Seismic Response Analysis And Vibration Mitigation Research Of Long-span Hybird Girder Single Pylon Cable-stayed Bridge

As a composite beam structure making use of different weight and stiffness of the steel and concrete,Hybrid girder cable-stayed bridge draws on each other's strength,showing the weight function of concrete material and the strong spanning ability of the steel,which win the opportunity for development.Therefore,it is of practical significance to analyze its seismic response.At present,the seismic response analysis of the cable-stayed bridge is mainly based on the response spectrum method and dynamic time history response analysis.The response spectrum analysis and the time history response analysis of one long-span composite beam cable-stayed bridge are discussed by choosing reasonable response spectrum which is determined by geological data and typical seismic waves come from record.Finally,the reasonable damping coefficient C and the velocity index N are obtained by the damper parameters research.The main research contents are as follows:(1)A long-span hybrid girder cable-stayed bridge was chosen as the engineering background,Midas/Civil is used to build the space finite element model,after the computation of the dynamic characteristics,the main vibration modes and corresponding frequencys are given,a model without pile is set for comparison at the same time,the effects of interaction between pile and soil are considered.(2)Seismic calculation is carried out by using the reaction spectrum method,and the seismic fortification grade in the design description for analysis is selected by referring to the standard and geological survey reports.The combination of reaction spectrum adopts longitudinal with vertical and horizontal with vertical combination for input.The seismic response chooses the representative section positions as the reference,so as to explore the change regulations.(3)The effect of traveling wave effect is considered in dynamic time history analysis.The response of inconsistent excitation under different wave velocities was calculated,and compared with the response of consistent excitation,the influence law of traveling wave effect was explored.(4)Through setting dampers at the bottom of beam and girder joint,The damping ratios under different parameter combinations are calculated,the laws of damping rate changing with the parameters are concluded,which is helpful to choose the suitable parameters for damper.