中文摘要：

当地震波沿不同的方向输入时,结构具有不同的动力响应,并存在最不利入射角度使结构响应最大。传统的最不利入射角度计算只考虑平面内水平两向地震动作用,没有考虑竖向地震动对结构最不利反应的影响。论证了弹性力学中的平面最大主应力方向理论与平面内结构最不利入射角度在机理上是相通的。在此基础上推导了空间最大主应力方向的表达式,进而提出结构考虑三维地震动的最不利入射角度计算公式。提出了基于有限元分析的弹塑性结构瞬时最不利入射角度计算方法。通过数值模拟讨论了空间最不利入射角度的特性和变化规律。通过计算实例证明对于以竖向振型为主的结构应考虑多维地震动并计算空间最不利入射角度。同时,结构弹塑性最不利入射角度具有瞬变特性并与结构损伤程度相关。

英文摘要：

The dynamic responses of the structure are different when the ground motions generate along different directions as excitations,and there exits a critical angle to attain the maximum response.The critical angle calculated based on traditional method is a horizontal angle because only the two-component ground motions in the plane are considered,and the adverse effect of the vertical ground motion is not concerned.The common mechanism between maximum principal stress direction in elastic mechanics analysis and the critical angle of structure in the plane is demonstrated.The expression of maximum principal stress direction in the space is derived and the formula of the structure critical angle for three-dimensional ground motions is proposed.The calculation method of the three-dimensional critical angle for inelastic structure in three-dimensional ground motions is presented based on nonlinear finite element analysis.The characteristics and regularity of the critical angle in three-dimensional ground motions is discussed based on numerical modeling.It is proved that the three-component seismic motion and the corresponding critical angle should be calculated for the structure has obvious vertical modal shapes,and the critical angle of the inelastic structure is transient and is related to the structural damage degree.