• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.4 s.56
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• pp.137-147
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• 2009

In this study, several flexural vibration characteristics of prestressed concrete girders due to changes in prestress forces are experimentally analyzed. In order to achieve the objective, the following approaches are implemented. First, several methods to extract vibration response features from output-only signal are selected. Next, a large-scaled prestressed concrete girder model is constructed to analyze relation between the prestress forces and the vibration features in the prestressed concrete girder. Then acceleration responses are measured from the girder for several prestress force scenarios. Finally, vibration characteristics of the prestressed concrete girder due to change in prestress force are experimentally analyzed. The values of features extracted by the selected methods are reduced due to prestress-loss. Especially, the value of features are linearly reduced in the early prestress-loss.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.361-364
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• 2008

This study was performed to estimate the anchorage behavior for Bi Prestressed Concrete Girder(Bicon girder) which could introduce effectively prestressed forces into concrete girders. A bicon girder is manufactured by means of introducing pure bending moment that prestress simultaneously the compressive member(steel bar) and the tensile member(steel tendon). Therefore, the steel bar and the steel tendon must be unified in both ends and compressive and tensile force be offset. Anchorage dimension of 6 test specimens was designed under PTI specification which defined maximum stress and deformation to estimate structural behavior. Test results showed that the stress and the deformation of anchorage were within limits if the steel bar behaviored elastically.

• Steel and Composite Structures
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• v.3 no.1
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• pp.65-73
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• 2003

A higher level of engineering standard in the field of construction, is the use of prestressing in building structures. The concept of prestressing steel structures has only recently been widely considered, despite a long and successful history of prestressing concrete members. Several analytical studies of prestressed steel girders were reported in literatures, but much of the work was not studied with reference to the optimal design and behaviour of the prestressed steel plate girder. A plate girder prestressed eccentrically, will behave as a beam-column, which is subjected to axial compression and bending moment which will cause the beam to buckle out. The study of buckling of the prestressed steel plate girder is necessary for stability criteria. This paper deals with the stability of prestressed steel plate girder using concept of "Vlasov's Circle of Stability" under eccentric prestressing force.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.40-43
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• 2004

A new design method for prestressed concrete girder is proposed in this study, which steps for manufacturing are; (1) the bottom part of concrete girder is placed and pretensioned by the first post-tensioning performed on the tendons located in the bottom part of concrete girder, and (2) the next step which consists of concrete placing and post-tensioning operation is followed by the previous step if required. This indicates that sufficient compressive stress can be effectively introduced at the bottom face in stepwise manner, when compared to conventional PSC girder. Two specimens are prepared and tested to investigate the short-term behavior of the PSC girders manufactured by the proposed method. Section Analysis results exhibit good agreements with the test results in terms of strain distribution across the girder section. In addition, flexural strength obtained from the tests is found to be similar to the expected based on Code(Korea). These demonstrate that the method proposed in this study is applicable to the design of PSC girders.

• KCI Concrete Journal
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• v.11 no.3
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• pp.99-107
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• 1999

In designing the Prestressed concrete box-girder bridge. dead load, prestressing force, creep and shrinkage of concrete are the main factors which influence the camber and deflection of segmental concrete structure under construction. Among these factors the creep and shrinkage are the functions of the time-dependent property which. therefore, must be considered with time. The prediction model for estimating creep and shrinkage of concrete has been suggested by ACI, CEB/FIP, JSCE and KSCE design code and EMM, AEMM, RCM, IDM and SSM has been suggested for analytical method in consideration of time-dependent characteristics. In this study the creep test was carried out for four different curing ages of concrete which were applied to the Prestressed concrete structure at the construction site, and the results of test were compared with the values of creep prediction proposed by the design code. Also the creep test was performed with step-wise incremental stresses and the results were compared to the analytical values.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.685-688
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• 1999

The analysis and design of composite girders prestressed by external tendons involve difficulties related to the position of anchorages and the construction sequences. In this paper, the efficiency of the external tendon profiles and the position of anchorages in examined for the internal and external prestressing of statically indeterminate structures. It is shown that strengthening of a prestressed girder can be accomplished using a variety of methods; bonded external prestressing, tendon replacement and unbonded external prestressing.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.2
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• pp.8-16
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• 2015

Prestressed concrete (PSC) is a method in which prestressed tendon is placed inside and/or outside the reinforced concrete member and the compressive force applied to the concrete in advance to enhance the engineering properties of concrete member which is weak under tension. In this paper we suggested the precast PSC girder assembled with segments of portable size and weight at the factory. The segments of precast PSC girder will be delivered and assembled as a unit of PSC girder at the site. Consequently, we suggested new-type of precast segmented PSC girder with different shapes of segment cross-section (i.e., I-shape, Box-shape). To mitigate the problems associated with the field splice between the segments of precast PSC girder anchor system is attached near the neutral axis of the girder and relatively uniform compression throughout the girder cross-section is applied. Prior to the experimental investigation, analytical investigation on the structural behavior of precast PSC girder was performed and the serviceability (deflection) and safety (strength) of the girder were confirmed. In addition, 4-point bending test on the girder was conducted to investigate the structural performance under bending. From the experimental investigation, it was found that the precast PSC girder spliced with 3 and 5 segments has sufficient in serviceability and safety conditions and it was also observed that the point where the segments spliced has no defects and the girder behaves as a unit.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1007-1013
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• 2004

A new type of girder named as Steel-Confined Prestressed Concrete Girder(SCP Girder) has been developed, which is composed of concrete, steel plate, and prestressing tendon. This girder may maximize structural advantages of these components, therefore it can be used to construct the middle or long span bridge with low-height girder. To verify the propriety of design, structural safety, and applicability of this girder, static load test was carried out. In this study, a design program was developed for practical design of railway bridge using SCP girder. And to verify the applicability of SCP girder to railway bridge, structural performance and economic efficiency based on the construction cost were compared with conventional railway bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.268-273
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• 1995

In recent years, precast prestressed concrete segmental box girder bridges have been increasingly constructed Expansion disphragm segment of this type bridge transfers forces from the superstructure onto bearing or column, and plays an important roll of anchorage zone for longitudinal prestressed forces. Non-linear stresses occur inside of diaphragms by these extensive concentrated forces. In this study, the strut-and-tie models are proposed to design an expansion segment rationally. A formula to determine the effective transverse prestressed forces is proposed on the basis of these models. The present study is expected to provide an effective tool to design expansion segment of prestressed concrete bridges rationally.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.2
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• pp.77-89
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• 2004

This study was carried out to find out the reasonable optimum design method for the design of prestressed concrete structures. The optimum design problems were formulated and computer programs to solve these problems were developed. To test the reliablity, efficiency, possibility of application and reasonablity of optimum design problems and computer programs, both continuous optimization method and mixed-discrete optimization method were applied to the design of prestressed concrete composite girder and application results were discussed. It is proved that mixed-discrete optimization method is more reliable, efficient and reasonable than continuous optimization method for the optimum design of prestressed concrete structures.