• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1306-1311
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• 2006

Most of design parameters of Railway Structures are determined by the serviceability requirements, rather than the structural safety requirements. The serviceability requirements come from Ensuring of Running Safety and Ride Comfort of Train, Reduction of Track Maintenance Work Track-Bridge Interaction should be considered in the design of railway structures. In this study, a numerical method which precisely evaluate an axial force in rail and a rail expansion and contraction when turnout exist in succession on a CWR on a ballasted or on a ballastless track of bridge is developed. From the parameter studies using the developed method, additional stress of stock rail almost 25% is generated due to stock and lead rail interaction, even embankment not bridge. In case of ballasted track, additional stress of stock rail on bridge is very greater than on embankment, and therefore require detailed review in bridge design with turnout. Stresses of turnout rails on bridge are very sensitive according to the installed positions. In case of ballastless track, Stresses of turnout rails are similar as those of normal track

• Structural Engineering and Mechanics
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• v.70 no.6
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• pp.723-735
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• 2019

Track-bridge interaction (TBI) problem often arises from the adoption of modern continuously welded rails. Rail expansion devices (REDs) are generally required to release the intensive interaction between long-span bridges and tracks. In their necessity evaluations, the key techniques are the numerical models and methods for obtaining TBI responses. This paper thus aims to propose a preferable model and the associated procedure for TBI analysis to facilitate the designs of long-span bridges as well as the track structures. A novel friction-spring model was first developed to represent the longitudinal resistance features of fasteners with or without vertical wheel loadings, based on resistance experiments for three types of rail fasteners. This model was then utilized in the loading-history-based TBI analysis for an urban rail transit dwarf tower cable-stayed bridge installed with a RED at the middle. The finite element model of the long-span bridge for TBI analysis was established and updated by the bridge's measured natural frequencies. The additional rail stresses calculated from the TBI model under train loadings were compared with the measured ones. Overall agreements were observed between the measured and the computed results, showing that the proposed TBI model and analysis procedure can be used in further study.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.2
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• pp.169-177
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• 2016

Sliding slab track system, which consists of low friction sliding layer between track slab and bridge deck, is recently devised to reduce track-bridge interaction effect of continuously welded rail(CWR) without applying special devices such as rail expansion joint(REJ). In this study, a series of track-bridge interaction analyses of a long-span bridge with sliding slab track and REJ are performed respectively and the results are compared. The bridge model includes PSC box girder bridge with 9 continuous spans, and steel-concrete composite girder bridge with 2 continuous spans. The total length of the bridge model is 1,205m, and the maximum spacing between the two fixed supports is 825m. Analyses results showed that the sliding slab track system is highly effective on interaction reduction since lower rail additional axial stress is resulted than REJ application. Additionally, horizontal reaction forces in fixed supports were also reduced compared to the results of REJ application. However, higher slab axial forces were developed in the sliding slab track due to the temperature load. Therefore, track slab section of the sliding slab track system should be carefully designed against slab axial forces.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1875-1881
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• 2007

Deformations of bridge deck ends on abutments or on transition between bridge decks can cause extreme deformations on track. Especially, since slab track is fixed onto the bridge deck slab on concrete slab track-installed bridges, deformations of bridge deck ends directly affect the track behavior, and thus these interactions can bring about the premature failure of rail fastenings or other deteriorations to lower the serviceability. In this study, a foreign standard to evaluate forces on track components caused by the track-bridge interactions and the serviceability of bridge deck ends is investigated, and for the real bridges, the serviceability of bridge deck ends according to several parameters of bridge and track is analyzed. It is found that arrangements and spring coefficients of bridge bearings, as well as distance between bridge bearing and last rail support, support spacings, rail support spring coefficient, are very important parameters.

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.145-151
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• 2018

In this study, the track-bridge interaction analysis was performed using an analytical model considering the track structure, thereby taking into account the linear conditions (R=650 m, cant variation $160{\pm}60mm$) and the dynamic characteristics of the bridge. As a result of the study, the allowable speed on the example bridge considered was calculated at 200 km/h based on vertical deflection, vertical acceleration, and irregularity in longitudinal level, but was also evaluated at 170km/h based on the coefficient of derailment, wheel load reduction, and lateral displacement of the rail head. It is considered desirable to set the speed 170km/h to the speed limit in order to secure the safety of both the bridge and the track. It is judged that there will be no problems with ensuring rail protection and train stability in the speed band.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.807-813
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• 2015

The CWR(Continuous Welded Rail) on a bridge shows complex structural behavior compared to those on the roadbed. The influence factors on the track-bridge interaction are the variation of temperature and vehicle load. The analysis methods for track-bridge interaction, material property, modeling method, loads and combination method are indicated in the domestic railway design principle, KR C-08080. The vehicle load in KR C-08080 was changed in 2014. In this study, to evaluate the effect of the changed vehicle load on the track-bridge interaction, the track-bridge interaction analyses were performed for 22 bridges by using finite element method.

• 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.

• Structural Engineering and Mechanics
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• v.63 no.6
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• pp.713-723
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• 2017

As a new type of ballastless track, longitudinal continuous slab track (CST) has been widely used in China. It can partly isolate the interaction between the ballastless track and the bridge and thus the rail expansion device would be unnecessary. Compared with the traditional track, CST is composed of multi layers of continuous structures and various connecting components. In order to investigate the performance of CST on a long-span bridge, the spatial finite element model considering each layer of the CST structure, connecting components, bridge, and subgrade is established and verified according to the theory of beam-rail interaction. The nonlinear resistance of materials between multilayer track structures is measured by experiments, while the temperature gradients of the bridge and CST are based on the long-term measured data. This study compares the force distribution rules of ballasted track and CST as respectively applied to a long span bridge. The effects of different damage conditions on CST structures are also discussed. The results show that the additional rail stress is small and the CST structure has a high safety factor under the measured temperature load. The rail expansion device can be cancelled when CST is adopted on the long span bridge. Beam end rotation caused by temperature gradient and vertical load will have a significant effect on the rail stress of CST. The additional flexure stress should be considered with the additional expansion stress simultaneously when the rail stress of CST requires to be checked. Both the maximum sliding friction coefficient of sliding layer and cracking condition of concrete plate should be considered to decide the arrangement of connecting components and the ultimate expansion span of the bridge when adopting CST.

• 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 Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7870-7877
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• 2015

In the case of CWR (Continuous welded rail) located on the railway bridge, the CWR has additional axial force due to interaction of bridge and track. Therefore, the CWR tracks located on the bridge have to secure the safety of running train and CWR track through mitigating influence for interaction of bridge and track. The railway design guide in Korea (KR C-08080) provides a certain value for property of longitudinal friction behavior of rail fastening system that is major parameter of interaction behavior by applying European codes. However, in order to apply to domestic railway, it is necessary to review property characteristics of the rail fastening system in actual use. In this paper, the experiment for longitudinal friction behavior of rail fastener applied to concrete track on the railway bridge in Korea was carried out, and statistical characteristic for property of the rail fastener was analyzed from the result of the experiment.