Seismic Response Analysis Of Continuous Rigid Frame Bridge Considering Hydrodynamic Pressure And Pile-soil Effect

With the rapid development of China's transportation engineering,there are more and more large-span continuous rigid-frame bridges with deep-water and high-piers are under construction and planning in western China.some of their piers are in the very deep water.The seismic activity in the western China is very active,and the deep-water continuous rigid-frame bridge is very difficult to repair after being damaged by earthquake.Therefore,it is of theoretical significance and application value to study its seismic performance and shock absorption measures in depth.In this paper,the deep-water continuous rigid frame bridge is used as the engineering background,and the seismic response characteristics of the bridge are analyzed by finite element software.The main contents and conclusions are as follows:(1)The dynamic characteristics and seismic response of the structure under different conditions of Hydrodynamic pressure and pile-soil effect are analyzed by two methods:response spectrum and dynamic time history analysis.The results show that the existence of hydrodynamic pressure and pile-soil effect will reduce the natural vibration frequency of the structure,and the hydrodynamic pressure will significantly increase the seismic response of the bridge.The maximum increase of the bottom pier stress and the top displacement of the pier is 26.2%and 10.6%,When considering the hydrodynamic pressure and the pile-soil effect,the stress at the bottom of the main pier will decrease,and the maximum stress at the bottom of the bridge under the action of the transverse bridge will be 26.4%,the displacement of the pier and the internal force of the main beam are different.Therefore,the hydrodynamic pressure and pile-soil effect should be considered simultaneously in the seismic response analysis of the structure.(2)Under the premise of considering the hydrodynamic pressure and the pile-soil effect,the influence of the two parameters of water depth and soil quality on the seismic response of the structure is analyzed.The research shows that the change of the "m" value of the soil has no effect on the structure.For the bridge,when the relative water depth is above 24.4%,the influence of hydrodynamic pressure on the structure needs to be considered.(3)After comparing the characteristics of common dampers,the liquid viscous damper is selected as the damping device and the parameters of the damper were analyzed.Since the selection of damping index and damping coefficient will affect the damping effect of the damper,after comparing the different damping index and damping coefficient combination,the liquid viscous damping with damping index of 0.7 and damping coefficient of 6000KN·m/s is selected.And compare and analyze the energy dissipation effect of the damper.The results show that the stress drop of the pier bottom reaches 25.5%after the installation of the damper,and the displacement of the pier top reaches 60.9%.The energy dissipation effect of the damper is obvious,which can be used as the damping device for improving the seismic performance of the deep water continuous rigid frame bridge.