斜拉桥考虑下部结构与水体相互作用的动力建模研究

The Study of Dynamical Model of Cable-stayed Bridge with Fluid-substructure Lnteraction

跨海大桥的不断涌现,使得桥梁下部结构受到较为严重的河流冲刷作用,而由于冲刷产生的桥梁的灾害远多于地震和台风产生的破坏。在已有流固耦合求解的基础上,改造了桥塔下部结构的振动与流体速度之间的相互作用的边界条件,通过逆解法求解在该边界条件下,扰动液体内部的任意点处的三维拉普拉斯方程,得出了作用在下部结构的动水压力。采用振型分解将动水压力以附加质量的方式作用在结构上。通过对流场的简化,建立了适合有限元分析的附加质量矩阵,并用通用有限元软件ANSYS实现上述功能。以大跨斜拉桥为例分析对比了下部结构与水体相互作用对斜拉桥动力特性的影响,得出了下部结构与水体的流固耦合作用对以主梁为主的振动频率影响较小,而对以桥墩为主的振动频率影响较大的结论。

Sub-structure receives more river sourcing with the emergence of sea-crossing bridge. In fact the disaster of bridge caused by river-scouring is more than earthquake and typhoon. Contra-solving is used to make three dimensions Laplace equation of disturbance in fluid internal basic on the solution of fluid-structure coupling and giving the boundary condition of interaction between vibration of the substructure and fluid velocity. The paper give the dynamic hydraulic pressure of the substructure , so these pressures is transfer to additional mass in the structure by model analysis. The additional mass matrix adapting for finite element analysis is formed through simplifying flows and these functions are fulfilled in ANSYS. The influence of fluid-substructure on dynamic characteristic of a long span cable-stayed bridge is ana- lyzed and compared. Coupling of fluid-substructure influence on frequency by beam vibration is trivial, but on frequency by pile vibration is big primarily.