A novel energy dissipation system that can achieve the amplified damping ratio for a frame-core tube structures is
explored, where vertical dampers are equipped between the outrigger and perimeter columns. The modal characteristics
of the structural system with linear viscous dampers are theoretically analyzed from the simplified finite element model
by parametric analysis. The result shows that modal damping ratios of the first several modes can increase a lot with this
novel damping system. To improve the control performance of system, the semi-active control devices,
magnetorheological (MR) dampers, are adopted to develop a controllable outrigger damping system. The clipped optimal
control with the linear-quadratic Gaussian (LQG) acceleration feedback is adopted in this paper. The effectiveness of
both passive and semi-active control outrigger damping systems is evaluated through the numerical simulation of a
representative tall building subjected to two typical earthquake records.
KEYWORDS: Control systems, Actuators, System identification, Systems modeling, Control systems design, Earthquakes, Mathematical modeling, Smart structures, Motion models, Linear filtering
The structural control can provide the potential protection through passive and active control techniques. Structures with
base isolations have been successfully implemented and proven effective in the vibration mitigation. To enhance the
functionality of base isolations, a hybrid control system can be considered using a combination with active control
devices. This research applies the hybrid control technique to a three-story two-bay steel building. The base isolation is
installed under the structural base, and three actuators are placed at the lowest level. The control objective is to reduce
the structural responses in the motion of three directions. First, the control system has been identified through the
proposed system identification technique and considered with the control-structure interaction. Different controllers are
designed to examine the performance under different types of excitation. Finally, this control system is tested on the
shake table for evaluation of the controllers, and the two-dimensional control strategy is also realized through the whole
procedures.
KEYWORDS: Control systems, Bridges, Control systems design, Vibration control, Sensing systems, Sensors, Electroluminescence, Earthquakes, Power supplies, Resistance
A new self-powered and sensing semi-active control system based on magnetorheological (MR) damper is presented.
The system includes four key parts: a rack and pinion mechanism, a linear permanent magnet DC generator, a current
adjustment MR damper, and a control circuit. Numerical simulations for seismic protection of elevated bridges equipped
with this system excited by two historical earthquakes are conducted. Linear quadratic regulator (LQR) is used for the
design of ideal active control system. LQR-based clipped optimal control as well as skyhook control is used to command
a MR damper in both the semi-active control with external power and self-powered semi-active control. It is shown that
five strategies (ideal active control, two semi-active controls and two self-powered semi-active controls) have similar
control performance in pier response as well as bearing response. It is noticed that only one accelerometer is needed to
monitor the response of the deck to realize the self-powered skyhook control, which greatly simplifies the classical semiactive
vibration control system based on MR damper.
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