Performance evaluation of innovative toggle brace damper for flexible structure seismic upgrade

Abstract

Amplifying the motion of viscous dampers has been recognized as an effective solution to mitigate structural response to wind and seismic excitation. Motion amplification devices are designed to amplify a small interstory drift to intensify the stroke of the dampers attached. The efficiency of such devices relies on their geometric configurations in addition to the stiffness of the support elements. This thesis focuses on the seismic performance evaluation of the toggle brace frame configuration employed for seismic upgrade. In order to carry out a performance evaluation of the toggle brace damper, a practical approach to performance-based earthquake engineering (PBEE) is presented in this study. The approach considers the seismic hazard, structural response, resulting damage, and repair costs associated with restoring the building to its original condition using a fully probabilistic analysis. The procedure is organized to be consistent with conventional building designs, construction, and analysis practices so that it can be readily incorporated into a design process. A nine-story moment frame located in downtown Los Angeles based on pre-Northridge design code is subjected to PBEE evaluation in this study. The performance of the structural frame is assessed by conducting a non-linear dynamic time history analysis in both cases, with and without the inclusion of the toggle brace damper. The results and comparisons are detailed in the chapters of this thesis.