Abstract：Operational modal parameters identification is output only modal analysis method. The modal parameters obtained from ambient vibration are subject to statistical uncertainty. The uncertainty can be evaluated by its statistical characteristics. Variance calculation in frequency spatial domain decomposition is illustrated based on sensitivity analysis of the algorithm. The calculation flow includes four steps: (1) Estimating covariance of power spectrum density (2) Calculating variance of enhanced power spectrum density. (3) Calculating poles covariance (4) Calculating modal parameters variance. Finally, a simulated case of four DOFs system and a measurement case of Zhang Jia Gang bridge are used to validate the accuracy and practicability of the presented calculation method.
2013, Vol. 34 
