研究改进动水压力算法的近断层区深水桥梁抗震设计

随着交通基础设施建设的突飞猛进，跨海(江)及库区桥梁不断涌现，部分深水桥梁靠近甚至跨越高烈度断层区。由于近断层地震动的大幅值、低频谱特性和长周期脉冲效应，显著改变动水环境下深水桥梁的振动性态和动力响应，而相关研究及规范规定尚不完善，此类特殊动力荷载下特殊桥梁的抗震设计是亟待解决的科学问题。本项目基于经典的流固耦合理论和辐射波浪理论，通过理论分析、振动台模型试验及深水桥梁单墩、全桥模型的全数值耦合动力计算，提炼不同的水环境、结构参数下地震动脉冲特性对动水压力和桥梁地震响应的影响机理，界定Morison方程法的适用范围并确定适用于典型深水桥梁的关键参数取值，检验并改进规范算法，考虑大直径柱体-流体间动力相互作用和水体可压缩性，发展基于辐射波浪理论的大跨径深水高墩动水压力的简化算法,揭示脉冲型近断层地震下深水桥梁的破坏机理及失效机制。供规范修编参考，为跨海(江)、库区桥梁的地震安全提供技术保障。

With the rapid development of transportation infrastructure, cross-sea, river and reservoir bridges are emerging, and some of these deep-water bridges are close to or even across active fault regions with high earthquake intensity. Because of the large acceleration and low-frequency characteristic as well as the long-period pulse effect of such kind of near-fault earthquakes, the vibration state and dynamic response feature of these bridges are affected significantly under hydrodynamic environment. However, related research and specifications are inadequate, and therefore the seismic design of such special bridges under the unique dynamic excitation is a scientific problem to be solved. Firstly, based on both the classic fluid-structure interaction theory and radiation wave theory, the action mechanism of pulse characteristic of near-fault ground motions on the hydrodynamic pressure and structural response is to be studied for deep-water bridges under different water environment parameters and structural parameters, by the ways of theoretical analysis, shaking table tests and full numerical dynamic calculation of typical equivalent single-pier as well as full-bridge models. And then, the applicable scope of Morison equation method will be defined, and the key parameters applicable to typical deep-water bridges will be identified. Moreover, the calculation methods of hydrodynamic pressure by related codes will be checked and correspondingly improved. Furthmore, by considering the dynamic interaction effect between large-diameter cylinder and fluid, as well as the compressibility of water, a simplified calculation method of hydrodynamic pressure for high piers of large-span bridges is to be developed with the radiation wave theory. Finally, the destruction mechanism and failure mechanism of deep-water bridges under pulse-type near-fault earthquakes will be revealed. These above achievements can be as reference for the revision of codes, and provide technical support for the seismic safety of cross-sea, river and reservoir bridges.