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Title |
Long-term Camber Analysis of PSC Composite Beam for Railway Bridge Considering Changes in Loading Time and Prestressing Force
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Authors |
김경현(Kyung-Hyun Kim) ; 김기현(Ki-Hyun Kim) ; 백인열(In-Yeol Paik) |
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DOI |
https://doi.org/10.11112/jksmi.2024.28.6.12 |
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Keywords |
크리프 처짐; PSC 합성보; 철도 교량; 증분 시간단계 해석; 재하 기간; 설계 활하중 Creep deflection; PSC composite beam; Railway bridge; Incremental time-step analysis; Loading period; Design live load |
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Abstract |
As part of a study to analyze the excessive camber occurring in prestressed concrete railway bridges, this paper develops a time-dependent camber analysis program for concrete structures and analyzes the change in camber according to the variation of applying time and duration of prestressing force and self-weight as well as the change in live load. The incremental time-step analysis method is applied in order to consider time-related variables such as the strength of concrete in early stage, the applying time and duration of the prestressing force and loads, and the decrease in prestressing force over time. The equations for calculating the creep coefficient and loss of prestressing force are applied according to the domestic bridge design codes. By applying the developed method to an example PSC composite beam for railway bridge, the instantaneous deflection at various loading points and the long term creep deflection for the loading period are obtained. Also the effect of reducing the camber is examined when the prestressing force is reduced considering the degree of allowance of the railway live load. Through numerical examples, it can be shown that the camber increases if the initial prestressing force is introduced early or the period to the slab placement is long or a combination of the two. When the live load is reduced by taking into account the actual train weight, the camber is reduced.
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