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3 360 Deg. Fault Normal (Jan. 17, 1994), peak acceleration: 0.59 g (100%); (4) Sylmar Channel 1 90 Deg
Fault Parallel (Jan. 17, 1994), peak acceleration: 0.461 g (80%); (5) Sylmar Channel 3 360 Deg. Fault
Normal (Jan. 17, 1994), peak acceleration: 0,84 g (100%); (6) Kobe NS (Jan. 17, 1995), peak acceleration:
0816 g (100%); (7) Kobe EW (Jan. 17, 1995), peak acceleration: 0.62 g (100%). The records are time
scaled by a factor of 2.236 to satisfy similitude requirements. The peak accelerations are scaled from the
original recorded values. Results are presented in Table 1 to Table 3. Table 1 shows peak values of relative
base displacement and normalized peak shear force at the isolation level (total of friction force, MR damper
force, and spring force normalized by total weight). Table 2 shows the peak values of first floor and second
floor inter-story drifts. Table 3 shows the peak values of first floor and second floor accelerations.
In Tables 1 to 3 in case of Sylmar, Newhall, and Kobe earthquakes, the relative base displacement
reductions range from 5 to 40 % in the passive high damping (4 volt) case when compared to the passive
low damping (0 volt) case. This occurs due to the increase in energy dissipation in high damping case, with
nearly 5 to 30 % increase in the peak total force at the isolation level when compared to the low damping case.
The semiactive controlled case gives an additional 5 to 15 % reduction in the base displacement response
over the passive high damping (4 volt) case. The controlled case also reduces or maintains the same level
of total force at the isolation level when compared to the high damping case. Hence, the controlled case
reduces the base displacement further, when compared to 0 volt and 4 volt cases, with no further increase
in force as compared to 4 volt case. The energy dissipation occurs more efficiently in the controlled case
revealing the potential of smart damping. In most cases the interstory drifts in the controlled case are the
smaller than the passive high damping case—which indicates the effectiveness of the smart isolation system,
The accelerations in the controlled case remain bounded by the high and low damping cases. As evident
from Table 1 in case of Sylmar 360 earthquake the peak relative base displacement, the largest amongst all
earthquakes, is reduced by 42% in the passive high damping (4 volt) case when compared to the passive low
damping (0 volt) case. The passive high damping (4 volt) case also reduces the total force at isolation level
by 4% when compared to the passive low damping (0 volt) case. The controlled case gives additional 7%
reduction in the base displacement response over the passive high damping (4 volt) case; the control case
also maintains the same level of total force at the isolation level as compared to that of the passive high
damping case. Thus based on the results in Tables 1, 2 and 3 it can be concluded that the controlled case
reduces the base displacement further and maintains the total force at the isolation level within bounds in
most earthquakes-the one exception being El Centro. In addition the controlled case maintains the interstory
drifts and acceleration response of the two-story model within bounds. Thus the newly developed
Lyapunov based control algorithm and the smart isolation system with MR damper is effective in reducing
the base displacements, without further increases in the total force at the isolation level, interstory drifts
and accelerations.
Table 1 Peak Relative Base Displacement and Normalized Peak Shear Force at the Isolation Level of the
Two-story Smart Sliding Isolated Structure
Earthquake Rel. Base Disp.(cm) Force at Isolation Level/W
El Centro(100%)
Sylmar 90 (80%)
Sylmar 90(100%)
Sylmar 360(105%)
Newhall 90(100%)
Newhall 360(100%)
Kobe NS(80%)
Kobe NS(100%)
Kobe EW
0 Volt
0.938
2.293
3.00
5.48
1.815
3.867
2.511
3.362
2.578
4 Volt
0.85
1.649
2.15
3.183
1.614
3.373
2.45
2.825
2.24
Control
0.77
1.484
2.1
3.02
1.276
3.294
2.105
2.543
2.22
0 Volt
0.16
0.224
0.254
0.354
0.21
0.293
0.204
0.235
0.236
4 Volt
0.244
L 0.263
0.292
0.343
0.28
0.349
0.29
0.312
0.305
Control
0.243
0.26
0.279
0.34
0.261
0.29
0.28
0.3
0.278
Comparison with Experimental Results
Comparison of analytical and experimental results are presented in Table 4 for three earthquakes: (1)