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Table 6. Dynamic properties of the unbraced thirty
story building
of WOBI and ESPS search methods for various
objective functions resulted in an improved per-
formance over those obtained by the sequential
search (SS) method.
It has been found that the optimal distribution
obtained with
J4
is very stable and not affected by
the selection of the search algorithm, but it strongly
depends on the nature of the earthquake record at
the site. Hence the best results for seismic excited
building can be obtained by minimizing J4 using
the design earthquake of the particular site.
Heuristic search methods using performance
indices have the advantage to be practical and
easy to implement and they can be applied both
to linear and nonlinear structures. However there
are some weaknesses in the methods:
Story
ω [rad/s]
T [s]
ζ [%]
ϵ [%]
1
2.37
2.65
2.00
76.03
2
6.39
0.98
2.00
12.04
3
10.52
0.60
2.73
4.34
4
14.68
0.43
3.59
2.16
5
18.81
0.33
4.48
1.37
6
22.82
0.28
5.36
1.00
7
26.88
0.23
6.26
0.72
8
30.59
0.21
7.10
0.37
9
34.66
0.18
8.01
0.33
10
38.23
0.16
8.82
0.28
11
41.83
0.15
9.63
0.19
12
45.47
0.14
10.46
0.15
13
48.88
0.13
11.23
0.12
14
51.75
0.12
11.88
0.12
1. A trial and error procedure must be employed.
2. A large computing cost is required, because
the time history structural response need to
be evaluated.
3. The optimal device distribution is affected
by the specific earthquake record employed
in the analysis.
15
55.02
0.11
12.62
0.12
16
57.52
0.11
13.19
0.09
17
60.25
0.10
13.81
0.05
18
62.24
0.10
14.27
0.05
19
64.59
0.10
14.80
0.08
20
66.82
0.09
15.31
0.04
21
68.68
0.09
15.73
0.05
Due to the great uncertainties in the nature of
the earthquake excitations, using different earth-
quake records can yield different optimal locations.
Therefore there is need for further research in
developing statistical methods that can overcome
the weaknesses of the above approaches.
22
71.79
0.09
16.44
0.03
23
73.87
0.09
16.91
0.03
24
77.44
0.08
17.72
0.04
25
79.74
0.08
18.25
0.03
26
84.24
0.07
19.27
0.03
27
87.40
0.07
19.99
0.05
28
92.48
0.07
21.15
0.05
29
96.82
0.06
22.14
0.01
FUTURE RESEARCH DIRECTIONS
30
103.61
0.06
23.69
0.03
Much of structural control research and applica-
tions in civil engineering have been concerned
with structures equipped with passive, hybrid,
or active control devices in order to enhance
structural performance under extraordinary loads.
In most cases, the structure and the control sys-
tem are independently designed and optimized.
On the other hand, an exciting consequence of
It has been observed that when the DOFs of the
building are reduced such as in the 6 story build-
ing, then SS, WOBI and ESPS search methods
bring to the same damper distribution for various
objective functions considered. However when
the complexity of the building increases such
as in the 30 story building, then the applications
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