Research On The Seismic Performance Levels Of Continuous Girder Bridge Piers Based On Hybrid Test

Most experimental research on seismic performance levels of piers in recent years is the analysis for the seismic performance of single pier component,and the loading method is single,are static loading,low cyclic loading,which can not accurately reflect the overall seismic response of bridge structure.Hybrid test method is an advanced seismic test method developed in recent years,which can obtain the accurate response of bridge structure under earthquake by combining the substructure pseudo dynamic test and finite element simulation.Based on this,this article studies the seismic performance level of reinforced concrete piers of continuous beam bridges under earthquake through the method of hybrid test.The specific contents are as follows:(1)Summarizing the existed seismic damage of bridge and analyzing damage characteristics and failure modes of reinforced concrete bridge piers.Giving method to judge the failure mode of the bridge according to the characteristics of the three types of failure of the pier.(2)Analysis domestic and foreign experts and scholars for the division of the performance level.According to the failure characteristics of bridge piers and the need of seismic design of bridge structures based on performance,grade the seismic performance level of pier to 5 levels from the applicability,maintainability,security and other aspects: normal use,temporary use,repair and use,life safety,prevent the collapse.Considering the current situation,feasibility and intuition,the drift ratio is selected as the structural performance index in the parameters which may be used as the index of the performance of the structure.(3)Before the hybrid seismic test,the mechanical analysis of the bridge is carried out to take out pier from the overall structure of the bridge,single column simplified in the longitudinal as the cantilever top free,namely single curvature column.And mainly focuses on the pier seismic performance finite element analysis,using OpenSees finite element modeling on the pier,and the Push-over static elastic plastic analysis,determine the failure mode of the pier is bending failure,and get the equivalent of the pier yield point and the plastic hinge length.(4)establish a system of hybrid test including the OpenSees simulation of substructure,the experimental substructure test conversion of part design,openfresco connection,test piece measuring points arrangement,test loading device settings and test conditions of selection.Selected El-Centro earthquake wave,loading the pier according to the order of E1 for intensity 7,E2 for intensity 7,E2 for intensity 8 and E2 for intensity 9,use drift ratio as a quantitative index.Through the experimental phenomena and data analysis,the seismic performance indexes of the bridge piers were studied,and compared with the research status at home and abroad.The results show that the drift ratio limit of pier obtained by hybrid test method for each performance level have little difference with domestic experts and scholars research results,but the results are coincident well with foreign experts and scholars research results.(5)to carry out low cycle reciprocating test,analyze the test phenomena and data,and compare with the mixed test.The results show that the destroy of pier has very big difference under the loading of low cycle fatigue test and hybrid test,the destroy of low cycle fatigue test is faster and more serious.The loading of hybrid test is a direct input of seismic wave,which can reproduce the real situation of component under the earthquake load and closer to the actual damage phenomenon of pier.