BEHAVIOUR OF A FLOATING PLATFORM WITH MARINE RISER IN DIRECTIONAL WAVES

In this paper, directional analysis if applied to study the behaviour of a floating platform connected to a deep water riser. Initially, numerical simulations of the sea surface elevation are carried out from wave spectra with directional spreading. The wave elevations are obtained for fixed positions in space which represent wave sensors, and they are analysed by the Maximum Likelihood Method (MLM) producing estimates of the directional wave spectra. The coupled system (platform/riser) is modelled and solved for a range of frequencies and directions of wave incidence, producing directional Response Amplitude Operators (RAO) for the six degrees of motions of the platform and for the riser bending stresses. With the platform motion RAO and the estimated wave spectra, directional response spectra are obtained and short-term prediction, in frequency domain, is performed to evaluate the first order motions of the platform in directional waves. The influences of the spreading parameter for head sea conditions and of the principal direction of wave incidence are investigated. Finally, short-term analysis is performed to evaluate the effects of wave spreading and of the wave principal direction on the total bending stresses of the riser.

• Supplemental Notes:
  • ISOPE 1992, 2nd Intl Offshore & Polar Engng Conf; 14-19 June 1992; San Francisco, USA. Sponsored by Intl Soc Offshore & Polar Engrs (ISOPE) et al. Procs. Pubs by ISOPE, ISBN 1-880653-03-6. Vol III, p 628 [8 p, 11 ref, 16 fig]
• Authors:
  • Morooka, C K
  • Yokoo, I H
• Publication Date: 1992

Language

• English

Subject/Index Terms

• TRT Terms: Bending; Bending stress; Mathematical models; Stresses
• Uncontrolled Terms: Mobile platforms
• Old TRIS Terms: Directional seas; Risers
• Subject Areas: Marine Transportation;

Filing Info

• Accession Number: 00706306
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Aug 14 1995 12:00AM