${T^{\prime }}_{\text{d0}}$ (s)

3.00

3.70

4.40

5.10

5.80

6.50

Frequency (Hz)

1.366

1.341

1.309

1.241

1.245

1.152

Damping ratio (%)

14.100

16.299

18.870

20.834

28.129

17.284

${T^{\prime }}_{\text{d0}}$ (s)

7.20

7.90

8.60

9.30

10.0

Frequency (Hz)

1.142

1.137

1.133

1.130

1.127

Damping ratio (%)

15.039

13.519

12.315

11.375

10.545