Study On Seismic Robustness Of Column Slab Hollow Tall Pier

Structural robustness refers to the ability of the structure to bear local damage and resist disproportionate damage under the action of accidental load.Structural seismic robustness is the study of transforming the above-mentioned accidental load into seismic load.In recent years,the earthquake damage has caused irreparable losses to people.The majority of scholars’ research on seismic robustness is mostly for building structures,while the research on seismic robustness of bridge structures is relatively less and immature.In addition,the current seismic design code only focuses on the seismic performance of the complete structure,and the research on the ability to resist progressive collapse after local damage is less.As a lifeline project,the ability of bridge structure to resist progressive collapse determines whether the post earthquake rescue work can be carried out quickly.Based on the natural science foundation of Gansu Province funded project "Research on seismic performance of corrugated steel plate composite hollow tall pier with recoverable reinforced concrete columns"(20JR10RA237),this paper focuses on the seismic performance,seismic vulnerability and seismic robustness of the new type of Column Slab hollow tall pier(5#pier)of Zongmugou super large bridge on Huang Han Hou railway,The main work includes the following aspects:(1)Through consulting a large number of literature,this paper introduces the earthquake damage and the damage forms of new tall pier in recent years,expounds the current situation of seismic research on tall pier bridges by scholars at home and abroad,summarizes the development and research of structural robustness and seismic robustness,and provides reference for the follow-up research on seismic robustness of bridges.(2)Taking the Zongmugou bridge as the research background of practical engineering,the spatial elastic-plastic finite element model of the whole bridge is established by using MIDAS / Civil finite element software.The column and slab of 5# pier are simulated separately,and the constitutive relation of reinforced concrete is defined.Considering the nonlinearity of column,the slab is simulated by multi vertical bar element model.At the same time,the concentrated spring is used to simulate the pile-soil interaction,and the natural vibration characteristics of the whole bridge are analyzed.(3)The vulnerable position and damage index of bridge pier are determined by structural seismic response analysis.Taking the curvature ductility ratio as the damage index of the pier column and the interlayer displacement angle as the damage index of the slab,the moment curvature analysis of the pier column section of the 5# pier is carried out,and the damage index of the key position is quantified.(4)According to the site type and fortification intensity,combined with the safety assessment report of Shaanxi section of Huang Han Hou railway,15 actual seismic records are selected from peer database,and the seismic responses of the bridge in transverse and longitudinal directions are calculated by IDA analysis method.Based on the reliability theory,the transverse and longitudinal seismic vulnerability curves of the 5# pier under seismic excitation are obtained,and the damage sequence of each layer of the pier and the slab between the columns is studied,and the seismic performance of the new type hollow high pier is comprehensively evaluated.(5)Based on the vulnerability curve of complete failure state of seismic vulnerability analysis,the vulnerability coefficient of seismic robustness of each key position of 5# pier and the importance coefficient of its influence on the seismic performance of the remaining structure after failure are calculated.Through the above two coefficients,the seismic robustness coefficient of the structure is obtained,and the seismic robustness of the 5# pier is studied with the coefficient.