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Smart Structures and Systems
  Volume 15, Number 2, February 2015 , pages 409-424
DOI: https://doi.org/10.12989/sss.2015.15.2.409
 


Locating and identifying model-free structural nonlinearities and systems using incomplete measured structural responses
Lijun Liu, Ying Lei and Mingyu He

 
Abstract
    Structural nonlinearity is a common phenomenon encountered in engineering structures under severe dynamic loading. It is necessary to localize and identify structural nonlinearities using structural dynamic measurements for damage detection and performance evaluation of structures. However, identification of nonlinear structural systems is a difficult task, especially when proper mathematical models for structural nonlinear behaviors are not available. In prior studies on nonparametric identification of nonlinear structures, the locations of structural nonlinearities are usually assumed known and all structural responses are measured. In this paper, an identification algorithm is proposed for locating and identifying model-free structural nonlinearities and systems using incomplete measurements of structural responses. First, equivalent linear structural systems are established and identified by the extended Kalman filter (EKF). The locations of structural nonlinearities are identified. Then, the model-free structural nonlinear restoring forces are approximated by power series polynomial models. The unscented Kalman filter (UKF) is utilized to identify structural nonlinear restoring forces and structural systems. Both numerical simulation examples and experimental test of a multi-story shear building with a MR damper are used to validate the proposed algorithm.
 
Key Words
    nonlinear structural systems; nonparametric identification; nonlinear restoring force; extended Kalman filter; unscented Kalman filter, incomplete measurements
 
Address
Lijun Liu: Department of Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005, China;
Department of Civil Engineering, Xiamen University, Xiamen 361005, China
Ying Lei and Mingyu He: Department of Civil Engineering, Xiamen University, Xiamen 361005, China
 

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