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RE: Wood Bottom Plates and bolting to wood or concrete

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Dave:


you said: [Don't forget "Seismic Cat. D or E" 2308.12.8 all sill plate
require the washers with minimum dimensions of 2x2x3/16. There is no mention
of the size of the sill and so it applies to all sills. This is clearly not
for sole plates. A clarification that sole plates are exempt would be
helpful.]


The IBC reads:  "2305.3.10 Sill plate size anchorage in Seismic Design
Category D, E, F.  Two inch nominal wood sill plates for shear walls shall
include steel plate washers, a minimum of 3/16 inch by 2 inches by 2 inches
in size...."

It does not say that the plate washers are required for "three inch nominal
wood sill plates".  I see where the UBC always require them and where the
NEHRP always requires them, but the way I've always understood the codes you
are not supposed to project what they do not say onto them. So by process of
elimination, the IBC does not say that 2x2x3/16 plate washers are required
for 3X sills.  This may be a typo but this is the way it reads.  What I want
to know is this a typo?


Thanks.


Scott M Haan P.E.
Plan Review Engineer
Building Safety Division 
Development Services Department
Municipality of Anchorage
http://www.muni.org/building
phone:907-343-8183  
fax:907-249-7399
mailto:haansm(--nospam--at)ci.anchorage.ak.us



-----Original Message-----
From: David B Merrick [mailto:mrkgp(--nospam--at)pacbell.net]
Sent: Wednesday, November 14, 2001 12:15 PM
To: SEAINT
Subject: Wood Bottom Plates and bolting to wood or concrete


For IBC 2305.3.10, the washers are only required for 2x material at the
sill plate. A sill plate is a "bottom plate" at the concrete foundation.
A "sole", is also a "bottom plate" higher up in the framing. The last
sentence of IBC 2305.3.10 references nailing of a sill to line 8 of
table 2304.9.1. Tabulated line 8 uses the term "sole". The IBC
disregards the difference in meanings of the terms "sill" and "sole".
The term "bottom plate" can be used when both "sill" and "sole" apply.
Most likely, the table needs the term "sole" changed to "bottom plate",
or else the larger washers applies to all bottom plates of 2x material.

Don't forget "Seismic Cat. D or E" 2308.12.8 all sill plate require the
washers with minimum dimensions of 2x2x3/16. There is no mention of the
size of the sill and so it applies to all sills. This is clearly not for
sole plates. A clarification that sole plates are exempt would be
helpful.

I was alerted to a fact that sole plate pressure treatments that appear
to be of a light green color with shallow cuts for penetration are sole
plates of Hem-Fir. Pressure treated Doug Fir is more of a chocolate
color with deeper cuts. The deeper cuts are needed for the harder
material. This reduces the bolting values by about 9 to 11% and the
nailing by 7%.

It appears from the discussions, that we had better not be using the
bolt tables until corrected or verified.

An alternate mental experiment for a mode II failure of a wood to
concrete connection is to rotate the large bolt to the angle required to
fail the concrete. That amount of rotation is much less than the
rotation required to fail the wood (rotation only). This is an
insignificant addition to the wood strain for its possible failure. The
wood bearing stress distribution might be mostly uniform.

I recommend checking mode II for wood to concrete. If we are to
disregard mode II for wood to concrete, there needs to be an addendum or
a review of test results. Is there testing for mode II for wood to
concrete?

David Merrick, SE
mrkgp(--nospam--at)pacbell.net.




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