• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.141-146
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• 2001

A post-tensioned steel plate girder bridge with cross-beams is analyzed by specially orthotropic laminate theory. The cross-sections of both girders and cross-beams are WF types. The result is compared with that of the beam theory. This bridge with simple support is under uniformly distributed vertical load, and axial loads and moment due to post-tension. In this paper, finite difference method for numerical analysis of simple supported bridge is developed. Relatively exact solution is obtained even with small number of meshes. Theory and analysis method of specially orthotropic laminate plates used in this paper can be used in design of new bridges, and maintenance and repair of old bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.718-723
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• 1998

The program which could determine cross-sectional dimension of the prestressed concrete box girder bridges at the stage of preliminary design was developed using the optimal technique in this study. It could minimize the cost required in the design of box girder bridges and the construction with the full staging method. Objective cost function consisted of six independent variables such as height of cross-section, jacking force and thickness of web and bottom flange. The SUMT(Sequntial Unconstrained minimization Technique) was used to solve the constrained nonlinear minimization optimal problem. Using the program developed in this study, optimum design was performed for existing bridges with one cell cross section of constant depth. The result verify the compatibility of the program.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.451-452
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• 2010

Prestressed concrete I girder bridge has been one of the most widely used bridges in the world because of its excellent construction feasibility, economic efficiency, serviceability, and safety. But in Korea, the PSC bridge has not been utilized for long span because of high girder height in its standard design. Thus, the results confirm that it is possible to applicate the continuous PSC girder with end cross beam anchorage system using multi-stage prestressing technique.

• Journal of Korean Society of Steel Construction
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• v.14 no.6
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• pp.691-699
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• 2002

A study on the evaluationof the proper spacing and required bending rigidity of cross beams in composite multiple I-girder bridge without lateral and sway bracing system was performed. For the purpose, a two-lane 40m simple span and 40+50+40m continuous sample bridge with four girders was designed. For the sample bridges, structural analysis under the design loads including dead load before and after composite, live load, and seismic loads has been performed. The material and geometric nonlinear analysis under dead load before composite has also been performed to evaluate lateral buckling strength of the steel-girder-cross beam grillage. Based on the two phase anlayses, proper spacing and bending righidity of cross beams were proposed.

• Journal of Korean Society of Steel Construction
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• v.18 no.2
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• pp.137-146
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• 2006

In this paper, a numerical study on the evaluation of the redundancy according to the dimension and spacing of cross beams in the composite twin steel plate girder bridges that are generally recognized as a non-redundant load path structures, has been performed. Specifically, a two-lane three-span continuous (40+50+40m) bridge with I-section cross beams which serve as cross bracing, and without a lateral bracing were considered. The material and geometric nonlinear analyses were conducted to evaluate the ultimate loading capacity of the intact and damaged bridge in which one of the two girders is seriously fractured. Through the numerical analyses, it was recognized that there is little difference in redundancy according to the variation of the dimension and spacing of the cross beams for both intact and damaged bridges.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.111-122
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• 1994

In this study, an algorithm which can be applied to the optimum design of simple steel plate girders was developed, and efficient optimization strategies for the solution of algorithm were found out. The optimum design algorithm consists of 3-levels of optimization. In the first and second levels of optimization, the absolute maximum bending moment and shearing force are extracted and in the third level of optimization, the optimum cross section of steel plate girder is determined. For the optimum design of cross section, the objective function is formulated as the total area of cross section and constraints are derived in consideration of the various stresses and the minimum dimension of flange and web based on the part of steel bridge in the Korea standard code of road bridge. Sequential unconstrained minimization technique using the exterior penalty function method(SUMT-EP), sequential linear programming(SLP) and sequential quadratic programming (SQP) are proved to be efficient and robust strategies for the optimum design of simple plate girder cross section. From the reliable point of view, SLP is the most efficient and robust strategy and SQP is the most efficient one from the viewpoint of converguency and computing time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.11-20
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• 1992

In general, the cross-section of a girder of a bridge has only one axis of symmetry. Therefore, lateral forces such as earthquake and wind may cause torsion coupled with lateral bending in the gider. This induces additional stresses especially in cables arranged in double-planes. Since this effect cannot be considered by using the conventional frame elements, the stiffness and the mass matrices of the geometrically nonlinear thin-walled frame element have to be used in order to model the girder. Theoretical development and verification of the frame element used in this study were made through a-previously presented paper. In this paper, seismic analysis of a three dimensional cable-stayed bridge considering the unsymmetry of the girder cross-section is performed to investigate the coupled flexural-torsional behaviors.

• Journal of the Korean Society for Railway
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• v.9 no.1 s.32
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• pp.102-109
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• 2006

The PSC girders which currently used at highway bridge have the standard cross sections about 25m, 30m and 35m span. Thus, in case of highway bridge design, the bridge designer can choose the adequate standard cross section according to constructional condition. However, in railway bridge design, there are limitations on reasonable bridge design considering circumstances of a construction site and conditions of location etc, because the PSC girders used at railway bridge have the cross section about only 25m span length. In this study, the optimum design for the PSC girder railway bridge with 30m span length has been performed. Also, in order to investigate the dynamic stability of railway bridge using the optimum section of PSC girder, dynamic analysis has been carried out. From the results of analysis, it is suggested to denote the optimum section which satisfied the structural safety, dynamic stability and economical efficiency all together.

• Journal of the Korean Society for Railway
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• v.8 no.1
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• pp.41-50
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• 2005

Steel -Concrete Composite two girder railway bridges applying high performance steel with extra thick plate have economic and aesthetic advantages due to the simplification of manufacturing and construction process. However, steel bridges are seldom adopted in domestic railway bridge, since steel bridges are not efficient as R.C bridges considering dynamic characteristics and noise, etc. While highway bridges do not have lower horizontal bracing and larger interval of diaphragm cross beam, railway bridges install lower horizontal bracings to control the torsion due to heavy eccentrical line load. Accurate finite element analysis were performed with the parameters of existence of bracing and bracing shape, with the cross beam interval and stiffness, etc. To find out the effects of secondary members such as horizontal bracings and diaphragms, static md dynamic analysis have been performed by using finite element method. In this study, few member plate-girder bridges are analyzed with variable span lengths to examine the dynamic behavior and limits of damping. And though lateral bracings are members against torsion, but lateral bracing's absence is no big problem. Time history analysis using mode superposition method makes proof of this result.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.3
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• pp.501-510
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• 2002

The middle diaphragm of box girder is to prevent the deformation of the cross section of box girder, to distribute load produced at upper flange onto the both sides of web. But if inner space of box girder is barred by the middle diaphragm, it is impossible to use in inner space of box girder and it is felt constraint on maintenance-management. The effect of middle diaphragm of box girder is intended to be expressed by the stiffness of diaphragm in comparing the diaphragm with opening of box girder with diaphragm without opening of box girder through the experiment.