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以深水桥梁的两座桥墩为研究对象,考虑混凝土的非线性力学行为,以可有效计入墩-水流固耦合效应的势流体完全数值法为基础建立势流体模型,并引入动水压力简化算法建立附加质量模型.讨论了墩周水域范围及势流体单元尺寸的合理取值,验证了简化算法在深水桥墩非线性动力分析中的有效性.对比讨论了弹性模型、非线性模型动力响应的差别,对比了近、远场地震下深水桥墩非线性动力响应的差异及分布特征.研究结果表明:当地震动峰值加速度(P_(PGA))较小时,桥墩非线性模型与弹性模型的动力响应相一致;随P_(PGA)的增大,非线性模型的墩底弯矩、剪力均小于弹性模型,说明强震下桥墩会进入开裂甚至弹塑性状态,其力学行为与弹性模型差别明显,应该考虑其在强震下潜在的非线性动力行为.近场地震下,深水桥墩的动力响应明显高于远场,墩底弯矩均值分别比远场地震下大80.4%和34.4%,剪力均值分别大23.7%和28.9%,表明近场地震下桥墩会进入更强的非线性状态,对近断层区深水桥梁的抗震设计提出了更高的要求.
Taking the two piers of deepwater bridge as the research object and considering the nonlinear mechanical behavior of concrete, a potential fluid model is established based on the complete numerical method of potential fluid that can effectively count the coupling effect between pier and water, and the dynamic water pressure simplification algorithm An additional mass model is established.The reasonable value of the water area around the pier and the size of the potential fluid is discussed.The effectiveness of the simplified algorithm in the nonlinear dynamic analysis of the deepwater pier is verified.The difference between the elastic model and the nonlinear model is discussed , The differences and distribution characteristics of nonlinear dynamic response of deep water piers under near and far earthquakes are compared.The results show that the dynamic response of bridge piers is consistent with the elastic model when the local peak acceleration (P_ (PGA)) is small . With the increase of P_ (PGA), the moment and shear of the bottom of the nonlinear model are less than that of the elastic model, which indicates that the pier will enter the cracking or even elastic-plastic state under the strong earthquake. The difference between the mechanical behavior and the elastic model is obvious. Its potential nonlinear dynamic behavior under strong earthquakes.In the near-field earthquake, the dynamic response of the deep-water pier is obviously higher than that of the far-field, and the mean value of the moment of pier bottom is far The earthquakes are large at 80.4% and 34.4% respectively, and the average shearing force is 23.7% and 28.9% respectively, which indicates that the pier will enter a stronger nonlinear state under near-field earthquake and put forward higher requirements for the seismic design of deep-water bridges in near-fault zone .