Preliminary communication

Numerical model of compliant tower oscillations

Vanja Travaš orcid.org/0000-0001-9829-7858 ; Faculty of Civil Engineering, University of Rijeka, Rijeka, Croatia

Abstract

For the purpose of conducting a dynamic analysis of compliant towers, a numerical algorithm was developed for calculating the structure of the movement field caused by hydrodynamic action of the sea. The stochastic nature of wave spreading in the sea is introduced into the analysis through the function of power spectral density of waves. The structure’s wave load is then defined by applying the Morison model of force action. Kinematic parameters of waves are defined by the linear theory. The wind impact on the distribution of marine circulation in the vertical direction is taken into account in the context of the Ekman spiral. The compliant tower is modelled with spatial Euler–Bernoulli final elements. The initiation of the dynamic calculation starts with the determining the movement field resulting from static activity of buoyant force, dead and permanent loads. The integration of the equations of motion is performed by applying the Newmark-β method. To develop numeric parameters, the presented algorithm is implemented in the MathCAD 15 programming environment. The numerical parameters include the analysis of free and forced oscillations of the structure and the FFT analysis of the records of the centre of gravity shift of the structure’s operating surface.

Keywords

dynamic analysis; hydrodynamic loads of the sea; modal analysis; complaint tower; resonance; static analysis

Hrčak ID:

197077

URI

https://hrcak.srce.hr/197077

Publication date:

19.3.2018.

Article data in other languages: croatian

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