Showing 82 results for Par
M. Khatibinia, A.h. Saeedi, E. Mohtashami,
Volume 15, Issue 3 (8-2025)
Abstract
Bracing-friction damper system (BFDS), one of passive control devices, consists of a Pall friction damper added in-line with a diagonal, which is utilized for the seismic retrofit of building structures. The BFDS can dissipate the input energy of earthquakes and mitigate a considerable amount of the hysteretic energy of structures. This study presents the optimal seismic retrofit of inelastic steel moment-resisting frames (SMRFs) through the optimum design of the BFDSs installed in each story of SMRFs. For this purpose, minimizing the maximum damage index of stories averaged over seven scaled earthquake excitations is selected as the objective function so that the story damage is uniformly distributed along the height of SMRFs. The damage index is calculated based on the Park-Ang damage model which is expressed based on a linear combination of deformation, moment, and absorbed hysteretic energy of structural elements imposed by an earthquake excitation. The results indicate that the optimized BFDSs-equipped SMRFs exhibits the better distribution of story damage than that of uncontrolled SMRFs. Finally, the seismic assessment of SMRFs is done by the fragility analysis. The results of the seismic fragility assessment demonstrate that the optimized BFDSs improve the seismic performance of retrofitted SMRFs compared to that of uncontrolled SMRFs at different damage states.
M. Arjmand, H. Naderpour, A. Kheyroddin,
Volume 15, Issue 4 (11-2025)
Abstract
The seismic resilience of existing reinforced concrete (RC) buildings can be improved by optimizing both energy dissipation and post-earthquake recovery. This study proposes a practical framework for upgrading RC moment-resisting frames using nonlinear fluid viscous dampers (NFVDs). Two typical frames, a four-story and an eight-story structure, were modeled and analyzed in OpenSees. Nonlinear time-history analyses with seven earthquake records were carried out to estimate the Park–Ang damage index, while incremental dynamic analyses (IDA) with 22 far-field records from FEMA P695 were used to evaluate fragility and collapse performance. The NFVDs were represented through a velocity-dependent Maxwell model, and the optimal damper parameters and locations were determined through a cost-based single-objective optimization scheme under predefined damage limits. The results show that the optimized damper configurations effectively reduced structural damage and improved post-event functionality recovery under seismic hazard levels corresponding to 10% and 2% probabilities of exceedance in 50 years. Overall, the proposed approach provides an efficient and economical solution for improving the seismic performance and resilience of existing RC frame buildings.
