marine structures 3

[brin]

Can someone tell me what is a typical range for factor of safety in ship or other marine structure?

 

[eureka]

There is no simple answer to the question. The F.S. (factor of safety) can vary greatly, depending on the type of material, structure type, degree of confidence in and probability of exceeding a specific load condition. The F. S. typically will be lower for long-term extreme events than for normal operating conditions. It also can not be directly applied to fatigue loading conditions. Ductility becomes more important.<br>
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A better approach is to look at the loading conditions, and structural capacity, or stress level.<br>
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For ship design, the following will be helpful:<br>
<br>
Modern Ship Design<br>
by Thomas C. Gillmer<br>
<br>
Introduction to Naval Architecture<br>
by Thomas C. Gillmer and Bruce Johnson<br>
<br>
For dynamic loading on ships, see:<br>
<br>
Dynamics of Marine Vehicles<br>
by Rameswar Bhattacharyya<br>
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For marine structures in general see:<br>
<br>
Design of Marine Facilities for the Berthing, Mooring, and Repair of Vessels<br>
by John W. Gaythwaite<br>
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For offshore structures specificily, see publications of API (American Petroleum Institite).<br>
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Other helpful sources can be obtained from SNAME (Society of Naval Architecture and Marine Engineering) and the Naval Institute Press.

 

[DENIRO]

i worked in the design of quay walls and it was 1.25 when check overturning and 1.5 when check sliding...but as eureka said there are a lot of factors affecting this factor of safety.<br><br>i hope this could help

 

[gregnordholm]

Much ship structure is designed by getting sizes or section properties, etc. from Rule books like American Bureau of Shipping, Lloyd's, Germanischer Lloyd, Det Norske Veritas, NKK, Etc.

I have gone back and using first principals figured out what the safety factors are that match the required structure that comes from many of these references and in most cases they are higher than those required by AISC or other land structure codes.

If I had to summarize, the normal safety factor might be say, 2 to 1 on yeild stress rather than 1.67 to 1.

Of the rule books mentined above, I have found that DNV (Det Norske Veritas) is the most objective.

 

[tobbe]

Typical F.S. for different operating conditions and failure modes are for instance found in the ABS rule-books which can be downloaded from their homepage:

http://www.eagle.org/rules/downloads.html

The F.S is dependent of type of structure (ship, fixed structure), as eureka states so make sure which rules you use.