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Fwd: Re: plywood shear transfer detail

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In a message dated 97-04-04 15:56:21 EST, ballense(--nospam--at)concentric.net wrote:

<<There are several sections to this Code where it is not appropriate even
for the simplest of structures. For example, the face nailing of the roof
rafter to the ceiling joist will not transfer the tension forces induced by
truss action of roof framing. Top plate splices are another example.  I
believe either this section should be removed from the Cod or the disclaimers
should me made more obvious so that it doesn't mislead Contractors or
Architects.>>

When I checked my first wood-framed house thirty plus years ago, I tried to
analyze the roof framing.  Strongbacks, collar ties, kickers, hip, ridge and
valley rafters that had no apparent supports, etc. tied me up in knots.
 Finally, one of the experienced engineers took me aside and said it didn't
matter what is shown on the plans, the carpenters will frame and/or modify
the roof using their rules of thumb and gut feel on what seems adequate based
on experience.  And the inspectors, who in the old days typically had
carpentry backgrounds as well, would eyeball the work in the same manner.
 And you know what?  In areas where heavy snowloads and high winds aren't
serious factors, the vast majority of these non-engineered roofs will perform
satisfactorily for the life of the building.  And the other rules of thumb
that formed the basis for the original 'conventional framing' provisions in
the code similarly have stood the test of time.

My wife is a toxicologist who at times is in controversies over the toxicity
and health risks of chemicals in the environment, often in very dilute or
trace amounts.  The public hearings often become surreal as industry folks,
environmentalists and nimbys battle it out.  One of her responses to the more
outrageous claims is also transferable to structural engineering deficiencies
and risks:  "Where are the bodies?"  The vast majority of folks in this
country, and an even greater percentage in the rest of the world, live, work
and recreate in non-engineered structures, and all without being aware that
some aspects of a building won't "calc out".  And they'd shrug their
shoulders and view us engineers as chicken littles if we tried to convince
them there are theoretical problems.  Calls for brick *hithouses to be
engineered just give the public impressions that engineers are a self-serving
lot.  To paraphrase my fire marshal friends ("we have zero-tolerance for
unsprinklered buildings"), Bill Allen's position amounts to a zero-tolerance
for unengineered buildings, something that the public will have zero
tolerance for.

Franklin Lew, SE


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Date: Fri, 4 Apr 1997 17:24:06 -0500 (EST)
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Subject: Re: plywood shear transfer detail
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__________________________________________________

Richard Lewis, P.E.
Missionary TECH Team
rlewis(--nospam--at)techteam.org

The service mission like-minded Christian organizations
may turn to for technical assistance and know-how.