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Smart Structures and Systems
  Volume 22, Number 3, September 2018 , pages 315-326
DOI: https://doi.org/10.12989/sss.2018.22.3.315
 


Identification of plastic deformations and parameters of nonlinear single-bay frames
Francis T.K. Auand Z.H. Yan

 
Abstract
    This paper presents a novel time-domain method for the identification of plastic rotations and stiffness parameters of single-bay frames with nonlinear plastic hinges. Each plastic hinge is modelled as a pseudo-semi-rigid connection with nonlinear hysteretic moment-curvature characteristics at an element end. Through the comparison of the identified end rotations of members that are connected together, the plastic rotation that furnishes information of the locations and plasticity degrees of plastic hinges can be identified. The force consideration of the frame members may be used to relate the stiffness parameters to the elastic rotations and the excitation. The damped-least-squares method and damped-and-weighted-least-squares method are adopted to estimate the stiffness parameters of frames. A noise-removal strategy employing a de-noising technique based on wavelet packets with a smoothing process is used to filter out the noise for the parameter estimation. The numerical examples show that the proposed method can identify the plastic rotations and the stiffness parameters using measurements with reasonable level of noise. The unknown excitation can also be estimated with acceptable accuracy. The advantages and disadvantages of both parameter estimation methods are discussed.
 
Key Words
    nonlinear single-bay frames; parameters estimation; plastic rotation; stiffness parameter; unknown excitation
 
Address
Francis T.K. Auand Z.H. Yan: Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
 

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