fuse at the mid length of deep beams, is proposed. SFTS with replaceable shear links (SFTS-RSLs) dissipate seismic energy through shear deformation of the link. In order to evaluate this proposal, buildings were designed to compare the seismic performance of SFTS-RSLs and SFTSs. Several sub-structures were selected from the design buildings and finite element models (FEMs) were established to study their hysteretic behavior. Static pushover and dynamic analyses were undertaken in comparing seismic performance of the FEMs for each building. The results indicated that the SFTS-RSL and SFTS had similar initial lateral stiffness. Compared with SFTS, SFTS-RSL had lower yield strength and maximum strength, but higher ductility and energy dissipation capacity. During earthquakes, SFTS-RSL had lower interstory drift, maximum base shear force and story shear force compared with the SFTS. Placing a shear link at the beam mid-span did not increase shear lag effects for the structure. The SFTS-RSL concentrates plasticity on the shear link. Other structural components remain elastic during seismic loading. It is expected that the SFTS-RSL will be a reliable dual resistant system. It offers the benefit of being able to repair the structure by replacing damaged shear links after earthquakes.

• 대한조선학회지
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• 제27권4호
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• pp.51-57
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• 1990

구조물을 용접할 시에는 열전도에 따른 온도 분포의 불균일에 의해 구조물에서 잔류 응력 및 변형이 발생되게 된다. 열전도에 따른 구조물의 거동을 기술하기 위해서는 열탄소성해석이 필요하게 되는데, 본 연구에서는 1차원 적층보 이론을 이용해서 보의 변형 및 잔류 응력을 계산하였다. 기존의 1차원 열탄소성 해석에서는 용접 길이가 무한해야만 성립하는 평형조건을 이용하고 있고, 경계 조건이 적절히 반영되지 못하는 제한성이 있었다. 그러나 증분 유한 요소법에 기초한 적층보 이론은 이런 제한성을 극복할 수 있다. 2차원 열탄소성 해석에서는 자유도의 증가에 따라 계산 시간이 방대해 지고, 변형 계산시에는 부정확성이 있는데에 비하여 적층보 해석에서는 2차원 해석과 같이 보 깊이 방향의 재료 성질 변화도 고려할 수 있고, 2차원 해석에 비해 자유도가 대폭 감소되었으며, 변형 계산에서도 실험치와 잘 부합되고 있다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 춘계학술발표대회 논문집
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• pp.53.1-56
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• 1999

The vibration behavior of glass-fabric reinforced plastic(GFRP) composite beams subjected to various transverse impacts has been investigated as a function of fiber orientation and void fraction. Theoretical results of resonant frequency damping coefficient and modal amplitude dispersion using the Euler-beam theory were obtained along with the finite element analysis which were compared with experimental ones Consequently it was shown that the transverse vibration characteristics were largely affected by fiber orientation and void fraction.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.867-872
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• 2000

A 1:12 scale 10-story RC building structure was constructed and the experiment was performed. The test results are presented and compared with the results of the analysis conducted with DRAIN-2DX. It is concluded that some local deformations cannot be described reasonably with the wall model using only Plastic Hinge Beam-Column Element(TYPE02) in DRAIN-2DX whereas the strength and stiffness of the whole structure can be predicted with high reliability.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.696-703
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• 2005

Recently, the collision problems between a bridge and a navigating ship are frequently issued at the stage of structure design. Even the many study results about vessel to vessel collision are presented, but the collision studies between vessel and bridge structure have been hardly presented. In this study, nonlinear dynamic analysis of vessel and fender system carry out using ABAQUS/Explicit commercial program with consideration of some parameters, such as bow structure we composed to shell element also ship's hull is modeling to beam element. Also, buoyancy effect is considered as spring element. The two types of fender systems was comparable with both collision analysis about steel materials fender system and rubber fender system On the purpose of study is analyzed the plasticity dissipated energy of vessel and fender system. We blow characteristic that kinetic energy is disappeared by plastic large deformation in case of collision. Also, We considered dissipated kinetic energy considering friction effect.

• 한국정밀공학회지
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• 제30권8호
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• pp.797-801
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• 2013

Today's automotive industry is evolving toward low-emissions or zero-emissions high-efficiency vehicles. Highly efficient power sources are required, as well as high strength steels for various parts to increase safety. In this study, we investigated the roll-forming process for the development of high strength, lightweight steel bumper beams. The roll-forming process was analyzed using the software package Shape-RF in combination with a rigid-plastic finite element method model. An optimal roll-forming process based on roll-pass was obtained using finite element method simulations.

• Steel and Composite Structures
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• 제15권6호
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• pp.679-703
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• 2013

This paper presents experimental investigations of the fundamental behavior of concrete filled steel tube (CFT) beam-columns under fire loading. A total of thirteen specimens were tested to determine the axial force-moment-curvature-temperature behavior of CFT beam-columns. The experimental approach involved the use of: (a) innovative heating and control equipment to apply thermal loading and (b) digital image correlation with close-range photogrammetry to measure the deformations (e.g., curvature) of the heated region. Each specimen was sequentially subjected to: (i) constant axial loading; (ii) thermal loading in the expected plastic hinge region following the ASTM E119 temperature-time T-t curve; and (iii) monotonically increasing flexural loading. The effects of various parameters on the strength and stiffness of CFT beam-columns were evaluated. The parameters considered were the steel tube width, width-tothickness ratio, concrete strength, maximum surface temperature of the steel tube, and the axial load level on the composite CFT section. The experimental results provide knowledge of the fundamental behavior of composite CFT beam-columns, and can be used to calibrate analytical models or macro finite element models developed for predicting behavior of CFT members and frames under fire loading.