• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.907-913
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• 1994

The design of railroad bridges differs from road bridges because of the interface between track structure and bridge structure. The track generally consists of Continuous Welded Rail(CWR) which is fixed by fasteners to the sleepers embedded in the ballast. The ballast provides the interface between the track structure and the bridge structure. Large longitudinal forces can develop from the temperature variation in rail and bridge structure. These longitudinal forces are specially important for long bridges because the bridge layout for span length, pier dimensions and arrangement and type of bearings can be governed by these forces. This report provides a comparison of longitudinal track forces determined by analysis and actual measured track forces. In recent practice the longitudinal track force for European railways is analyzed using a finite element analysis method. This method is very time-consuming and requires the detail design of the bridge to be complete. Redesign is required if the design criteria for longitudinal track forces are not satisfied. There is a need to develop a simple analysis method considering the large number of bridge structures and a relatively short design time on the Korean High Speed Rail Project. The analysis results presented herein, based on a simplified analysis, show good agreement with those obtained by finite element analysis, as well as with those measured on an actual track. The proposed analysis method is particularly useful for the preliminary design of bridge structures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.589-597
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• 2015

In this paper, the live load model for the design of high-speed railway bridge is analyzed by statistic and probabilistic methods and the safety level that is given by the load factors of the load combination is analyzed. This study is a part of the development of the limit state design method for the railway bridge, and the train data collected from the Gyeongbu high-speed railway for about one month are utilized. The four different statistical methods are applied to estimate the design load to match the bridge design life and the results are compared. In order to examine the safety level that the design load combination of the railway bridge gives, the reliability indexes are determined and the results are analyzed. The load effect from the current design live load for the high-speed rail bridge which is 0.75 times of the standard train load is came out greater than at least 30-22% that from the estimated load from the measured data. If it is judged based on the ultimate limit state, there is a possibility of additional reduction of the safety factors through the reliability analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.6
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• pp.751-760
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• 2021

Most bridges in Korea are over 20 years old, and many problems linked to their deterioration are being reported. The current practice for bridge inspection mainly depends on expert evaluation, which can be subjective. Recent studies have introduced data-driven methods using building information modeling, which can be more efficient and objective, but these methods require manual procedures that consume time and money. To overcome this, this study developed an image-based automaticbridge component classification network to reduce the time and cost required for converting the visual information of bridges to a digital model. The proposed method comprises two convolutional neural networks. The first network estimates the type of the bridge based on the superstructure, and the second network classifies the bridge components. In avalidation test, the proposed system automatically classified the components of 461 bridge images with 96.6 % of accuracy. The proposed approach is expected to contribute toward current bridge maintenance practice.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.9
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• pp.620-627
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• 2015

Long continuous bridge deck can become contracted considerably as temperature drops, which can lead to a large expansion of sleeper span at the end of it. Since this huge sleeper span then can cause problems both with safety of train operation and structural stability of tracks, it is necessary to take the issue into consideration systematically in the designing process of the bridge. In this paper, an evaluation process through the analysis of train-track interaction was presented which can basically review the effects of the expansion of sleeper span at the end of long continuous bridge deck on the safety of the train and the structural stability of the track. The analyses of the interaction between the light rail train and tracks were carried out targeting the sleeper span as a main parameter. The safety of train operation and structural stability of tracks in a light rail system due to the expansion of the sleeper span were evaluated by comparing the numerical results with the related criteria.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.52-59
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• 2015

In the conventional model for the prediction of the railway environmental noise, one used an empirical formula of the total noise level at specific distances. Only a function of the distance to the source was also used to calculate the noise level near the railway bridges. However, the noise varies depending on the position of the receiver as well as the distance from the source especially at concrete bridges. In this paper, a noise propagation model in the railway concrete bridge was derived by considering the diffraction at the bridge deck and the ground effect and applying the ISO 9613-2 noise propagation model. We compared the predicted and measured values of environmental noise at a high-speed railway bridge, and it was confirmed that this prediction model gives relatively small errors.

• Journal of Korean Society of Steel Construction
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• v.15 no.2
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• pp.187-196
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• 2003

Today, the Working Stress Rating (WSR) is being widely used for the capacity-rating and the safety assessment of railroad steel bridges. Since it cannot incorporate the uncertainties, several studies have been carried out in order to get over the incompleteness of the conventional capacity-rating and safety assessment. A system reliability-based equivalent capacity-rating method, which can evaluate the capacity of existing bridges, has been recently proposed. For more efficient reliability analysis, probabilistic parameters of the random variables in the limit-state models should be reasonably evaluated. Especially, uncertainties for live load effects must be realistically included. In this study, an improved limit-state model was used for the system reliability-based equivalent strength method. This model can incorporate the probabilistic parameters obtained from ambient measurement data. To demonstrate the applicability of the improved system reliability-based equivalent capacity rating method, this was applied to the existing steel plate girder bridge for comparison with the conventional capacity-rating and safety assessment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6D
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• pp.867-874
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• 2011

The ballast abrasion occurs on the ballasted track upon bridges more than soil roadbed because the track vibration occurs a lot in the ballasted track upon bridges due to girder vibration when a train's weight is loaded onto track even though the identical ballast is used. The phenomena of mud pumping especially, which occurs when drainage is not properly secured for heavy rain, leads to the increase of maintenance work load and the decline of ride comfort. The ballast thickness range in domestic railroad construction rule is uniformly set up according to the design speed of railroad and passing tonnage of train without considering field conditions which is considered in foreign railroad companies. The purpose of this study is to verify the effect of vibration decrease by measuring the acceleration, displacement and ride comfort of ballasted track with the change of ballast thickness on the ballast tracked bridges and to suggest the optimal height of ballast on the Yocheon Bridge built for the test in Honam Line.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7957-7963
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• 2015

R&D trend for Auxiliary Power Supply(APU) of electric vehicle can be well understood by analyzing patents at home and abroad. Based on this trend analysis, domestic technology development direction is proposed. To get technique trend, patents of Korea, Japan, Europe and America published until February of 2014 are analyzed by WIPS DB. First, power converter and transformer two big category are classified. Power converter can be classified into resonant DC to DC converter and resonant Half bridge inverter; transformer can be classified into high frequency transformer, ferrite transformer and matching transformer. By analyzing R&D trend of different counties, companies and years, specific technology needed to be developed and trend of technology can be accurately grasped.

• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.89-96
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• 2015

To reduce noise inside an elevated railroad station, the vibration of the station structure should be lowered, and to establish more effective anti-vibration measures it is required that, reflecting the track-bridge-structure interaction, the transfer characteristics of vibration induced by a train is well identified. In this paper, the current status of domestic railroad stations is classified, and the vibration transfer characteristics is analyzed via measurement data from representative elevated stations. From the analysis results on the measurement data, in transferring vibration from the track to the structure, remarkable vibration reduction in higher frequency range is observed, and, in some stations, amplified response characteristics in lower frequency range is identified. Also, for stations with floating track system or TPS type, relatively greater reduction in transferred vibration is observed.

• Journal of the Korean Society for Railway
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• v.16 no.4
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• pp.286-297
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• 2013

In this paper we evaluated dynamic stability, considering the effects of modeling and analysis methods on moving load analysis, for which a sophisticated 3 dimensional model of a PSC-I type girder bridge was used. For this purpose, we suggested a reasonable modeling method and the physical properties of the concrete and ballasted track system involved. We also analyzed the response characteristics according to: 1) the type of track system; 2) whether or not the track was modeled; 3) whether or not the distance between the girder center and the bearing were considered; 4) the analysis method (i.e., direct integral and modal analysis); 5) whether or not the frequency was filtered.