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CONCLUSION
the widely used clipped optimal and optimal FLCs
is shown. From the results reported, it can be
concluded that the performance of the proposed
nonlinear controllers are better than those from the
widely used clipped optimal and optimal FLCs.
Both clipped optimal and optimal FLCs decrease
the isolator displacement but at the cost of an in-
crease in base and superstructure acceleration. The
dynamic inversion and the integrator backstepping
controllers provide a tradeoff between the isola-
tor displacement and superstructure acceleration
responses, offering the engineer a suite of options
for selecting a design.
The nonlinear force-input voltage relation of
MR damper introduces challenges in modeling
the damper characteristic as well as in develop-
ing proper control strategy to effectively use the
damper capacity. Existing model based algorithms
switch the MR damper input voltage between zero
and maximum, based on force feedback from the
damper and the desired control force. Another
drawback of the existing algorithms is that none
of them consider the dynamics of the input volt-
age in to the algorithm. These two drawbacks in
existing control schemes formed two objectives of
the present chapter. In this chapter, development
of various nonlinear control schemes are shown
along with the most widely used linear control
method. First a fuzzy logic based intelligent con-
trol a technique is studied. Various parameters,
the membership function and the fuzzy rule base
are optimized using micro-genetic algorithm. A
novel geometric way of designing the fuzzy rule
base is shown. The FLC system is optimized
for a three storey base isolated building, which
is then used to control the building in real time
experiments. The experimental details and results
are also reported. The results show a good match
between the experimental and numerical analysis.
The optimal FLC is seen to control the system
responses as desired.
In a separate section two model-based semi-
active control algorithms are developed using
modern nonlinear control techniques. The de-
veloped algorithms not only update the voltage
supply to the damper smoothly, but also take
care of the MR damper supplied to commanded
voltage dynamics in the algorithms. Furthermore,
unlike other model based control algorithms, the
proposed algorithms do not switch between zero
and maximum voltage values, and as a conse-
quence they provide all voltages within zero and
the maximum allowed as an input to the damper.
Numerical studies are conducted in the same three
storey base isolated building. A comparison with
FUTURE RESEARCH DIRECTIONS
There are still many issues that need to be addressed
and further explored in the area of response control
of structures, such as the development of highly
efficient and reliable control systems, large scale
testing of various control devices, applications of
control in the design and retrofit of structures, code
adoption of seismic protective systems in future
design guidelines, etc. In terms of the applica-
tion of seismic protective systems in earthquake
engineering, ground motion characteristics need
to be better addressed in the future design and
application of various control systems.
Based on the present study following recom-
mendation for future studies can be suggested
•
Due to hardware constraints and the com-
putational efforts required in real time
optimization using genetic algorithm, the
experimental study is performed using off-
line optimization. The experimental study
can be conducted using various hardware
that are specifically made for GA optimi-
zation. Further investigation can be carried
out with 3D building considering bi-direc-
tional seismic excitation supplied simulta-
neously and considering the torsional re-
sponse of building in the analysis.
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