Study On Dynamic Response Of Deep-water Bridge Foundation Under Seismic, Wave And Flow

At present, the bridge-building towards a greater development of the span, at the same time, there have been more and more deep-water bridge that is part of its foundation or piers located in deep water. The load applied to deep-water bridge, not only include its own gravity,live load , but also include fluid wave, wind, seismic effects etc.These loads act on the bridge structure in the form of dynamic load. Therefore, the study on dynamic response of deep-water bridge structure under seismic and fluid wave affects and the establishment of effective analytical method is of great significance for its analysis and design.This paper is divided into two parts:In the first part of the paper, the fluid wave theories under the ideal conditions are extracted and summarized, the principle of waves act on the structure, current calculation method applied in the project were introdeuced, and its advantages and disadvantages are summed up. Analysis and calculation is finished in the paper, in the background of Sutong bridge main base. It focus on the comparison of seismic dynamic response of main base with and without fluid wave load, in which fluid wave load based on airy wave theory and stokes fifth-order wave theory, and seismic waves based on El-Centro wave, shanghai artificial wave, and taft wave. We can conclude that:(1) Wave action on the effects of earthquakes can be divided into two phases: In the first stage, the contribution to structure response is not obvious, sometime enhance and sometimes reduce; In the second stage, fluid wave actions slow the response greatly, it makes the structure kinetic energy reduce more than half.(2) Fluid wave effects the piles and tower acceleration response a little, and Fluid wave effects the piles and tower relative displacement a little.(3) Fluid wave effects the tower root axial force a little, but affects tower root bending moment obviouslyIn the second part of the paper, recognizing the shortage, I make a new research method, Fluid-structure interaction (FSI) method, on the base of consulting other industries fields research method. In this method, pure numerical simulation is used to simulate structure dynamic response under fluid impact, and it can detach the limitations of semi-theoretical semi-empirical formula. Using FSI method to research the dynamic response can improve the semi-theoretical semi-empirical formula, or we can find a new simple method.