Table 3: Natural vibration property.
(a) Xa

Mode  no.Natural period (sec)Effective mass ratio  (%)Order
direction direction

10.367 0.300 0.260 6.06 77.74  1
20.133 0.108 0.094 71.82 2.10 1 
30.095 0.077 0.067 12.68 0.04 2 
40.054 0.044 0.038 0.03 4.46  3
50.045 0.037 0.032 7.47 7.75 32

(b) Xb

Mode
no.
Natural period (sec)Effective mass ratio  (%)Order
direction direction

10.356 0.290 0.252 6.86 77.42 31
20.131 0.107 0.092 70.50 2.70 1 
30.093 0.076 0.066 14.09 0.13 2 
40.054 0.044 0.038 0.11 3.97  3
50.044 0.036 0.031 6.63 7.98  2

(c) Wa

Mode
no.
Natural period (sec)Effective mass ratio  (%)Order
direction direction

10.361 0.295 0.256 4.55 88.91  1
20.128 0.104 0.090 72.98 1.60 1 
30.100 0.082 0.071 15.59 0.27 2 
40.057 0.047 0.041 0.41 5.73  2
50.045 0.036 0.032 5.05 2.13 33

(d) Wb

Mode
no.
Natural period (sec)Effective mass ratio  (%)Order
direction direction

10.350 0.286 0.248 5.29 88.68 31
20.126 0.103 0.089 71.34 2.13 13
30.099 0.081 0.070 17.76 0.48 2 
40.057 0.047 0.040 0.21 5.24  2