Code Development for Ship Structures—A Demonstration

[+] Author and Article Information
A. E. Mansour

Naval Architecture and Offshore Engineering, University of California at Berkeley, NA Building, Room 202, Berkeley, CA 94720

P. H. Wirsching

University of Arizona, Tucson, AZ

B. Ayyub

University of Maryland, College Park, MD

G. White

U.S. Naval Academy, Annapolis, MD

J. Offshore Mech. Arct. Eng 119(2), 114-119 (May 01, 1997) (6 pages) doi:10.1115/1.2829052 History: Received May 01, 1996; Revised October 01, 1996; Online December 17, 2007


A demonstration summary of a reliability-based structural design code for ships is presented for two ship types: a cruiser and a tanker. One reason for the development of such a code is to provide specifications which produce ship structure having a weight savings and/or improvement in reliability relative to structure designed by traditional methods. Another reason is to provide uniform safety margin for ships within each type. For both ship types, code requirements cover four failure modes: hull girder bulkling, unstiffened plate yielding and buckling, stiffened plate buckling, and fatigue of critical detail. Both serviceability and ultimate limit states are considered. Because of limitation on the length, only hull girder modes are presented in this paper. Code requirements for other modes will be presented in future publication. A specific provision of the code will be safety check expression, which, for example, for three bending moments (still water Ms , wave Mw , and dynamic Md ), and strength Mu , might have the form, following the partial safety factor format:

γsMs + γwMw + γdMd ≤ φMu
γs , γw , γd , and φ are the partial safety factors. The design variables (M ’s) are to be taken at their nominal values, typically values in the safe side of the respective distributions. Other safety check expressions for hull girder failure that include load combination factors, as well as consequence of failure factors, are considered. This paper provides a summary of safety check expressions for the hull girder modes.

Copyright © 1997 by The American Society of Mechanical Engineers
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