Study On The Bridge Dynamic Response With The Consideration Of Diffracted Wave Action

As the development of recent years,the research of dynamic water pressure makes some achievements.There are some requirements for earthquake dynamic water pressure in"Seismic design code of highway construction" In some special cases,such as the huge wave caused by the earthquake,it’s obviously not precise enough to calculatue or analye according to the code. Many researches of these days are confined to the still water,which ignore the widespread existence of the wave,or the calculation is appropriate for the small dimension structures.Just under such background,this dissertation has some researches on the structure stress caused by incident and diffracted wave. The primary achievements of this dissertation are as follows:(1) Based on the research of this case that the wave encountering large cylindrical structure, the computational formula of first order wave forces is derivated.Refer to the radiational wave theory,there is a preliminary research on the computaion of the second order wave forces.(2) Some calcuation and analysis for the first order forces has been done.By comparing the changes of the wave force under various parameters change, it can be found that the first order wave force is affected by the wave amplitude,wavelength,structure size, the depth of water; the frequency of wave force is affected by the wave period.(3) Taking a reservoir bridge as an example.Calculate the deformation and stress of piers which are influenced by large wave forces, and analyse the impaction by the earthquake on the same anhydrous model.By comparing, it is shown that the first order wave force can’t be ignored for the big wave; and the routine small wave can be ignored.Calculate the base frequency, then select different frequencies of wave forces, study the resonance effect on bridge piers.