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Optimal Retrofitting of the Steel Moment Resisting Frames Using Friction Dampers

Afzalinia, Farshad | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50286 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Moghaddam, Hassan
  7. Abstract:
  8. The purpose of this thesis is the optimal retrofitting of the moment resisting frames with friction dampers, using the adaptive approach. In this regard, numerical modeling of the frictional behavior has been presented firstly. Also a 6-story moment resisting frame has been modeled in the OpenSees environment and the time history analysis has been carried out under a specific earthquake record. It is shown that inter-story drifts of the frame exceeds the acceptance criteria which has been assumed 2.5% according to the Life Safety limit. Then, the optimal retrofitting of the frame has been done. It is demonstrated that the maximum inter-story drift of all stories is 2.5% or less, while the slip load and placement of the dampers have been optimized simultaneously. Thereafter, the remarkable properties of the adaptive theory like high convergence rate, independency of the final answer to the first arbitrary distribution of dampers, multi-criteria optimization and following a simple algorithm have been explained. It has been shown that adaptive theory gives an unique distribution of friction dampers for each earthquake record, while it is not possible to predict the exact properties of the earthquakes that may occur in the effective lifetime of the structures. In order to overcome this limitation, a new approach has been presented. To achieve this approach, 15 natural earthquake records have been used. This approach has been presented for 2, 4, 6 and 8 stories moment resisting frames. It is demonstrated that this approach leads to the optimal design of friction dampers to retrofit the steel moment resisting frames in which the maximum inter-story drifts of all frames in range of 2 to 8 stories with different periods, with acceptable assurance will be below 2.5%
  9. Keywords:
  10. Steel Moment Resistant Frame ; Adaptive Method ; Optimization ; Friction Damper ; Time History Analysis ; OpenSees Software ; Nonlinear Dynamic Analysis

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