Effects of Precast Cladding Systems on Dynamic Characteristics of Steel Frame Buildings by Ambient and Free Vibration Tests

Table 3

Natural frequencies and damping ratios estimated from ambient vibration tests.

Case	Peak acc.; (×10^−2 m/s^2)	Frequency			Damping ratio
		f (Hz)	(Hz)	COV (%)	ζ (%)	(%)	COV (%)
1	0.90	3.40	0.001	0.029	0.1	0.01	10.0
2	0.27	3.92	0.001	0.026	2.0	0.05	2.6
3	0.50	4.07	0.002	0.049	1.9	0.07	3.7
4	0.47	3.95	0.001	0.025	1.3	0.04	3.0
5	0.63	4.42	0.001	0.023	1.5	0.01	0.7
6	0.86	3.90	0.001	0.026	1.7	0.09	5.3
7	1.43	4.27	0.007	0.163	0.9	0.06	6.5
8	1.00	3.59	0.005	0.139	1.2	0.12	9.9
9	0.85	3.76	0.003	0.080	1.3	0.05	3.9
10	0.52	4.65	0.006	0.129	1.9	0.02	1.1

Note: f denotes mean value of natural frequency;  ζ  denotes mean value of damping ratio;  σ  denotes standard deviation; and COV denotes coefficient of variation = standard deviation/mean.