This paper presents the findings of a numerical investigation into the strength of minimum structure platforms subject to a ship impact. The study has identified important design issues that should be addressed in order to improve the survivability and continued serviceability of minimum structures after a ship impact. It was found that, due to a lack of research effort, design guidelines governing ship impact on minimum structures are lacking in comparison with conventional jacket platforms. In particular, requirements governing the minimum amount of plastic energy absorption in minimum structures are not clearly defined. Ship impact analyses were therefore carried out in order to compare their structural integrity with that for a jacket under ship collision conditions and to evaluate the effects on their ultimate strength. The study not only established any degradation of system strength, but has also determined the amount of plastic energy absorption under various impact scenarios.

Issue Section:
Technical Papers
Keywords:
mechanical strength, structural engineering, impact (mechanical), offshore installations, plastic deformation, failure analysis, finite element analysis
Topics:
Caissons, Collisions (Physics), Ships, Deformation, Damage
1.
Grewal, G. S., 2002, “Dynamic Response of Offshore Minimum Structures Subjected to Ship Impact,” Ph.D. thesis, University of Wales Swansea.
2.
MSL, 1999, “JIP Comparative Evaluation of Minimum Structures and Jackets: Effect of Vessel Impact on Intact and Damaged Structures,” Doc Ref C209R007 Rev1, MSL Engineering Limited, Ascot, UK.
3.
American Petroleum Institute, 1993, “Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms—Load and Resistance Factor Design,” 1st ed., API RP2A-LRFD.
4.
Atkins, W. S., 2002, “Comparative Evaluation of Minimum Structures and Jackets,” HSE Books, Offshore Technology Report, 2001/062.
5.
ABAQUS/AQUA, 1999, “User’s Manuals Rev 5.5-5.8,” Hibbit, Karlsson and Sorensen Inc., Rhode Island.
6.
BS7191, 1989, “Weldable Structural Steels for Fixed Offshore Structures,” British Standards Institution.
7.
Furnes, O., and Amdahl, J., 1980, “Ship Collisions With Offshore Platforms,” Proceedings of INTERMARITEC Symposium, Hamburg.
8.
Det Norske Veritas, 1981, “Load Impact From Boats,” DNV Technical Note TN A202.
9.
Department of Energy, 1990, Offshore Installations: Guidance on Design, Construction and Certification, 4th ed., London, HMSO, pp. 15.6–15.7.
10.
Atkins, 1999, Private communication with Navil Shetty and Jacek Gierlinski, WS Atkins Science and Technology, Epsom, Surrey, England.
11.
Ricles
,
J. M.
,
Gillum
,
T. E.
, and
Lamport
,
W.
,
1994
, “
Grout Repair of Dented Offshore Tubular Bracing—Experimental Behavior
,”
J. Struct. Eng.
,
120
, No. 7.
Copyright © 2004
 by ASME
You do not currently have access to this content.