|M.Sc Student||Nseir Ihsan|
|Subject||Analysis/Redesign Methodology for Seismic Retrofit of|
Framed Structures Using Friction Dampers
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Robert Levy|
|Full Thesis text|
This work is focused on the implementation of the Analysis/Redesign methodology for seismic retrofit of framed structures with added friction dampers, subject to a performance index, and exited by an ensemble of realistic ground motion records. The performance index is the maximal interstory drift for the duration of the earthquake. The intention here is to further develop the approach which was already proven to be satisfactory and valid for framed structures with added viscous dampers and to show its suitability to handle shear frames damped with friction devices.
A dynamic model that uses bilinear hysteretic behavior for the braced frame is used and a procedure based on analysis/redesign that is analogous to static fully stressed design of trusses is used for the optimization design process. The methodology allows for zero values and thus initially assigned dampers are removed during the iteration process. The methodology process starts with an “active” ground motion record, to be selected from the earthquake ensemble, by comparative displacement criterion, in which a single degree of freedom having the same fundamental period, as the bare frame is analyzed subject to all the records in the ensemble. The active record is the one with the largest response.
The proposed methodology is implemented in the actual design of three examples. The results are as expected i.e. fully stressedness with dampers assigned just to stories that reached allowable drifts as a performance indices, and the final designs not violating drift limitation for all the records in the earthquake ensemble.