• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.347-354
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• 2001

Extradosed PSC Box bridges, newly emerging type of structures in construction market, have a characteristic in that external tendons are used for strengthening PSC Box girder like stay cables in cable stayed bridges. In this study, a series of constructions stage analysis procedure, including initial shape analysis, backward analysis and forward analysis, have been performed in order to investigate long-term behavior of extradosed PSC box bridges, using PCCAP-a computer program for time-dependent stage analysis of PSC cable stayed bridges. CEB-FIP 1978 model was used for the consideration of time-dependent effect of concrete material. Showing the validity of the analysis results with RM SPACE FRAME, it has been confirmd that time-dependent effects become less consequential as the stiffness of girder becomes larger.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.235-242
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• 2001

An optimization algoriam for the optimum design of prestressed concrete (PSC) box girder bridges is proposed in this paper. In order to optimize the tendon profile efficiently, a reduced basis technique is introduced. The optimization algorithm which includes the tendon profile, tendon size and concrete dimensions optimization problem of the PSC box girder bridges is verified on the Genetic algorikhm (GA) from the numerical examples. it may be positively stated that the optimum design of the PSC box girder bridges based on the new approach proposed in this study will lead to more rational and economical design compared with the currently available designs.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.5
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• pp.97-105
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• 2006

PSC box girder bridges usually have a lot of tendons, and the difference of the bursting forces lies in the prestressing order of the tendons. As a result of the lack of studies on the prestressing order for the bridges, the order depends on the designer's intuition and experiences. In this paper, with investigation into various methods determining the bursting force of the anchorage, reasonable prestressing order is determined by analysis of PSC beam bridge and PSC box girder bridge with most suitable method. It may be stated that this study would be useful for determining the reasonable prestressing order of tendons for the PSC box girder bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1157-1162
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• 2000

Transverse stress and longitudinal crack which are induced by temperature difference in box-girder sections and slab of which box-girder is composed have an important effect on endurance and economical efficiency of bridges. The study on longitudinal behavior of bridges which are subject to thermal load is reflected on the design of bridges. But, the study on transverse behavior of bridges has been performed just recently in foreign countries of finding the cause of longitudinal crack and in Korea, has not been tried in spite of large temperature variance due to geographical condition. This study examines temperature distribution feature in box-girder sections and bridge behavior due to thermal load, with measuring temperature distribution and stress of PSC box-girder bridge which is being constructed actually, and investigates appropriateness of design thermal load of highway bridge design code.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.3
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• pp.309-318
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• 2004

This research automatically designed psc-box girder bridges by using an optimum design program and applied the results to the various types of bridges to verify if common facts used in steel bridges or concrete bridges can be applied to PSC bridges. Namely, it investigated appropriate unequal span length division by comparing with bridge of unequal and equal span length division, and verified the influence of the load factors which are changed by time or specification applying the results to various types of bridge. and it applied reinforced concrete bridge and steel bridge's variable girder depth which is slender and effective to save material costs to PSC box girder bridges. Technical solution of optimum design program used SUMT procedure, and Kavlie's extended penalty function to allow infeasible design points in the process. Powell's direct method was used for searching design points and a gradient's approximate method was used to reduce the design time.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.591-594
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• 2003

It is reported that the amount of reinforcements for domestic PSC box girder bridges is used two times more that those for foreign PSC box girder bridges, which is considered to be irrational and uneconomical. Therefore, we have come to the conclusion through this study that the advanced design direction can reduce the amount of reinforcements under the condition that the static load test and the nonlinear analysis for the specimen of the PSC box girder bridge with reduced reinforcements which is designed by advanced design direction was carried out in order to verify the validity of the advanced design direction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.2
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• pp.103-109
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• 2001

In this paper, the prestressing order of tendons is studied to minimize a bursting force of an anchorage. The bursting forces is a primary factor of anchorage failures. The forces of the anchorage depend on the prestressing order and size of the tendons, if a lot of tendons are introduced to the anchorage. Many studies have been made to analyze the bursting force of the anchorage. However, the studies have been limited to the bursting forces of the anchorage having one or two tendons. PSC box girder bridges usually have a lot of tendons. And the difference of the bursting forces lies in the prestressing order of the tendons. As a result of the lack of studies on the prestressing order for the bridges, the order depends on the designer's intuition and experiences. It may be stated that this study should be useful for determining the reasonable prestressing order of tendons for the PSC box girder bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.701-705
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• 1998

The objective of this study is to develop the practical program which can check the constructible possibility of prestressed concrete box girder bridges for design. Checking constructible possibility is defined as checking the interference of each elements in a PSC box girder bridge and computing the distances of each elements. To check the constructible possibility of a PSC box girder bride, bridge must be modelled using solid in three dimension. By using a 3 dimensional solid modeling system, engineers can get the photo realistic 3D viewing images of the bridge and produce FEM analytic model of it. Users can manipulate their drawings easier and take off quantity of the whole structure and its elements as well as check the constructible possibility of their PSC box girder bridges.

• Journal of the Korean Society of Safety
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• v.21 no.3 s.75
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• pp.94-100
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• 2006

The goal of this study is to show the way to increase the safety of deteriorated PSC beam bridges by the to-box reinforcing method. This method is to change the open girder section into the closed box section by connecting bottom flanges of neighboring PSC girders with the precast panels embedding PS tendons at the anchor block. The box section is composed of three concrete members with different casting ages, RC slab, PSC beam, precast panel. This different aging requires a time-dependent analysis considering construction sequences. Reliability index and failure probability are produced by the AFOSM reliability analysis. Transversely five schemes and longitudinally two schemes are considered. The full reinforcing scheme, transversely and longitudinally, shows the highest reliability index, but it requires more cost for retrofit. The partial reinforcing scheme 4, 4-1 are recommended in this study as the economically best scheme.

• Journal of the Korean Society of Safety
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• v.21 no.4 s.76
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• pp.95-101
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• 2006

It is well known that the thermal load in PSC(prestressed concrete) box-girder bridge is the principal cause of detrimental crack. The longitudinal stress caused by the lateral stress from the temperature gradient in slab of PSC box-girder bridge has a considerable influence on the durability and economy of bridge structures. As the basic study for the rational consideration of thermal load and the derivation of design guide, the inverse thermal analysis program for PSC box-girder bridges using field measurement data is developed. In this paper, thermal analyses are performed using field monitoring data for the sample PSC box-girder bridge. It is proposed that the link between monitoring program and the inverse analysis program is available.