A Study On The Dynamic Rsponse Of Pier Foundation Under Sea Wave

With the development of economy and the progress of society, the ocean engineering has been developed rapidly in recent decades in China. A lot of ocean engineering structures have been designed and built, for example ocean platforms, offshore storage tank, artificial islands, submarine pipelines, long-span bridges across the sea and so on. Most of these ocean engineering structures with different dimensions and types are built in exposed sea area and suffer great wave forces, meanwhile, the wave conditions are different when ocean engineering structures are in different states, including survival state and operation state, so it is vital for those ocean engineering designer to determine wave forces acting on ocean engineering structures and their dynamic response which directly affect the safety and reliability of ocean engineering structures. This article firstly summarizes different computation methods of wave force acting on structures and dynamic response,meanwhile some factors that affect computation results are discussed, including the effects of free surface fluctuation, the selection of different hydrodynamic coefficients and wave theories, and the effects of free surface fluctuation is a key point of this study. Secondly, numerical simulation technology is introduced, including harmonic wave superposition method and linear-filtering method. Based on the numerical simulation technology, the velocity and acceleration of water particle and wave surface in a place of an actual bridge across the sea are simulated through linear-filtering method by using MATLAB, a mathematic softwares, and the results of simulation are compared with target spectrums. Lastly, the results of simulation are introduced to derive the time history of wave force on a pier foundation of this bridge, and the dynamic response of this pier foundation is computed by using ANSYS, a FE software, meanwhile the traditional design spectrum method considering the effects of free surface fluctuation is adopted to compute the dynamic response of this pier foundation. Then the horizontal displacement, velocity and acceleration of some nodes of the pier foundation and their PSD are selected, and the results are compared.