Estimation of structural system parameters from stationary and non-stationary ambient vibrations: An exploratory-confirmatory analysis

The natural frequency and damping parameters of a building structure are estimated from a long ambient vibration record that shows considerable non-stationarity. The long record is segmented into 57 approximately independent one minute duration stationary time series segments. Each segment is low pass filtered to reject unwanted higher frequency modes and is analyzed by a 2SLS (two stage least squares) time domain parametric model procedure. The scatter diagrams of the estimates of the natural frequency and damping parameters exhibit considerable variability. Estimates of the natural frequency and damping parameters and coefficient of variation expressions of their reliability are obtained by an exploratory-confirmatory data analysis of those 57 vibration time series. A procedure that can obtain the structural parameter estimates with the reliability that is available from stationary analysis from a long and not necessarily stationary record is indicated.