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

• Journal of The Korean Society For Urban Railway
• /
• v.6 no.4
• /
• pp.383-392
• /
• 2018

This study investigated the change of additional axial stress of rail and reaction force at bridge bearings due to the track-bridge interaction when laying CWR on non-ballasted railway bridges including truss bridges with relatively long span. According to the results of the present study, additional axial stresses of rail and reaction forces at bridge bearings showed a large increase when CWR is installed on the non-ballasted railway bridge. The additional axial stress of rail can be acceptable if sufficient lateral resistance can be obtained. However, if the reaction force increases, there is a risk of damage of the bearing or pier, and therefore, it is necessary to take measures to mitigate the reaction force. It is found that additional axial stress of rail decreases when considering the frictional resistance of the bridge movable support, but its effect on the bearing reaction force is very small. On the other hand, when the longitudinal track restraint decreases, both additional axial stress of rail and bearing reaction force are reduced to a large extent. Also, when the ZLR fastening devices are applied to the region where the additional axial stress of rail is highest, bearing reaction force as well as additional axial stress of rail greatly decreased. Therefore, the application of ZLR fastening devices with the reduction of the longitudinal track restraints is very effective for installing CWR on non-ballasted railway bridges.

• Journal of The Korean Society For Urban Railway
• /
• v.6 no.4
• /
• pp.327-337
• /
• 2018

Since the track of the ballastless steel plate girder bridge is connected to a main girder without a deck and a ballast, the impact generated by train passage is transferred directly to bridge main members, and it can cause frequent damage of the bridge as well as higher noise and vibration level. Applying the CWR (Continuously Welded Rail) technology can reduce this structural problems, and, to this end, it is necessary to understand the characteristics of factors influencing vehicle-track or track-bridge interaction. In this paper, experimental study results are presented for examining the longitudinal resistance characteristics of the track, including a rail fastener, a sleeper fastener, and a track skeleton, installed on a ballastless steel plate girder bridge. The experiment is conducted using a disposed bridge from service, which is transported to a laboratory. The experimental results show that the rail fastener satisfies the performance criteria of the longitudinal resistance presented in KRS TR 0014-15, and the longitudinal resistance of old and new type sleeper fasteners is higher than the values provided in the existing research. Also, the unloaded longitudinal resistance of the ballastless track is between the ballast and the concrete tracks.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.2
• /
• pp.131-140
• /
• 2022

Installing Continuous Welded Rail (CWR) is one of the economical ways to resolve the challenges of noise, vibration, and the open-deck steel railway bridge impact, and the SSF method using the interlocking sleeper fastener has recently been developed. In this study, the method employed for determining the optimum vertical stiffness of the sleeper pad installed under the bridge sleeper, which is utilized to adjust the rail height and absorb shock when the train passes when the interlocking sleeper fastener is applied, is presented. To determine the optimal vertical stiffness of the sleeper pad, related existing design codes are reviewed, and, running safety, ride comfort, track safety, and bridge vibration according to the change in the vertical stiffness of the sleeper pad are estimated via flexible multi-body dynamic analysis,. The flexible multi-body dynamic analysis is performed using commercial programs ABAQUS and VI-Rail. The numerical analysis is conducted using the bridge model for a 30m-long plate girder bridge, and the response is calculated when passing ITX Saemaeul and KTX vehicles and freight wagon when the vertical stiffness of the sleeper pad is altered from 7.5 kN/mm to 240 kN/mm. The optimum stiffness of the sleeper pad is calculated as 200 kN/mm under the conditions of the track components applied to the numerical analysis.

• Journal of Korean Society of Steel Construction
• /
• v.22 no.1
• /
• pp.13-20
• /
• 2010

Seismic risk assessment of railway bridges is an important issue for a transportation network, because loss of functionality of railway bridges could result in severe disruption of the railway line, as no redundant routing systems generally exist. Although many studies have been conducted by numerous researchers regarding fragility analyses of bridge structure, little or no studies have been done for fragility analyses of a class of bridge structures considering their geometric variability. This study performs a fragility analysis for Track-on Steel-Plate-Girder (TOSPG) railway bridges in Korea considering their span variability. Seismic fragility curves are developed for a series of bridges with different spans varying from 2 to 15. At last, the fragility curves for the whole TOSPG bridges in Korea are also developed using the total probability theorem. This study is expected to effectively contribute to the seismic risk assessment of railway lines, where a number of bridges are present.

• Journal of Korean Society of Steel Construction
• /
• v.21 no.1
• /
• pp.45-53
• /
• 2009

More than 40% of railway bridges on the conventional lines in Korea consist of track-on-steel plate girder (TOSPG) bridges. This type of bridge is typically designed without considering seismic loadings, as most of them were built before 1970. The seismic performance of this particular type of bridge could be upgraded through various seismic retrofit schemes, and seismic risk assessment could play a key role in decision-making on the level of the seismic retrofit. This study performed a seismic risk assessment of TOSPG bridges in Korea. The seismic damage of several crucial components of TOSPG bridges--fixed bearings, free bearings, and piers--were probabilistically estimated, and their seismic fragility curves were developed. The probability that the components would exceed their predefined limit states was also calculated by combining the fragility curves and the seismic hazard function. The analysis showed that the piers of TOSPG bridges, which are made of plain concrete without rebars, have relatively low risk against seismic loadings in Korea. This is because the mass of the superstructures of TOSPG bridges is relatively small, and hence, the seismic loading being transferred to the piers is minimal. The line-type bearings typically used for TOSPG bridges, however, are exposed to a degree of seismic risk. Among the bearings, the probability of the free-end bearings and the fixed-end bearings exceeding the slight damage state in 50 years was found to be 12.78% and 4.23%, respectively. The gap between these probability values lessened towards more serious damage states. This study could effectively provide an engineering background for decision-making activities on the seismic retrofit of railway bridges.

• Proceedings of the KSR Conference
• /
• 2006.05b
• /
• pp.493-500
• /
• 2006

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.1
• /
• pp.94-101
• /
• 2019

Most of the existing rail structures have undergone a lot of aging since a considerable period of time has passed from completion. In particular, among existing railway bridges, many of the plate girder bridges are older bridges that have lived 40 to 60 years or more. Since the treadmill is directly connected to the girder without the ballast, the running load of the vehicle is directly transmitted to the bridge. Therefore, the shock and noise applied to the bridge are larger than those of the ballast bridge, and the dynamic shock and vibration are also relatively large. Therefore, it is very urgent to develop appropriate maintenance, repair and reinforcement technology for existing steel plate bridge. In this study, the authors introduced the characteristics of embedded rail (ERS) developed for improving the performance of the existing plate girder bridge and the techniques solving the vibration and noise problems. In order to evaluate the vibration and noise reduction performance of ERS, a non-ballast plate girder bridge with 5m length of sleepers installed and a plate girder bridge with ERS were fabricated. And, then, the vibration response generated under the same excitation condition was measured and analyzed. Also, the radiated noise analysis was performed using the vibration response data obtained from the experiment as the input data of the acoustic analysis model. As a result of experiments and analyses, it was confirmed that the plate girder bridge's vibration using ERS was reduced by 15.0~18.8dB and the average noise was reduced by 7.7dB(A) more than the non-ballast bridge.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.6
• /
• pp.206-216
• /
• 2020

As the number of aging railway bridges in Korea increases, maintenance costs due to aging are increasing and continuous management is becoming more important. However, while the number of old facilities to be managed increases, there is a shortage of professional personnel capable of inspecting and diagnosing these old facilities. To solve these problems, this study presents an improved model that can detect Local damage to structures using machine learning techniques of AI technology. To construct a damage detection machine learning model, an analysis model of the bridge was set by referring to the design drawing of a non-ballasted plate-girder railroad bridge. Static strain data according to the damage scenario was extracted with the analysis model, and the Local damage index based on the reliability of the bridge was presented using statistical techniques. Damage was performed in a three-step process of identifying the damage existence, the damage location, and the damage severity. In the estimation of the damage severity, a linear regression model was additionally considered to detect random damage. Finally, the random damage location was estimated and verified using a machine learning-based damage detection classification learning model and a regression model.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.41 no.3
• /
• pp.201-208
• /
• 2021

In this paper, the effect on the lateral and torsional behavior of ballastless railway plate girder bridge by the installation of the lower horizontal bracing has been reviewed. First of all, the most efficient lower bracing arrangement has been reviewed by comparing and examining the lateral displacement due to the train load, targeting analysis models with different arrangement types of lower bracing. Next, the research on torsional behavior of plate girder bridge with lower bracing has been conducted. In addition, the torsion constant from FEM analysis results has been compared with the torsion constant of a railroad plate girder bridge with a closed section by substituting the upper and lower horizontal bracing with equivalent thickness. Based on this comparison, the impact on the bridge span length and the cross section area of the lower bracing has been examined. Through this study, the curve graph related to lateral buckling moment and torsional constant ratio is presented and the range of plate girder bridge requiring torsional reinforcement is proposed.