• Steel and Composite Structures
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• v.27 no.3
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• pp.327-335
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• 2018

This paper presents structural assessment of a steel railway bridge for current condition using modal parameter to upgrade finite element modeling in order to gather accurate result. An adequate monitoring, such as acceleration, displacement, strain monitoring, is important tool to understand behavior and to assess structural performance of the structure under surround vibration by means of the dynamic analysis. Evaluation of conditions of an existing steel railway bridge consist of 4 decks, three of them are 14 m, one of them is 9.7 m, was performed with a numerical analysis and a series of dynamic tests. Numerical analysis was performed implementing finite element model of the bridge using SAP2000 software. Dynamic tests were performed by collecting acceleration data caused by surrounding vibrations and dynamic analysis is performed by Operational Modal Analysis (OMA) using collected acceleration data. The acceleration response of the steel bridge is assumed to be governing response quantity for structural assessment and provide valuable information about the current statute of the structure. Modal identification determined based on response of the structure play significant role for upgrading finite element model of the structure and helping structural evaluation. Numerical and experimental dynamic properties are compared and finite element model of the bridge is updated by changing of material properties to reduce the differences between the results. In this paper, an existing steel railway bridge with four spans is evaluated by finite element model improved using operational modal analysis. Structural analysis performed for the bridge both for original and calibrated models, and results are compared. It is demonstrated that differences in natural frequencies are reduced between 0.2% to 5% by calibrating finite element modeling and stiffness properties.

• Smart Structures and Systems
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• v.30 no.5
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• pp.479-500
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• 2022

In this study, a new type of isolation bearing is proposed by combining S-shaped steel plate dampers (SSDs) with a spherical steel bearing, and the seismic control effect of a five-span standard high-speed railway bridge is investigated. The advantages of the proposed S-shaped steel damping friction bearing (SSDFB) are that it cannot only lengthen the structural periods, dissipate the seismic energy, but also prevent bridge unseating due to the restraint effectiveness of SSDs in the large relative displacements between the girders and piers. This study first presents a detailed description and working principle of the SSDFB. Then, mechanical modeling of the SSDFB was derived to fundamentally define its cyclic behavior and obtain key mechanical parameters. The numerical model of the SSDFB's critical component SSD was verified by comparing it with the experimental results. After that, parameter studies of the dimensions and number of SSDs, the friction coefficient, and the gap length of the SSDFBs were conducted. Finally, the longitudinal seismic responses of the bridge with SSDFBs were compared with the bridge with spherical bearing and spherical bearing with strengthened shear keys. The results showed that the SSDFB can not only significantly mitigate the shear force responses and residual displacement in bridge substructures but also can effectively reduce girder displacement and prevent bridge unseating, at a cost of inelastic deformation of the SSDs, which is easy to replace. In conclusion, the SSDFB is expected to be a cost-effective option with both multi-stage energy dissipation and restraint capacity, making it particularly suitable for seismic isolation application to high-speed railway bridges.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.119-128
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• 2012

In this study, experimental vibration tests are performed on a real full-scale railway steel plate girder bridge, which resides in open-space environments. Using experimental modal analysis techniques, the modal parameters of the railway steel plate girder bridge yielded by the modal testing of the impact hammer are compared and investigated with the natural frequencies and mode shapes obtained by finite element analysis. This work focuses on the application of model updating techniques to measured experimental data and output-only data from an analytical vibration study that takes into account various geometric and material properties of the bridge members. A finite element model of the railway bridge structure is used to verify the modal experimental results. It is subsequently updated using the corresponding modal identification technique. The basic database is provided to evaluate damage, which can be determined based on the changes in the element properties, resulting from the process of updating the finite element model benchmark and experimental data.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.65-71
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• 2009

In this study, dynamic serviceability of PSC, PreStressed Concrete, simple railway bridge with 25m span was estimated. All of the high speed and general train loads were considered at estimation. Natural frequency is estimated about 8Hz and includes within optimum natural frequency extent of the railway bridge. Also, the bridge was detected that resonance occurrence possibility does not exist. When travel the Moogunghwa train, acceleration response was measured to 0.43g that exceed limitation value 0.35g. Also, rotation angle of girders end did not satisfy design standard of railway bridge for high speed train, but impact coefficient and deflection satisfied design standard. As a result, that railway bridge was detected that is securing dynamic safety and serviceability partially, but methods to decrease vibration acceleration response are required.

• The Journal of the Convergence on Culture Technology
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• v.5 no.1
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• pp.389-394
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• 2019

In case of damaged timber sleepers, maintenance is carried out according to the track inspection standard. However, it is difficult to detect the extent of damage on the bridge, and maintenance is depended on inspector's judgment. In this study, we propose to improve the evaluation criterion of timber sleepers for the ballast-less tracks on serviced urban railway bridge. The timber sleepers on railway bridge was classified according to degree of damage, and damage scores were calculated for each damage grade. Also we have improved the maintenance system of the timber sleepers through the history management system of the individual timber sleepers on railway bridge. As a results, it was judged that systematic management of timber sleepers could be possible during maintenance.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.774-782
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• 2011

In-site Continuous Method to improve the dynamic performance of railway plater girder bridge was developed. In this study, the In-site Continuous Method in the existing railway plate girder bridge was applied. Comparison of the results obtained from the field experiment were presented. The reductions in vertical acceleration were shown to approximately 24.8%, 45.4% and 27.5% in case of the freight train, passenger train and express tilting train, respectively. The reductions of lateral acceleration were shown to approx. 31%, 39% and 15% in the previous case. In the vertical displacement, the reductions were shown to approx. 20%, 13% and 12.6%, respectively. Through this method, we expect the problem of the restriction in speed up of train to be solve.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.689-694
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• 2006

Most of design parameters of Railway Structures are determined by the serviceability requirements, rather than the structural safety requirements. The serviceability requirements come from Ensuring of running safety and ride comfort of train, reduction of track maintenance working Track-Bridge interaction should be considered in the design of railway structures. In this study, a numerical method which precisely evaluate an axial force of rail and a rail expansion and contraction when turnout exist in succession on a CWR of bridge is developed.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1450-1459
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• 2007

Line type rigid bearings for Open-Steel-Plate-Girder railway bridges have several problem in service, and they are unstable structurally. Thus, spherical bearings having advanced maintenance capability and device to resistance up-lift are developed and replace the existing ones. A experiment of maintenance for a new placed spherical bearings under real Open-Steel-Plate-Girder bridge is conducted and their good maintenance performance is proved. The dynamic behavior of the bridge is measured and analyzed for the two cases of the existing and replacing bearings. Therefore, the effect of the new spherical bearings on the railway bridge is assessed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.103-110
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• 1999

Dynamic responses of steel composite bridges for the Korean high-speed railway are analyzed by a modal analysis. The bridge is modeled as a simply supported beam structure and a vehicle of TGV-K is modeled using a moving load assumption. When the train is moving on a bridge, its deck shows resonance phenomenon at a critical velocity. However, it is observed that the dynamic response is greatly reduced at a special range of the span length. The results show that the reduction effect should be considered ill designing the railway bridges. A parametric study of tile dynamic response is performed for different span lengths, and specific train speeds train should be considered in designing the high speed railway bridge are suggested.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.545-551
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• 2006

Along with the steady development of Korean Railway construction technology, Contemporary society needs more modernized structures which can meet not only structural value but also aesthetic and environmental value. To follow this demand of society, Pre-Stressed Concrete U-girder bridge(Somg-Lim Gyo, L=330m) is introduced in 'JINJOO-KWANGYANG RAILWAY CONSTRUCTION PROJECT'. On the environmental point of view, the huge noise due to the operation of train can be reduced remarkably by the side beam of U-girder which is high enough to substitute soundproofing wall. Moreover, by aesthetic variation of the shape of outer beams and coping of piers, the exterior view of the bridge can be improved and in accordance with surroundings. Pre-Stressed Concrete U-Girders which are built up above the outer sides of slab deck make easier to secure the clearance of a bridge and make it possible to lower the distance of centroid between superstructure and railroad tracks.