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Re: 2x4 stud walls in High Wind areas

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Buddy:

I am going to play dumb for a moment (something that I have some natural
talent in <grin>).

How can you design the studs for bending from only Components and Cladding
wind load and not include axial loads from gravity loads?  I would think
that axial loads from gravity loads should be checked in combination with
either MFWRS winds loads _OR_ C&C loads.  The only difference would be
that with MFWRS winds loads, it is possible (even highly likely) that
there will be some additional axial loading (either tension or compression
depending on the roof configuration) due to the MFWRS loads (i.e. suction
on the roof or downward thrust on the roof), where as for C&C loads you
are only considering the wind loads on that one member (which means that
the C&C wind loads for bending would like be significantly large due to
the smaller tributary area).

I will look at that article that you mentioned because it might explain
it, but I am curious as to an explanation for what you stated.

Thanks,

Scott
Ypsilanti, MI


On Thu, 12 Dec 2002, AWC Info wrote:

> Here's a link for more information on the document John referenced below:
>
> http://www.awc.org/Standards/wfcm.html
>
> Also not that stud walls can be designed as follows for wind and gravity
> loads:
>
> 	Bending only using C&C wind loads independent of axial stresses
>
> 	Bending plus compression using MWFRS wind loads and axial loads
>
> There's more detail on this issue in the following paper:
>
> http://www.awc.org/technical/considerations.pdf
>
> HTH
>
> Buddy Showalter, P.E.
> AF&PA/AWC
>
> ************
>
> From: John D. Rose [mailto:jrose36(--nospam--at)earthlink.net]
> Sent: Monday, December 09, 2002 1:26 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: 2x4 stud walls in High Wind areas
>
>  Contact Buddy Showalter at American Forest & Paper Assn./American Wood
> Council (awcinfo(--nospam--at)afandpa.org) and ask for their 2001 Wood Frame Construction
> Manual. This document has engineered and prescriptive design recs for wood
> frame construction in high wind areas, including not only walls but also
> roofs and connections of roof-wall-floors and to foundation.
> John Rose
> APA (retired)
> Tacoma, WA
>
> Nick Bingham wrote:
>  I'm in 85mph exp C country and have a contractor wanting to build a home
> with 2x4 at 16" oc walls, with 10' plate height. I have about 550 plf down
> (DL plus snow). I can get close on the stress, but deflection is killing it,
> especially with a stucco finish. I'm getting the usual, " The last engineer
> I used had no problem with it". Contractors look table 23-IV-B in the '97
> UBC and see that a 2x4 wall should go 10'  supporting one floor and the
> roof. I realize that this table does not apply in high wind areas, which I
> am in, and that it's the 85 mph wind that is killing the 2x4. I'm looking
> for some input - have others found a way to get a 10' (plate to plate) 2x4
> wall to figure?Thanks!Nick Bingham
>
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