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Study on Semi-Active Isolation Systems for Sensitive Equipment Subjected to Earthquake

Zebarjad, Leila | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43199 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Bakhshi, Ali
  7. Abstract:
  8. Sensitive equipment, are vulnerable to strong earthquakes, and failure of these equipment may result in a heavy economic loss. Recent studies have revealed that a conventional passive seismic isolation system may induce an excessive displacement when it is subjected to a near-fault earthquake that possesses strong longperiod components.
    Semi-active control devices are capable of offering the adaptability of active devices and stability and reliability of passive devices that have been considered by many researchers.
    Magnetorheological (MR) damper is a reliable semi-active control device which works in a wide range of temperature besides its mechanical simplicity at a modest cost.
    This research presents the performance evaluation of semi-active control in the equipment isolation systems for earthquake protection. In order to reduce the vibration of the equipment, a symmetrical 6 story and an asymmetrical 8 story steel frame structure have been modeled using ETABS software. Structure and equipment characteristics, besides equipment position- obtained from the modeling- are the inputs to MATLAB program.
    A 3000N capacity MR damper has been simulated using the dynamic midified Bouc–Wen model. In the analysis semi-active control algorithms, Clipped-Optimal and the Maximum Energy Dissipation, are used to obtain optimum damper votage. The passive-on and passive-off control of MR damper are employed as references for the discussion on the control effectiveness.
    The results reported from other researchers have been employed to validate this research.
    The effect of changes in the equipment mass, period and location and Peak Ground Acceleration have been considered to investigate MR damper performance in controlling the responses of sensitive equipment.
    In this study a new dimensionless parameter considering the effect of system period has been introduced in order to prevent damper lock.
    Simulation results demonstrate that the mentioned semi-active control technique is effective in protecting vibration-sensitive equipment from both far-field and near-field earthquake excitations
  9. Keywords:
  10. Magnetorheological Damper ; Sensitive Equipments ; Clipped Optimal Control Algorithm ; Semiactive Control ; Earthquake Excitation

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