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RE: More Plywood Diaphragm's

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Title: Re: More Plywood Diaphragm's
I agree with William's question since footnote "g" states that intermediate framing shall be 2x, which leads me to believe that it has no bearing on the tabulated shear values for either 2x or 3x edge and boundary framing.
 
Doug Mayer, SE
Structural Engineer

TaylorTeter Partnership

7535 North Palm Ave., Suite 201
Fresno, CA 93711

(559) 437-0887 Ph.
(559) 438-7554 Fax
doug.mayer(--nospam--at)taylorteter.com


From: William Haynes [mailto:gtg740p(--nospam--at)gmail.com]
Sent: Thu 11/6/2008 7:02 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: More Plywood Diaphragm's

I am confused as to why if you are using 2x intermediates for field
that you have to use the lower values, as long as you are still using
3x at the adjoining edges?

WH

On Thu, Nov 6, 2008 at 9:47 AM, AWC Info <AWCInfo(--nospam--at)afandpa.org> wrote:
> We don't specifically address it in the 2005 SDPWS Commentary. However,
> it looks like we tried to clarify it in the 2008 SDPWS
> http://www.awc.org/Standards/SDPWS.html section 4.2.7.1.1 which states
> that both blocked and unblocked diaphragms shall be constructed as
> follows:
>
> "The width of the nailed face of framing members and blocking shall be
> 2" nominal or greater at adjoining panel edges except that a 3" nominal
> or greater width at adjoining panel edges and staggered nailing at all
> panel edges are required where:
> a. Nail spacing of 2-1/2" on center or less at adjoining panel edges is
> specified, or
> b. 10d common nails having penetration in to framing members and
> blocking of more than 1-1/2" are specified at 3" on center or less at
> adjoining panel edges."
>
> So, my interpretation is if you have 2" nominal framing or blocking for
> intermediate members for field nailing, you would use the lower
> tabulated value that corresponds to the Minimum Nominal Framing Width of
> 2". I'd be interested to know if you all have seen or specify 2x
> blocking or intermediate framing with 3x framing at adjoining panel
> edges? Seems like that could be potentially confusing for the
> contractor.
>
> Not sure of the background on that, but Tom Skaggs at APA could probably
> shed some light or weigh-in if I'm wrong.
>
> HTH
>
> Buddy
>
> John "Buddy" Showalter, P.E.
> Director, Technical Media
> AF&PA/American Wood Council
> 1111 19th Street, NW, Suite 800
> Washington, DC 20036
> P: 202-463-2769
> F: 202-463-2791
> http://www.awc.org
>
> The American Wood Council (AWC) is the wood products division of the
> American Forest & Paper Association (AF&PA). AWC develops
> internationally recognized standards for wood design and construction.
> Its efforts with building codes and standards, engineering and research,
> and technology transfer ensure proper application for engineered and
> traditional wood products.
>
> *********************
> The guidance provided herein is not a formal interpretation of any AF&PA
> standard.  Interpretations of AF&PA standards are only available through
> a formal process outlined in AF&PA's standards development procedures.
>
> *********************
>
> From: "David Topete" <d.topete73(--nospam--at)gmail.com>
> To: seaint(--nospam--at)seaint.org
> Subject: Re: More Plywood Diaphragm's
>
> Note "d" is in the nail size column for 10d nailing... note "c" takes
> precedence at the tighter nail spacing. And, i agree that note "g"
> allows 2x intermediate members for field nailing. It leads me to believe
> that the you can use either value listed. Obviously the lower value
> would be more conservative for your design... I'll be curious to check
> the NDS Commentar= y for an explanation on the two values being
> listed... Good question, Doug.
>
> On Wed, Nov 5, 2008 at 2:33 PM, Doug Mayer
> <doug.mayer(--nospam--at)taylorteter.com>wrot=
> e:
>> In Table 2306.3.1 of the 2007 CBC (I would assume this also appears
>> in the 2006 IBC), plywood diaphragms with nail spacing at less the 3"
>> o.c. require 3x framing at all panel edges per note "c" and "d". In
>> light of this, why are there shear values for both 2x and 3x framing
>> members at pa=
> nel
>> edges and boundaries for nail spacings of 2.5" o.c. and 2" o.c.? Is
>> it because you could still have 2x framing at field nailing? I'm
>> thinking n=
> ot
>> because note "g" states that "The minimum nominal width of framing
>> member=
> s
>> not located at boundaries or adjoining panel edges shall be 2 inches."
>
>> T=
> his
>> leads me to believe that the intermediate framing member, as long as
>> it i=
> s a
>> 2x, does not play a role in the capacities of the diaphragm.
>>
>> By the way, where is note "d" in the table? I can't seem to find it.
>> Anyway, what am I missing here? I'm surprised I haven't noticed this
>> apparent contradiction until now. Thanks for any help=85.
>>
>> Doug Mayer, SE
>
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