Seismic Fragility Analysis Of FPS Isolated High-speed Railway Bridge Based On Response Surface Method

In recent years,high-speed railway and the special line for passenger transport in our country has been developing rapidly.In order to save land and reduce the impact on the natural environment,most of the railway line use "bridges instead of roads",and more and more bridge structures appeared in the high-speed lines.With the continuous development of the isolation technique,the bridge of high-speed railway has been used isolation bearing.However,there are few relevant researches on the isolated high-speed railway bridges,and most of the high-speed railway bridges in the service period have not been tested by the earthquake.In this paper,taking a practical project of our country on a friction pendulum system isolation of high-speed railway bridge as the background,introduce the vibration isolation design of the bridge,use the finite element software to verify the isolation effect,seismic fragilities are obtained by the earthquake response of the structure of the fragility analysis curve,and laid a foundation for the structure of the earthquake economic loss calculation.The main research contents are as follows:1 、 Summary of the research status of high-speed railway bridge: This paper introduces the principle of bridge isolation technology and the application of isolation technology in high-speed railway bridge,and compares the seismic performance of lead rubber bearing and friction pendulum.This paper summarizes the research status of seismic analysis and full-life cost analysis of bridges at home and abroad,and points out the necessity of the analysis of vulnerability and full-life cost of high-speed rail bridges.2、Analysis of seismic performance of FPS isolated high-speed railway bridges: The finite element model of non-isolated high-speed rail bridges and isolated high-speed rail bridges was established using SAP2000 finite element software,the Mander constitutive model was used for pier concrete,and the Friction Idolator connection unit in software was used for friction pendulum bearing.Elastic beam element is used to simulate the workingcharacteristics of the main beam.Two natural waves and one artificial wave were input for nonlinear dynamic time-history analysis.The seismic response of non-isolation bridge structure and isolation bridge structure under seismic action was compared and verified,and the effectiveness of friction pendulum bearing was verified.The maximum displacement of friction pendulum bearing under rare earthquakes and extremely rare earthquakes was analyzed and calculated,and the displacement of the bearings was checked.3 、 The vulnerability analysis of friction pendulum isolation high-speed railway bridges: The main methods of vulnerability analysis and the basic theory of response surface method are introduced.According to the target response spectrum,10 natural seismic records were selected from the PEER,and the deformation failure criteria were selected when calculating the damage index of the bridge.The central composite design method is used for simulation test design,and the structure-ground vibration parameters corresponding to each group of tests are input into the SAP2000 for nonlinear time-history analysis.The mean and standard deviation of seismic response obtained from the time interval analysis are used to fit the average response surface function and the standard difference response surface function of the component,and the seismic vulnerability of the component is finally obtained by combining the 1000 samples extracted by the Latin supercube and the defined damage index curve.By comparing the fragility curves of the piers before and after the isolation of the high-speed rail bridge,the effect of the vibration isolation of the friction pendulum supports was evaluated from the perspective of probability.The vulnerability of the whole system of non-isolation and isolation high-speed rail bridge is analyzed by means of the method of width limit.4 、 Seismic economic loss estimation of FPS isolated high-speed railway bridge:Based on the results of seismic vulnerability analysis before and after the isolation of high-speed railway bridge,combined with seismic hazard analysis,the failure probability and direct economic loss of different grades of damage occurred in the design service life(100years)of the non-isolation high-speed railway bridge and the isolation high-speed rail bridge.