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Re: NDS 97 GLU-Lam 24F-V8 shear value

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Marlou
This is a complicated subject. The short answer is yes.  The values in the
1997 NDS were increased.

The tabular design values for shear for 24F-V4 and V8 Western Species were
increased to 190 psi in 1994 based on application of the methods in ASTM
D3737.  The old value of 165 psi had been adopted in the 1960's based on
observations of glulam beams using "old growth" Douglas Fir. Since most of
the laminating stock being used now is second and third growth timber, this
subject was reviewed and AITC and APA decided to use the higher value
allowed by the ASTM D3737 method.

Even more recently, APA has tested glulam beams and higher values that are
code accepted are:

for beams supporting dead, Fvx (shear value for bending about the x-x axis)
live, construction, snow, wind and seismic loads have increased to 240 psi.

for beams subject to impact and cyclic loading, the shear value remains at
190 psi.

No beam tests have been conducted to justify higher values for impact and
cyclic loading conditions.

The higher values have been accepted by all the codes. For ICBO, both APA
(ER 5714) and AITC (ER 5745) have evaluation reports that have be issued by
ICBO.  For BOCA and SBCCI, see NER 486 or NER 466. Contact either AITC or
APA  and request APA Report T97-25 for test results.

Shear values for other combinations have also increased. For example, 24F-V3
Southern Pine has increased to 270 psi.

AITC is currently revising AITC 117--Design with these new design values.
Final approval is targeted for February 2001.

Bruce Pooley
Timber Design
3448 South Newland Court
Lakewood, CO 80227


----- Original Message -----
From: "Rodriguez, Marlou" <mrodriguez(--nospam--at)BiggsCardosa.com>
To: "'SEAINT Newslist'" <seaint(--nospam--at)seaint.org>
Cc: <AWCINFO(--nospam--at)afandpa.org>
Sent: Tuesday, November 07, 2000 12:04 PM
Subject: NDS 97 GLU-Lam 24F-V8 shear value


Does anyone know how the Fvxx changed from 165 psi in the 1991 NDS to 190
psi in the 1997 NDS for the 24F-V8 and 24F-V4 Glu-Lams?  Was there more test
done, if so are these tests available to view?

Thanks for your help

*************************************************************
Marlou B. Rodriguez
Biggs Cardossa Associates Inc.
Structural Engineers
1871 The Alameda, Suite 200
San Jose, California 95126
408-296-5515 Fax 408-296-8114

Note:  The opinions that I write are my opinions and
are not necessarily the opinions of BCA.
*************************************************************