倾斜入射地震下结构-地基的透射边界

为正确反映结构-地基动力相互作用,消除传统固定边界模型将地震能量全部陷入计算模型的不合理现象,该文提出倾斜入射地震下结构-地基动力反应分析的有限元模型及其透射边界.有限元模型由主网格、自由场网格和侧边透射层网格组成,地震以入射平面波形式输入,以入射波运动作为非惯性参考坐标系建立相对运动的动力方程.结构-地基实际反应为相对运动与入射波动之和,算例表明透射边界模型能有效地透射倾斜入射地震下结构-地基动力反应的辐射分量.

Transmitting boundary for structure-foundation system subject to inclinedly input earthquake

In order to be able to account correctly the dynamic interaction of structure foundation systems,and to overcome the drawbacks of the classical fixed boundary dynamic model of structure foundation,which traps completely the earthquake energy into the computation model,a transmitting boundary model is proposed for earthquake response analysis of structure foundation systems subject to inclinedly propagated earthquakes.The model consists of three parts,which are main mesh,free field column and transmitting layer.The input earthquake is defined as the in coming propagated plane waves and is taken as the non inertia reference frame to formulate the dynamic equations in terms of relative motion quantities.The real response of structure foundation systems should be the superposition of the computed relative motion and the reference motion of the in coming plane earthquake waves.The numerical example included shows that the proposed transmitting boundary model can efficiently transmit waves out of the computation model.