Application Study Of Pushover Analysis In Ductility Seismic Design And Seismic Isolation Design

As a critical component in the transportation process,it is essential to assess the seismic performance of bridge structures according to a reasonable and accurate method.The Pushover analysis method is a performance-based seismic analysis method with simple calculations and brief concepts.This paper studies the application of Pushover analysis method to the seismic performance analysis of a continuous rigid bridge using ductile seismic design and a continuous girder bridge using seismic isolation design in the following aspects:(1)The common forms of seismic hazards in bridge structures are introduced,the development of bridge seismic analysis theory is reviewed,and the researches on the application of Pushover analysis method in bridge seismic performance evaluation in recent years are summarized.(2)The theoretical basis and the specific implementation procedures of the Pushover analysis method are described,the common lateral load distribution methods are listed and the influence of different lateral load distribution methods on the calculation results and the reasons for the influence are discussed.(3)Based on an engineering example of a continuous rigid bridge,a finite element model is established,and Pushover analysis is applied on the structure using six different lateral load distribution methods.The results obtained by using incremental dynamic analysis(IDA)were used to evaluate the accuracy of the Pushover analysis results and to conduct comparative analysis to study the influence of different load distribution methods on the results..The study shows that the Pushover analysis result using the adaptive lateral load distribution is closer to the IDA results in the transverse and longitudinal directions.According to comparative analysis,with the increase of the displacement value of the observation point,the relative error of the analysis results in the longitudinal and transverse bridge directions did not exceed 20%,and the minimum values were 1.2% and 1.11%respectively.When the structure enters the plastic state,the relative errors in both directions are within 10%,which proves that the method has high accuracy(4)A method to evaluate the seismic performance of bridges using the curvature ductility coefficient is proposed.Based on the analysis results of the Pushover analysis,the seismic performance of bridge structure is evaluated by solving the performance points under different seismic intensities.Meanwhile the material strain value,stiffness ratio,and displacement ductility coefficient are used as indicators to evaluate the seismic performance of the same structure respectively,and the accuracy of the method is verified based on the comparative analysis of the results(5)The applicability of Pushover analysis method in the seismic performance analysis of seismic isolated bridges is investigated.The results show that the errors of bearing displacements and base shear force obtained by Pushover method are 17.4%,19.3%,14.7%and 22.2% in longitudinal direction and transverse direction,respectively,compared with the nonlinear time analysis.It is proved that this method can be applied to the seismic performance analysis of friction pendulum seismic isolated bridge structures and has certain reference significance.