Adaptive extended Kalman filter for parameter tracking of base-isolated structure under unknown seismic input

Base isolation systems have been widely used in civil structures as protective devices against earthquakes, hurricanes, etc., and the state assessment using vibration data for the safety, reliability and integrity of base-isolated structures is very important in structural health monitoring. In the case of field engineering applications, external excitations, such as seismic inputs, wind inputs, etc., usually could not be measured, or even could not be measurable. Herein, an adaptive extended Kalman filter approach for structural parameter tracking under unknown seismic input, which is referred to as AEKF-UI approach, is developed to on-line track the base-isolated structural time-varying parameters, including the damping, stiffness, nonlinear hysteretic parameters, etc., and identify the unmeasured seismic input. The experimental results of vibration tests demonstrate the fact that the AEKF-UI method developed is able to achieve real-time parameter tracking of base-isolated structure under unknown seismic input, leading to the on-line identification of structural damages.