利用局部振动频率识别框架结构构件刚度参数

An Analytic Approach to the Identification of Component Stiffness in a Frame by Using Local Vibration Measurement

鉴于依据结构整体动力反应很难准确识别结构局部构件的物理参数 ,提出了结构局部激振检测方法 ,即对结构局部进行激振 ,依据结构局部激振反应提取其固有频率 ,再利用此固有频率运用解析方法识别结构局部构件的物理参数。本文将框架结构中的梁柱简化为两端有弹性约束、具有等刚度和等分布质量的杆件模型 ,推导了这一模型的频率特征方程 ,并进一步分析了两端弹性约束对其振动固有频率的影响。仿真算例表明 :在固有频率误差较小的情况下 ,本文方法可准确地给出构件抗弯刚度和边界条件。

In view of the fact that it is quite difficult to accuratly identify the component physical parameters of a structure by its global dgnamic response. A method is presented in the paper for identifying the component parameters by loal excitations, i.e.to excite the structure locally, and extract the natural frequencies of the component from its response, and then to identify its physical parameters from the frequencies by an analytical approach. Taking a frame structure as an example in the paper, the columns and beams in the structure are idearized as a uniform beam with rotational spring restrains at its both ends. The frequency eigen equation of the beam is derived, from which the relationship between natural frequencies and flexural stiffness including boundary spring stiffness can be established. Simulation results show that the component flexural stiffness and boundary conditions can be accuratly identified, if the errors in the natural frequencies are small.