Abstract
Pulse-type near-fault earthquakes have obvious long-duration pulses, so they can cause large deformation in a base-isolated system in contrast to non-pulse-type near-fault and far-field earthquakes. This paper proposes a novel self-tuning fuzzy logic control strategy for seismic protection of a base-isolated system, which can operate the control force of the piezoelectric friction damper against different types of earthquakes. This control strategy employs a hierarchic control algorithm, in which a higher-level supervisory fuzzy controller is implemented to adjust the input normalization factors and output scaling factor, while a sub-level fuzzy controller effectively determines the command voltage of the piezoelectric friction damper according to current level of earthquakes. The efficiency of the proposed control strategy is also compared with uncontrolled and maximum passive cases. Numerical results reveal that the novel fuzzy logic control strategy can effectively reduce the isolation system deformations without the loss of potential advantages of base-isolated system.
Highlights
Over the past decades, base isolation has been demonstrated to be an effective means to protect crucial structures and their contents from the destructive effects of dynamic excitations.The performance of base-isolated structures against near-fault earthquakes characterized by long-duration pulses with peak velocities has been investigated by several researchers [1,2]
The isolation system is composed of lead rubber bearing (LRB) and assumed to have nonlinear force–deformation behavior with viscous damping
FLC can automatically adjust the value of the normalization factors to different types and intensities ensure that the piezoelectric friction damper (PFD) will operate in an effective manner during a non-pulse-type near-fault earthquake of earthquakes
Summary
Base isolation has been demonstrated to be an effective means to protect crucial structures and their contents from the destructive effects of dynamic excitations. In order to enhance the performance of the base-isolated structures subjected to pulse-type near-fault excitations, many kinds of control devices have been proposed [9,10,11]. A controller designed for near-fault earthquakes that cause significant deformations in the isolation system might develop large damper forces during a far field earthquake of generally moderate excitation. If the controller is designed for an earthquake with far-field characteristics, the damper force may not be large enough to effectively reduce the structural responses during the pulse-type ground motion. Zhao and Li [21] proposed a new fuzzy logic controller that is designed for seismic protection of base-isolated structures utilizing piezoelectric friction damper against near-fault earthquakes for different ground sites. A series of numerical simulations for the base-isolated building is performed to assess the performance of the control strategy
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