• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.2
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• pp.151-157
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• 2019

Concrete bridge constructed in metropolitan cities has different superstructure members like slabs and girders, and their carbonation depths vary with different design strengths and local environmental conditions. In this paper, 54 concrete cores were obtained from prestressed concrete girders and the related tests were performed for compressive strength and carbonation depth measurement. Referred to the specified compressive strength of 24MPa for slab and 35MPa for I-type girder, the strengths from cores were evaluated to 82% and 73% of design grade, respectively. For carbonation depth, the slab member showed 30.6mm of average with 32.9% of COV(Coefficient of Variation) and I-type girder showed 16.7~17.0mm with 22.8~33.6 of COV. The I-type girder has much lower carbonation depth and COV compared to slab member, however it has higher COV than column structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.77-83
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• 2014

Prestressed concrete girder bridge has been one of the most widely used bridges in the world because of its excellent construction feasibility, economic efficiency, serviceability, and safety. In certain situations, the prestressing tendon is supposed to be bent by the construction error and the radius of curvature at the continuous joint of PSC girders, and this leads to the loss of prestressing force. However, this kind of prestress loss is not considered in the design and construction processes. This study proves that the prestress loss occurs at the continuous joint due to the local bending of tendon by the construction error or the radius of curvature. Also, a method that can reduce this type of prestress loss is proposed, and proved by the experiment. The result shows that maximum 10% of prestress loss occurs at the continuous joint and the proposed block-out method can reduce the prestress loss ratio by maximum 5%, approximately. This means that the block-out method can enhance the prestressing efficiency of continuous PSC girder bridges.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.171-180
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• 2007

Reliability analysis of prestressed steel and concrete(PSSC) girders is conducted for deflection, stress and moment strength limit state. PSSC girder has strong advantages in terms of construction cost and vertical clearance for the span length of over 40 meters. In this paper, example PSSC girders with different span lengths, section dimensions and design stress levels are designed and analyzed to calculate the midspan deflection, stress and the section moment strength. Deflection limit state, stress limit state and strength limit state functions are assumed and the reliability indexes are obtained by Monte-Carlo simulation and Rackwitz-Fiessler procedure. The results show that the reliability of PSSC girder for deflection limit state is appropriately higher than the stress limit state and the reliability for moment strength is significantly conservative.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.04a
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• pp.105-110
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• 1992

This study deals with the effect of a series of moving trucks on the Dynamic Load Factor (DLF). The DLF is calculated by investigating the load effect of moving trucks. Therefore, analytical models for frocks, bridge, and road profiles were developed and dynamic structural analysis computer program were developed. Then the DLFs are calculated as a ratio of maximum dynamic load effect and maximum static load effect. Trucks used in this study are 5 axle semi tractor-trailer with the weight of 36 and 54 ton. Simply supported prestressed concrete box girder bridges with 20 and 40m span length are selected. From the results of the DLF for various headway distances, they show a very scattered and relatively high values of the DLF in case of a 20m span length bridge. For a 40m span length bridge, the results show less scattered and small increase of the DLF compared to a 20m span length bridge.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.401-407
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• 2001

Out of 412km long Kyung-bu high-speed railway, 302km was designed in tile form of either bridges or tunnels. Most of bridges were designed to be prestressed concrete box girder type. The precast span method was selected because of good quality of bridge section secured by factory manufacturing, fast construction speed, low construction cost with mechanized construction and the safety fur field workers. The precast span method has been mainly utilized in bridges consisted of repeated simple spans. However, we applied the precast span method to continuous bridge for high-speed railway Since it was the first attempt to apply ate precast span method to a continuous bridge for high-speed railway, many design and construction details were studied and implemented in the construction. Design and construction processes of a continuous bridge construction using tile precast span mettled are briefly described in this paper.

• Journal of Korean Society of Steel Construction
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• v.29 no.4
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• pp.311-321
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• 2017

This paper deals with the flexural performance of a composite girder system designed to readily form a composite section without a formwork and to easily realize multistage preflexing and prestressing. After a 3-Dimensional finite element modeling for construction stage analysis, the parametric numerical analysis was performed to analyse the stress distribution on the composite girder sections and the prestressing effects along with concrete pouring method and strand tensioning method. Based on the stress distribution analysis, a favorable construction stage model has been rationally chosen and then the ultimate flexural strengths were evaluated to conduct a comparative study, which exceed the nominal flexural strength suggested by the current design specification(ASD). It can be concluded that the proposed composite girder and fabrication procedure should have a sufficient structural performance.

• Structural Engineering and Mechanics
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• v.81 no.1
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• pp.69-79
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• 2022

The dynamic responses of a pier-pile-soil system subjected to a barge/flotilla collision are analyzed. A coupled high-speed train and bridge system with a damaged pier after barge/flotilla collision is established by taking the additional unevenness of the track induced by the damaged pier as the self-excitation of the system. The whole process of a CRH2 high-speed train running on the 6×32 m simply-supported PC (prestressed concrete) box-girder bridge with a damaged pier is simulated as a case study. The results show that the lateral displacements and accelerations of the bridge with a damaged pier are much greater than the ones before the collision. The running safety indices of the train increase with the train speed as well as with the number of barges in the flotilla. In flotilla collision, the lateral wheel/rail forces of the train exceed the allowable values at a certain speed, which influences the running safety of the trains.

• Journal of the Society of Disaster Information
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• v.9 no.2
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• pp.188-194
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• 2013

As the high speed railroad line increases, researches on developing a more economic high speed railroad bridge system have been actively conducted. In this paper, a new type of prestressed concrete girder based on the bi-prestressing technique, which can introduce additional prestress, is presented. The additional prestress can be introduced using a wedge-shaped pin bar into the upper part of the girder section. The applicability of the new girder technique to the high speed railroad bridge is verified via the dynamic stability analysis. Dynamic moving load analyses using the KTX train load are conducted on bridge systems with the span lengths of 30m, 35m, and 40m, respectively. The results of the analysis show that all bridge systems satisfy the limits prescribed in the design specifications to ensure structural stability, driving safety, and ride quality.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.3
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• pp.219-227
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• 2016

In this study, we have proposed a method of monitoring of bridges under construction in view of the long-term behavior of the prestress concrete bridge of which the Free Cantilever Method is applied. As a method to confirm the ability of the long-term behavior of the concrete box girder, temperature sensors and strain gauges were installed, and the measured data was used to calculate creep coefficient. Moreover, we have measured the stress of the concrete box girder during construction which was applied with creep coefficient and compared with the changes in temperature to analyze the vertical displacement along the segment. In conclusion, monitoring of the FCM bridge during construction in consideration of the long-term behavior can be analyzed efficiently by suing temperature and displacement data without the use of laser displacement meter or laser delfectometer.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1158-1164
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• 2007

Recently, the demand on the practical application of life-cycle cost effectiveness for design and rehabilitation of civil infrastructure is rapidly growing unprecedentedly in civil engineering practice. Accordingly, it is expected that the life-cycle cost in the 21st century will become a new paradigm for all engineering decision problems in practice. However, in spite of impressive progress in the researches on the LCC, so far, most researches in Koreahave only focused on roadway bridges, which are not applicable to railway bridges. Thus, this paper presents the formulation models and methods for uncertainty-based LCCA for railroad bridges consideringboth objective statistical data available in the agency database of railroad bridges management and subjective data obtained form interviews with experts of the railway agency, which are used to anew uncertainty-based expected maintenance/repair costs including lifetime indirect costs. For reliable assessment of the life-cycle maintenance/repair costs, statistical analysis considering maintenance history data and survey data including the subjective judgments of railway experts on maintenance/management of railroad bridges, are performed to categorize critical maintenance items and associated expected costs and uncertainty-based deterioration models are developed. Finally, the formulation for simulation-based LCC analysis of railway bridges with uncertainty-based deterioration models are applied to the design-decision problem, which is to select an optimal bridge type having minimum Life-Cycle cost among various railway bridges types such as steel plate girder bridge, and prestressed concrete girder bridge in the basic design phase.