Optimal properties of hysteretic dampers to minimize peak floor accelerations in multi-story buildings subjected to earthquakes

In this study, the optimal reduction of seismic peak floor accelerations in buildings equipped with hysteretic dampers is investigated. The structures are modeled as linear elastic shear buildings, and the seismic demand is modeled as a stochastic process. The optimal properties and height-wise distribution of the hysteretic dampers are found using a pattern search optimization algorithm. The objective function is defined in terms of the stochastic non-stationary response of the structure, which is obtained using the Explicit Time Domain Method in combination with statistical linearization. Possible influence of the fundamental period of the structure, the frequency content of the excitation, and the number of stories, on the optimal properties of the hysteretic dampers are analyzed. The effects of the optimal solutions on other response quantities, such as inter-story drifts, ductility demand on the hysteretic dampers, energy dissipation, and floor response spectra, are also assessed. Findings of this study are validated by a case study that considers a real building model subjected to actual ground motion acceleration records. The main findings are: a) optimally designed hysteretic dampers are indeed effective in reducing the seismic peak floor acceleration response; and b) optimal non-uniform height-wise distributions of hysteretic dampers are essentially equal to or at most somewhat better (but not by a wide margin) than optimal uniform height-wise distributions.