• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1050-1055
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• 2007

In the case of a rail road bridge extension work, especially single track to double track, the foundation of new substructure which supports the extended part of superstructure could be interfered by the exist foundation of an old bridge. When these two foundations are jointed to prevent such fatal effects of the structure as unequal subsidence of soil foundations, it is important to prove the structural behaviour of the joining surfaces between new foundation and old foundation. 3-Dimensional Finite Element Analysis Method have been studied for the solutions of the structural behaviour of the foundations. In this analysis, 'Contact Element' which allows the sliding of each adjoining member is used for the joint of the boundary surface of the old and new pier foundations. Furthermore, Material Nonlinear Behaviour Analysis also supports the accuracy of the result in this study because the foundations consist of concrete main bodies and reinforced steel bars. These detailed analyses secure the verification of the structural safety of the foundations in the extension work more firmly.

• Advances in concrete construction
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• v.10 no.1
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• pp.49-59
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• 2020

Precast concrete elements in accelerated bridge construction (ABC) extends from superstructure to substructure, precast pile foundation has proven a benefit for regions with fragile ecological environment and adverse geological condition. There is still a lack of knowledge of the seismic behavior and performance of the precast pile foundation. In this study, a 1/8 scaled model of precast pile foundation with elevated cap is fabricated for quasi-static test. The failure mechanism and responses of the precast pile-soil interaction system are analyzed. It is shown that damage occurs primarily in precast pile-soil interaction system and the bridge pier keeps elastic state because of its relatively large cross-section designed for railways. The vulnerable part of the precast pile with elevated cap is located at the embedded section, but no plastic hinge forms along the pile depth under cyclic loading. Hysteretic curves show no significant strength degradation but obvious stiffness degradation throughout the loading process. The energy dissipation capacity of the precast pile-soil interaction system is discussed by using index of the equivalent viscous damping ratio. It can be found that the energy dissipation capacity decreases with the increase of loading displacement due to the unyielding pile reinforcements and potential pile uplift. It is expected to promote the use of precast pile foundation in accelerated bridge construction (ABC) of railways designed in seismic regions.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.71-77
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• 2010

It is increasing annually that the cost for bridge Maintenance Repair & Rehabilitation (MR&R) in developed countries. Based on Intelligent Technology, Bridge Management System (BMS) is developed for optimization of Life Cycle Cost (LCC) and reliability to predict long-term bridge deteriorations. However, such data are very limited amongst all the known bridge agencies, making it difficult to reliably predict future structural performances. To alleviate this problem, an Artificial Neural Network (ANN) based Backward Prediction Model (BPM) for generating missing historical condition ratings has been developed. Its reliability has been verified using existing condition ratings from the Maryland Department of Transportation, USA. The function of the BPM is to establish the correlations between the known condition ratings and such non-bridge factors as climate and traffic volumes, which can then be used to obtain the bridge condition ratings of the missing years. Since the non-bridge factors used in the BPM can influence the variation of the bridge condition ratings, well-selected non-bridge factors are critical for the BPM to function effectively based on the minimized discrepancy rate between the BPM prediction result and existing data (deck; 6.68%, superstructure; 6.61%, substructure; 7.52%). This research is on the generation of usable historical data using Artificial Intelligence techniques to reliably predict future bridge deterioration. The outcomes (Long-term Bridge deterioration Prediction) will help bridge authorities to effectively plan maintenance strategies for obtaining the maximum benefit with limited funds.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1056-1061
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• 2007

Railroad roadbed was consisted into structure types that earthwork, tunnel, bridge and joint sections. Joint section was affected a large factor confidence and safety of the train running by stiffness transition zone that track substructure stiffness change section as like between tunnel and earthwork from ballast track to concrete track. These problems are the results of increased dynamic wheel loads, which also lead to wear and tear on vehicle components and contribute to poor ride quality. The study presented in this paper was conducted on model test by using Wheel Moving Loading System.

• 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

• Journal of the Korean Geosynthetics Society
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• v.12 no.4
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• pp.109-121
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• 2013

This paper studied the characteristics of bearing capacity of railway reinforced with geosynthetic against repetitive loading of train. The railway that was based on the porous pavement substructure ground and reinforced with geosynthetic was copied. In order to analyze load carrying capacity of geosynthetic, we have had 3cases experiments - in the first case, the ground was non reinforced, second case was reinforced geocell and last case was reinforced geogrid - and all of them were reduced-scale laboratory tests. The results of the analyses indicated that the bearing capacity of the reinforced geogrid increases much more than the reinforced geocell. Residual deformation of the initial cyclic load was larger than the secondary cyclic loads.