Title: Identification of weak non-linearities in cables of cable-stayed footbridges

Authors: Anil Kumar; Luca Zanotti Fragonara

Addresses: Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee 247 667, India ' Department of Structural, Building and Geotechnical Engineering, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129, Torino, Italy

Abstract: A time-frequency identification technique for the non-linear identification of a cable element was proposed in this paper. A polynomial form of non-parametric method was used. A long cable of a newly constructed cable-stayed footbridge was modelled in the ANSYS structural software. The model was reduced to a SDoF system, by applying a harmonic force in the first modal frequency and the first mode shape. A good match between the identified and numerical data was obtained. Some interesting non-linear phenomena were observed: only a cubic type of non-linearity was identified. Moreover, the values of the damping and cubic parameters stabilised at higher load amplitudes. However, parameter relevant to linear-frequency was increasing with the loading amplitude showing a typical hardening behaviour of cable structures. Superharmonics were present in the response at higher loading amplitudes. Therefore, the identification procedure was found to be effective at higher load amplitudes.

Keywords: cable response; nonlinear identification; cable-stayed footbridges; weak nonlinearity; non-parametric methods; STFT; short-time Fourier transform; performance evaluation; cables; modelling; finite element method; FEM; damping; load amplitudes; superharmonics.

DOI: 10.1504/IJLCPE.2013.058222

International Journal of Lifecycle Performance Engineering, 2013 Vol.1 No.3, pp.292 - 313

Received: 07 Sep 2012
Accepted: 03 Sep 2013

Published online: 10 Dec 2013 *

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