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Re: 1/3 stress increase for 5 psf interior wind load

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> From: "Dan Vines" <dan(--nospam--at)>

> Dale/Incor, in their catalog, provides allowable axial loads for various
> stud sizes at various heights under various wind loading condtions (other
> manufacturers provide the same info).  Anyway, they have a footnote that
> states:
> For components subjected to 5 psf and greater lateral wind loads, the actual
> bending and axial stresses were multiplied by 0.75 in accordance with AISI
> Section A4.4
> AISI sect. A4.4 states:  Where load combinations specified by the applicable
> building code include wind or eq loads, the resulting forces may be
> multiplied by 0.75.
> The question is:  does the 5 psf interior wall loading prescribed by code
> constitute a WIND load.  My boss and I both think so, but I would love a
> second, third, or twelfth opinion.

This has been interesting from the perspective of load interpretation.
We see many different explanations for the surface pressure load and how
to handle the pressure in combinations. This reminds me somewhat of
similar discussions regarding loads on guards ...

As others have suggested, all manner of loads can exist on interior
walls including lazy people, seismically influenced filing cabinets,
enthusiastic firemen and wind induced loads ... the net effect of
interior pressure and suction on opposite faces can be larger than the
suggested 5 psf. So, the situation will determine your requirements.

The stress reduction relates to short duration loads when combined with
loads, other than dead load, to account for a reasonable expectation of
occurence. If the other loads are relatively constant (dead loads,
storage, etc.) then it is unjustifiable to use this stress reduction
since the load combination may easily be experienced.

Paul Ransom, P. Eng.
Burlington, Ontario, Canada
<mailto:ad026(--nospam--at)> <>