Research On Mechanical Characteristics Of Hollow Frame Bridge

The great weight of the frame bridge is the main cause of the accident in the process of jacking construction, such as the collapse of the roadbed, the deviation of the bridge body and the collapse of the back. In order to ensure the normal operation of the railway transportation and progress and quality of construction, optimization design of frame bridge is carried out by referring to the principle of hollow slab structure design:high strength thin-walled hollow tubes are placed in the roof of frame bridge to form hollow frame bridge. In this paper, the section size and the mechanical characteristics of hollow frame bridge are studied based on the practical engineering. The specific research contents include the following:The arrangement direction of the hollow tube is determined by calculating and analyzing the bending stiffness of hollow plate in two directions. In the case of different diameter and different net distance, the hollow frame bridge with different span is simulated and analyzed on the basis of the section size of the prototype frame bridge. The section size of the roof of the hollow frame bridge and the application of the hollow frame bridge are obtained judged by strength, stiffness and crack width.The design of the reinforcement of the hollow frame bridge is carried out through theoretical analysis and numerical calculation:The plane model can be used to get good results when the transverse main steel bars are configured. It can meet the requirements of the bearing capacity when longitudinal stress reinforcement area is as 0.25 times as the area of transverse main force reinforcement.Utilizing the finite element analysis software to establish the three-dimensional model of the hollow frame bridge and the prototype frame bridge, the advantages of hollow frame bridge are summed up and seismic performance is explored through the comparative analysis of the static characteristics and dynamic characteristics.The three typical stages are selected to analyze the deformation characteristics of the hollow frame bridge in the construction process. In the starting phase and the sliding phase, the displacement with the change of the force is obtained by changing the structure length and jacking force. The change law of displacement is obtained by simulating of piecewise jacking in buried stage.