Identification of Local Time-Varying Systems Based on Dynamic Response Sensitivity

Abstract

A new method based on dynamic response sensitivity is proposed for the identification of local linear time-varying (LTV) system. The unknown local LTV structural stiffness is modeled by orthogonal polynomial approximations, and the sensitivities of structural dynamic response with respect to orthogonal coefficients are derived. The identification equation is set up based on Taylor’s first order approximation, and is solved with the damped least-squares method. A fifteen-story shear building is studied to validate the proposed method. Three ideal cases of LTV systems, with periodically, abruptly and randomly varying stiffness at the 8th story of the structure, are investigated to illustrate the capability of the algorithm to track the variations of the systems. Numerical simulation with noisy measured accelerations shows that the proposed method can accurately identify various kinds of local time-varying system from only several responses of the structure. This method provides a new approach for detecting local time-varying stiffness of structures with incomplete measured output information.