On the reliability of a class of system identification techniques: insights from bootstrap theory

The estimation of structural damping from systems with unknown input can be particularly challenging but is vital to furthering the understanding of energy dissipation in structural motions. The random decrement technique and spectral analysis are commonly invoked system identification schemes for this problem. Although there is well-established theory regarding the bias and variance errors of power spectra and random decrement signatures, the theoretical error formulae give only approximate indications of errors inherent to the estimated dynamic properties. This study addresses this through a bootstrap approach to assess the quality of system identification by providing surrogate estimates of damping and natural frequency to generate useful statistics and confidence intervals. (C) 2002 Elsevier Science Ltd. All rights reserved.