Study On The Effects Of Hydrodynamic Force On The Dynamic Performance Of Deep-water Bridges Subjected To Strong Earthquake

In world wide, more and more sea-crossing, river-crossing,reservoir-crossing and other long span deep-water bridges are constantly planedand constructed. In seismic, the effect of hydrodynamic force to the dynamicperformance of long span deep-water is an urgent researched topic. The researchof hydrodynamic force is less generally in the world. It is lack that systematic andeffective method to calculate the hydraulic. The existing domestic bridge seismicdesign specification of the hydraulic is no longer suitable to the designrequirements of long span deep-water bridges.First of all, based on the ideal potential fluid theory, a set of simplifiedmethod for the hydrodynamic force on the substructure of bridges applied to theseismic dynamic time-history analysis of large span deep-water bridges isproposed. Compared with the results in the numerical method, the precise andeffectiveness of the method is verified in rectangular cross section piers,cylindrical piles and elevated pile platform structures. A simplified method for thehydrodynamic force is supplied for the performance design of the large-span deepwater bridges considering the effect of the hydrodynamic.Secondly, the seismic dynamic response of rectangular cross section piersand cylindrical piles structures is analyzed taken into account of the role ofhydraulic water by numerical method. The results showed that the hydrodynamicforce on the rectangular cross section piers and cylindrical piles structures and theeffect to the dynamic response in seismic are increasing with the water depthincreased. The influence of water depth should be considered in the analysis ofbridge dynamic response in consider of the hydraulic water. There are someshortcomings in the Chinese and Japanese bride design specifications ascalculating the hydrodynamic force and the effect to the seismic dynamic responseof bridges.Based on the study of the effect principle of hydrodynamic on varied piers,the distributed regularity of hydraulic water along the height and width directionof the upstream face is verified. Through the study of hydraulic water on varied of seismic waves, the distributed regularity and effect characteristic are confirmed.The effect of hydraulic water to the seismic dynamic response of rectangular crosssection piers and cylindrical piles structures are different in near field and far fieldearthquake. It should use different types of seismic waves in the bridge dynamicresponse considered the hydraulic water.Through shaking table tests considering the interaction of the water andelevated pile platform structural model, the effect principal of the hydraulic wateron the structure under harmonic loads is confirmed. The results of the shakingtable tests confirmed that the hydraulic water surrounded the structures wouldincrease the predominant period and influence the dynamic response. Thefrequency of dynamic loads would change the effect of hydrodynamic force to thedynamic response.Finally, taken the3rd Nanjing Yangtze River Bridge as prototype, thedynamic response of the long span deep-water cable-stayed bridge was analyzedtaken into account the effect of hydrodynamic force. In earthquake, thehydrodynamic force had a great impact to the internal force of various elements inthe cable-stayed bridge. For this reason, it is necessary to consider the influence ofthe hydrodynamic force to the dynamic response in the seismic design of thecable-stayed bridge.