Seismic Response Analysis Of Continuous Girder Bridge In High-speed Rail Considering The Seating Properties

During high-speed rail development in our country,the proportion of lines occupied by bridges is higher.The maximum value of the power amplification coefficient ?max in the Code for Seismic Design of Railway Engineering(2009)is lower than that in the Seismic Ground Motion Parameters Zonation Map of China(2015),and the damage probability of bearing and bearing design parameters on the seismic performance of bridge structure and other work remains to be in-depth.In view of the above situation,supported by the key project of the National Natural Science Foundation(No.U1434210):Theory and method of high-speed rail earthquake warning,the seismic response of high-speed continuous beam bridge is analyzed,then the influence of changes of the bearing performance on the seismic response of the bearing and pier is studied under the change of the damping hysteresis parameter and the yield index,and the vibration reduction effect of the dampers is verified.The main content of this paper is as follows:(1)The research status of seismic codes,bearing performance and bridge seismic response at home and abroad is reviewed and summarized,and the contents of this paper are clarified.(2)The constitutive model of the material when modling the high-speed bridge is summarized;comparative study on domestic fortification criterion of the seismic standard about railway and others is made;the site division is compared and the corresponding seismic wave is selected based on the site type;the "six-spring" pile-soil interaction model is established.(3)Taking the typical 40m + 64m + 40m three-span continuous bridge as an example,the bending moment-curvature of the main pier is analyzed and the model of the main pier bottom section is established based on the cross-section analysis software Xtract with different axial compression ratio and longitudinal reinforcement ratio.Based on the finite element analysis software Midas/civil,a full bridge model of continuous bridge is established to calculate the dynamic response in longitudinal and transverse bridges respectively under three level earthquake.As a conclusion,with the increase of the axial compression ratio and the longitudinal reinforcement ratio,the yield bending moment of the pier cross-section increases gradually and the ductility decreases;longitudinal pier bottom bending moment and transverse pier top displacement are close to the yield value under rare earthquakes.(4)By changing the damping hysteresis parameters and the yield index,the influence of the change of the bearing constitutive relation on the seismic response of the bearing and pier is analyzed.Experiments indicate that,changing the damping hysteresis parameter has a great influence on the displacement index based on displacement.In most cases however,the yield index is set to infinity in the bearing simulation,which is too ideal for the seismic capacity of the longitudinal bearing,and too conservative for the seismic capacity of the transverse bearing.The combination of different types of bearings is used to study the variation of the pier bottom shear force,the pier bottom bending moment and the pier top displacement under different bearing configuration,and the optimal configuration of the bearing is explored.(5)The effect of viscous dampers on the seismic performance of high-speed continuous bridges is investigated,then the recommended damping parameters for the structure of this paper are obtained,and as a result it is proved that the viscous dampers can improve the seismic performance of the structures.The correlation between the bearing and the pier response is explored and the damping effect of the viscous damper is verified by the numerical simulation of the finite element model of continuous beam bridges,which provides technical support for the safety of the continuous beam bridge and the development of the seismic design.