An Extended Time Series Algorithm for Modal Identification from Nonstationary Ambient Response Data Only

Table 3

Results of natural frequency and damping ratio identification of the 3-DOF system subjected to nonstationary white noise through the nonstationary ARMA algorithm with curve-fitting technique.

Mode	Natural frequency (rad/sec)			Damping ratio (%)
	Exact	ARMA	Error (%)	Exact	ARMA	Error (%)
1	8.84	8.84	0.01	2.95	3.30	11.86
2	13.66	13.63	0.22	2.74	2.91	6.20
3	18.31	18.29	0.11	2.90	2.97	2.41