• Proceedings of the KSR Conference
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• 2008.11b
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• pp.870-873
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• 2008

레일패드는 궤도전체의 탄성확보 뿐만 아니라 열차하중에 의해 침목으로 전달되는 충격을 완화시켜 침목과 도상의 파손을 방지하는 역할을 하는데, 통과톤수의 증가와 기후적 요인에 의하여 패드가 열화되면 패드의 강성이 증가하게 된다. 패드의 강성이 증가하게 되면 레일을 통해 침목으로 전달되는 충격하중이 증가하게 되어 침목의 파손을 유발할 수 있을 뿐만 아니라 침목하면의 도상에도 과도한 충격하중을 전달하여 도상의 손상을 가속화시킬 수 있다. 또한 레일패드의 강성변화는 궤도의 소음과 레일의 파상마모의 진전에도 영향을 미치게 된다. 따라서 레일패드의 공용기간 중에 적정한 강성을 유지할 필요가 있으며, 통과톤수의 증가에 따른 레일패드의 경화도를 산정하는 방법과 레일패드의 경화가 궤도에 미치는 영향을 정량적으로 분석하여 레일패드의 교체주기에 관한 기준을 마련할 필요가 있다. 본 연구에서는 슬래브의 질량과 일정속도대역에서의 패드강성의 민감도분석을 하여 그 결과를 비교하고 레일패드경화에 따른 대상궤도의 동적거동을 수치해석을 통하여 패드강성과 차량주행속도에 따른 윤중의 변동량과 레일의 변위, 가속도 그리고 침목의 변위, 가속도의 변화정도를 분석해 보았다. 궤도시스템의 동적해석을 위한 해석 프로그램으로는 네덜란드 델프트 공과대학에서 개발된 궤도시스템 전용 해석 프로그램인 DARTS(The dynamic analysis of a rail track structure)를 사용하였다. 대상궤도는 국내 1단계 경부고속철도에서 사용되고 있는 3중보 무도상궤도를 사용하였다.

• Journal of Korean Society of Steel Construction
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• v.17 no.3 s.76
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• pp.295-306
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• 2005

In this study, the dynamic characteristics of the two open-steel-plate-girder bridges was analyzed using the pads' stiffness estimated in the previous accompanying paper.Also, it was determined that the variation in the dynamic behavior of the two bridges due to the pads corresponds to the codes describing the restriction for the steel bridges' behavior.The pads installed at the bridges increase the displacement at mid-span.However, the increase does not exceed code restrictions and does not have an adverse effect on the riding quality of the running trains. The natural and Chloroprene rubber pads are not suitable for bridge bearings since they are more deformed than the code regulated ones.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.347-352
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• 2020

In this study, the variation of track impact factor according to the spring stiffness change rate of sleeper resilience pad was analyzed based on field measurements. In addition, the correlation between field measurement results and 7 million fatigue test results was verified. The fatigue effect diagram of the sleeper resilience pads was presented considering the nonlinear deterioration characteristics of the sleeper resilience pads used for the STEDEF track. Based on the field measurement results, the nonlinear characteristics of the track impact factor for the spring stiffness change rate over 30% of sleeper resilience pad on the track impact factor-track support stiffness diagram were analyzed to be consistent with the fatigue test results.

• Journal of Korean Society of Steel Construction
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• v.17 no.3 s.76
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• pp.307-316
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• 2005

This study analyzed the characteristics of four kinds of bridge rubber pads and suggested a method of determining the stiffness and the damping ratio of the pads.The stiffness of rubber pads can be estimated by a direct static test and a dynamic test indirectly.This study used both methods to determine the pad's stiffness.The damping ratio of pads can be obtained using the dynamic test and the damping ratio of polyurethane rubber pads was estimated to aproximate that of natural and chloroprene rubber pads.The polyurethane rubber pads are harder than natural and chloroprene rubber pads and thus carry larger load bearing capacity.In addition, they showed higher stiffness with the same shape factor than the others and thus are more available for bridge bearings.Although natural and chloroprene rubber pads are elongated to large deformation in the horizontal direction due to vertical loads, polyurethane rubber pads almost do not generate horizontal deformation due to vertical loads regardless of the thickness and hardness of the pads.Therefore, they do not need reinforced plate to restrict horizontal deformation.

• Journal of the Korean Society for Railway
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• v.18 no.1
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• pp.33-42
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• 2015

The vertical static stiffness of rail pads or baseplate pads, which are important components in rail fastening systems for track safety, is a key factor to determine the total track stiffness and a guideline of quality control in the manufacturing process. The vertical static stiffness can be checked by laboratory testing: test methods are EN 13146-9 and KRS TR 0014, which are widely used in the railway field. In this paper, to correct some problems, namely the preloading step, the unloading level, and the holding time in the loading program in the vertical static stiffness test of EN 13146-9 and KRS TR 0014, domestic and foreign test standards of pads were analyzed and then certain schemes for a vertical static stiffness test were proposed. To assess the reliability of the proposed schemes, the vertical static stiffness tests were performed with 4 pads and the validity of the test results was estimated.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.335-340
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• 2020

The purpose of this study was to compare the dynamic behavior of STEDEF track that of the sleeper floating track on urban rapid transit according to replacing the resilience pads and analyze the necessity of replacing the resilience pads experimentally. It was analyzed that the uniformity of the track support stiffness could be secured by replacing the used resilience pads with new resilience pads. Therefore, by replacing the used resilience pads, the measured track impact factor was found to be dramatically reduced below the track design standard, and it was analyzed that the track support stiffness could be restored to the design value. As a results, it is possible to restore track support stiffness to the design value and reduce track impact factor by replacing timely resilience pads, which is important to securing durability and improving service life of track components.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.1057-1063
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• 2023

The urban railway sleeper floating track, the subject of this study, is an anti-vibration track to reduce vibration transmitted to the structure. currently, the replacement cycle of resilience pad for sleeper floating tracks is set and operated based on load. however, most previous studies were conducted on load-based structural safety aspects, such as fatigue life evaluation of sleeper anti-vibration pads and increase in track impact coefficient and track support stiffness due to increase in spring stiffness. therefore, in this study, we measure the vibration acceleration of the ballast for each analysis section and use the results of 7 million fatigue tests to calculate the spring stiffness of the resilience pad for each section. the spring stiffness of the resilience pad calculated for each section was set as the analysis data and the concrete vibration acceleration was derived analytically. the adequacy of analysis modeling was verified as the analyzed concrete bed vibration acceleration for each section was within the field-measured concrete bed vibration acceleration range. using the vibration acceleration curve according to the derived spring stiffness change, the spring stiffness of the resilience pad is estimated from the measured vibration acceleration. therefore, we would like to present a technique that can estimate the spring stiffness of resilience pad of a running track using the vibration acceleration of the measured concrete bed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.485-488
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• 2011

본 연구에서는 경부고속철도의 콘크리트궤도에서 열차주행안전측면에서 관리해야할 레일패드강성의 상한값을 차량 및 궤도의 동특성과 운영환경을 고려하여 결정하는 방법을 제시하였다. 차량과궤도의 상호작용의 해석의 중요 입력파라메타인 궤도틀림과 관련하여 프랑스 및 독일에서 제시한 궤도틀림 PSD(Power Spectral Density)와 경부 1단계구간 콘크리트궤도에서 계측한 궤도틀림 자료를 통하여 얻은 PSD를 기초로 하여 넓은 범위의 주파수영역에서 적용할 수 있는 콘크리트궤도의 궤도틀림 PSD를 제시하였다. 제시된 PSD 기준모델을 사용하여 시간영역에서의 궤도틀림 입력을 Random Generation을 통하여 구한 후 개발된 차량-궤도 상호작용해석 기법을 사용하여 레일패드에 따른 윤중감소율을 산정하였다. 산정된 윤중감소율에 대하여 국내 철도차량 안전기준에 관한 규칙의 탈선계수 규정을 적용하여 주행안전측면에서 허용할 수 있는 레일패드강성의 상한값을 제시하였다.

• Journal of the Korean Society for Railway
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• v.18 no.2
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• pp.139-148
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• 2015

By increasing the vertical stiffness of the rail fastening system, the dynamic wheel load of the vehicle can be increased on the ballast track, though this increases the cost of track maintenance. On the other hand, the resistance acting on the wheel is decreased, which lowers the cost of the electric power to run the train. For this reason, the determination of the optimal fastener stiffness is important when attempting to minimize the economic costs associated with both track maintenance and energy to operate the train. In this study, a numerical method for evaluating the optimal vertical stiffness of the fasteners used on ballast track is presented on the basis of the process proposed by L$\acute{o}$pez-Pita et al. They used an approximation formula while calculating the dynamic wheel load. The evaluated fastener stiffness is mainly affected by the calculated dynamic wheel load. In this study, the dynamic wheel load is more precisely evaluated with an advanced vehicle-track interaction model. An appropriate range of the stiffness of the fastener applicable to the design of ballast track along domestic high-speed lines is proposed.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.261-269
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• 2015

To overcome the weaknesses of viaduct bridges and the non-economic efficiency of underground LRT, the study of near-surface railway systems is in progress. To apply a box structure to the low depth transit, a connection joint to precast modules are very important when applying precast modular structures to replace temporary structures. In this study, wall to wall connections were applied in diverse cases such as rebar connections, guiding structures that were used to fit the verticality of precast walls during construction, and non-reinforcement structures used only for waterstop. Experimental performance verification was carried out for the bending, shear and splitting of the wall to wall connection. Precision of construction joints between wall to wall was identified as a factor that influenced the structural performance of the precast wall. A structure that can serve as a guide during the vertical insertion of a wall is confirmed for the most suitable case, but it will be necessary to modify this structure for detailed cases.