动水压力作用对深水桥墩地震响应的影响

地震激励下水与桥墩的相互作用会对桥墩产生动水压力,本文研究动水压力作用对深水桥墩地震响应的影响,对提高深水桥墩长大桥梁的抗震安全性尤为重要。分别采用Morison方程和辐射波浪理论,建立了动水压力计算方法,分析了动水压力作用对桥墩地震响应的影响,并比较了两种方法计算的动水压力对桥墩地震响应影响的差异;分析了考虑土-结构相互作用时以及双向地震作用下动水压力作用对桩基桥墩地震响应的影响。研究表明:动水压力作用不仅会改变桥墩的动力特性,而且会增大桥墩的地震响应,其影响随相对水深的增大而增强;当桥墩迎水面宽度较大时,采用Morison方程计算的动水压力对桥墩地震响应的影响明显大于采用辐射波浪理论计算动水压力的影响;考虑土-结构相互作用会降低动水压力对桥墩地震响应的影响,但其影响仍不容忽视;考虑双向地震作用会加剧动水压力对桥墩地震响应的影响。由此得出结论,在深水桥墩长大桥梁的抗震分析中,需考虑动水压力作用对桥墩地震响应的影响。

Influence of hydrodynamic pressure on seismic response of bridge piers in deep water

Hydrodynamic pressure on bridge piers would occur during water-pier interaction under earthquakes. The influence of hydrodynamic pressure on the seismic response of bridge piers is studied. Hydrodynamic pressure formula is established using both the Morison equation method and the radiation wave theory. The influence of hydrodynamic pressure on the seismic response of bridge piers is studied and the two methods are compared. The influence of hydrodynamic pressure on the seismic response of a pier with pile foundation is analyzed with consideration of soil-structure interaction and bidirectional earthquake action. The results indicate that the dynamic characteristics of pier changed and the seismic response is augmented because of the hydrodynamic pressure effect, and this effect becomes more significant with the increase of the relative water depth. For piers with wider upstream face, the influence of hydrodynamic pressure from the Morison equation is obviously larger than that from the radiation wave theory. The action of hydrodynamic pressure decreases if the soil-structure interaction is considered, but the influence of hydrodynamic pressure cannot be ignored. The influence of hydrodynamic pressure will be enhanced under bidirectional earthquake action. In conclusion, the influence of hydrodynamic pressure on the seismic response of piers needs to be considered in seismic analysis of large bridge piers in deep water.