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Design and Modeling of an Improved Passive Viscous Damper Based on the Reduction of the Effects of Brace Flexibility

Kheyri Torghabeh, Farid | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47271 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ahmadizadeh, Mehdi
  7. Abstract:
  8. By comparing the control systems, researcherstypically believe that the active systems of control have better performance than passive ones. However, the high costs and the required technology for their erection and maintenance have limited the use of active control systems. In order to improve the control system performance at lower costs, semi-active control systems were also considered. Their performance is based on creating the desired control force by changing the instrument characteristics.Moreover, recent researches have shown that the improved performance of these instruments in structures compared to passive control systems, are typically due to reducing the flexibility of the braces. Particularly, it is shown that choosing the damping coefficient and creating control force, based on a decentralized equation in order to reduce the flexibility of the braces eventuates functionality similar to the case that active control algorithms are used. Present research, following these activities, is trying to present a conceptual design for a passive damper in which proper orifice profiles are designed to give functionality close to a semi-active viscous damper based on the reduction of the effects of brace flexibility. To achieve this goal, the relation previously obtained for semi-active dampers, will be used to design chambers and orifices.Thus, this research would be to introduce a passive damper with improved performance without requiring external power supply. There are moving parts defined in the damper’s orifice structure, when the shaft moves, it forces oil to flow, and the drag force exerted on the moving parts, causes the orifice cross section to change. These changes on the damping coefficient are studied. Due to the numerous variables ahead, a number of variables are assumed to be constant, and for four particular cases, studies have been conducted.Finally, it was shown that the applied modifications and the installation of the defined mechanism caused a significant improvement in the performance of damper
  9. Keywords:
  10. Brace Flexibility ; Viscous Damper With Varying Orifice ; Passive Damper

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