Assessments on seismic performance of self-centering hybrid damping systems under far-field and near-field ground motions

Abstract

This research is conducted to perform the assessment on seismic performance of novel self-centering systems equipped with hybrid energy dissipaters, which are composed of hysteretic energy dissipaters in parallel with viscous energy dissipaters. The hybrid energy dissipating mechanism equips the self-centering system with significant energy-dissipating capacity. An equivalent self-centering damping ratio ξSC is firstly proposed to quantify the energy-dissipating capacity from the two types of dampers, respectively. Single-degree-of-freedom systems (SDOF) with different dynamic parameters are then developed. Nonlinear response history analyses on SDOF are performed using a suite of far-field and near-field ground motions to make the assessment. It is shown that the near-field ground motions will lead to much more ductility demands and acceleration responses for the considered systems compared with far-field ground motions. Increasing the damping for the system will decrease the ductility demand but will lead to the dramatic acceleration amplification. Moreover, adjusting the equivalent self-centering damping ratio between the two types of damping will change dynamic response of the system. Increasing the proportion of hysteretic damping will decrease the ductility demand and increase the acceleration response of the considered system, especially under far-field ground motions. Ductility demand spectra of the considered system for seismic design are established based on results from SDOF analyses. Finally, system-level analyses are performed on a novel knee bracing frame with self-centering hybrid damping capacity to validate the practicability of ductility demand spectra, and conduct the assessment.