弯剪型结构与轴力型结构振型特征分析

Modal characteristic analysis of member shear resistance structures and member axial resistance structures

框架结构和大跨度拱结构是工程中广泛应用的结构形式.在水平激励作用下,框架结构的抗侧刚度主要由竖向构件的抗弯刚度和抗剪刚度提供,是典型的弯剪型结构;而拱结构以构件的轴向刚度为结构主要刚度,是典型的轴力型结构.二者的振型特性均具有较强的代表性.本文以集中质量法为基础,锁定节点质量变量,考察两种结构的振型几何坐标与振型参与系数的关系,获得弯剪型结构和轴力型结构的振型特征.数值分析结果对比表明,弯剪型框架结构振型参与系数值按振型阶数递减,而轴力型拱结构的振型参与系数值与阶数并无规律可循.

Multi-storey frames and arches are widely used in engineering.A multi-storey frame is a typical structure of member shear resistance structures（MSRS）which the lateral stiffness is provided by the bending stiffness and shear stiffness of the column under lateral loads.But the arch is a typical structure of member axial resistance structures（MARS）which the stiffness is provided by the axial stiffness.Both of their mode shapes have prominent characteristic.In this paper,based on centralized mass method,the relationship of modal geometrical coordinate and modal participation factors of MSRS and MARS are studied.It is found that with the increase of modal order,the modal participation factors of MSRS decrease,while the modal participation factors of MARS show strong randomness.