Study On Seismic Response Of Ultra-high Pier And Long-span Continuous Rigid Frame Bridge

In recent years,an important form of bridge that is called long-span continuous rigid frame bridge has been widely used and rapidly developed in bridge engineering.Generally,large-span continuous rigid-frame bridges have relatively tall piers,large spans,and complex site conditions in the bridge site area,which result in complex bridge seismic responses that can endanger the bridges.Therefore,it is necessary to study the seismic response characteristics of long-span continuous rigid-frame bridges.In previous researches that study continuous rigid frame bridges under the action of earthquakes,few researchers focus on the vertical collision at side spans.This paper took the ultra-high pier and long-span continuous rigid frame bridge in the main part of the Caijiagou Extra Large Bridge(80m+3×144m+80m)as an example.In this paper,the vertical impact model of the high pier and long-span continuous rigid frame bridge structure was established by using the finite element program,Midas Civil.Then,the beam-end collision response of the bridge under earthquake action was studied,and the influence of the beam-end collision on the seismic response of the bridge was analyzed.The main research contents of this paper are as follows.(1)The acceleration time history of Imperial Valley wave,Kobe wave and Kocaeli wave were used as input ground motions.The vertical impact response of the end of a super-high pier and long-span continuous rigid frame bridge under uniform excitation was studied,and the impact of vertical impact on the seismic response of the bridge was analyzed;One-dimensional and two-dimensional ground motion excitations were performed on the high-pier and long-span continuous rigid frame bridge,respectively.And,the calculation results under different excitations were compared to analyze the influence of the excitation method on the vertical impact response of the bridge end.(2)Taking the X-component displacement time history of Imperial Valley wave,Kobe wave and Kocaeli wave as the input ground motion,displacement input method was used to analyze the seismic response of the high-pier and long-span continuous rigid frame bridge under traveling wave effect,and the results of consistent excitation calculations were compared to summarize the influence law of traveling wave effect on the vertical impact response of beam end.(3)The longitudinal impact response of the main approach bridge end of an ultra-high pier and long-span continuous rigid frame bridge under uniform seismic excitation was studied,and the influence of the longitudinal impact of the main approach bridge end on the seismic response of the bridge was analyzed.The seismic response analysis of the long-span continuous rigid frame bridge under one-dimensional and two-dimensional ground motion excitations was carried out,and the calculation results were compared to analyze the influence of different excitation methods on the longitudinal impact response of the main bridge end.(4)The results that consider both the vertical collision of the beam end and the longitudinal collision of the main bridge end,were compared to the calculation results that only consider the vertical collision,or the longitudinal collision,respectively,and the mutual influence law between the vertical collision and the longitudinal collision was summarized.