• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.965-975
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• 2014

Pretension PSC (Prestressed Concrete) members are subjected to a certain limit of size as they are generally produced in the off-site plant and transferred to the site due to the large scale of the product on system. In this study, a portable pretensioning production system has been developed, which allow us to apply the pretension method on site. Considering that a 50m span PSC girder using the pretension method requires a pressing device to endure a large jacking force, the portable pretension production system has to ensure safety against such a large pretension jacking force. In this study, the portable pretensioning system to produce a 50m span pretension girder was manufactured by using CFT (Concrete Filled steel Tube) members. In order to understand the stability of the system and the behavior of the elements, a static loading test was conducted and the stability of the proposed portable pretensioning production system was confirmed. The developed portable pretension system was applied to several construction sites and was investigated the problems on site. During the pretension girder and slab members that was producted by this pretension system in construction site, it has be found the several advantages such as simple fabrication processes, reduction of prestress-loss, and a decrease of 15% compared with the fabrcation cost of post-tension girder. After due consideration of the problems, this portable pretension system will be improved.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1741-1751
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• 2013

The main purpose of this study is to investigate the static behavior of a prestressed concrete (PSC) girder using pre-tension method. A 30m long full-scale pretension PSC girder is fabricated by the portable fabrication system and tested. All results have been compared to those obtained from F.E.A results. Deflections at the middle of girders have been measured for evaluation. Also, strains of concrete at the middle of span have been measured. From the results of experimental, the load when initial crack was developed was obtained to be 1.75 time the unfactered design load in the full-scale girder specimen. Also, the data of specimen are satisfied the desgin requirements of ductility on the Korea Bridge Design Specification(2010). In service state, the vertical deflection at center of test specimen when a initial crack was developed is satisfied the vertical deflection requirement under live load of the Korea Bridge Design Specification(2010). To verify the experimental results, we numerical analyze the test and confirmed that the data were similar with results from the test above. The pretension girder fabricated in site were found to have enough strength for safety under and after construction.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.515-525
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• 2016

Parameter analysis of a pretension girder bridge for urban maglev transit was performed to identify the main design parameters and their effect. Girder deflection at mid-span is the most important design criteria of urban maglev transit. Therefore, concrete compressive strength, girder height, girder length, and unbonded tendon length were selected as the design parameters that relate to girder deflection. In addition, tendon layout and unbonded tendon ratios were also considered as design parameters to control the top stress of the pretension girder section at the support. The analysis results show that both the girder height and length are dominant design parameters governing girder deflection, more important than compressive strength and unbounded tendon length. And, sensitivity analysis makes this study suggest design weight value. In terms of stress, a tendon layout that can satisfy the unbounded tendon rule requires an additional tendon or rebar at the upper section to control the tensile stress on top of the section. Therefore, to improve feasibility and constructability in the future, an enhanced unbonded tendon rule considering the load characteristics of the urban maglev system should be studied.

• Journal of Korean Society of Disaster and Security
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• v.16 no.3
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• pp.17-26
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• 2023

Prestressed Concrete (PSC) girders are divided into pre- and post-tension types as prestressing method, and I- and U-type as cross-sectional shape. There are both advantages and disadvantages depending on each prestressing method and cross-sectional shape, and each method is applied to bridge construction sites. In this study, a new girder design was attempted to develop that overcomes its shortcomings by using the pretension method and U-type cross sectional shape. Its structural performance was verified in this study. Pretension type girders are mainly manufactured in factories because they require a reaction arm and related facilities, and have the disadvantage of being limited in weight and span length for road transportation. In addition, in the case of the U-type cross-section, structural stability is very reliable during construction against overturning, but its own weight is relatively large comparing to I-type, and the post-tension method is mainly applied after on-site production. In this study, a PSC girder manufacturing method using the field pretension was proposed and a span length of 40 m real-scale test specimen was manufactured and verified its structural performance.

• Magazine of the Korea Concrete Institute
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• v.27 no.1
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• pp.45-48
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• 2015

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.463-464
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• 2010

Pre-tension Girder using Precast Concrete bed System have advantage of simplifying construction process, reducing prestress-loss and cost compared with post-tension Girder. That is because it is possible to produce pre-tension Girder by prefabricated concrete bed in site not factory. This paper present pre-tension girder method using precast concrete bed system and field application.

• Structural Engineering and Mechanics
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• v.65 no.2
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• pp.183-190
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• 2018

The prestressed concrete (PSC) technology that was first developed by Freyssinet has significantly improved over the past century in terms of materials and structural design in order to build longer, slender, and more economic structures. The application of prestressing method in structures, which is determined by the pre-tension or post-tension processes, is also affected by the surrounding conditions such as the construction site, workforce skills, and local transportation regulations. This study proposes a prestressed concrete girder design based on a hybrid segment concept. The adopted approach combines both pre-tension and post-tension methods along a simple span bridge girder. The girder was designed using newly developed 2400 MPa PS strands and 60 MPa high-strength concrete. The new concept and high strength materials allowed longer span, lower girder depth, less materials, and slender design without affecting the lateral stability of the girder. In order to validate the applicability of the proposed hybrid prestressed segments girder, a full-scale 35 m girder was fabricated, and experimental tests were performed under various fatigue and static loading conditions. The experimental results confirmed the feasibility of the proposed long-span girder as its performance meets the railway girder standards. In addition, the comparison between the measured load-displacement curve and the simulation results indicate that simulation analysis can predict the behavior of hybrid segments girders.

• Magazine of the Korea Concrete Institute
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• v.25 no.1
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• pp.59-63
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• 2013

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.434-441
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• 1999

The newly proposed Precast Segmental Mettled (PSM), which makes use of precast elements for election, is relatively new, efficient and fast mettled for the construction of prestressed box girder bridges. A precast segment of 25m long pretensioned in the fabrication yard is transported by a special trailer and a launching truss to its final position. The segments are then connected in the site by post-tensioning to make a continuous prestressed concrete box girder bridges. The purpose of this parer is to analyze and evaluate the design of precast prestressed concrete box girder bridges. The detailed analyses including time-dependent behavior of PSM bridges are conducted. The major results and findings, which have been obtained from finite element analysis of PSM bridge, are discussed in this paper and these results will be a good base for the design and analysis of a new precast bridges.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.419-424
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• 2012

This study is a research on the buckling analysis of a portable prestressing device using finite element analysis program, ABAQUS. In order to produce 50m-span PSC girders using pretensioning method, a portable prestressing device has to endure a large jacking force about 10MN. Therefore it shall be safe and stable about the jacking force. In this study, the buckling analysis technique is developed and the buckling analysis of a portable prestressing device is performed using previous studies about the analytical model that the validity of the analytical model was demonstrated by comparing analytical results with experimental results. The stability of the device to produce 10m span PSC girders is investigated.