深水桥梁结构的地震反应分析

南水北调工程丹江口二桥主桥为四跨预应力混凝土变截面连续箱粱,其2号主墩基础入水深度超过40 m,在动力荷载作用下水对该类结构的动力特性和地震反应的影响不可忽略。以丹江口二桥为例,用有限元程序ANSYS建立了该桥的有限元模型,模拟了该桥的动力特性和地震反应,利用分析结果探讨了水对该桥动力特性的影响。输入地震波后,由于水的附加质量引起的惯性力和动水阻力的影响,结构的位移和内力较之不考虑水的情况会有所增加,但由于桩质点运动的速度和加速度较小,导致附加质量引起惯性力和动水阻力较小,所以给结构带来的影响较小。分析结果为同类结构的抗震分析提供了参考。

Earthquake Response of Deep Water Bridge Structure

The second bridge on Danjiangkou reservoir is a four-span variable cross-section continuous box girder prestressed concrete bridge,the foundation depth of the No.2 pier is over 40 m.The influence of water upon the dynamic characteristic and earthquake response of this kind structure can not be neglected under the dynamic load.Taking the second bridge on Danjiangkou reservoir as an example,the dynamic characteristic and earthquake response of this bridge is simulated by using finite element analysis software ANSYS.The impact of water on dynamic characteristic of this bridge is discussed with the analysis results.After importing the earthquake wave,the displacement and the inner force of the structure are larger than those of the structure without the influence of water due to the inertia force and the resistance force which induced by the water,but the the inertia force and the resistance force are small as the speed and the acceleration of the pile particle are small,which resulting the influence on the structure is small.The results can be used as a reference for the seismic analysis of this kind structure.