On system identification and response prediction of degrading structures

Abstract

All structures degrade when acted upon by cyclic forces associated with earthquakes, high winds, and sea waves. Identification and prediction of degradation is thus a problem of considerable practical significance in the field of engineering mechanics. Under cyclic excitation, degradation manifests itself in the evolution of the associated hysteresis loops. Two principal tasks in connection with hysteretic evolution are addressed in this paper. First, a robust identification algorithm is devised to generate hysteretic models of a deteriorating structure from its experimental load–displacement traces. This algorithm is based upon the generalized Bouc–Wen model and the latest theory of differential evolution, streamlined through global sensitivity analysis. It can account for strength degradation, stiffness degradation, and pinching characteristics in the evolution of hysteretic traces. Second, it is shown experimentally that a hysteretic model obtained by identification can be used to predict the future performance of a degrading structure. Prediction of degradation through identification is a brute-force approach that offers a close representation of reality. There is not any method based upon the fundamental postulates of mechanics that can predict the response of a degrading structure well beyond its linear range. Copyright © 2005 John Wiley & Sons, Ltd.