Influence Of Base Swing Pier On Seismic Response Of High Pier And Long Span Continuous Girder Bridge During Construction

Under rare earthquakes,base-swing-isolated bridge piers can cause bridge piers and foundations to oscillate at the separation plane.The rocking of bridge piers consumes part of the seismic energy,which reduces the seismic response of the superstructure of the bridge to a certain degree and protects piers.This thesis takes the main bridge of the Chaoan Hanjiang River Bridge as the background,adopts the form of seismic isolation and isolation of base-swing-isolated bridge piers.And a study on the reduction and isolation under each cantilever construction phase and the completion phase was conducted.Mainly research work is engaged as follows:(1)A large number of domestic and foreign literatures on earthquake resistance of long span continuous girder bridges have been reviewed.The author summarizes and analyzes the status quo,points out the deficiencies in existing research,and finds that there are relatively few researches on base isolation,which is the basis for the analysis and calculation of the thesis.(2)The basic principle of base swing bridge pier’s seismic isolation and its advantages have been expounded.And the numerical simulation method of the swing isolated pier have been introduced.In this thesis,a double-spring-model is used to simulate the swaying effect of the piers,and a Maxwell-model is used to simulate the swing isolation pier considering the lateral slippage of the piers.(3)The spatial finite element models of maximum cantilever state of the main bridge’s 11 pier of the Chaoan Hanjiang special bridge and of the full bridge bridge stage have been established.The dynamic characteristics of the bridge have been analyzed with the influence of pile soil interaction.The results show that the design of swing pier isolation causes the constraint between the pier and the foundation to weaken,and the overall stiffness of the structure decreases.Therefore,the period of adopting the model of swing isolated pier is larger than that of the unused one,and the modal mode of the structure changes obviously.(4)Compared with the results of nonlinear time history analysis of bridge with base swing bridge piers isolation and non use of this method,it is found that the base swing bridge pier can effectively reduce the internal force of the pier bottom of the main pier in the construction stage,but the displacement of the pier top is obviously increased.Thereafter,the influence of various design parameters of swing isolated pier on the seismic effect during construction stage is studied.(5)The influence of base swing bridge pier isolation design on the seismic performance of the finished bridge stage is analyzed,and the layout of the swing pier is optimized.It is found that the swing pier can effectively reduce the internal force of pier bottom of the main pier during the completion stage,but the top displacement of each pier increases obviously.After that,the influence of various design parameters of swing pier on pier top displacement and pier bottom internal force during the completion stage is analyzed.It provides reference for the seismic design of the similar bridges in the future.