• 한국철도학회논문집
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• 제19권6호
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• pp.765-776
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• 2016

본 연구에서는 철도 교대를 위한 표준단면을 선정하고, 선정된 단면에 대하여 토압산정방법과 내부마찰각에 따른 직배면과 가상배면에 작용하는 주동토압을 비교 분석하였다. 또한, 기존토압과 개량시행쐐기법의 토압을 이용하여 내부마찰각에 따른 교대의 외적 안정성, 부재력 및 경제성을 분석하였다. 본 연구로부터 가상배면에서의 주동토압은 직배면에서의 주동토압보다 크며, 내부마찰각이 증가함에 따라 감소한다는 것을 알 수 있었다. 기존토압(Rankine, Coulomb, 시행쐐기법) 및 개량토압(개량시행쐐기법) 모두 내부마찰각이 증가함에 따라 부재력은 크게 감소하였고, 경제성은 향상되는 것으로 평가되었다.

• 한국구조물진단유지관리공학회 논문집
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• 제20권2호
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• pp.40-48
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• 2016

본 연구는 지진이 발생할 경우 장대레일교량에 있어 레일과 상판 간의 종방향 상호작용에 미치는 영향을 검토하기 위한 것으로, 해석모델에 여러 하중조합과 함께 지진하중을 적용함으로써 대상 철도교량 레일에서의 축방향 부가응력과 레일-상판 간 상대변위의 변화를 산출하였다. 해석 결과, 본 연구 대상 철도교량의 경우 철도시설공단에서 제시하고 있는 표준응답스펙트럼을 적용할 때 레일부가응력은 대부분의 하중조합에 대해 허용기준 내의 값을 보이고 있는 반면, 레일-상판 상대변위는 공단에서 제시하는 허용기준을 초과하고 있는 것으로 나타났다. 따라서 레일-상판 상대변위가 레일부가응력에 비해 상대적으로 더 허용기준을 만족시키기 어렵다는 것을 알 수 있었으며, 아울러 고베 대지진과 같은 큰 규모의 지진이 발생하면 레일부가응력과 레일-상판 상대변위는 허용기준을 충족시키지 못하므로 이에 대한 적절한 내진 대비가 필요하다.

• 한국철도학회논문집
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• 제9권2호
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• pp.131-136
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• 2006

Most modern railways, especially the high speed railway tracks, use continuous welded rail(CWR) for the less maintenance. For the CWR track has very few expansion joints, track buckling has always been an unpredictable event and it happens mainly by high compressive stress in rail in summer period. Therefore, it is important to understand the variation of rail stress induced by thermal loads which has direct influence on the rail buckling and stability of railway track. This paper describes the experimental investigation of the variation of rail temperature and stress in a high speed railway track on bridge structure. Field measurement was performed to examine the correlation between the rail temperature and rail stress on the Korean High Speed Railway line. Regression functions were derived from measured data to determine the rail stress f3r an arbitrary rail temperature varies from 20 to 50 degree Celsius.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.3156-3159
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• 2011

In case of the continuous welded rail(CWR) track is supported by the railway bridge, the additional axial force is occurred in the CWR due to the track-bridge interaction. In the various design codes such as Korean code, European code, UIC code, etc, three important loads(temperature variation in the bridge-deck, braking/acceleration and the bending of the bridge-deck resulted from the passing train) are treated as the independent loading case. In other words, the additional axial force can be obtained by summing up the three different values calculated by the three independent analysis. However, this analysing method may have an error because the behavior of the longitudinal resistance between the rail and the bridge-deck is under the highly nonlinear. Therefore, in order to exactly analyse the track-bridge interaction, nonlinear loading history and the change of the longitudinal resistance owing to the loading history must be considered in the analysis process. In this study, the loading history effect on the track-bridge interaction is investigated considering the resonable combination of three loads and the longitudinal resistance change.

• 한국철도학회논문집
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• 제9권2호
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• pp.160-168
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• 2006

The major objective of this study is to investigate the effects and application of external post-tensioning method far steel plate girder bridge. It analyzed the mechanical behaviors of steel plate girder bridge with applying external post-tensioning on the finite element analysis, field test and laboratory test fur the lateral dynamic characteristics. As a result, the reinforcement of steel plate girder bridge the external post-tensioning method are obviously effective for the lateral dynamic response which is non-reinforced. The analytical and experimental study are carried out to investigate the post-tension force decrease lateral acceleration and deflection on steel plate girder bridge for serviceability. And the external post-tensioning method reduce dynamic maximum displacement(about $10{\sim}24%$), the increase of dynamic safety is predicted by adopting external post-tensioning method. From the dynamic test results of the servicing steel plate girder bridge, it is investigated that the change degree of natural frequency is very low with applying the external post-tensioning method The servicing steel plate girder bridge with external post-tensioning has need of the reasonable reinforcement measures which could be reducing the effect of lateral dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

• 한국철도학회논문집
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• 제2권3호
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• pp.36-45
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• 1999

The basic idea of cable-stayed girder bridges is the utilization of high strength cables to provide intermediate supports for the bridge girder so that the girder can span a much longer distance. In the cable-stayed bridge, the cables exhibit nonlinear behavior because of the change in sag, due to the dead weight of the cable, which occurs with changing tension in the cable resulting from the movement of the end points of the cable as the bridge is loaded. Techniques required for the static analysis of cable-stayed bridges has been developed by many researchers. However, little work has been done on the dynamic analysis of such structures. To investigate the characteristics of the dynamic response of long-span cable-stayed bridges due to various dynamic loadings likes moving traffic loads. two different 3-D cable-stayed bridge models are considered in this study. Two models are exactly the same in structural configurations but different in finite element discretization. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept was presented by using divided a cable into several elements in order to study the effect of the cable vibration (both in-plane and swinging) on the overall bridge dynamics. The result of this study demonstrates the importance of cable vibration on the overall bridge dynamics.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.395-400
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• 2007

LRT(Light Railway Train), which is a intermediate system of train and bus, is arose for the solution of subway construction cost and the transportation capacity of bus. LRT was introduced in 1980's. About 30 local governments are plan to introduce LRT or constructing LRT, at present. AGT(Automated Guide-way Transit) system, which is a kind of LRT, is operated without driver. Rubber wheeled AGT system can reduce the noise and vibration compare to steel wheeled AGT, so it is estimated as ideal transportation system for urban area. And live loads at bridge are classified as the static load of vehicle and the dynamic wheel contact load which is occurred from the interaction of bridge and vehicle vibration, and the surface roughness. In the case of AGT system, the dynamic increment factor of bridge is greater than the normal train bridge and roadway bridge, because, the weight of AGT vehicle is more light that the train of truck. The exact method for dynamic increment factor is experiment. But this method is needed much money and time, moreover, this method cannot be adopted in design. Therefore, a simulation program for the interaction of AGT bridge, vehicle and surface roughness was developed, in this study. And the program was verified by experiment. As a result, the accuracy of the simulation program can be verified.

• Earthquakes and Structures
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• 제11권5호
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• pp.841-859
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• 2016

Bridge bearings are important connection elements between bridge superstructures and substructures, whose health states directly affect the performance of the bridges. This paper systematacially presents a new method to identify the bridge bearing damage based on the neural network theory. Firstly, based on the analysis of different damage types, a description of the bearing damage is introduced, and a uniform description for all the damage types is given. Then, the feasibility and sensitivity of identifying the bearing damage with bridge vibration modes are investigated. After that, a Radial Basis Function Neural Network (RBFNN) is built, whose input and output are the beam modal information and the damage information, respectively. Finally, trained by plenty of data samples formed by the numerical method, the network is employed to identify the bearing damage. Results show that the bridge bearing damage can be clearly reflected by the modal information of the bridge beam, which validates the effectiveness of the proposed method.

• Structural Engineering and Mechanics
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• 제67권1호
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• pp.9-20
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• 2018

In this paper, a framework is proposed for dynamic analysis of train-bridge systems with a damaged pier after barge collision. In simulating the barge-pier collision, the concrete pier is considered to be nonlinear-inelastic, and the barge-bow is modeled as elastic-plastic. The changes of dynamic properties and deformation of the damaged pier, and the additional unevenness of the track induced by the change of deck profile, are analyzed. The dynamic analysis model for train-bridge coupling system with a damaged pier is established. Based on the framework, an illustrative case study is carried out with a $5{\times}32m$ simply-supported PC box-girder bridge and the ICE3 high-speed train, to investigate the dynamic response of the bridge with a damaged pier after barge collision and its influence on the running safety of high-speed train. The results show that after collision by the barge, the vibration properties of the pier and the deck profile of bridge are changed, forming an additional unevenness of the track, by which the dynamic responses of the bridge and the car-body accelerations of the train are increased, and the running safety of high-speed train is affected.

• Structural Engineering and Mechanics
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• 제77권5호
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• pp.627-635
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• 2021

The speed of rail vehicles become higher and higher over two decades, and China has unveiled a prototype high-speed train in October 2020 that has been able to reach 400 km/h. At such high speeds, wheel-rail force items that had previously been ignored in common computational model should be reevaluated and reconsidered. Aiming at this problem, a new model for investigating the vehicle-bridge interaction at high moving speed is proposed. Comparing with the common model, the new model was more accurate and applicable, because it additionally considers the second-order pseudo-inertia forces effect and its modeling equilibrium position was based on the initial deformed curve of bridge, which could include the influences of temperature, pre-camber, shrinkage and creep deformation, and pier uneven settlement, etc. Taking 5 km/h as the speed interval, the dynamic responses of the classical vehicle-bridge system in the speed range of 5 km/h to 400 km/h are studied. The results show that ignoring the second-order pseudo-inertia force will underestimate the dynamic response of vehicle-bridge system and make the high-speed railway bridge structure design unsafe.