2ND-ORDER STRUCTURAL IDENTIFICATION PROCEDURE VIA STATE-SPACE-BASED SYSTEM-IDENTIFICATION

A theory is presented for transforming the system-theory-based realization models into the corresponding physical-coordinate-based structural models. The theory has been implemented into a computational procedure and applied to several example problems. The results shea that the present transformation theory yields an objective model basis possessing a unique set of structural parameters from an infinite set of equivalent system realization models. For proportionally damped systems, the transformation directly and systematically yields the normal modes and modal damping. When nonproportional damping is present, the relative magnitude and phase of the damped mode shapes are separately characterized, and a corrective transformation is then employed to capture the undamped normal modes and nondiagonal modal damping matrix.