Reduce Load Factors for simultaneous wind and waves loads?

Question

Reduce Load Factors for simultaneous wind and waves loads?

alexbprice (Structural)

(OP)

3 Jun 09 08:56

We are designing seafastening for equipment to a barge.
Loads being considered include selfweight, wind load, and accelerations due to waves.

According to DNV the load factors for ULS are:

load condition a
The load factor is 1.3 for permanent loads and 0.7 for environmental loads.

load condition b
The load factor is 1.0 for permanent loads and 1.3 for environmental loads.

Load condition b gives worst case for overturning. There is no mention as to whether the environmental factor can be reduced when considering multiple environmental loads simultaneously. Can this factor of 1.3 be reduced?

Thanks

swearingen (Civil/Environmental) · Answer 1 · 2009-06-03 11:00:58

I would doubt that you could reduce the factor considering that when the wind loads are high, there are likely to be large waves and vice versa.

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BigInch (Petroleum) · Answer 2 · 2009-06-11 07:40:34

No. All environmental loadings must be considered concurrently, except for wind and seismic, or similar unrelated events, (seismic + tsunami perhaps is not one of those). You would need to consider wind, wave and current load simultaneously.

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femarie (Marine/Ocean) · Answer 3 · 2009-06-12 16:14:53

Just take 0.5 g athwartships (ay), o.2 g in longitudinal direction(ax) and 0.3 g =az(total 1.3) vertically.
Applied these factors before when transporting crawler cranes on barges from europe to north africa.
In case of high deck cargoes use 0.65 g for ay.

regards,
Femarie

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Reduce Load Factors for simultaneous wind and waves loads?