粘弹性人工边界的虚位移原理

PRINCIPLE OF VIRTUAL DISPLACEMENTS OF VISCOUS-SPRING ARTIFICIAL BOUDARIES

该文将结构及其近场地基作为动力平衡系统,将在人工边界上的波动分解为自由波和散射波,并将输入地震波动转化为作用于人工边界上的等效荷载以实现波动输入。基于以上假设通过分析结构及其近场地基系统的动力平衡关系和自由场的传播机制,给出了自由场的位移表达式、速度表达式,以及在人工边界上由自由场产生的等效荷载一般表达形式,最后建立了粘弹性人工边界统一的动力学积分弱解形式,同时基于有限元程序自动生成系统(FEPG)开发了粘弹性边界条件元件程序。经过计算验证:该文建立的具有粘弹性人工边界的动力学问题的积分弱解方程粘弹性边界条件元件程序可靠、正确。利用这些元件程序,在前处理中可像加位移或应力边界条件一样简便快捷地施加粘弹性边界条件。

The paper takes the structure and near-field foundation as a dynamic equilibrium system and decomposes the input wave on artificial boundaries into free waves and dispersion waves that are mutually independent. Based on the above assumptions, the paper analyzes the dynamic equilibrium relation between the structure and near-field foundation and promulgation mechanism of free fields, deduces uniform expressions of the displacement, velocity and equipollent loads acting on artificial boundaries, and then sets up the dynamical integral week equations of viscous-spring artificial boundaries. Meanwhile, based on Finite Element Program Generator （FEPG）, boundary element codes are developed for viscous-spring boundary conditions. Thus viscous-spring boundary conditions can be simply and rapidly applied like general displacements and stress conditions. The computational results show that element codes are accurate and reliable.