| Frame bridge structure is more commonly used to solve the problem of the cross form of rail and road. Urban traffic volume has increased, the need for a bridge to span larger framework to meet traffic requirements. Now in engineering design 16m span reinforced concrete structure, to meet the stiffness requirements, the thickness of roof has more than 1m. Excessive structure size not only increases the weight of the structure, but also greatly increase the difficulty and risk jacking construction. In this paper, steel reinforced concrete structure is creatively introduced into the frame bridge. According to the advantages of steel reinforced concrete structure, under the premise of not reducing the span, for the purpose of reducing the section height of the frame Bridge beam, optimizing the structure design and reducing the construction difficulty, study on steel reinforced concrete structure is suitable for large-span bridge frameworks. In this paper, the research work and conclusions are as follows:(1) Combined with practical engineering cases, in order to bridge the roof frame and cross-sectional thickness of steel containing variable rate control, using the planar deformation theory analysis frame bridge in different roof thickness and maximum deflection and internal forces sectional steel ratio conditions, according the specification limit to trade-offs. The results show that the thickness of steel concrete frame bridge which span is 16m not less than 750mm, and sectional steel ratio of 3% to 4% is appropriate.(2) According to the results of planar deformation theory, using finite element software to build the spatial finite element model of the frame bridge, calculating the model’s internal forces under different load combinations, finding the most unfavorable load cases; through elevating and reducing the structure’s temperature to compare the impact of temperature change on the reinforced concrete and steel reinforced concrete frame bridge; checking each section bearing capacity.(3) In order to analyze the dynamic characteristics of steel reinforced concrete frame,building the finite element model of the bridge and the surrounding soil, based on this model to calculate the vibration characteristics of different height structures, and according to these results to determine a reasonable damping coefficient and time step.(4) Calculating framework bridge in the power train loads of responses. For train load of features that simplify train vibration load caused by vehicle vibration from the geometric irregularity conditions start to simulate the vertical vibration of train loads of different speeds, to study affect the speed frame bridge height change trains and dynamic response, and the results meet the criteria bridge dynamic performance; beside, selecting the force of the most unfavorable loading condition to analyse the structure’s safety. |
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