• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.159-168
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• 2007

The problem of determination of axial force in continuous welded rail(CWR) has attracted a number of railroad engineers due to its practical importance in prevention of accidents related to buckling and pull apart. In this paper, we investigated the application of the beam-column theory to presume the axial force in CWR and proposed the development process of the prediction equation and model to presume the axial force in CWR.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.442-449
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• 1999

Due to temperature variations, considerable longitudinal rail forces and displacements may develop in continuous welded rail(CWR) track on long-span bridges or viaducts. Excessive relative displacements between sleepers and ballast bed may disturb the stable position of the track in the ballast which results in a lower frictional resistance. Generally, these problems are solved by installing rail expansion devices. However the application of expansion devices in high-speed tracks on existing bridges, as a means to prevent excessive longitudinal displacements and forces, is not attractive method due to comfort, safety and maintenance aspects. An alternative and very effective solution is possibly the use of so-called zero longitudinal restraint(ZLR) fastenings over some length of the track. The calculations, carried out in this respect, show a considerable reduction of track displacements, track forces, and the relative sleeper/ballast displacements. This reduction depends on the length over which these fastenings are installed. In this paper calculations of the longitudinal displacments and forces in a CWR track and substructure resulting from thermal, mechanical and kinematical loads were carried out using the FEM analysis program LUSAS

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.99-105
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• 2009

This research presents the method to decide proper locations for destressing of CWR using a non-destructive equipments to measure the longitudinal force(installation temperature) in CWR. The effect and necessity of destressing were analyzed by estimating changes of longitudinal force. The installation temperature was measured to find changes of longitudinal force in high speed and conventional lines before and after destressing or track maintenance at the locations where destressing was planed or where change of longitudinal force was expected during track maintenance. Past destressing was carried out within qualitative decision criteria. This research proposes the quantitative criteria to decide the priority order of the destressing locations reasonably by considering the difference of air temperature and stress free temperature during the track maintenances, the grade of ballast resistance force recovering and the length of destressing, etc.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.787-792
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• 2004

LRB(Lead rubber bearing) has small resistance force against slowly acting loadings such as temporal and creep loadings vice versa large resistance force against rapid loadings such as earthquake and braking loadings. By those mechanical characteristics, it has the advantage to reduce longitudinal load acting on abutments and piers, and moreover to in1prove the running stability of train by restricting the behavior of bridge under the required level. In this study, a stability evaluation method of CWR on the bridge with LRB is presented. Several parametric studies are carried to investigate how LRB contributes to the improvement of CWR stability.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.356-363
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• 2003

The CWR of the plate girder bridges in non-ballast causes the additional axial force on the rail and the bearing due to the temperature axial force and the interaction between the CWR and bridges. This study shows the remarkable improvement of reducing the axial force of the CWR on the non-ballast bridge, compared to conventional methods. New method, which is differently designed in terms of longitudinal semi-rigid bearing, reduces the axial force on the bearing by making the girder act both directions. This method is applicable to most cases of bridges regardless of the restriction of length, and useful to reduce the abrasion and damage of the track material.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.415-422
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• 2000

The Seoul Subway Line 4 crossing downtown diagonally constructed in February 1980 and opened on October 11, 1983. The line 4 is thus able to link southern and northern parts of Seoul with the downtown as well as with the Seoul outskirts. More than 810,000 people use it everyday. Line 4 was constructed like Line 1,2,3 with ballast track system causing much maintenance cost gradually and espicially much public discontent due to wheel and rail contact noise by railway viaduct with sharp curves. CWR on railway viaduct with sharp curves, 180m$\leq$R$\leq$300m, hasn't been designed and constructed ever in domestic. Therefore in order to reduce noise and vibration caused by interaction between wheel and rail the possibility and the methods of CWR(Continuous Welded Rail) on railway viaduct with sharp curve less than R300 will lead it to the maintenance free system.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1289-1292
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• 2006

The demand on a turnout layed on a bridge is rising owing to the increasing number of stations on the viaduct. And also the demand on a turnout with CWR is rising to upgrade running speed of the passing train. A CWR connected with turnout is subjected to additional axial force induced by the actions due to change in temperature, braking and starting force, and bending of the deck. But magnitude and distribution of the axial force in rails of turnout is not clear yet. So, in this study, a field measurement was conducted to know them. The strain gage method was adopted for field test. The FBG sensor for the strain measurement was used to ensure stability of test value and durability of gage for long term. It is expected that we can get data on the axial force in rail connected with turnout with respect to seasonal temperature change by the established field test system.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.959-964
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• 2007

In this study, it is offering a numerical method which assesses running safety of the freight car loaded CWR when passing through on the conventional railway by additional lateral load. It is suggested based on the numerical reviews of the safety against derailment after seeking the derailment coefficient estimated by wheel load-lateral force equation in the section that curve radius is small

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.242-249
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• 2002

This research suggests the assessment method of the additional lateral force caused bending moment of CWR when a freight car loading it is passing over turnout system or curves. The characteristics of lateral lone are analyzed by calculating the lateral pressure acting on the rails of conventional railway.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.234-241
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• 2002

In this study, a numerical method which assesses running stability of freight car loading 300m CWR and structural safety of conventional railway track when passing over curves and steel girder bridges is presented. Optimal speed of the freight car is suggest on the basis of numerical reviews for stability of derailment of the freight car and structural safety of track at weak points of the conventional line.