• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.387-394
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• 2019

In this study, in order to evaluate the damage and deterioration of the track components of sleeper floating track (STEDEF), the field samples(specimens) were taken from the serviced line over 20 years old, and the track components were visually inspected, and investigated by laboratory tests and finite element analysis. As a result of visual inspection, the damage of the rail pad and fastener was slight, but the rubber boot was worn and torn at the edges of bottom. The resilience pads were clearly examined for thickness reduction and fatigue hardening layer. As a result of spring stiffness test of rail pad and resilience pad, the deterioration of rail pad was insignificant, but the deterioration of resilience pad exceeded design standard value. Therefore resilience pad was directly affected by train passing tonnage. As a result of comparing the deterioration state of the field sample and the numerical analysis result, the stress and displacement concentration position of the finite element model and the damage position of the field sample were coincident.

• Journal of the Korean Society for Railway
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• v.20 no.5
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• pp.649-657
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• 2017

In this study, fatigue testing was carried out for long-term use of rail according to track type. From S-N curves for 50%~0.01% failure probability, the fatigue life of the long-term use rail for each track type was derived using the weight probability analysis technique on the experimental data. Because the rails used in the fatigue test have different cumulative tonnages, the number of repetitions was modified by averaging the cumulative tonnage. In addition, the bending stresses of rail bottoms, considering rail surface irregularities, track support stiffnesses and train speeds, were evaluated using the predicted rail bending stresses derived from existing studies. As a result, for rail fatigue life evaluation, the fatigue life of rail on the ballast track was found to be more than 200 million tons higher than the standard value for rail replacement. Also, the fatigue life of rail on concrete track is more than 300 million tons higher than that on ballast track. The Haibach rule is adaptable for the fatigue life evaluation of rail for stress range under fatigue limit.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.474-482
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• 2021

An average of two to three typhoons that occur in the Philippines or Taiwan pass through Korea each year owing to the influence of the geographical location and western winds. Because Jinhae Bay is known as Korea's representative typhoon refuge, it is filled with ships during typhoons and later becomes saturated with ships anchored to the surrounding routes. If a strong wind drags an anchored ship, a collision accident may occur because of the short distance between the ships. Therefore, a systematic anchoring safety management of Jinhae Bay is required. In this study, the minimum wind speeds of a dragging anchor based on the water depths of Jinhae Bay anchorages were investigated. When 7-9 shackles were given, the minimum wind speeds were 48-63, 46-61, and 39-54 knots at depths of 20, 35, and 50 m, respectively. As the water depth increased, the length of the cable laid on the sea bed became shorter than 5 m owing to the external force, and the minimum wind speed showed a significant difference of 4-8 knots. In addition, ships with high holding power anchors (AC-14 type) had higher minimum wind speeds than ships with conventional anchors (ASS type). Finally, it was confirmed that at a depth of 50 m, dragging easily occurred even when a high holding power anchor was applied.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.515-524
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• 2022

The turnout system of the sleeper floating tracks (STEDEF) on urban transit is a Anti-vibration track composed of a wooden sleeper embedded in a concrete bed and a sleeper resilience pad under the sleeper. Therefore, deterioration and changes in spring stiffness of the sleeper resilience pad could be cause changes in sleeper support conditions. The damage amount of manganese crossings that occurred during the current service period of about 21 years was investigated to be about 17% of the total amount of crossings, and it was analyzed that the damage amount increased after 15 years of use (accumulated passing tonnage of about 550 million tons). In this study, parameter analysis (wheel position, sleeper support condition, and dynamic wheel load) was performed using a three-dimensional numerical model that simulated real manganese crossing and wheel profile, to analyze the damage type and cause of manganese crossing that occurred in the actual field. As a result of this study, when the voided sleeper occurred in the sleeper around the nose, the stress generated in the crossing nose exceeded the yield strength according to the dynamic wheel load considering the design track impact factor. In addition, the analysis results were evaluated to be in good agreement with the location of damage that occurred in the actual field. Therefore, in order to minimize the damage of the manganese crossing, it is necessary to keep the sleeper support condition around the nose part constant. In addition, by considering the uniformity of the boundary conditions under the sleepers, it was analyzed that it would be advantageous to to replace the sleeper resilience pad together when replacing the damaged manganese crossing.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.480-493
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• 2007

Many railway-advanced countries are using the various types of track to reduce the track maintenance and repair cost according to the improvement of velocity. It spends on much maintenance and repair cost for ballast track due to abrasion of ballast, track irregularity and unisotropical ballast-support stiffness. The ballast track on railway bridge is accelerating the deterioration of ballast according to interaction of railway bridge and track. As continuing the deterioration, it is caused dynamic loads. Due to these effects, it increases negative loads of track and bridge. However, when designing the railway bridge, the effect of ballast track was applicate only dead load, so elastic behavior effect of ballast track is not influenced. Therefore, this paper presumes the stiffness of ballast track on railway bridge considering dynamic behavior of railway bridge, it was evaluated that effect on dynamic behaviors of railway bridge according to ballast track stiffness.