The Dynamic Response Analysis Of Deep-water Suspension Bridge Under Earthquake And Wave

Now a lot of large-scale deep-water bridges have been built at home and abroad.When the earthquake happens,the dynamic water pressure on deep-water piers could make the substructure or even the whole bridge damage.In order to ensure the safety of the deep-water bridge,it is necessary to make further research on the dynamic characteristics of deep-water bridge.This paper takes Qingdao bay bridge as an example.Considering the uniform excitation and traveling wave effect of the input seismic wave,the dynamic response of deep-water suspension bridge under earthquake and wave is analyzed.Main contents are as follows:(1)Using MIDAS/CI VIL2012,Qingdao bay bridge finite element model is established.The modal analys is is carried out.El-Centro wave,Taft wave and an artificial wave are chosen for seismic response analys is under the uniform excitation and traveling wave effect,to research the influence of traveling wave effect on structure displacement and internal force.For node displacement,the displacement of tower top under wave velocity is most prominent.For the unit internal force,in a certain range of the wave velocity,the traveling wave effect will make the internal force of the bridge increase.When the wave velocity is 2000m/s,the influence of traveling wave effect on the internal force of the main cable,sling,stiffening girder and cable tower is smaller than other wave velocities.(2)Bridge finite element model under water condition has been established,using added mass method.The modal analysis is taken,compared the natural vibration frequency and vibration characteristic of the bridge with that under anhydrous condition.Us ing the linear wave theory and Morison equation,regular wave load is obtained by Matlab programming.The influence of dynamic water pressure and the traveling wave effect on the displacement and internal force under the earthquake and wave is analyzed.The effect of dynamic water pressure is volatile,that is to say,the effect of dynamic water pressure can either increase or reduce seismic response of different nodes.When the wave velocity is 2000m/s,the effect of dynamic water pressure on the seismic response of the bridge is the largest.(3)Taking P-M spectrum as the target spectrum in random wave numerical simulation,random wave load is obtained by Matlab for the Qingdao bay bridge dynamic analysis under wave and earthquake.Compared with the regular wave,the influence of random wave on the displacement and internal force has been got.Under most conditions,considering random wave action,the results are mainly the same as that of the regular wave,and the influence coefficient of random wave is small.But under certain conditions,the influence coefficient of random wave will be large.