• Title/Summary/Keyword: continuous slab track

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Analysis of Slab Joint Opening Due to Temperature Drop in Continuous Precast Concrete Slab Track (연속 프리캐스트 콘크리트 슬래브궤도에서의 온도하강에 따른 슬래브 이음매 개구량 해석)

  • Jang, Seung-Yup;Lee, Jeong-Wan
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.1659-1663
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    • 2011
  • Precast concrete slab track is a track structure to be installed by transporting and assembling precast concrete slabs manufactured at the factory. This method can improve concrete quality, provide easy maintenance and reduce construction time, compared with in-situ concrete track. However, the concrete slabs being continuously connected in longitudinal direction, due to the temperature change between summer and winter, the openings at slab joints have occurred. Thus, in this study, to identify the cause of this opening of slab joint, the joint opening caused by temperature drop in the longitudinally continuous precast concrete slab track has been predicted using three-dimensional finite element analysis, and compared with field measurements. Based on the proven model, the slab joint opening, and the stress pattern of concrete slab and steel reinforcement according to concrete slab-base friction properties, concrete-reinforcement bond properties, and prestressing were analyzed.

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Evaluation of Stress Reduction of Continuous Welded Rail of Sliding Slab Track from Track-Bridge Interaction Analysis (궤도-교량 상호작용 해석에 의한 슬라이딩 슬래브 궤도의 장대레일 응력 저감 효과 분석)

  • Lee, Kyoung Chan;Jang, Seung Yup;Jung, Dong-Ki;Byun, Hyung-Kyoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.35 no.5
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    • pp.1179-1189
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    • 2015
  • Continuous welded rail on bridge structure experiences typically a large amount of additional longitudinal axial forces due to longitudinal track-bridge interaction under temperature and traction/braking load effect. In order to reduce the additional axial forces, special type of fastener, such as ZLR and RLR or rail expansion joint should be applied. Sliding slab track system is known to reduce the effect of track-bridge interaction by the application of a sliding layer between slab track and bridge structure. This study presents track-bridge interaction analysis results of the sliding slab track and compares them with conventional fixed slab track on bridges. The result shows that the sliding slab track can significantly reduce the additional axil forces of the continuously welded rail, and the difference is more significant for long and continuous span bridge.

Development of Evaluation Method of Vibration-Reduction Efficiency in Slab Track (슬래브궤도의 방진효율성 평가기법 개발)

  • 양신추;강윤석;김만철;이종득
    • Proceedings of the KSR Conference
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    • 1999.11a
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    • pp.463-470
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    • 1999
  • In this paper, a numerical method for evaluating the efficiency of vibration reduction of substructure under slab track is developed for optimal design of floating slab track. The equation of motion for train and track interaction system is derived by applying compatibility condition at the contact points between wheels and rails. The train is modelled by 3-masses system and the track by continuous support beam system. Numerical analyses are carried out to investigate the effect of train speed, stiffness and damping of slab-pad, and track irregularity upon vibration reduction in substructure under the track.

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3- D Analysis of Concrete Slab Track System (콘크리트 슬래브 궤도의 3차원 거동해석)

  • Kim, Jeong-Il;Jang, Seung-Yup
    • Proceedings of the KSR Conference
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    • 2004.06a
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    • pp.955-960
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    • 2004
  • In this study, three dimensional FE analysis of concrete slab track has been performed in order to develop the realistic design of precast concrete slab track. The precast slab track system including the precast concrete slab panel and the grout layer is modeled using the three dimensional solid element with crack softening effect. The input load is computed from the one dimensional beam element model constituting the rail and several discrete springs. To investigate the effect of the longitudinal connection of slab panels, two different systems-continuous and discrete systems - are modeled. The analytical results show that the stresses of both the slab panel and the grout layer are in the range of linear elastic, and, at the interface between two adjacent panels, the primary stresses of the grout layer of the discrete system are higher than those of the continuous system. However, The overall stress levels of the grout layer are very low relative to the strength of th grout.

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A comprehensively overall track-bridge interaction study on multi-span simply supported beam bridges with longitudinal continuous ballastless slab track

  • Su, Miao;Yang, Yiyun;Pan, Rensheng
    • Structural Engineering and Mechanics
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    • v.78 no.2
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    • pp.163-174
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    • 2021
  • Track-bridge interaction has become an essential part in the design of bridges and rails in terms of modern railways. As a unique ballastless slab track, the longitudinal continuous slab track (LCST) or referred to as the China railway track system Type-II (CRTS II) slab track, demonstrates a complex force mechanism. Therefore, a comprehensive track-bridge interaction study between multi-span simply supported beam bridges and the LCST is presented in this work. In specific, we have developed an integrated finite element model to investigate the overall interaction effects of the LCST-bridge system subjected to the actions of temperature changes, traffic loads, and braking forces. In that place, the deformation patterns of the track and bridge, and the distributions of longitudinal forces and the interfacial shear stress are studied. Our results show that the additional rail stress has been reduced under various loads and the rail's deformation has become much smoother after the transition of the two continuous structural layers of the LCST. However, the influence of the temperature difference of bridges is significant and cannot be ignored as this action can bend the bridge like the traffic load. The uniform temperature change causes the tensile stress of the concrete track structure and further induce cracks in them. Additionally, the influences of the friction coefficient of the sliding layer and the interfacial bond characteristics on the LCST's performance are discussed. The systematic study presented in this work may have some potential impacts on the understanding of the overall mechanical behavior of the LCST-bridge system.

Interaction analysis of Continuous Slab Track (CST) on long-span continuous high-speed rail bridges

  • Dai, Gonglian;Ge, Hao;Liu, Wenshuo;Chen, Y. Frank
    • 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.

Vibration Analysis Method for Railway Structure with Floating Slab (방진궤도가 부설된 역사의 진동해석 기법)

  • 양신추;김태욱;강윤석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.561-566
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    • 2003
  • In this paper, a numerical method for evaluating the efficiency of vibration reduction of substructure under floating slab track is developed for optimal design of floating slab track. The equation of motion for train and track interaction system is derived by applying compatibility condition at the contact points between wheels and rails. The train is modelled by 3-masses system and the track by continuous support beam system. Numerical analyses are carried out to investigate the effects of train speed, stiffness and damping of slab-pad, and track irregularity upon vibration reduction in substructure under the track.

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Comparative Analysis of Track-Bridge Interaction of Sliding Slab Track and Rail Expansion Joint for Long-Span Railway Bridge (장경간 철도 교량에 적용된 슬라이딩 궤도와 레일신축이음장치의 궤도-교량 상호작용 비교)

  • Lee, Kyoung Chan;Jang, Seung Yup;Lee, Jungwhee;Choi, Hyun Sung
    • 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.

A Parametric Study on the Serviceability of Concrete Slab Track on Railway Bridges (철도교 콘크리트 슬래브궤도의 사용성에 관한 매개변수 영향 연구)

  • Park, Hong-Kee;Jang, Seung-Yup;Yang, Sin-Chu;Park, Yong-Gul
    • Journal of the Korean Society for Railway
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    • v.12 no.1
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    • pp.95-103
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    • 2009
  • Deformations of bridge deck ends on abutments and piers bring about severe problems in track geometry and require maintenance work. In case of concrete slab track, more severe deformation and additional forces on rail and rail supports can be induced by bridge deck deformation, which affect the serviceability of track structure since concrete slab track is much stiffer than ballasted track and the behavior of track structure is integrated with that of bridge deck. In this study, the design variables affecting the serviceability of track structure are selected and the influence level is estimated by a parametric study. As a result, it is found that continuous span is advantageous than simply supported span and the stiffness of bridge bearing and rail fastener as well as the distance between last rail support and bridge bearing are most important parameters.

Parametric analysis on Deformation of Sharp Curved Ballasted Track (급곡선 자갈궤도의 궤도변형에 관한 매개변수 해석)

  • Choi, Jung-Youl;Kim, Jun-Hyung;Son, Gab-Soo;Kim, Sang-Jin
    • 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.