Nonlinear Structural Control Using Magnetorheological Damper - Design Optimization of Active and Passive Structural Control Systems - page 308

diagram of the experimental test set-up for the
control of the hybrid base isolated building using
optimal FLC is shown in Figure 3. The hybrid
isolation is achieved using four sliding bearing
at the four column bases of the building and an
MR damper connected at the base. In the ex-
perimental set up GA based optimal FLC is used
as the controller. The stiffness of the bearing at
the base is augmented using four linear springs
placed co-axially with the sliding bearings. Figure
4a shows a photograph of the experiment with
LVDT positions. Figure 4b shows connections
at the base in fixed base condition, base isolated
condition and the MR damper connection. Ac-
celeration responses and inter-storey drifts are
measured on all floors. In addition, acceleration
and relative displacement ( w.r.t. shake table) at
the base isolator and acceleration and absolute
displacement of the shake table are measured.
Velocity at each floor is hardware integrated from
the acceleration data.
Data acquisition is carried out using Dewetron
acquisition system at a sampling rate of 1 kHz.
For real time control implementation, dSPACE
real-time controller, which has an on-board digi-
tal signal processor (DSP) is used. Thus the

processing speed depended only on the DSP, which
is designed specifically for real-time tasks. The
optimal FLC is encoded in MATLAB Simulink
using real time workshop (RTW) interface and
dSPACE hardware and software. The isolator
acceleration at the damper location and pseudo
velocity are used as feedback to the RTW to obtain
the voltage to be supplied to the MR damper.
Figure 5 shows the Simulink block diagram of
the controller implementation. The embedded
fuzzy function contains the off-line simulated
optimal fuzzy parameters and the rule base. The
fuzzy parameters and the rule base are specifi-
cally optimized for this particular experiment.

Base Isolated Building Model and
System Identification

For the simulation and experimental study pre-
sented in this chapter a three-storey base isolated
building is considered. A single MR damper is
connected at the base of the building. Base isolated
buildings are designed such that the superstructure
remains elastic. Hence, the superstructure is mod-
eled as a three-dimensional linear elastic shear

Figure 3. Schematic diagram of the experimental set-up