Substructure identification for shear structures I: Substructure identification method

A substructure identification method for shear structures is proposed herein. A shear structure is partitioned into many simple substructures; an inductive identification procedure is derived to estimate the structural parameters from top to bottom. In each identification step, the dynamic equilibrium of a one-floor substructure is utilized to construct a substructure identification problem, estimating the story stiffness and damping coefficient. An identification error analysis for least-square error identification problems, based on the linearization of the least-square error problem, is proposed and applied to the substructure identification method. The results show that the identification errors are closely related to two important structural responses: the frequency response of the interstory acceleration of the identified story and the frequency response ratio between adjacent interstory accelerations. Further, these responses are critical to the substructure identification only near a certain frequency, the substructure natural frequency of the identified story substructure. The larger the first response is and/or the smaller the second response is, the more accurate the estimation results will be. A numerical example of a five-story shear structure is given to demonstrate the effectiveness of the proposed substructure identification method and to verify the identification error analysis results. From the results of the identification error analysis, a companion paper proposes a controlled substructure identification method, utilizing specially designed algorithms for structural control devices to change the two key structural responses that affect the identification accuracy, to improve the accuracy of the substructure identification.