Seismic Response Analysis On (50+90+50)m Continuous Rigid Bridge Of The Mati River

Continuous rigid frame bridges are widely used in many places with high mountains,deep waters and ravines due to their strong spanning ability,high rigidity,and convenient construction.With the continuous increase in the height of piers and span of continuous rigid frame bridges in China,in order to ensure the safety and stability of the structure,it’s necessary to analyze the seismic response and study the seismic performance of continuous rigid frame bridges with high-pier and long-span.This thesis takes the(50+90+50)m continuous rigid frame bridge of the Mati River as the research object,uses midas Civil to establish the finite element model,conducts response spectrum analysis and time-history analysis,and studies the influence of changing of main pier’s height difference and quantity of straining beams on the seismic performance of continuous rigid frame bridge,the main work is as follows:(1)Analyze and compare the dynamic characteristics of the two models of the continuous rigid frame whether the pile-soil interaction is considered or not.The results show: The flexibility of the bridge increases after considering the pile-soil interaction,the bridge is prone to horizontal deformation under earthquake action.(2)Using the response spectrum analysis method,under the action of E1 earthquake,analyze and compare the displacement and internal force responses of the two models whether the pile-soil interaction is considered or not.The results show:the internal force response of the short pier is greater,and the displacement response of the top of the high pier is greater.After considering the pile-soil interaction,the displacement response of each section of the bridge is significantly increased,and the internal force response of the pier is significantly reduced,the pile-soil interaction should be considered.(3)Using the time-history analysis method,under the action of the E1 earthquake,select three seismic waves according to the code and modulate their amplitudes to obtain the displacement and internal force responses of the continuous rigid frame,analyze and compare them.The results show: The displacement and internal force response ratios of time-history analysis and response spectrum analysis are both greater than 80%,meeting the code requirements.(4)Using the time-history analysis method,under the action of the E2 earthquake,increase peak acceleration of earthquakes,carry out the elastic-plastic time-history analysis of the piers,and the plastic hinge produced by the pier is studied.The sequence of appearance of pier plastic hinge and the influence of pier reinforcement on the development of plastic hinge are obtained.(5)Models of different main pier height differences and straining beam settings of the Mati River Bridge were established,and the effects of the continuous rigid frame main pier height difference and straining beam settings on its seismic performance were studied.The results show: Reducing the height difference of the main pier of the continuous rigid frame can make the structure more uniform in stress,setting two straining beams in the original bridge can effectively increase the stiffness of the pier and improve the seismic performance of the pier.