REDUCING SIMULATION LENGTHS IN EXTREME RESPONSE ESTIMATION OF A FLEXIBLE RISER

This paper addresses the problem of efficiently estimating the extreme distributions for the response of a flexible riser in a short- term storm condition. Response quantities such as displacements and axial forces may be significantly non-Gaussian due to both non- Gaussian environmental loads and nonlinear system behaviour. Results from long nonlinear time domain simulations are therefore usually needed in order to estimate the extreme response distributions with acceptable accuracy. The procedure proposed attempts to reduce the duration of the nonlinear simulations by efficiently utilizing information gained from preliminary frequency or time domain analysis. The basic idea is to generate time series of linearized response by fast fourier transform of a response spectrum found from a preliminary analysis, and then assume that the largest extremes in a nonlinear time domain simulation will appear at the same time as seen in the linear case. By choosing the harmonic component phase angles appropriately, consistent time series of wave elevation, fluid velocities and accelerations and response quantities can be computed. It is therefore possible to carry out a nonlinear simulation that is consistent to the linearized portions of the wave record that contain large extremes in the linear case.

  • Supplemental Notes:
    • OMAE 1995, 14th Intl Conf on Offshore Mechanics & Arctic Engng; 18-22 June 1995; Copenhagen, Denmark. Sponsored by ASME et al. Procs. Publ by ASME, ISBN 0-7918-1308-8. Vol II, p 99 [8 p, 6 ref, 1 tab, 9 fig]
  • Authors:
    • Passano, E
  • Publication Date: 1995

Language

  • English

Subject/Index Terms

Filing Info

  • Accession Number: 00718758
  • Record Type: Publication
  • Source Agency: British Maritime Technology
  • Files: TRIS
  • Created Date: Mar 27 1996 12:00AM