Seismic Response Analysis Of A Long Span Continuous Rigid Frame Bridge With High Piers In Deep Resevervior

With the development of traffic in China,continuous rigid frame bridges with high piers and long-span are widely used,when they cross the ocean,lakes,reservoirs or deep rivers,some of their high piers are deep in the water.China is located in the central Pacific seismic belt and the Eurasian seismic zone,the seismic fault zone is very active,So the study on seismic performance of continuous rigid frame bridge with long-span and high piers in deep water has important theoretical and practical value.In this paper,taking a continuous rigid frame bridge with long-span and high piers in deep water as the engineering background,the seismic response of the bridge under different working conditions is analyzed and compared.First of all,the natural vibration characteristics and seismic response of the bridge are analyzed separately considering both the dynamic water pressure and pile-soil interaction,considering only the dynamic water pressure and without considering the dynamic water pressure and pile-soil interaction,the results show that the dynamic water pressure and pile-soil interaction should be considered when continuous rigid frame bridge with long-span and high piers in deep water is calculated and analyzed.Secondly,based on the model considering both the dynamic water pressure and pile-soil interaction,seismic time-history response are analyzed and compared with different water depth or different geological conditions.Research shows that the water depth had significant effects on the dynamic characteristics and seismic response of the bridge,not all water depths corresponding to the maximum seismic response in different position of the bridge are the same,the seismic response of the bridge is relatively low sensitivity to the geological condition when piers supported by group pile foundation.Finally,based on the model considering both the dynamic water pressure and pile-soil interaction,changing the transverse slope of all piers,side piers transverse stiffness or the lateral dampers of the side piers,seismic time-history response are analyzed and compared.Research shows that:the seismic response of bridge structures has some changes when the transverse gradient of the bridge piers is different;adjusting side piers’ section size to a reasonable value,can improve the seismic performance greatly,effectively prevent the girder falling in a earthquake,and improve the pier transverse stiffness is economical and feasible because side piers’ height of most continuous frame bridge is relatively low;Mounting lateral dampers on the top of side piers can improve transverse seismic performance of the bridge structure significantly.The results of this paper can provide some reference for the design of similar continuous rigid frame bridge with long-span and high piers in deep water.