• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1444-1451
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• 2010

This paper aims for proposed the deflection limit on vibration serviceability of high-speed railway bridges considering the exposed time duration when a train passes a railway bridge. For this purpose, bridge-train transfer function was derived and bridge-train interaction analysis was performed by using the derived function. The vertical acceleration signals of passenger cars obtained from bridge-train interaction analysis were compared with them from the bridge-train transfer function by moving constant force analysis. Therefore it was estimated possible to induce the comfort deflection limit of railway bridge by using bridge-train transfer function. The deflections by moving force of single span bridge and continuous bridge were assumed as sine and haversine wave. The deflection limit on vibration serviceability of high-speed railway bridges considering the exposed time duration can be expanded using bridge-train transfer function and bridge comfort limit considering serviceability due to bridge vibration. And it was compared to other allowable deflection limits of railway bridge design specifications.

• Structural Engineering and Mechanics
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• v.29 no.4
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• pp.355-380
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• 2008

In this study, the new three-dimensional finite element analysis model of guideway structures considering ultra high-speed magnetic levitation train-bridge interaction, in which the various improved finite elements are used to model structural members, is proposed. The box-type bridge deck of guideway structures is modeled by Nonconforming Flat Shell finite elements with six DOF (degrees of freedom). The sidewalls on a bridge deck are idealized by using beam finite elements and spring connecting elements. The vehicle model devised for an ultra high-speed Maglev train is employed, which is composed of rigid bodies with concentrated mass. The characteristics of levitation and guidance force, which exist between the super-conducting magnet and guideway, are modeled with the equivalent spring model. By Lagrange's equations of motion, the equations of motion of Maglev train are formulated. Finally, by deriving the equations of the force acting on the guideway considering Maglev train-bridge interaction, the complete system matrices of Maglev train-guideway structure system are composed.

• Journal of the Korean Geosynthetics Society
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• v.20 no.2
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• pp.35-43
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• 2021

In this paper, the sub-structuring technique-applied train-bridge interaction analysis model, which is formulated based on the simplified three-dimensional train-bridge interaction analysis model for high-speed bridge-train interaction analysis, is presented. In the sub-structuring technique, the super-structure and the supporting structure of railway bridges can be modeled as sub-structures, and train-bridge interaction analysis can be efficiently performed. As a train analysis model, two-dimensional train model is used, and the Lagrange equation of motion is applied to derive the equation of motion of two-dimensional train. In the sub-structuring technique, the number of degrees of freedom can be reduced by using the condensation method, thus reducing the time and cost for calculating the eigenvalues and eigenvectors, and the time and cost for the subsequent calculation. In this paper, Guyan reduction method is used as sub-structuring technique. By combining simplified three-dimensional bridge-train interaction analysis and Guyan reduction method, the efficient and accurate bridge-train interaction analysis can be performed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.444-451
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• 2003

In this study, a new three-dimensional finite element analysis model of high-speed railway bridges considering train-bridge interaction, in which various improved finite elements are used for modeling structural members, is proposed. The box-type bridge deck of a railway bridge is modeled by the NFS(Nonconforming Flat Shell) elements with 6 degrees of freedom. Track structures are idealized using the beam finite elements with the offset of beam nodes and those on Winkler foundation with two parameters. And, the vehicle model devised for a high-speed train is employed, which has an articulated bogie system. By Lagrange's equations of motion, the equations of motion of a bridge-train system can be formulated. Finally, by deriving the equations of the forces acting on a bridge considering bridge-train interaction the complete system matrices of total bridge-train system can be constructed. As numerical examples of this study, 2-span PC box-girder bridge is analyzed and results are compared with experimental results.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1555-1561
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• 2011

The dynamic behavior of a bridge under moving loads has been investigated over many years. Especially, with the introduction of High Speed Railway, numerous theoretical studies on the interaction problem between bridges and trains are carried out. In the present study, advanced bridge/train interaction analyses are performed and compared with field tests of a simply-supported 40m long PSC box girder bridge of Kyung-Bu High Speed Railway. Vertical displacements and vertical accelerations of a bridge with increasing speeds are analyzed. In addition, wheel load reduction rates and accelerations of a car-body of the train are investigated for a study of appropriateness of traffic safety criteria of bridge design specification.

• Structural Engineering and Mechanics
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• v.76 no.2
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• pp.207-222
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• 2020

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train subjected to fluctuating crosswind. To ensure the safe operation in metro lines in mountain cities, running safety of the metro train over the high-pier bridge under crosswind is analyzed in this paper. Firstly, the dynamic model of the wind-train-bridge (WTB) system is built, in which the speed-up effect of crosswind is fully considered. On the basis of time domain analysis, the basic characteristics of the WTB system with high-pier are analyzed. Afterwards, the dynamic responses varies with train speed and wind speed are calculated, and the safety zone of metro train over a high-pier bridge subjected to fluctuating crosswind in mountain city is determined. The results indicate that, fluctuating crosswind triggers drastic vibration to the metro train and high-pier bridges, which in turn causes running instability of the train. For this reason, the corresponding safety zone for metro train running on the high-pier is proposed, and the metro traffic on the high-pier bridge should be closed as the mean wind speed of standard height reaches 9 m/s (15.6 m/s for the train).

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.414-421
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• 1999

In this paper, the simplified method for 2-dimensional train/track/bridge interaction analysis is utilized in the analysis of dynamic behavior of bridges in which the eccentricity of axle loads and the effect of the toriosnal forces acting on the bridge are included for the more accurate train/track/bridge interaction analysis. Inverstigations mainly into the influence of vehicle speed on train/track/bridge interactions are carried out for the two cases. The first case is that only train and bridge are considered in the modelling and the other case is that train, track and bridge are considered.

• Structural Engineering and Mechanics
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• v.51 no.4
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• pp.581-599
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• 2014

In this paper the overall dynamic response of simple railway bridges subjected to high-speed trains is investigated numerically based on the mechanical models of simply supported single-span and continuous two-span Bernoulli-Euler beams. Each axle of the train, which is composed of rail cars and passenger cars, is considered as moving concentrated load. Distance, magnitude, and maximum speed of the moving loads are adjusted to real high-speed trains and to load models according to Eurocode 1. Non-dimensional characteristic parameters of the train-bridge interaction system are identified. These parameters permit a spectral representation of the dynamic peak response. Response spectra assist the practicing engineers in evaluating the expected dynamic peak response in the design process of railway bridges without performing time-consuming time history analyses.

• Structural Engineering and Mechanics
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• v.59 no.2
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• pp.277-290
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• 2016

This paper investigates the ground vibration induced by high-speed trains moving on multi-span continuous bridges. The dynamic impact factor of multi-span continuous bridges under trainloads was first determined in the parametric study, which shows that the dynamic impact factor will be large when the first bridge vertical natural frequency is equal to the trainload dominant frequencies, nV/D, where n is a positive integer, V is the train speed, and D is the train carriage interval. In addition, more continuous spans will produce smaller dynamic impact factors at this resonance condition. Based on the results of three-dimensional finite element analyses using the soil-structure interaction for realistic high-speed railway bridges, we suggest that the bridge span be set at 1.4 to 1.5 times the carriage interval for simply supported bridges. If not, the use of four or more-than-four-span continuous bridges is suggested to reduce the train-induced vibration. This study also indicates that the vibration in the train is major generated from the rail irregularities and that from the bridge deformation is not dominant.

• Structural Engineering and Mechanics
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• v.54 no.2
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• pp.199-219
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• 2015

This paper presents the non-destructive evaluation of a high-speed railway bridge using train-induced strain responses. Based on the train-track-bridge interaction analysis, the strain responses of a high-speed railway bridge under moving trains with different operation status could be calculated. The train induced strain responses could be divided into two parts: the force vibration stage and the free vibration stage. The strain-displacement relationship is analysed and used for deriving critical displacements from theoretical stain measurements at a forced vibration stage. The derived displacements would be suitable for the condition assessment of the bridge through design specifications defined indexes and would show certain limits to the practical application. Thus, the damage identification of high-speed railways, such as the stiffness degradation location, needs to be done by comparing the measured strain response under moving trains in different states because the vehicle types of high-speed railway are relatively clear and definite. The monitored strain responses at the free vibration stage, after trains pass through the bridge, would be used for identifying the strain modes. The relationship between and the degradation degree and the strain mode shapes shows certain rules for the widely used simply supported beam bridges. The numerical simulation proves simple and effective for the proposed method to locate and quantify the stiffness degradation.