Prefabricated Bridge Pier Concrete Filled Steel Tube Column In The Seismic Analysis And Application In Highway Bridge Crossing The Reconstruction And Expansion

In order to solve the interference of normal traffic in the main line caused by the construction of the interchange ramp bridge in expressway extension, and complete the demolition, construction, traffic flow in the shortest time which can be controlled in two weeks, the technology of pile prefabrication and fast assembling is put forward. It relies on the prefabricated bridge substructure of interchange ramp in Baoding the expressway extension project from Beijing to Shijiazhuang, in which the bridge pier is built up by circular steel tube concrete. For the strength of circular concrete filled steel tube column is same in any direction, it can be effective for this structure to resist to earthquake whose direction is uncertain. At the same time, in order to reduce concrete creep and shrinkage, improve the bearing capacity and ductility of steel tube concrete pier, and improve the stress state in elastic stage, a certain amount of longitudinal reinforcement and spiral stirrups can be added in circular concrete filled steel tube column, with the consideration of that the longitudinal reinforcement can improve the compressive strength directly, and the stirrup can increase the constraint of the core concrete.The advantage of this technique is that it can save the template amount, shorten time to cut off traffic, improve economic efficiency, and use standardized plant site assembled method. Firstly, the substructure safety of the bridge in the operational phase is verified used finite element software ANSYS, in which the stress analysis is carried out in both the bearing capacity and limit state, the results can meet regulatory requirements. Secondly, aiming at the seismic performance, the detailed research is carried out as follows:Due to the upper and lower pier girder structure is fabricated, it is a kind of breakthrough and innovation in the history of the domestic bridge. Through the necessary simplification of real bridge, the elastic response spectrum analysis and nonlinear dynamic time history analysis are carried out using the finite element software Midas civil. Moreover, theoretical calculation of its seismic performance is carried out, and the ductility and energy dissipation of bridge pier are analysed combining with the pier plastic hinge zone moment- rotation hysteresis curve from the time history analysis, which can draw conclusions that it has good seismic performance. With the comparation of the bearing capacity and ductility of concrete piers which adopted by reinforced concrete, ordinary concrete filled steel tube and reinforcement steel tube through XTRACT cross section analysis software, the conclusion is drew that the cross-section bearing capacity and ductility of reinforced concrete filled steel tube column are higher than the former two. The research of how to choose its piecewise node location is required further analysis if this kind of bridge piers are used in prefabricated high pier bridge structure. In this article, aiming at its mechanical characteristics in transverse and longitudinal bridge direction under earthquake, the location choose of nodes is calculated with aspects of the internal forces and stress, the conclusion of how to segment can be more conducive to seismic is drew finally.