• Proceedings of the KSR Conference
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• 2003.10b
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• pp.385-390
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• 2003

Recently, use of Continuous Welded rail(CWR) is increased for structural, economical reason but new problem is caused accordingly and phenomenon that give threat in traveling by ship stability of train is led. According as rail is prolonged, excessive relative displacement and longitudinal force can happen to rail by temperature change and external force. Specially, buckling or fracture of rail can happen in railroad bridges because relative displacement by bridge and properties of matter difference between rail grows and additional axial force happens to rail by behavior of bridge. According to several study, longitudinal force of rail in bridge is influenced with ballast resistance, elongation length, boundary condition, stiffness of framework. Non-linear behavior of ballast acts by the most important factor in interaction between rail and bridge. Therefore, must consider stiffness of bridge construction with non-linear characteristic of ballast and stiffness of base for accuracy with longitudinal force calculation and analyze. In this study, perform material non-linear analysis for longitudinal force of CWR and three dimensional buckling analysis to decide buckling force.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.376-381
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• 2005

This paper presents the rail structure interaction analysis of the elevated viaducts which contains the curved alignments with smallest radius of 300 metre. The aim of this study is to check the compatibility between the track and the curved structure in order to verify the safety of the continuous welded rail track under service conditions. To perform the rail structure interaction analysis, nonlinear static rail structure interaction calculation is implemented. The bridge structures, the rails and the track behaviour are modelled according to the UIC774-3 and the Eurocode prEN1991-2 recommendations. Criteria in Eurocode prEN1991-2 are investigated to check the compatibility between the track and the structure for the rail structure interaction effects.

• Journal of the Korean Society of Safety
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• v.32 no.4
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• pp.28-33
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• 2017

A sharp curved ballasted track on earthwork that was connected with a direct fixation slab track on steel box railway bridges have been deformed and damaged despite the frequently maintenance by a restoring force of sharp curved rail and track-bridge interaction forces such as axial forces and longitudinal displacement of continuous welded rail(CWR) owing to their structural characteristics, calling for alternatives to improve the structural safety and track irregularity. In this study, the authors aim to prove a cause of deformation for the sharp curved ballasted tracks to enhance the structural safety and track irregularity of ballasted track in service. A track-bridge interaction analysis and a finite-element method analysis for the sharp curved ballasted track were performed to consider the axial force and longitudinal displacement of CWR, the temperature and the effect of restoring force of sharp curved rail. From the results, the deformation of the sharp curved ballasted track with adjusted sleeper spacing from 833mm to 590mm were significantly reduced.

• Journal of the Korean Society for Railway
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• v.19 no.5
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• pp.638-646
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• 2016

CWR (continuous welded rail) tracks on high-speed railway bridges have much more complicated axial force distributions caused by track-bridge interaction than those behaviors on embankments, and additional problems caused by track-structure interaction with the axial force of the CWR. In order to analyze and limit other physical phenomena caused by track-bridge interaction, a design guideline (KR C-08080, longitudinal track-bridge interaction analysis) is used when designing CWR track on bridges. Domestic analysis and design methods for track-bridge interaction follow the UIC 774-3R, and they suggest conservative methods and deterministic properties. Recently, many studies analyzing the methods of track-bridge interaction considering the loading history are being carried out; however, there has been insufficient studies of the variation of the resistance properties with a consideration of the actual loading history. In this study, the performances of rail fastening systems used for concrete track on bridges were tested and analyzed while considering the loading history. For this purpose, longitudinal and vertical loading combinations, applied in order to simulate the practical conditions and resistance characteristics (stiffness and elastic limit displacement), are analyzed through the experimental results. Also, a comparison study was conducted with the properties in the KR Code.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.27-34
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• 2010

Recently, high-speed railway systems have gained increased interest as a means of environmental friendly transportation, and numerous bridges for high-speed railways have been constructed accordingly. However, bridge design for high-speed railways requires more consideration than conventional railway design because fast-moving trains will lead to significant impact on bridge structures. Thus, this research proposes a revised design considering both bridge-rail longitudinal interaction and dynamic effect of trains to ensure stability of fast travelling trains. To validate the proposed design algorithm, numerical analyses are performed and compared using a constructed 250 m long bridge with 5 spans for a high-speed railway. From the numerical results, the proposed optimum design of high-speed railway bridges exhibits the most economic life-cycle-cost (LCC) when compared with several existing design approaches.

• Journal of the Korean Society for Railway
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• v.17 no.4
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• pp.245-250
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• 2014

This paper, as a study for the serviceability design of railway bridges with concrete track, presents the effects of design parameters of tracks and bridges on the forces acting on the rail supports of the track. To calculate the forces acting on the track, an unequal spacing discrete supported model with different spacing of rail supports was induced. Design parameters are the rail support spacing of expansion joints above abutments or piers of bridges, the distance from the support of a girder to the last rail support on the end of the girder, and the number of additional rail supports. The causes of the displacement of track are axial force, unit vertical displacement, and unit rotation. From the analysis, the maximum compressive force and the maximum uplifting force acting on the rail supports were determined and the effects of the rail support spacing on the forces acting on the track were presented.

• International journal of steel structures
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• v.18 no.5
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• pp.1617-1630
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• 2018

The crucial differences between conventional rail with split-type connectors and continuous welded rails are axial stress in the longitudinal direction and stability, as well as other issues generated under the influence of loading effects. Longitudinal stresses generated in continuously welded rails on railway bridges are strongly influenced by the nonlinear behavior of the supporting system comprising sleepers and ballasts. Thus, the track structure interaction cannot be neglected. The rail-support system mentioned above has properties of non-uniform material distribution and uncertainty of construction quality. The linear elastic hypothesis therefore cannot correctly evaluate the stress distribution within the rails. The aim of this study is to apply the nonlinear finite element method using the nonlinear coupling interface between the track and structural model and to illustrate the welded rail behavior under the loading effect and uncertain factors of the ballast. Numerical results of nonlinear finite analysis with a three-dimensional solid and frame element model are presented for a typical track-bridge system. A composite plate girder, modeled by solid and shell elements, is also analyzed to consider the behavior of the welded rail. The analysis result showed buckling under the independent calculations of load cases, including 'temperature change', 'bending of the supporting structure', and 'braking' of the railway vehicle. A parametric study of the load combination method and the loading sequence is also included in this analysis.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.31-38
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• 2010

In this study, it is suggested that it has to reliability-based design methodology with respect to bridge structure-rail longitudinal interaction and bridge structure-vehicle interaction. For the structural analysis, commercial package, ABAQUS, are used for a three-dimensional finite element analysis. The optimization process utilizes a well-known optimizer, ADS(Automated Design Synthesis). Optimization technique is utilized the ALM-BFGS method for global area search and Golden Section Method for 1-D search. In general, ALM-BFGS method don't need the 1-D search, and that algorithm converge a 0.1~0.2 of Push-Off factor. But in this study, value of Push-Off factor is used 90, therefore 1-D search should be needed for effective convergency. That algorithm contains the "heuristic decision method". As a result of optimum design of 2-main steel girder birdge with 5${\times}$(1@50m), design methodology suggested in this study was demonstrated more economic and efficient than existing design and LCC optimization not considering bridge-rail longitudinal interaction and bridge-vehicle interaction.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.117-122
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• 2003

Cheongdam Bridge in Seoul Metropolitan Subway Line No.7 recently constructed has 180 meters (2@90m) of expansion length of structure (distance between fixed points). Track type is all ballasted track and rail expansion joint is installed at every movable point. However, there is no expansion joint at the transition area between ballasted track ,end deck. By this reason, the rail buckling has been occurred every year and there is actually an abnormal behavior in expansion. In this study, based on the modeling of the Cheongdam Bridge, the element of interacting relationship between track and structure which is influential to track displacement in long-span bridge was analyzed and, finally, the methodology to ensure the continuous-welded rail in Cheongdam Bridge was suggested.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.9
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• pp.620-627
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• 2015

Long continuous bridge deck can become contracted considerably as temperature drops, which can lead to a large expansion of sleeper span at the end of it. Since this huge sleeper span then can cause problems both with safety of train operation and structural stability of tracks, it is necessary to take the issue into consideration systematically in the designing process of the bridge. In this paper, an evaluation process through the analysis of train-track interaction was presented which can basically review the effects of the expansion of sleeper span at the end of long continuous bridge deck on the safety of the train and the structural stability of the track. The analyses of the interaction between the light rail train and tracks were carried out targeting the sleeper span as a main parameter. The safety of train operation and structural stability of tracks in a light rail system due to the expansion of the sleeper span were evaluated by comparing the numerical results with the related criteria.