• Journal of Korean Society of Steel Construction
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• v.17 no.3 s.76
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• pp.295-306
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• 2005

In this study, the dynamic characteristics of the two open-steel-plate-girder bridges was analyzed using the pads' stiffness estimated in the previous accompanying paper.Also, it was determined that the variation in the dynamic behavior of the two bridges due to the pads corresponds to the codes describing the restriction for the steel bridges' behavior.The pads installed at the bridges increase the displacement at mid-span.However, the increase does not exceed code restrictions and does not have an adverse effect on the riding quality of the running trains. The natural and Chloroprene rubber pads are not suitable for bridge bearings since they are more deformed than the code regulated ones.

• Journal of Korean Society of Steel Construction
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• v.13 no.1
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• pp.41-52
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• 2001

In this paper the analysis of laminate composite folded plates with arbitrary angle connection like box girder is studied by finite strip method Total stiffness of laminated plate is obtained by integration of the stiffness in each layer or lamina through laminate thickness and total stiffness in each layer or lamina through laminate thickness and total tiffness matrix is obtained by substitutionto equilibrium equation derived from the minimum total potential energy theorem. The assumed displacement functions for a finite strip method in plate or box girder analysis are combinations of one-way polynomial functions in the transverse direction and harmonic functions in the span-wise direction. Finite strip method with the merits of the simplification in modeling and the reduction of analytical time is accurate in the analysis of laminate composite folded plates shaped like box firders.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.2
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• pp.187-193
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• 2023

This paper presents the buckling behavior of a pile considering its self-weight. The differential equation and boundary conditions governing the buckling of partially embedded piles in nonhomogeneous soils are derived. The buckling load and mode shape of the pile are numerically computed by the Runge-Kutta method combined with the Regula-Falsi algorithm. The obtained numerical solutions for bucking loads agree well with the results available from the literature. Numerical examples are given to analyze the buckling load and mode shape of the piles as affected by the self-weight, embedment ratio, slenderness ratio and boundary condition of the pile as well as the aspect ratio and rigidity ratio of the subgrade reaction. It is found that the self-weight of the pile leads to the reduction of the buckling load, indicating that neglecting the effect of self-weight may overestimate the buckling load of partially embedded piles.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.175-183
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• 2004

The most important element is a rise ratio when regarding beauty and economics of arch bridges. Only the effect of dead load has been considered to decide the rise ratio. In this study, when going over the rise ratio of arch bridges, examined the problems, that the determination of the rise ratio by the dead load has, by adding the factor of a determination of optimum rise ratio, which is not only the effect of the dead load that has been currently considered but also the problem with respect to dynamic stability that is now taken seriously. Synthetically, when deciding rise ratio that is investigated in basic step of design, it is necessary to consider the evaluation dynamic stability.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.343-350
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• 2017

The RC flat plate system has benefits such as a short construction time, an improvement of workability and a floor height reduction. In the case of long span slab, cracking damages and large deflections tend to occur due to the low flexural stiffness of flat plates. Specially, over-loading by self-weight of slab during construction increases short and long-term deflections. These problems may be solved by the use of void slab that has benefits of the reduced self-weight. In this study, to analyze an effect of self-weight reduction of void slab on slab deflections, the parametric study is performed. Including variable conditions such as a concrete strength, a slab construction cycle, the number of shored floors, a compressive reinforcement ratio and a tensile reinforcement ratio, slab construction loads and deflections are calculated by considering the construction stages, concrete cracking, and long-term effects. The short-term deflections during construction and the long-term deflections after construction of both of normal and void slabs are compared and the effects of void slab on the reduction of slab deflections are analyzed.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.32.5-33
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• 2009

카네기 천문대에서 주도하여 개발 중인 구경 25.4m GMT 망원경 사업에 한국도 공식적으로 참여하였다. 현재 한국천문연구원은 GMT(Giant Magellan Telescope)부경부를 국내에서 개발하고자 이와 관련된 연구를 진행하고 있다. GMT 부경은 직경 1.06m 오목거울 7장이 모여 전체 직경 3.2m인 타원면을 형성하고 초점비는 F/0.7이다. GMT 부경개발 선행 연구과제로 카네기 천문대에서 개발되어 현재 운용중인 구경 6.5m 마젤란 망원경의 부경을 선택하였는데, 이는 마젤란 부경의 형상과 직경, 부경시스템 운영방식이 GMT 와 유사하기 때문이다. 천체관측 망원경에서 거울면의 변형에 가장 큰 영향을 미치는 인자는 거울의 자중이다. 거울의 직경이 커지면 자중이 증가하게 되어 거울면의 처짐이 커지게 된다. 이를 극복하고자 다양한 거울 support들이 개발되었다. 그중에서 counterweight lever 시스템 같은 부양(float) 시스템은 자중의 영향을 보상해 줌으로써 그것에 의한 거울의 변형을 최소화하는 역할을 하는데, GMT 부경 개발에 근간이 되는 마젤란 부경 또한 부양 시스템을 도입하였다. 마젤란 부경의 부양시스템은 counterweight lever 시스템과 유사한 진공 시스템을 도입하였다. 마젤란 부경의 support는 axial 방향으로 거울을 지지하는 axial support와 lateral 방향으로 거울을 지지하는 lateral support가 있는데, 이중에서 axial support가 진공시스템으로 구성된다. Lateral 방향의 지지는 경량화된 거울의 hole 안에 3개의 판스프링을 삽입하여 단지 거울과 판스링의 강성에 의해서만 이루어진다. 이 논문에서는 망원경이 작동을 할때 즉, 천정각(zenith angle)이 변할 때 axial support와 lateral support의 조합(combination)에 의해 지지되는 마젤란 부경의 표면 정밀도 RMS 값을 비교하였다.

• Journal of Korean Society of Steel Construction
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• v.23 no.6
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• pp.691-704
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• 2011

This paper presents an investigation on the ultimate behavior of steel cable-stayed bridges in the construction stage, considering various geometric nonlinearities and material nonlinearities. To numerically determine the state of cable-stayed bridges in the construction stage, initial shape analysis and construction stage analysis via backward process analysis were done sequentially. Then nonlinear analysis of the state under the construction load condition, considering the weight of the derrick crane and the key segment of the girder loaded onto the tip of the center span, was performed to investigate the ultimate behavior of the structure. The effects of the girder-mast stiffness ratio, the cable-arrangement types, and the area of the stay cables on the ultimate behavior were also extensively investigated. Moreover, the results of the ultimate analysis, considering both geometric nonlinearities and material nonlinearities, were compared with the results of the geometric nonlinear analysis, for a more meaningful investigation of the ultimate behavior of steel cable-stayed bridges in the construction stage.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.4
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• pp.231-237
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• 1999

A geometric non-linear finite element formulation of spatial ocean cable under currents is presented using multiple noded curved cable elements. Tangent stiffness and mass matrices for the isoparametric cable ele¬ment are derived and the initial equilibrium state of ocean cable subjected to self-weights, buoyancy, and current as well as support motions is determined using the load incremental method. Free vibration analysis of ocean cables is performed based on the initial equilibrium configuration. Numerical examples are presented and discussed in order to demonstrate the feasibility of the present finite element method and investigate dynamic characteristics of ocean cables.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.441-444
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• 2010

대공간 구조물과 초고층 빌딩에 있어 건축물의 자중 감소에 대한 요구가 늘어나고 있으며 이에 대한 가장 효과적인 방법 중 하나는 경량 콘크리트를 사용하는 것이다. 본 연구는 최외단 철근의 순인장 변형률에 따른 경량콘크리트 보의 휨 거동 및 휨 성능을 평가하는 것에 그 목적이 있다. 크기와 형상이 동일한 보통중량 콘크리트 보 1개와 경량 콘크리트 보 4개의 총 5개 시험체를 제작하여 최외단 철근의 순인장 변형률을 변수로 실험을 수행하였으며 이를 통해 순인장 변형률에 따른 경량콘크리트 보의 강도와 연성의 변화를 분석하였다. 실험 결과 최외단 철근의 순인장 변형률이 증가할수록 시험체의 연성비는 증가하였으며 최대하중과 강성은 감소하였다. 특히 순인장 변형률 0.005 이상에서 연성지수 2 이상을 확보할 수 있었다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.4
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• pp.173-188
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• 1999

Kim et al.(I999) presented a non-linear finite element formulation of spatial ocean cables using multiple noded cable elements. The initial equilibrium state of ocean cables subjected to self-weights, support motions, and current forces was determined using the load incremental method and free vibration analysis were performed considering added mass, In this paper, the methods to generate regular and irregular waves and calculate wave forces due to these waves are discussed and challenging example problems are presented in order to investigate dynamic non-linear behaviors of ocean cables subjected to wave loadings.