Abstract：Abstract：Research purposes： The structure selection of bridge across the existing lines should not only consider the construction method and construction schedule, but also consider the operation safety of the existing railway. Reasonable structure selection can not only ensure the successful completion of the project, but also minimize the interference to the operation of the lower line. Continuous steel box girder is a new railway bridge structure, the structure shape closed can effectively avoid the construction debris fall, also has a flexible matching condition, without temporary pier construction, which is suitable for bridge construction with limited space, is the best choice across existing lines. In this paper, taking the Extra-long Bridge of Datong-Xi′an dedicated passenger tie-line as the engineering background, the calculation method of steel box girder, the temperature value, the fracture mode of bridge deck concrete and the stress concentration at the abutment are explored. Research conclusions： (1) The whole bridge is calculated by full bridge model and simplified calculation, and the comparison is made. (2) For the uneven heating, the current standard only prescribes on the steel structure and concrete box girder with concrete bridge deck, and didn't make provisions on the steel box girder structure, the design refers to the British standard BS 5400 value. (3) For the bridge deck concrete, break-joint form of partial disconnecting is adopted. (4) The bridge support relies on vertical stiffener plate based on irrigation, partial filling of micro expansive concrete in the floor support, with shear stud connections between steel plate and concrete, which can make full use of the good compressive property of concrete and advantageous tensile property of steel, can effectively improve the bearing stiffness, significantly optimize the stress distribution. (5)The research results can provide reference for the design of the similar bridges in the future.
2017, Vol. 34 
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