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RE: 20 year wood study question[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
- Subject: RE: 20 year wood study question
- From: AWC Info <AWCInfo(--nospam--at)afandpa.org>
- Date: Fri, 16 Mar 2007 08:46:17 -0400
Title: RE: 20 year wood study question
There is also a short write-up in the 1991 NDS Commentary. See Part 4 at this web page:
Additional references are noted.
From: Scott Maxwell <smaxwell(--nospam--at)engin.umich.edu>
Subject: RE: 20 year wood study question
The Breyer et al textbook refers to the "In-Grade Testing Program" and
mentions it as being done in 1978. The reason for it was that all the old
values were based soley on testing of small samples of wood. The
In-Grade Test program tested actual pieces of dimension lumber (2xs etc).
The Breyer book offers that the program tested about 73000 pieces of
full-sized Dimensional lumber in bending, tension, and compression
parallel to grain. Here is a quote from the text:
"The objective of the In-Grade Testing Program was to verify the
published design values that had been determined using the
clear-wood strength method. Although some of the values from the
In-Grade Testing Program were close, there were enough differences between
the In-Grade results and the clear-wood strength values that a new method
of determining allowable stress properties was developed. These
procedures are given in ASTM Standard D 1990."
On Thu, 15 Mar 2007, Dennis Wish wrote:
> March 15, 2007
> Reply: 20 year study
> Thanks Buddy. I am not sure that this is the study I am referring to
> although it could be based on the PDF file for Chapter 06 of FPL's document
> having been updated through 1998 and referencing the IBC. There is no real
> mention of the discussion related to the samples taken over the 20 year
> period starting in the very early 70's and the reductions discussed are not
> clear as to the reasons based on the reduced availability of quality lumber
> that I thought was the point of the study and subsequent stress reductions
> used in the UBC codes.
> Can anyone else provide a bit more clarity to confirm if this is a correct
> memory of the stress changes in the 94 or 97 UBC? I need to reference the
> document to a friend producing a wood text and I believe this was an
> important piece of data that needs to be footnoted or referenced.
> Dennis S. Wish, PE
> California Professional Engineer
> Structural Engineering Consultant
> C-41250 (Exp. 3/31/07)
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> From: AWC Info [mailto:AWCInfo(--nospam--at)afandpa.org]
> Sent: Thursday, March 15, 2007 6:16 AM
> To: 'seaint(--nospam--at)seaint.org'
> Subject: 20 year wood study question
> I think you are referring to the In-grade test program. Here's a link to an
> FAQ on our website that lists several resources:
> 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
> 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
> 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: "Dennis Wish" <dennis.wish(--nospam--at)verizon.net>
> To: <seaint(--nospam--at)seaint.org>
> Subject: 20 year wood study question
> March 14, 2007
> Re: Trying to find documents about wood stress reduction
> I am trying to locate information that is relatated to a 20 year study done
> on available wood used in construction and which was used in either the 1991
> or 1994 UBC to reduce bending and shear values in the code. I know this goes
> back to the mid to late 90's but I am in need of a summary of the study and
> can't recall if it was done by the Forest Products Lab, AF&PA or AITC. Those
> of you in California may recall that the summary indicated that mature
> Douglas Fir harvested since the study started in the late 60's or early 70's
> concluded that choice lumber was no longer as plentiful as it had been. The
> 1994 UBC (if I recall) reduced material stresses or possibly the Modulus of
> Elasticity for lumber and also introduced more finger-jointed lumber into
> construction for stud use.
> I can't recall where the study originated and would like to find a copy for
> reference. I remember that we discussed it for a while on the SEAINT List
> and it may have not have been adopted until the 97 UBC was codified.
> If anyone has the document or any information that can lead me to the 20
> year study, please let me know by e-mailing me privately or by posting back
> on this list.
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