• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.64-67
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• 2007

In the present study, the wind pressure transients on platform screen door in side platforms caused by passing trains have been investigated numerically. The transient compressible 3-D full Navier-Stokes solution is obtained with actual operational condition of subway train and the moving mesh technique is adopted considering the train movement. To achieve more accurate analysis, the entrance and exit tunnel of platform are included in a computational domain and detailed shape of train is also modeled Numerical analyses were conducted on five operational condition which are different velocity variation of subway train, existence of stationary train and passing each other trains. The results show that pressure load on platform screen door is maximized when the two trains are passing each other. It is also seen from the computational results that the maximum pressure variation was found to be satisfactory to various foreign standards.

• Journal of computational fluids engineering
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• v.12 no.4
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• pp.1-6
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• 2007

In the present study, the wind pressure transients on platform screen door in side platforms caused by passing trains have been investigated numerically. The transient compressible 3-D full Navier-Stokes solution is used with actual operational condition of subway train by adopting the moving mesh technique considering the train movement. To achieve more accurate analysis, the entrance and exit tunnel connecting the stations are included in a computational domain with modeling the detailed shape of the train. Numerical analyses are conducted on five operational conditions which include the variation of the train speed, case with or without the train stopped in the other track, and case for two trains passing each other inside the station. The results show that pressure load on platform screen door is maximized when the two trains are passing each other. It is also seen from the computational results that the maximum pressure variation for the cases considered in the present study is found to be satisfactory to various foreign standards.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.360-367
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• 2003

This paper presents passive vibration control method to suppress train-induced vibration on a long-span steel arch bridge. According to the train load frequency analysis, undesirable resonance of a bridge will occur when the impact frequency of the train axles are close to the modal frequencies of the bridge. Because the first mode shape of the long-span steel arch bridge may take anti-symmetric shape along the bridge direction, however, the optimal control configuration for resonance suppression should be considered carefully In this study, bridge-vehicle element is used to estimate the bridge-train interaction precisely. From the numerical simulation of a loom steel arch bridge under TGV-K train loading, dynamic magnification influences are evaluated according to vehicle moving speed and efficient control system with passive dampers are presented in order to diminish the vertical displacement and vertical acceleration.

• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.43-49
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• 2012

In the design of high speed railway bridges is important a impact factor as a tool of assessing the dynamic capacitys of bridges. However, the impact factor(or dynamic amplification factor, DAF) of high speed railway bridges may essentially be changeable because the dynamic response is affected by the long train length(380 m), number of axles and high speed velocity(300 km/h)(Korea Train eXpress: KTX). Therefore, on this study will be examined the dynamic capacity and stability of the typical PSC Box Girder of high speed railway bridge. At first, the static/dynamic analysis is performed considering the axle load line of KTX based upon existing references. Additionally, the KTX moving load is transformed into the dynamic time series load for conducting various parameter studies like axle length, analytical time increment, velocity of KTX. The time history analysis is repeatedly performed to get maximum dynamic responce by varying axle load length, analytical time increment, velocity of KTX. The study shows that dynamic analysis has resonable results with optimal axle load length(0.6 m) and time increment(0.01 sec.) and maximum DAF and dynamic resonance happens at 270 km/h velocity of KTX.

• Journal of the Korean Society for Railway
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• v.16 no.4
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• pp.298-304
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• 2013

This paper systematically analyzes the dynamic effects of structure approaches which are expected to have direct effects on train loads - according to the train's acceleration as the area under consideration is located in a section where acceleration of high speed railway vehicles and the train's operating speed happens. In addition, through an examination of the dynamic train loads, dynamic behavioral characteristics of embedded structures and structure approaches were analyzed and a numerical analysis has been carried out in order to evaluate the performance of track subgrade and the safety of the structure. As a result, we reach the conclusion that the dynamic effects by train loads is low, but somewhat high vertical acceleration occurs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.2
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• pp.1-10
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• 1989

In this paper, dynamic response of a truss bridge due to constantly moving train loads is analysed. Dynamic response of the bridge is found by the mode superposition method with the solution of the eigenvalue problem by Householder transformation and QL algorithm. To prove the validity of the analysis procedure, the response due to a very slowly moving load is compared with the result from the static analysis program, and the dynamic response is also compared with the result from the direct integration method. Based upon this, the variation of dynamic amplification factors is investigated by changing the train types and speeds, and the result is compared with the code specified impact factor. From this study, it was known that the dynamic amplification factor is not quite different by train types in low speeds but in high speeds it is, and in the case of electric car and U. I. C. loads the factor could exceed the code specified impact factor depending upon the speed.

• Structural Engineering and Mechanics
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• v.82 no.1
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• pp.31-40
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• 2022

In structural engineering, the material properties of the structures such as elastic modulus, shear modulus, density, and size may not be deterministic and may vary at different locations. The dynamic response analysis of such structures may need to consider these properties as stochastic. This paper introduces a stochastic finite element method (SFEM) approach to analyze moving loads problems. Firstly, Karhunen-Loéve expansion (KLE) is applied for expressing the stochastic field of material properties. Then the mathematical expression of the random field is substituted into the finite element model to formulate the corresponding random matrix. Finally, the statistical moment of the dynamic response is calculated by the point estimation method (PEM). The accuracy and efficiency of the dynamic response obtained from the KLE-PEM are demonstrated by the example of a moving load passing through a simply supported Euler-Bernoulli beam, in which the material properties (including elastic modulus and density) are considered as random fields. The results from the KLE-PEM are compared with those from the Monte Carlo simulation. The results demonstrate that the proposed method of KLE-PEM has high accuracy and efficiency. By using the proposed SFEM, the random vertical deflection of a high-speed railway (HSR) bridge is analyzed by considering the random fields of material properties under the moving load of a train.

• Advances in Computational Design
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• v.4 no.3
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• pp.307-326
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• 2019

A low computational cost semi-analytical method is developed, based on eigenfunction expansion, to study the vibration of rectangular plates subjected to a series of moving sprung masses, representing a bridge deck under multiple vehicle or train moving loads. The dynamic effects of the suspension system are taken into account by using flexible connections between the moving masses and the base structure. The accuracy of the proposed method in predicting the dynamic response of a rectangular plate subjected to a series of moving sprung masses is demonstrated compared to the conventional rigid moving mass models. It is shown that the proposed method can considerably improve the computational efficiency of the conventional methods by eliminating a large number of time-varying components in the coupled Ordinary Differential Equations (ODEs) matrices. The dynamic behaviour of the system is then investigated by performing a comprehensive parametric study on the Dynamic Amplification Factor (DAF) of the moving loads using different design parameters. The results indicate that ignoring the flexibility of the suspension system in both moving force and moving mass models may lead to substantially underestimated DAF predictions and therefore unsafe design solutions. This highlights the significance of taking into account the stiffness of the suspension system for accurate estimation of the plate maximum dynamic response in practical applications.

• International Journal of Railway
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• v.6 no.4
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• pp.155-159
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• 2013

The purpose of this study was to develop a theoretical model to analyze the vibration of finite railways forced by distributed moving loads. The vibration characteristics of compliantly supported beam utilizing compressional damping model were investigated through the Rayleigh-Ritz method. The distributed moving load was analyzed as the cross correlation function on railways. This allowed the use of statistical characteristics for simulation of the moving train wheels on the rail. The results showed there is a critical velocity inducing resonant vibration of the rail. The mass spring resonance from the rail fastening systems exhibited significant influence on the resulting vibration response. In particular, the effect of the viscoelastic core damping was investigated as an efficient method for minimizing rail vibration. The decrease of the averaged vibration and rolling noise generation by the damping core was maximized at the mass-stiffness-mass resonance frequency.

• Journal of the Korean Society for Railway
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• v.16 no.4
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• pp.278-285
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• 2013

The suppression of residual settlement is required on earthwork sections as concrete track is introduced. Use of pile-slab structure is one of the settlement restraining methods applied on soft ground. The slab distributes the upper embankment load and piles transfer the load from the slab to the stiff ground. While this method is very effective in terms of load transfer, it has not yet been established for dealing with the vibration transfer effects and interaction characteristics between a structure and the ground. It is possible that vibration caused by a moving train load is propagated in the upper embankment, because the slab acts as a reflection layer and waves are multi-reflected. In this present paper, wave propagation generated by a moving train load is evaluated in the time and frequency domains to consider a roadbed structure using an artificial impact load and field measured train load. The results confirmed the wave reflection effect on the pile-slab structure, if the embankment height is sufficient, vibration propagation can be stably restrained, whereas if the height is not sufficient, the vibration amplitude is increased.