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

Table 6

Results of natural frequency and damping ratio identification of the 3-DOF system subjected to nonstationary white noise through the nonstationary ARMA algorithm with polynomial base function.

Mode	Natural frequency (rad/sec)			Damping ratio (%)
	Exact	ARMA	Error (%)	Exact	ARMA	Error (%)
1	8.84	8.82	0.23	2.95	3.00	1.69
2	13.66	13.65	0.07	2.74	2.69	1.82
3	18.31	18.29	0.14	2.90	2.92	0.69