• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.569-577
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• 2012

In this study, a theoretical investigation of optimized sleeper spacing which can suppress resonances of a railway track is attempted. To achieve this, we introduced a minimization problem in which the objective function is given by the wave transmittance and the design variable is defined by sleeper distribution. In the analysis the rail is modeled by a Timoshenko beam and the sleeper is represented by a mass. The infinite track analysis is realized by attaching the transmitting boundaries at both ends of the finite optimization region. Through numerical analyses the sleeper spacing effective in reduction of the transmittance is discussed. Furthermore, the feasibility of the proposed method is validated in the aspect of vibration reduction through response analyses for a harmonic load.

• 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.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.214-221
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• 2010

The transitional zone between tunnel and earthwork is one of the most vulnerable areas site for railway lines and because of differential settlement due to different stiffness of each supporting layer, it has to conducted a maintenance work constantly. In this study, it is conducted to compare the effect of reinforcement by wheel load and displacement of the sleepers after existing sleepers are replaced with the large sleepers for 20m long in-field transitional zone. Also, numerical parametric study using multi-layer elastic method has been performed to compare rail force, settlement and stresses of ballast while varying size and space of the sleeper. The field test and numerical results show that replacing the large sleepers improves about 10% of total settlement and coefficient of wheel force than conventional sleepers. Effectiveness of improvement is about 9.3%, 4%, 14.5% for rail seat force, settlement of sleepers and ballast pressure respectively with size of sleepers.

• Journal of the Korean Society for Railway
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• v.13 no.6
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• pp.565-569
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• 2010

Sleepers perform bearing rails and are underneath rails. Therefore, the current and voltage of rails are related to the resistance of sleepers. In case that the resistance of sleepers are low, operation problems of relays in tr ack circuits are occur because of flowing leakage current through sleepers. So the condition that the track circuit is always occupied by a train is kept. Currently, the creosote has been used in wood sleepers due to prevention against putrefaction. After a long time, the material is changeable to the chemistry material bases on carbon dioxide or carbon. So, the insulation resistance of wood sleepers is lower than the initial insulation resistance. In case of effecting wood sleepers as conductors, amplitude of the current and voltage on rails is decreased. This phenomenon causes that a train does not receive signals. In this paper, four-network model on the track circuit including the insulation resistance of sleepers is suggested. Also, the standard value of the resistance in straight section is proposed in the wood sleeper.

• Journal of the Korean Society for Railway
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• v.5 no.3
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• pp.10-14
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• 2002

2 열의 레일을 침목에 일정한 간격으로 고정한다고 하는 궤도의 구조는 철도의 발상 직후부터 현재에 이르기까지 기본적으로 변하지 않고 있다. 궤도는 옥외에 건설되는 장대한 선형 모양의 구조물이며 자연의 영향을 항상 받아 때로는 재해를 받아 파손되는 것도 피할 수 없는 점에서 취약하게 보이지만, 극히 유연성이 높은 궤도구조가 채용되어왔다고 하는 사정이 있다. 그러나, 대형화, 고속화, 고밀도화 등 차량의 운전 성능 향상에 따라 궤도는 그 기능을 점차 향상시켜 왔다. (중략)

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.725-732
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• 2011

The vibration resulting from railway operation is transmitted through the tunnel to adjacent buildings and the transmitted vibration radiates structure-borne noise which is causing a lot of public complaints by its negative effects to the buildings near tunnel. This study performed the parametric study about sleeper space and track support stiffness in order to reduce vibration on the concrete track and near structures. In this study, it was compared and performed vibration analysis and field test about these. In addition, as changing the sleeper space and track support stiffness, vibration of the structures was evaluated. Via this study, in terms of reducing the figure of the sleeper space and track support stiffness to the half, as vibrating acceleration transmitted through concrete round is getting reduced, it transmitted through the tunnel was analysed to the same phenomena. In conclusion, suggested track structure into this study, it can be applied to the track structure of existing line, and it is expected to be a new effective anti-vibration method to prevent public complaints.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1248-1253
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• 2011

It is increasing construction of long span railway bridge with concrete track system for speed up of railway and efficient maintenance of track. As the sleeper of the concrete track system layed on a bridge is fixed on deck of the bridge, the displacement of the sleeper and deck is same. Therefore, the spacing between two sleeper installed at the end of the adjacent deck near the expansion joint of bridge becomes vary according to the longitudinal expansion of a deck by temperature change. By the way, if the spacing of sleepers become increase excessively, it causes large bending stress of in a rail, and it can leads failure or reduction of fatigue life of the rail. Further more, the excessive displacement of the rail may induce decrease ride comfort as well as corrugation of rail surface. Therefore, it is required to determine the allowable maximum sleeper spacing to prevent such problems. For the purpose, investigation on the influence factor on sleeper spacing for straight track was carried out. Variation of bending moment in a rail, wheel force, and the ratio of primary and secondary deflection of the rail according to sleeper spacing was investigated, and, as a result, the maximum allowable sleeper spacing at the bridge expansion joint was suggested.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.2
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• pp.40-45
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• 2015

The load of a maglev train, which is being considered a future transportation, is uniformly loaded on a levitated surface of a rail unlike a typical train because the maglev train is magnetically levitated and propelled. In addition, the driving performance is superior since the maglev train doesn't directly contact the railway. A integrated track system, to which a sleeper is installed toward a longitudinal direction instead of a perpendicular direction, is suggested, considering this loading characteristic. The longitudinal sleeper of this system is expected to contribute to stiffness increase of a bridge and weight-reduction of a girder. In this study, the structural characteristics of proposed and typical systems have been numerically compared and analyzed. In addition, the improvement of the integrated system has been proposed.

• Journal of the Korean Society for Railway
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• v.12 no.3
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• pp.396-404
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• 2009

With developing the next generation high speed railway, there need to be plans to make sure of running safety though researchs on the crack and break of rail by rolling contact fatigue. Therefore, this study performed the parametric analysis effecting on the fatigue life of rail using simplified equations. It analyzed the internal stress of rail according to the track quality, train velocity, wheel radius, track stiffness, sleeper space, wheel load. For the more, via the finite element method, it analyzed shear force on the rail head which could be changed by the early length of crack, angle of crack and temperature. As a result, this study continued the main parameter effecting on the fatigue life of rail.

• Journal of the Korean Society for Railway
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• v.9 no.1 s.32
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• pp.125-130
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• 2006

고속철도 교량구간에 차량(KTS)이 주행할 경우 교량 바닥판에서는 큰 가속도 응답이 계측된다. 이러한 가속도의 원인으로는 큰 단면의 국부 진동, 일정한 간격의 침목의 충격 그리고 차량 자체의 진동 등 여러 가지 원인이 있다. BRDM(Bridge Design manual)에서는 이러한 동적 특성치들에 대한 제한치를 규정하고 있는데, 가속도인 경우는 0.35G이하고 규정하고 있다. 실교량 실험에 의해 계측된 가속도 응답은 규정한 제한치인 0.35G 보다는 작지만, 이러한 가속도 응답치들은 차량이 고속으로 주행할 경우 안전성에 문제를 일으킬 수 있다. 본 논문에서는 큰 단면에서 과도한 국부 진동을 지배하는 가속도 응답을 줄이기 위해서 진동저감 방법을 연구하였다. 비록 휨이나 비틀림 같은 전체 진동모드에는 효과가 작지만 일반적으로 매우 큰 단면을 가진 고속철도 프리스트레스트 상자형 교량의 국부진동인 날개짓 모드를 감소시키는데 진동저감 장치는 효과적이라고 판단된다. 실교량에서 진동저감장치의 실험은 추후 연구를 수행할 예정이다.