Abstract
A method is proposed to design an effective semiactive control system composed of a linear low damping base isolation and a supplemental magnetorheological (MR) damper when the structure subjected to multiple earthquakes. In the proposed design method, the parameters of semiactive control system have been determined based on minimizing the average of maximum response of isolated structure under multiple design ground motions. To select appropriate value for force related weighting parameter, defined in performance index, a range has been suggested for each design objective. For numerical simulations, a scaled three-story base-isolated frame subjected to different scaled real earthquakes as well as filtered white noise excitations and the proposed method has been applied to design semiactive base isolation system under multiple earthquakes. The results of numerical simulations have shown the capability of the proposed method in designing an effective semiactive base isolation system, the performance of which under multiple earthquakes has been almost close to the case that it is designed optimally for each earthquake separately. Also, under multiple earthquakes, using the passive-off and passive-on forms of MR damper can be recommended, respectively, regarding to the objectives of minimizing the maximum acceleration and base drift.
Highlights
Base isolation system is widely recognized as one of the most effective control strategies used for mitigating the structural response, which helps a structure survive a potentially devastating seismic impact through a proper initial design or subsequent modifications
A method has been presented for designing a semiactive control system composed of a low damping base isolation system and a supplemental magnetorheological (MR) damper under multiple earthquake records to mitigate the maximum superstructure acceleration and base drift of the isolated structure. e H2/linear quadratic Gaussian (LQG) and clipped-optimal control algorithms have been used to determine MR damper force
In the proposed method where the main focus has been designing the semiactive base isolation system to be effective under multiple design records, first the appropriate range for the parameter of control system has been determined for each design objective under each excitation, and based on mitigating the average of responses under multiple earthquakes, the control system design parameters have been selected
Summary
Base isolation system is widely recognized as one of the most effective control strategies used for mitigating the structural response, which helps a structure survive a potentially devastating seismic impact through a proper initial design or subsequent modifications. Hybrid active base isolation systems have been studied by a number of researchers [4,5,6] and have shown effective performance in both mitigating the base drift and adapting to different conditions. In previous researches which use only one excitation in designing semiactive base isolation systems, the effect of earthquake characteristics on designing and performance of semiactive base isolation has not been studied in detail. Erefore, following this recommendation and extending it in designing control system to be effective under different earthquakes, in this paper, it has been decided to design the semiactive base isolation system based on considering multiple earthquakes in the design procedure that the earthquake records have been selected randomly. The performance of control system designed based on using multiple records in the design procedure has been evaluated under different test records
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