• Journal of the Korea Concrete Institute
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• v.12 no.4
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• pp.121-130
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• 2000

Current engineering practice in determining sectional dimensions of prestressed concrete (PSC) girders for bridges is primarily based on the code-specified allowable concrete stresses at different loading stages. It is customary that tendons and sectional dimensions are calibrated and tendon forces are applied at once at the initial stage to keep the subsequent stresses occurring at different loading stages within the allowable stresses. This traditional tensioning method, however, usually results in a too conservative sectional depth in view of ultimate capacity of a girder. A new design method which can realize the reduction of sectional depth of PSC girders is theoretically suggested in this study. Tendons are tensioned twice at different loading stages: the initial stage and the stage after fresh slab concrete is cast. It can be shown that according to this technique, sectional depth can be significantly reduced and larger span can be realized compared to traditional ones. Parametric studies are performed with due considerations given to its practical applications.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1707-1721
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• 2014

Half-depth panels were developed with the merits of CIP (Cast In Place) decks and precast decks for constructability and fast construction. In this paper, details of half-depth panels with pre-tensioning were suggested. For evaluation of structural performance, five half-depth panel specimens were fabricated and static tests were conducted. The cross-sections of these specimens were composed of pre-tensioned half-depth panels and pre-tensioned two-span half-depth panels. Test parameters were the amount of the prestressing force and the longitudinal reinforcements. Static tests on simply-supported slabs showed that ultimate strength was 1.55 times greater than calculated nominal strength. The flexural strength was only 10 % increased and the influence on crack width control was negligible when the member of tendons was increased twice. For two-span continuous specimens, the ultimate strength increased 1.2 times and 1.38 times respectively as the reinforcement was additionally provided. The verified half-depth panels by this research can be effectively utilized for the fast replacement or construction of bridges.

• Journal of the Korea Concrete Institute
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• v.24 no.1
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• pp.71-78
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• 2012

In order to improve the shear strength of conventional pre-tensioned spun high strength concrete (PHC) pile, concrete-infilled composite PHC (ICP) pile, a PHC pile reinforced by means of shear reinforcement and infilled concrete, is proposed. Two types of specimens were cast and tested according to KS (Korean Standards) to verify the shear strength enhancement of ICP pile. Based on the test results, it was found that the KS method was not suitable due to causing shear failure of ICP pile. However, shear strength enhancement was clearly verified. The obtained shear strength of the ICP pile was more than twice that of conventional PHC pile. In addition, the shear strength of ICP pile reinforced with longitudinal reinforcement was estimated to be more than 2.5 times greater than that of conventional PHC pile. The allowable shear force of ICP pile, which was determined by the allowable stress design process, indicated a large safety factor of more than 2.9 compared to the test results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.149-158
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• 2003

It is customary that tendons and sectional dimensions are calibrated and tendon forces are applied at once at the initial stage to keep the subsequent stresses occuring at different loading stages within the allowable stresse in prestressed concrete (PSC) bridge design. However, this traditional tensioning method usually results in a too conservative sectional depth in view of ultimate capacity of a girder. A new design method which can realize the reduction of sectional depth of PSC girder is theoretically suggested in this study. Tendons are tensioned twice at different loading stages: the initial stage and the stage after fresh slab concrete is cast. It can be shown that according to this technique, sectional depth can be significantly reduced and larger span can be realized compared to traditional ones. In this paper, there is an example about the design of bridge by means of new PSC design theory, having a longer span than a existing railway bridge. Also, a new method by continuous tendon profiles is presented to be continuous a IPC bridge.