Dynamic Response Research Of The Bridge Pier In Deep Water Under Earthquakes

With the continuous development of world economy, Large-scale bridge project across river and sea is emerging to build up more convenience traffic networks.The planning and construction of deep-water bridges spanning great rivers,sea straits and sea bays in the world bring tremendous opportunities and challenges to bridge engineering. Those long-span bridge pier are usually in deep water. The dynamic interaction of the fluid-structure couplied system during earthquake are very complicated.Now, in the domain of dynamic analysis of bridge,the effects of hydrodynamic pressure induced by the earthquake on the deep water structures have received relatively little attention in exiting literatures,especially for the nonlinear waves reaction.In this dissertation,dynamic interaction between deep-water bridges and water during earthquake were studied.Some main achievements of this dissertation are described as follows:1)Basing on lots of literatures,the theories and methods about the issue of seismic response of structures,hydrodynamic pressure of deep-water structures and nonlinear vibration were summarized.2)The model of bridge pier in deep water with considering fluid-structure inter-action was established,taking some deep-water bridge pier as example,the dynamic responses of deep water pier under the effect of earthquake excitation is carried out.It is shown that:(a) The effect of hydrodynamic pressure on seismic responses of bridge piers is notable;(b) Water depth has great effect on fluid-structure interaction,In gen-eral,as the water level increased,the effect of hydrodynamic pressure on the piers is increasing trend.So it is necessary to consider the effect of hydrodynamic pressure in the seismic design to the long-span bridge in deep water.3)The nonlinear vibration of structure in deep water was studied.According to nonlinear dynamical equations of deep-water structure subjected to waters and seismic excitation,by means of the method of multiple sales,the approximate solutions and corresponds to theirs steady state solutions of primary resonance,1/3 subharmonic resonance,3 superharmonic resonance,1/2 subharmonic resonance as well as 2 superharmonic resonance are obtained and numerical calculations are carried out by using MATLAB.The influences of the damping ratio,seismic parameter, waters speed on the response curves of the system are analyzed.