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Re: WOOD: Wind Uplift on Rafters

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The IRC 2000 says at the beginning that it cannont be used for wind speeds
of 110mph and higher. I forget the section it's within the first 5-10 pgs. I
never use the tables in the codes anyway just NDS and ASCE 7. WFCM is good
because it is based purely on those two standards.

Rand


----- Original Message ----- 
From: "Bill Polhemus" <bill(--nospam--at)polhemus.cc>
To: <seaint(--nospam--at)seaint.org>
Sent: Tuesday, September 14, 2004 1:04 PM
Subject: Re: WOOD: Wind Uplift on Rafters


> Rand Holtham, P.E. wrote:
>
> > "So why don't we consider the rafters are seeing the wind load as a
> > distributed load acting "outward" from the building?"
> >
> > We do...You should design loading on wood exactly the same as you do
> > for steel, concrete or masonry. The rafter has several load cases to
> > consider...those acting upward and those acting down. Incidently wind
> > acts in both directions depending on roof pitch and that has to be
> > considered.
> >
> >
> > HTH,
> >
> > Rand
> >
> > I had noticed in the tables in the 2000 IRC (and Im certain this is the
> > same as in the earlier SBC, BOCA and UBC as well), the rafter loading
> > considered is always DL & LL, Wind is never mentioned.
> >
> >
> >
> > Now Im looking at the newly-purchased WCFM, and the tables therein for
> > Roof and Wall Sheathing Suction Loads (Table 2.4) states
> > specifically that
> > its for sheathing and sheathing attachment).
> >
> >
> >
> Well, thanks, Rand, for opting for the case that I'm not an idiot.
>
> So, if this is true why is it not mentioned, at least as a "caveat," in
> the design tables in the publications I cited?
>
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