Identification Of Modal Parameters Based On Time-frequency Analysis

The safety of engineering structures has been a widespread concern. How to conduct non-destructive identification of structural damage and then determine the structural safety is a pressing problem. Modal parameters reflect the characteristics of the structure itself. It is an important factor for dynamic characteristics of structural damage identification and health assessment. Because of the civil engineering structure is large and complex, the plus in centives is difficult, the use of environmental incentives obtain modal parameters of civil engineering structures is considered an effective method.Firstly, studying the displacement modal parameter identification method based on the complex Morlet wavelet for freedom vibration and viscous damping system. Using ANSYS and MATLAB simulate single degree of freedom, two degrees of freedom and three degrees of freedom system. Using MATLAB to identify modal parameters and study the parameters which affect the method.Then, Using the relationship between displacement and strain get the identification of strain modal parameter method. Using ANSYS simulate a cantilever and fixed beam. Writing MATLAB programs of the displacement modal parameter identification and the strain modal parameter identification for the cantilever and fixed beam. Using the filter method improve the identification of modal parameter method.Finally, verifying the modal parameter identification method by identifying of modal parameter for Jantougou Bridge and Beichuan River Bridge. Analyzing the identification results and comparing with the stochastic subspace identification results. Verifying the identification of modal parameter method based on complex Morlet wavelet and filter method are effective.