• 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.

• Structural Engineering and Mechanics
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• v.69 no.4
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• pp.371-381
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• 2019

A hybrid prestressed segmental concrete (HPSC) girder utilizing low carbon materials was developed in this paper. This paper introduces the hybrid prestressing concept of pre-tensioning the center segment and assembling all segments by post-tensioning, as well as the development process of the low carbon HPSC girder. First, an optimized mix proportion of 60 MPa high strength concrete containing high volume blast furnace slag was developed, then its mechanical properties and durability characteristics were evaluated. Second, the mechanical properties of 2,400 MPa high strength prestressing strands and the transfer length characteristics in pre-tensioned prestressed concrete beams were evaluated. Third, using those low carbon materials and the hybrid prestressing concept, the HPSC girders were manufactured, and their structural performance was evaluated. A 30-m long HPSC girder for highway bridges and a 35-m long HPSC girder for railway bridges were designed, manufactured, and structurally confirmed as having sufficient strength and safety. Finally, five 35-m long HPSC girders were successfully applied to an actual railway bridge for the first time.

• Journal of the Society of Disaster Information
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• v.12 no.4
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• pp.422-431
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• 2016

This study was evaluated in the performance of the connection according to the details of the concrete casing segment in the prestressed composite girder by fabricating and testing specimens with different segments. A total of four comparative specimens were fabricated by using the variables of general composite girders, reinforcement or non-reinforcement, and details of reinforcing bars in the segments so as to evaluate the structural behavior of steel girders. In addition, the possibility of non-cracking grade design of segmented composite girders as well as the effects of stiffness and strength according to the loop connection types after cracking were analyzed, and the appropriateness of the crack width control both the embedded steel plate and the concrete surface were evaluated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.277-286
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• 2010

Derrick or caterpillar crane is generally used for the long-span/cable-stayed bridge construction by pre-cast segment lifting from over-land or water transportation. The heavy weight of them, however, could make defects on unstable under-construction structure and, furthermore a method of conventional segment transportation is also able to occur additional time and cost. In this study, in order to improve conventional construction method, the newly developed derrick crane is mainly considered. It could be not only eccentrically loadable on constructing girder but having rotatable boom for segment transportation from back-side. A series of construction stage using developed derrick crane is defined and also its numerical analysis is conducted. To reflect load characteristics of developed derrick crane on construction stage analysis, on/out of service load is separately calculated by considering vertical/lateral rotation range of boom and it is loaded on 4 fixed positions of crane. The derrick crane on this study could be time and cost saving solution for cable-stayed bridge construction and also make contributions to construction load reduction in its process.