Seismic Response Analysis Of A Large Span Continuous Rigid Frame Bridge With High Piers In Deep Water Reservoir

In recent years, more and more deep-water bridges have been built with the development of large-span bridges to cross water areas, and many deep water bridges have been constructed or are being planned to be constructed in our country. Nowadays the deepest under water foundation of deep-water bridges constructed have reached 168m. Under the effects of the earthquake, hydrodynamic pressure of structures will be occurred because of the relative movement between a structure and wate induced by radiation wave movement of fluid around the structure. The dynamic characteristics and the dynamic responses of the structures will be changed due to the effects of the hydrodynamic pressure. If neglects the hydrodynamic pressure, the earthquake internal force will be induce to a big erroneous even wrong results when calculates the entire dynamic performance of the bridge.However, the effects of hydrodynamic pressure induced by the earthquake on the deep water structures, such as underwater foundation of large span bridges have received relatively little attention in exiting literaturea.The dynamic responses of deep-water bridges under the earthquake are studied based on extensive analysis. The main achievements of this dissertation are as follows:(1) The necessity to consider the hydrodynamic pressure for the deep waterbridge is elaborated, the art of the research state of the hydrodynamic pressure is also presented.(2) A continuous rigid frame bridge is taken as an example which has the main span of 220 meters and pier high of 173 meters. Using the Morison equation, variable cross-section three dimensional finite element model of this bridge is set up.(3) Combined with Chinese seismic design code, carries on modal, response spectrum and time-history response analysis of this bridge.(4) The interaction between structure and water was studied when various earthquake records were input.The results show that under the action of the hydrodynamic pressure, the natural vibration frequency of the bridge decreases obviously and the displacement and internal force of pier and beam increases remarkably.The research methods and conclusions are useful to the design of similar bridges.