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the building system considered is a scaled model, the amplitude of the
earthquake was scaled to ten percent of the full-scale earthquake. The
various control algorithms were evaluated using a set of evaluation
criteria based on those used in the second generation linear control
problem for buildings (Spencer and Sain 1997) such as
FIGURE 1
SCHEMATIC DIAGRAM
(Jansen and Dyke 2000)
where x t (f) is the relative displacement of the zth floor over the entire
response, x"^ denotes the uncontrolled maximum displacement. h t is the
height of each floor (30cm), d t (t) is the interstory drift of the above
max
ground floors over the response history, d n denotes the normalized
peak interstory drift in the uncontrolled response, x m (r) is the absolute
accelerations of the zth floor, x is the peak uncontrolled floor
acceleration, and W is the total weight of the structure (1335 N). The corresponding uncontrolled
responses are as follows: x*** =1.313 cm, JT = 0.00981 cml'xT (t) = 146.95 cm/sec 2 .
The resulting evaluation criteria are presented in Table 1 for the control algorithms previously studied
(Jansen and Dyke, 2000). The numbers in parentheses indicate the percent reduction as compared to
the best passive case. To compare the performance of the semiactive system to that of comparable
passive systems, two cases are considered in which MR dampers are used in a passive mode by
maintaining a constant voltage to the devices. The results of passive-off ( 0 V ) and passive-on (5V)
configurations are included.
FIGURE 2 VARIATIONS OF EVALUATION CRITERIA WITH WEIGHTING PARAMETERS
FOR THE ACCELERATION FEEDBACK
For modal control, three cases of the structural measurements are considered; displacements, velocities
and accelerations. Using each structural measurement, a Kalman filter estimates the modal states. Fig.
2 represents the variations of each evaluation criteria for increasing weighting parameters in a 3-
dimensional plot JT is the summation of evaluation criteria, //, /2 and /. We can find the weighting
for reduction of overall structural responses from the variations of JT, whereas we can find the
weighting for reduction of related responses from //, J and /j, Designer can decide which to use
according to control objectives. By using the controller (H2/LQG) with designed weighting matrices