Estimation of hysteretic behaviors of a seismic isolator by using the bilinear model and measured-isolation-mode-accelerations

Hysteretic behaviors of a seismic isolator under earthquakes are estimated by using the bilinear model and measured-isolation-mode-accelerations. Dynamic responses of a seismically isolated structure are approximated from the SDOF ordinary differential equation in the isolation mode space. A time domain system identification (TDSI) method is employed to identify the hysteretic behaviors based on the bilinear model and SDOF ordinary differential equation. A regularized output error estimator is adopted in the TDSI, in which the differences between measured-isolation-modeaccelerations and calculated-isolation-mode-accelerations are minimized. The validity of the proposed method is demonstrated through the numerical examples of a 6-DOF seismically isolated structure