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are presented in the lower part of Table 1. Peak control forces are maximum under the Gebze earthquake
for the LQG controller, whereas these quantities are maximum under the El Centro earthquake for both
H 2 B-EB and H 2 B-PB controllers as shown Table 1. It is observed that the peak control forces of all
actuators for the proposed controllers are quite close to the upper limit 1 OQOkN. The main reason for the
superior performance of our proposed controllers is that they are capable of pushing the control
resources (i.e., peak control forces) of all actuators at all locations to the limit This is a significant
advantage of the proposed new control strategies over other control methods. It is further observed from
Table 1 that most of the response quantities of the bridge have been reduced significantly through the
installation of control devices.
CONCLUSIONS
Two H- based control strategies with "energy-bounded" or peak-bounded excitations have been
proposed and their applications to the seismic response control of a benchmark cable-stayed bridge have
been presented. For design loads specified by a class of "energy-bounded" or peak-bounded excitations,
both controllers are derived by minimizing the upper bound of the HI performance. The design syntheses
of these control strategies are developed and formulated within the framework of linear matrix
inequalities (LMIs), so that the LMI toolbox in MALAB can be used effectively and conveniently. The
performance of these two control strategies in reducing the seismic response of structures has been
demonstrated using a benchmark cable-stayed bridge. Simulation results indicate that: (i) the
performance of the proposed control strategies is excellent in comparison with the LQG sample
controller, and (ii) the seismic response of cable-stayed bridges can be reduced significantly through the
application of control technology. Although actuators are considered in this paper as a possible control
device, it has been shown that passive and semi-active control systems, including passive viscous
dampers, MR dampers, resetting semi-active stiffness dampers and semi-active friction dampers, can be
used to effectively reduce the seismic response of the cable-stayed bridge [ e.g., Moon et al (2002),
Agrawal et al (2002) ].
References
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Control Systems For A Benchmark Cable-Stayed Bridge", Proc 3 rd World Conference on Structural
Control, Como, Italy.
Dyke, S.J., Bergman,, L.A., Turan, G. and Caicedo, J.M. (2000), "Benchmark Control Problem For
Seismic Response of Cable-Stayed Bridge", Proc. 3 rd International workshop on Structural Control,
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