WAVE INDUCED INSTABILITIES OF SEMI-SUBMERSIBLE OIL DRILLING PLATFORMS

Quadratic nonlinear terms are retained in the heave, roll, and pitch governing equations of motion for a semi-submersible platform in a regular sea and the method of multiple scales is used to predict the response. Due to nonlinear effects, unstable motions are found to occur when the wave frequency is approximately twice one of the natural frequencies (heave, pitch, or roll) of the platform and when the wave frequency is near either the sum of the heave and roll natural frequencies or the sum of the heave and pitch natural frequencies. The occurrence of the instabilities depends on the magnitude of wave excitation, and since the instabilities occur at wave frequencies where ample energy from the sea exists for excitation, the possibility of large platform motions is enhanced.

• Supplemental Notes:
  • Fluid Mechanics in the Petroleum Ind, Symp, ASME Winter Annual Meeting, Houston, Texas, November 30-December 5, 1975.
• Corporate Authors:

  American Society of Mechanical Engineers

  Two Park Avenue
  New York, NY  United States  10016-5990
• Authors:
  • Marshall, L R
  • Morrow, T B
• Conference:
  • Fluid Mechanics in the Petroleum Ind, Symp, ASME Winter Annual Meeting, Houston, Texas, November 30-December 5, 1975.
• Publication Date: 1975

Media Info

• Features: References;
• Pagination: p. 9-15

Subject/Index Terms

• TRT Terms: Excitation; Force; Motion; Offshore platforms; Waves
• Old TRIS Terms: Platform motions; Wave forces on structures
• Subject Areas: Bridges and other structures; Marine Transportation; Terminals and Facilities; Vehicles and Equipment;

Filing Info

• Accession Number: 00135376
• Record Type: Publication
• Source Agency: Engineering Index
• Files: TRIS
• Created Date: Jul 13 1976 12:00AM