Study On Mechanical Behavior And Design Method Of Steel Reinforced Concrete Frame Bridge

With the continuous development of the communication and transp of our country, the original form of the cross rail has greatly restricted the development of transportation in China, changing the level-crossing into the overpass roads has become a trend.At the same time, the level-crossing is easy to cause the traffic safety problem, because of its own advantages and applicability, it has been widely recognized by the community, and has been widely used in urban construction.Due to the constraints come from the original building.. the existing railway line.. geological conditions、 construction technology and economic, it puts forward more strict requirements on weight reduction, structural optimization design and decrease the cost of project. In this paper, taking advantage of combined structure principle, replacing a single reinforced concrete structure with combined structure, the utility model has the advantages of thin roof, increasing the effective space, the bridge of light weight, low cost, convenient construction, saving the construction period. Therefore, the steel reinforced concrete frame bridge is carry on static analysis and seismic dynamic response analysis. The static analysis is carried out mainly from different span, different plate thickness, different steel ratio and different structural forms, dynamic analysis of two kinds of frame bridges is mainly carried out on the elastic and plastic analysis of the dynamic response.(1) Different plate thickness and steel ratio of steel reinforced concrete frame bridge is carried out finite element analysis,finding the influence of plate thickness and steel ratio on the structural properties, the two structural forms of frame bridge are comparative analysed, the stress characteristic is consistent. Steel reinforced concrete frame bridge has better resistance to train action, and the change of temperature has great influence on the internal force and displacement of the two kinds of frame bridge, the change of steel ratio has no effect on the internal force and displacement under the action of temperature.(2) With different steel ratio and different thickness of the roof frame bridge finite element analysis and theoretical calculation under the different span, it get conclusion is that the reasonable steel ratio is 4% to 6% and the thickness of the plate is 1/18-1/23 of the span in the span of 10m-25m.(3) Elastic plastic analysis theory based on fiber beam column element, the finite element analysis model of traditional frame bridge and steel reinforced concrete frame bridge are established,the two kinds of bridge are carried on the seismic dynamic time history response analysis, the dynamic response of the two kinds of bridges under different levels of earthquake is studied for the first time. By comparing the elastic and plastic energy dissipation capacity of the key parts of the two kinds of bridges under earthquake action, proving frame bridge with strong seismic performance, and the steel reinforced concrete frame bridge is better than the traditional frame bridge.(4) The design of steel reinforced concrete structure is carried out on an example frame bridge, comparing with the two kinds of structures, it is proved that the span is related to the reasonable steel ratio and the thickness of the plate, the example shows that the steel reinforced concrete frame bridge can reduce the height of structure, reduce the weight, reduce the cost and so on.