• 한국철도학회논문집
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• 제9권2호
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• pp.222-229
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• 2006

Recently, the development of the paved track is required as a low-maintenance of conventional line. The main reason is that the line capacity and bearing of track are increased progressively. The important factors of paved track are stability and applicability. To be based on this subject, Cement Mortar Pouring(CMP) paved track is developed. CMP paved track is a kind of ballast reinforced track using the prepacked concrete technique. The most important thing to design the paved track is to optimize the track structure considering various conditions. Because construction environment is very limited, cost is expensive and it has very complicated behavior. On this paper, structural characteristics of the paved track are investigated using the 3D finite element analysis to verify the optimized structure of the CMP track.

• Structural Monitoring and Maintenance
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• 제1권1호
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• pp.131-157
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• 2014

Special track systems used to divert a train to other directions or other tracks are generally called 'railway turnout'. A traditional turnout system consists of steel rails, switches, crossings, steel plates, fasteners, screw spikes, timber bearers, ballast and formation. The wheel rail contact over the crossing transfer zone has a dip-like shape and can often cause detrimental impact loads on the railway track and its components. The large impact also emits disturbing noises (either impact or ground-borne noise) to railway neighbors. In a brown-field railway track where an existing aged infrastructure requires renewal or maintenance, some physical constraints and construction complexities may dominate the choice of track forms or certain components. With the difficulty to seek for high-quality timbers with dimensional stability, a methodology to replace aged timber bearers in harsh dynamic environments is to adopt an alternative material that could mimic responses and characteristics of timber in both static and dynamic loading conditions. A critical review has suggested an application of an alternative material called fibre-reinforced foamed urethane (FFU). The full-scale capacity design makes use of its comparable engineering characteristics to timber, high-impact attenuation, high damping property, and a longer service life. A field trial to investigate in-situ behaviours of a turnout grillage system using an alternative material, 'fibre-reinforced foamed urethane (FFU)' bearers, has been carried out at a complex turnout junction under heavy mixed traffics at Hornsby, New South Wales, Australia. The turnout junction was renewed using the FFU bearers altogether with new special track components. Influences of the FFU bearers on track geometry (recorded by track inspection vehicle 'AK Car'), track settlement (based on survey data), track dynamics, and acoustic characteristics have been measured. Operational train pass-by measurements have been analysed to evaluate the effectiveness of the replacement methodology. Comparative studies show that the use of FFU bearers generates higher rail and sleeper accelerations but the damping capacity of the FFU help suppress vibration transferring onto other track components. The survey data analysis suggests a small vertical settlement and negligible lateral movement of the turnout system. The static and dynamic behaviours of FFU bearers appear to equate that of natural timber but its service life is superior.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.722-728
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• 2012

In railway vehicle, riding comfort depends mainly on the secondary lateral damper and track condition. When the damping force of lateral damper becomes abnormal condition or the track condition is worse, the running stability and ride comfort of the railway vehicles go down. In addition, the lateral motion of carbody is increased. Therefore, the lateral motion of carbody is reviewed carefully by considering lateral damping force and track condition of the railway line in design stage. In this study, the lateral displacement of carbody was studied in accordance with lateral damping force and track condition. The target vehicle is EMU for subway line.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1719-1724
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• 2010

In the areas susceptible to vibration and noise induced by railway traffic such as downtown area and stations under railway lines, the vibration and the structure-borne noise can be solved by floating slab track system separating the entire track structure from its sub-structure using anti-vibration mat or springs. In other countries, the core technologies for vibration-proof design and vibration isolator - one of key components - have been developed and many installation experiences have been accumulated. However, in Korea, since the design technology of system and components are not yet developed, the foreign systems are being introduced without any adjustment. Thus, in this study, the vibration isolator has been developed and its performance are investigated by the dynamic analysis of a station structure under railways lines and the floating slab track system. For this purpose, the loads transferred from the vibration isolator of the floating slab track were evaluated by train running simulation considering vehicle-track interaction, and then the dynamic analysis of station structure subjected to these loads was performed. The dynamic analysis results show that the proposed floating slab track can reduce the vibration of structure by about 25dB compared with that in conventional ballast track without floating system.

• 한국철도학회논문집
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• 제17권4호
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• pp.281-288
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• 2014

본 연구는 고가정거장 구간에 부설된 고무방진매트 플로팅궤도시스템의 방진성능 및 적용효과를 실험적으로 입증하고자 고무방진매트가 적용되지 않은 개소와 비교 측정을 수행하였다. 또한 고무방진매트 플로팅 궤도시스템의 측정 궤도지지강성 및 궤도충격계수를 산출하고 이론 및 설계치와 비교하여 현재 시공된 고무방진매트 플로팅궤도시스템에 대한 궤도상태의 건전성 및 궤도 충격의 수준을 평가하였다.

• Geomechanics and Engineering
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• 제32권5호
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• pp.483-494
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• 2023

High-speed trains became common nowadays due to the need for fast and safe mean to transport goods and people. However, the use of high-speed trains necessitates the examination of the critical speed, which is the train speed at which the maximum settlement of the railway track occurs. The critical speed and railway track settlement have been investigated considering only one train in previous studies. However, it is normal to have two adjacent trains moving at the same time. This paper aims to understand how the interference of two moving trains affects the settlement and critical speed of ballasted railway track. Calibrated three-dimensional finite element models of railway track subjected to one moving train and two moving trains have been developed to address the aim of the study. It is found that the interference dramatically increases the railway track settlement with a percentage increase ranges between 5 and 100%. It is also found that the percentage increase of the railway track settlement depends on the train speed and the distance between the moving trains. In addition, it is found that the thickness of the ballast layer and the stiffness of the subgrade have minor influence on the percentage increase of the settlement. Importantly, the results of this paper illustrate the importance of the interference of the moving trains on the dynamic response of the railway track. Thus, there is a need to consider the dynamic interaction between the adjacent moving trains in the design of railway track foundation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.55-65
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• 2009

This study is objected by analyzing whether it is applied to the analysis model considering the track stiffness or not when the railway bridge is designed or reviewed for the dynamic stability. It is performed that the analysis model is verified by comparing the field test result with the analysis result. Also, The dynamic response of railway bridge through the existing analysis model is compared with the analysis model considered the track stiffness. In addition, it is performed by analyzing the model considering the stiffness of concrete track. Therefore, this study is suggested that the design of railway bridge apply to the existing analysis model considering the mass of track and the dynamic stability review of railway bridge apply to it considered the stiffness & mass of track. Also, it is suggested that the stiffness of concrete slab on the bridge must consider when it is designed or checked over the dynamic stability.

• 한국철도학회논문집
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• 제13권2호
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• pp.186-193
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• 2010

철도교에서는 일정한 간격의 축중을 가지는 차량하중이 반복적으로 재하되므로 정적성능과 더불어 동적성능이 매우 중요하다. 또한 철도교의 상부에 부설되는 궤도시스템은 교량의 정 동적 성능에 영향을 주는 것으로 알려져 있다. 본 연구에서는 실제 궤도시스템을 적용한 거더시험체를 제작하여 궤도시스템에 따른 교량의 정 동적거동을 분석하였다. 정적거동 분석에서는 교량 처짐 및 응력을 검토하고 중립축위치를 분석하였으며, 동적거동 분석에서는 고유진동수, 감쇠비, 하중크기, 하중진폭에 대한 영향을 궤도시스템별로 검토하였다. 궤도부설에 따른 정적처짐 변화검토를 통해 궤도 부설전에 비해 자갈궤도는 약 7%, 콘크리트궤도는 약 50%의 강성 증가 효과가 있음을 확인하였고, 궤도 부설 시 교량의 고유진동수가 낮아졌으나 감쇠비 변화는 없는 것으로 분석되었다. 또한, 최대하중 크기가 증가할수록 철도교량의 동적응답(처짐 및 가속도)이 선형적으로 증가하였으며, 하중진 폭은 공진 시 교량의 동적응답을 크게 증가시키는 것으로 분석되었다. 따라서, 자갈궤도는 교량의 강성을 일정 부분 증가시키고, 콘크리트궤도의 경우 자갈궤도 부설 교량에 비해 상당한 강성기여도를 가지고 있음을 실험적으로 입증하였으나, 정량적인 강성기여도의 크기는 자갈궤도 및 콘크리트궤도의 설계값에 따라 상이할 수 있기 때문에 이를 적용할 수 있는 궤도의 질량 및 강성기여도 분석방법 개발이 필요할 것으로 판단된다.

• Steel and Composite Structures
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• 제22권3호
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• pp.537-565
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• 2016

Australian railway networks possess a large amount of aging timber components and need to replace them in excess of 280 thousands $m^3$ per year. The relatively high turnover of timber sleepers (crossties in a plain track), bearers (skeleton ties in a turnout), and transoms (bridge cross beams) is responsible for producing greenhouse gas emissions 6 times greater than an equivalent reinforced concrete counterparts. This paper presents an innovative solution for the replacement of aging timber transoms installed on existing railway bridges along with the incorporation of a continuous walkway platform, which is proven to provide environmental, safety and financial benefits. Recent developments for alternative composite materials to replace timber components in railway infrastructure construction and maintenance demonstrate some compatibility issues with track stiffness as well as structural and geometrical track systems. Structural concrete are generally used for new railway bridges where the comparatively thicker and heavier fixed slab track systems can be accommodated. This study firstly demonstrates a novel and resilient alterative by incorporating steel-concrete composite slab theory and combines the capabilities of being precast and modulated, in order to reduce the depth, weight and required installation time relative to conventional concrete direct-fixation track slab systems. Clear benefits of the new steel-concrete composites are the maintainability and constructability, especially for existing railway bridges (or brown fields). Critical considerations in the design and finite element modelling for performance benchmarking of composite structures and their failure modes are highlighted in this paper, altogether with risks, compatibilities and compliances.

• 문화기술의 융합
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• 제9권4호
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• pp.633-638
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• 2023

본 연구에서는 공용중인 강철도 복합교량의 케이블 장력변화가 철도교량 상 자갈궤도의 궤도틀림에 미치는 영향을 해석적으로 분석하였다. 케이블 장력에 대한 설계 및 해석결과 비교 결과, 약 3% 미만의 차이가 나타나 해석모델링은 설계조건을 잘 반영하는 것으로 분석되었다. 또한 현장측정결과와 해석 케이블 장력과 비교하여 해석모델링의 적정성을 입증하였다. 케이블 장력 변화를 변수로 설정하여 강철도 복합교량의 궤도틀림을 해석적으로 분석하였다. 분석결과, 전체 및 편측 케이블 장력변화는 궤도틀림 항목 중 고저틀림에 직접적인 영향을 미치는 것으로 분석되었다. 또한 케이블 위치와 근접한 구간에서 궤도틀림의 변화가 발생하는 것으로 나타났다. 케이블 장력 변화는 수평방향에 의한 궤도틀림(방향틀림 및 궤간틀림)보다는 연직방향과 직접적인 상관성을 갖는 궤도틀림(고저틀림 및 수평틀림)에 보다 직접적인 영향을 미치는 것으로 분석되었다.