A MINIMIZATION SCHEME FOR THE MOTIONS AND FORCES OF AN OCEAN PLATFORM IN RANDOM SEAS

An analytical procedure for the optimal design of a vertical float-supported ocean platform as derived from minimizing its motion in rough seas, is considered in this paper. The method of calculus of variations, together with the penalty function method, are used to determine a set of necessary conditions from which an integral equation is obtained for the volume distribution which minimizes the platform's motion in a random sea. To simulate real sea conditions, the ITTC wave spectral density function is used. For obtaining numerical solutions, the kernel in the integral equation is first replaced by a summation, then this nonlinear equation is solved using an iterative method. For the purpose of comparisons, a buoy and a platform previously tested in waves are chosen as standards. Then, an optimal buoy and an optimal platform which possess the same major characteristcis as the former two standards respectively are derived numerically. A significant reduction in significant heave amplitude and significant vertical displacement for higher sea states are observed for the optimal buoy and platform. It is concluded that this technique is useful in preventing unwanted excessive motions of a platform in random seas. The basic approach used here can be easily adapted to a wide class of practical shapes for ocean platforms.

• Supplemental Notes:
  • Presented at the Winter Meeting of the Gulf Section of SNAME, February 11, 1977.
• Corporate Authors:

  Society of Naval Architects and Marine Engineers

  601 Pavonia Avenue
  Jersey City, NJ  United States  07306-2907
• Authors:
  • Chou, F S
• Publication Date: 1977-2-11

Media Info

• Features: Appendices; Figures; References;
• Pagination: 58 p.

Subject/Index Terms

• TRT Terms: Amplitude (Physics); Force; Hydrodynamic pressure; Motion; Offshore platforms; Structural design; Waves
• Uncontrolled Terms: Heaving
• Old TRIS Terms: Heave amplitude; Hydrodynamic forces; Offshore platform design; Platform motions; Wave forces on structures
• Subject Areas: Bridges and other structures; Design; Marine Transportation;

Filing Info

• Accession Number: 00164844
• Record Type: Publication
• Source Agency: Society of Naval Architects and Marine Engineers
• Files: TRIS
• Created Date: Oct 29 1977 12:00AM