环境激励下桥梁结构模态识别与损伤检测的新方法

已有的环境激励下模态参数识别的方法对模态频率的识别精度相对较高,而对位移模态的识别则误差较大。本文提出一种利用移动质量块在不同位置时对桥梁的模态频率进行多次测量,用各次测得的频率值确定位移模态的新方法,使得位移模态识别的精度接近频率识别的精度,推导了频率与位移模态关系的理论公式,并给出利用以曲率形式表示的单元模态应变能对结构进行损伤标定的基本方法。最后,通过数值模拟对该方法的有效性进行说明。

New Approach for Modal Analysis and Damage Identification of Bridges Based on Ambient Excitation

In this paper,a new modal analysis and damage identification method is developed for bridge structures,in which the displacement mode and curvature mode can be obtained by nature frequency and so local damage are characterized by only the nature frequency measured from the damaged structures,in contrast with most of the existing vibration-based damage identification methods.By the method proposed in this paper,the displacement mode can be obtained with the same accuracy as that from nature frequency.The damage identification based on the changes of modal strain energy is also discussed and the modal strain energy is described by curvature mode.Finally,a computer simulated case study is made to illustrate the capability of modal analysis and damage evaluating.