Seismic Performance Analysis And Seismic Economic Risk Assessment Of CFST Arch Bridge Over High-speed Railway

In recent years,concrete filled steel tube(CFST)arch bridge has been got fast development and wide application in projects of high speed railway bridge with advantages of good mechanical properties,superior economy and shorter construction period.Taking the Shuangdongzi CFST arch bridge on Wuwei Road of Baoji-Lanzhou High-speed Railway as the object of research,the nonlinear seismic response characteristics of CFST arch bridge are deeply analyzed,thus provided a reference theoretical basis for similar CFST arch bridge seismic design.This paper takes the seismic behavior and vulnerability of a high speed railway CFST tied arch bridge as the main line.The main research contents are as follows:(1)On the basis of reviewing a large number of literature,the development of bridge structure seismic design and seismic performance research present situation was elaborated.This paper introduced the seismic vulnerability analysis in the field of bridge engineering application,and summarized the current situation of the development of the seismic performance of CFST arch bridge.(2)This dissertation is concentrated on a CFST arch bridge on a high speed railway line.This part built bridge spatial elastic-plastic finite element model by Midas/Civil.Then obtained the constitutive relation of CFST short column,with the same material and geometric characteristics of the arch rib,through axial compression text with equal scale.Using the Midas/FEA,the correctness of test results was simulated and checked.Then the constitutive relation was entered into the cross section of the arch ribs.Finally,the self-vibration characteristic of the whole bridge was analyzed.(3)Using the Pushover and MPA static elastic-plastic analysis method,the transverse seismic response of CFST arch rib is analyzed comparatively and the IDA analysis is carried out by artificial seismic waves fitted by SIMQKE software.The applicability and accuracy of Pushover and MPA methods in seismic analysis of this kind of bridges are verified based on the results of IDA calculation.(4)A series of seismic records are selected from the PEER earthquake database in the US,according to the factors such as the bridge site type and the self-vibration period of the structure.Based on the incremental dynamic analysis,the IDA curves under the seismic action of transverse bridge and forward bridge are established,the seismic performance and failure process at different key sections are analyzed in detail.(5)The bending moment and curvature relationship of the cross section of CFST arch rib was calculated,the different damage state of the arch ribs was defined,then selecting curvature ductility ratio as evaluation index of arch rib damage.Using the IDA method to study the seismic response of the bridge under transverse direction.Based on the traditional reliability theory and the method of calculating the upper and lower limit of failure probability,the seismic behavior of the arch rib is analyzed and evaluated.(6)Taking the annual expected loss(EAL)as the evaluation index of seismic economic risk,the earthquake economic risk of the high speed railway CFST tied arch bridge is analyzed quantitatively,and the total loss ratio curve of the bridge under earthquake action is obtained.For the relevant decision makers to consider the seismic economic risk of the bridge and make reasonable decision for the bridge seismic design and the reinforcement or the new construction of the bridge after the earthquake.