Substructure Identification for Shear Structures with Nonstationary Structural Responses

Abstract

In previous studies by the authors, a substructure identification method for shear structures was proposed to identify all structural story stiffness and damping parameters from top to bottom inductively. In the method derivation, the structural responses were required to be wide sense stationary to convert structural dynamic equations to differential equations in the correlation functions of structural responses, which are used to formulate substructure identifications. In this paper, this method is extended to accommodate nonstationary structural responses. A different derivation procedure is adopted to formulate substructure identifications directly from the Fourier transform of the structural dynamic equations, resulting in a formulation nearly the same as its stationary response predecessor. An identification error analysis for the substructure identification method reveals how structural responses affect the identification accuracy. On the basis of this result, a smart reference selection rule is proposed to choose the best reference response candidate, needed for forming the substructure identifications, to improve the identification accuracy. A 10-story shear building structure is used to illustrate the effectiveness of the substructure identification method with two kinds of nonstationary excitations: a long nonstationary response and a group of short earthquake excitations. The simulation results show that this substructure identification method provides very accurate identification results even with very large measurement noise and nonstationary responses.