Rapid structural evaluation of bridges after earthquakes is imperative to recover quickly. While structural displacement is an essential indicator, direct measurement is difficult. Indirect estimation of displacement by numerical integration of measurement acceleration is inaccurate due to integration errors. In this research, estimation of displacement by only using acceleration measurements is proposed. Extended Kalman filter (EKF) assuming a simple non-linear hysteretic behavior and a genetic algorithm to identify parameters of the non-linearity are combined to achieve the displacement estimation. The displacement estimation capability of the proposed method is confirmed with simple models and a nonlinear RC pier model simulating an E-defense shaking table specimen.
