Evaluation of Storm Loadings on and Capacities of Offshore Platforms
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 123, Issue 2
Abstract
Currently, there are approximately 3,000 major platforms offshore the United States and an equal number of platforms offshore other countries around the world. Approximately one-third of these platforms have exceeded their design lives and are now being called on for extended service. Reassessment and requalification of this massive infrastructure has required development of new engineering procedures. This paper summarizes development of a simplified procedure to evaluate storm loadings imposed on offshore platforms and to evaluate the ultimate limit state lateral loading capacities of such platforms. Verification of these procedures has been accomplished by comparing results from the simplified analyses with results from three-dimensional, linear, and nonlinear analyses of a variety of template-type platforms. Several of these platforms failed, were near failure, or survived loadings from severe hurricanes. The simplified procedure is able to replicate the loadings and capacities indicated by the complex analyses. Verification of the second-generation procedures indicate lateral capacity biases (ratio of result from nonlinear analysis to result from simplified analysis) in the range of 0.80–1.26 with a mean value of 0.95. The simplified procedure is able to replicate the observed performance of the platforms. These methods can be used to help reassess and requalify platforms that are being evaluated for extended service. Because the simplified procedure is much less prone to human errors, this procedure can be used to help verify results from complex analytical models.
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References
1.
American Petroleum Institute. (API). (1993). Recommended practice for planning, designing and constructing fixed offshore platforms—Load and resistance factor design (RP 2A-LRFD), 1st Ed., July, Washington, D.C.
2.
American Petroleum Institute (API). (1996). “Draft section 17.0, Assessment of existing platforms.”API RP 2A-WSD 20th Ed., Jan., API, Washington, D.C.
3.
Bea, R. G. (1983). “Characterization of the reliability of offshore piles subjected to axial loadings.”Proc., ASCE Struct. Congr., ASCE, New York, N.Y.
4.
Bea, R. G. (1987). “Dynamic response of marine foundations.”Proc., Oc. Struct. Dyn. Symp. '84, Oregon State Univ., Corvallis, Ore., 12–74.
5.
Bea, R. G.(1992). “Pile capacity for axial cyclic loading.”J. Geotech. Engrg., ASCE, 118(1), 34–50.
6.
Bea, R. G. (1995). “Development & verification of a simplified method to evaluate storm loadings on and capacities of steel, template-type platforms.”Proc., Energy & Envir. Expo 95, Am. Soc. of Mech. Engrs., New York, N.Y.
7.
Bea, R. G., and Craig, M. J. K. (1993). “Development in the assessment and requalification of offshore platforms.”Proc., Offshore Technol. Conf., Soc. of Pet. Engrs., Richardson, Tex., OTC paper 7138.
8.
Bea, R. G., and DesRoches, R. (1993). “Development and verification of a simplified procedure to estimate the capacity of template-type platforms.”Proc., 5th Int. Symp. Integrity of Offshore Struct., D. Faulkner et al., eds., Emas Scientific Publ., Glasgow, Scotland, 129–148.
9.
Bea, R. G., and Mortazavi, M. (1995). “Simplified evaluation of the capacities of template-type offshore platforms.”Proc., 5th Int. Offshore and Polar Engrg. Conf., Int. Soc. of Offshore and Polar Engrs., Golden, Colo.
10.
Bea, R. G., Mortazavi, M., Loch, K. J., and Young, P. L. (1995). “Verification of a simplified method to evaluate the capacities of template-type platforms.”Proc., Offshore Technol. Conf., Soc. of Pet. Engrs., Richardson, Tex., OTC Paper 7780.
11.
Bea, R. G., and Young, C. (1993). “Loading and capacity effects on platform performance in extreme condition storm waves & earthquakes.”Proc., Offshore Technol. Conf., Soc. of Pet. Engrs., Richardson, Tex., OTC paper 7140.
12.
Billington, C. J., Bolt, H. M., and Ward, J. K. (1993). “Reserve, residual and ultimate strength analysis of offshore structures: State of the art review.”Proc., Third Int. Offshore and Polar Engrg. Conf., Int. Soc. of Offshore and Polar Engrs., Golden, Colo., 125–133.
13.
Cardone, V. J., and Cox, A. T. (1992). “Hindcast study of hurricane Andrew, offshore Gulf of Mexico.”Rep. to Joint Industry Proj., Oceanweather Inc., Cos Cob, Conn.
14.
Cardone, V. J., et al. (1994). “Final report—Hindcast study of wind wave and current fields in hurricane Andrew—Gulf of Mexico.”Rep. to Minerals Mgmt. Service, Dept. of Interior, Herndon, Va.
15.
Det Norske Veritas. (1993). “WAJAC. Wave and current loads on fixed rigid frame structures.” DNV SESAM AS. Version 5.4-02, Oslo, Norway.
16.
Frieze, P. A. (1993). “Determination of platform overall reliability given reserve strength ratio (RSR).”Rep. to Health and Safety Executive, PAFA 012/1, London, U.K.
17.
Hellan, ∅., Moan, T., and Drange, S. O. (1994). “Use of nonlinear pushover analyses in ultimate limit state design and integrity assessment of jacket structures.”Proc., Seventh Int. Conf. on Behavior of Offshore Struct., Boss '94, C. Chryssostomidis, ed., Elsevier Science Inc., New York, N.Y., Vol. 3, Structures.
18.
Hellan, ∅., Tandberg, T., and Hellevig, N. C. (1993). “Nonlinear re-assessment of jacket structures under extreme storm cyclic loading.”Proc., Offshore Mech. and Arctic Engrg. Conf., Am. Soc. of Mech. Engrs., New York, N.Y.
19.
Imm, G. R., O'Connor, J. M., Light, J. M., and Stahl, B. (1994). “South Timbalier 161A: A successful application platform requalification technology.”Proc., Offshore Technol. Conf., Soc. of Pet. Engrg., Richardson, Tex., OTC paper 7471.
20.
Loh, J. T. (1993). “Ultimate strength of dented tubular steel members.”Proc., 3rd Int. Offshore and Polar Engrg. Conf., Int. Soc. of Offshore and Polar Engrs., Golden, Colo.
21.
McDonald, D. T., Bando, K., Bea, R. G., and Sobey, R. J. (1990). “Near surface wave forces on horizontal members and decks of offshore platforms.”Final Rep., Coast. and Hydr. Engrg., Dept. of Civ. Engrg., Univ. of California at Berkeley.
22.
Mortazavi, M., and Bea, R. G. (1994). “ULSLEA, Simplified nonlinear analysis for offshore structures.”Final Rep. to Joint Industry—Government Sponsored Project, Marine Technol. Development Group, Dept. of Civ. Engrg., Univ. of California at Berkeley.
23.
Petrauskas, C., Botelho, D. L. R., Krieger, W. F., and Griffin, J. J. (1994). “A reliability model for offshore platforms and its application to ST151 “H” and “K” platforms during hurricane Andrew (1992).”Proc. of the Behavior of Offshore Struct. Systems, Boss '94, MIT, Cambridge, Mass.
24.
Petrauskas, C., Heideman, J. C., and Berek, E. P. (1993). “Extreme wave force calculation procedure for 20th edition of API RP 2A.”Proc., Offshore Technol. Conf., Soc. of Pet. Engrs., Richardson, Tex., OTC paper 7153.
25.
SINTEF. (1994). “USFOS. A computer program for progressive collapse analysis of steel offshore structures.”Publ. N-7034, Revised Version 6.0, Trondheim, Norway.
26.
Smith, C. E. (1993). “Effect of Hurricane Andrew on offshore oil and gas facilities.”Proc., Int. Workshop on Wind and Earthquake Engrg. for Offshore and Coast. Fac., Port and Harb. Res. Inst., Yokosuka, Japan.
27.
Stear, J. D., Mortazavi, M., and Bea, R. G. (1996). “Manual of operation—ULSLEA ultimate limit state limit equilibrium analysis.”Rep. to Joint Industry—Government sponsors, marine technology and management group, Dept. of Civ. & Envir. Engrg., Univ. of California at Berkeley.
28.
Tang, W. H. (1988). “Offshore axial pile design reliability.”Rep. to the Am. Pet. Inst., Dallas, Tex., March.
29.
Tang, W. H. (1990). “Offshore lateral pile design reliability.”Rep. to the Am. Pet. Inst., Dallas, Tex., Aug.
30.
Vannan, M. T., Thompson, H. M., Griffin, J. J., and Gelpi, S. L. (1994). “An automated procedure for platform strength assessment.”Proc., Offshore Technol. Conf., Soc. of Pet. Engrs., Richardson, Tex., OTC paper 7474.
Information & Authors
Information
Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 123 • Issue 2 • March 1997
Pages: 73 - 81
Copyright
Copyright © 1997 American Society of Civil Engineers.
History
Published online: Mar 1, 1997
Published in print: Mar 1997
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