Study On The Seismic Response Feature Of Deepwater Bridge Pier Wave-current Environment

With the continuous development and perfection of the transportation foundations,large scale sea-crossing bridges emerge continuously.The foundations of sea-crossing bridges,like the group of piles,pile-cap and foot stall,are constructed partially or completely in the environment with the interaction of waves and current(seawater,tide),which definitely leads to the potential influence on the structural dynamic response under earthquake,nevertheless,correlational researches are still in blank.Therefore,it is necessary to carry out study on the seismic dynamic response feature of deepwater bridge pier in wave-current environment,and provide references for seismic design of these bridges and revision of the relevant norms.In this paper,based on the regular wave theory and linear wave-maker theory,with CFD and FSI numerical computation method,taking an equivalent single pier model submerged in deep water as example,the wave-current environment of pier is simulated.And coupling analysis between pier and current,wave,wave-current are accomplished,respectively.The seismic dynamic responses of pier in no water,still water,wave-current environment are analyzed systematically and studied comparatively.The main research works in this paper are as follows:(1)Taking a three-dimensional numerical water-tank as the main object of this study,based on the regular wave theory and linear wave-maker theory,with the effective solution to the problem of wave height attenuation of three-dimensional numerical wave,three-dimensional numerical waves with different parameters(period,depth,wave height)are simulated.The theoretical values of fluctuation displacement time-history tally with the simulation values.(2)The scope and mesh generation of fluid field in three-dimensional numerical are studied systematically.Using the stability of dynamic response value of pier as an indication,the length,width and scope of water around pier are determined.(3)Three-dimensional numerical model of pier-wave-current interaction is built,the dynamic responses of pier excited by current,wave,wave-current are studied comparatively.The results show,when pier exciting by wave-current,the dynamic response of pier augment with the increase of current velocity,water depth,wave height,respectively;The dynamic action by wave is in the main,but the influence of current can nor be neglected;The danamic response of pier by wave-current effect may be greater or less than that of pier by wave alone,and it is not the simple superposition of response value by wave and current respective action.(4)Taking an equivalent single pier model submerged in deep water as object,the seismic dynamic responses of pier in no water,still water,wave-current environment are analyzed systematically and studied comparatively.The results show,the seismic response of pier in wave-current environment may be greater or less than that of pier in no water environment,and it is not the simple superposition of response value excited by earthquake and wave-current respectively;Wave-current environment to the seismic response of pier shows augment or diminution effect,that is closely related with the spectral characteristic and phase difference between wave and earthquake wave.