Study On Wave-Current And Seismic Response Of Bridges In Deep Water Area

In recent years,more and more bridges have been built in deep water areas,and the water environment is complex.It is necessary to consider the influence of fluid-solid coupling effect on structural dynamic response.In this paper,the deep-water continuous rigid frame bridge is taken as the research object.Based on the existing fluid-solid coupling analysis theory,the numerical simulation method based on the fluid element method is used to study the dynamic response of the bridge under different influencing factors.The main research contents of this paper are :(1)The whole bridge model of continuous rigid frame bridge considering pile-soil effect is established.The reliability of the model is proved by comparing with the dynamic characteristics of the model established by typical finite element software.The numerical model of fluid domain is established,and the second-order Stokes wave simulation is carried out.The wave height is in good agreement with the theoretical value.Taking the stability of bridge dynamic response time history curve as a measure index,the influence of fluid domain size is analyzed,and the fluid domain calculated in this paper is finally determined to be 224m×149m.(2)Using the two-way fluid-solid coupling analysis method,the influence of different water depths on the dynamic response of the bridge under the action of velocity and wave height alone and combined action is compared and analyzed.The results show that the response value increases with the increase of wave height and flow velocity,and reaches the maximum value at about 20 m water depth.The response value under the combined action of wave and current is not equal to the linear superposition of the two alone.The trend of response value with water depth is similar to that of wave alone.The positive maximum value of dynamic response is slightly larger than the linear superposition of the two,and the negative maximum value is less than the linear superposition of the two and the gap is large.(3)The seismic waves are reasonably selected,the dynamic response changes of continuous rigid frame bridge under different seismic excitations in still water with different water depths and dynamic water environment considering wave load are analyzed.The results show that the bending moment of pile-soil interface increases with the increase of water depth,and other indexes decrease with the increase of water depth.When the wave load and seismic wave are coupled,the dynamic response of the bridge is not equal to the linear superposition of the two.The effect of the coupling is affected by the spectral characteristics of the seismic wave and the initial phase of the wave.Different response indexes will obtain larger values in different water depths.