Bruce,
I'm not sure on the species used most frequently where Bob was doing
work, however down here in
Southern California it's a pretty wide range, including Western Hemlock
(also called West Coast Hemlock),
and that has an SG of 0.44, which would use the multiplier of 1.17.
I'll be happy to admit that the book I have on this is over 40 years
old, and there may be very different
species of wood being used out there now. More questions for the
structural engineer of record, I guess.
PARSLEY CONSULTING
Ken Wagoner, SET
760.745.6181 voice
760.745.0537 fax
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> e-mail
www.ParsleyConsulting.com <http://www.ParsleyConsulting.com> website
[EMAIL PROTECTED] wrote:
Are you really seeing mostly doug fir? In Pugetopolis it seems I mostly see
"HemFir". I haven't seen market numbers. Hemfir as I understand it is Western
Hemlock and several of the true fir species.
Yours,
Bruce Verhei
-------------- Original message ----------------------
From: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
Bob,
Your conclusion is correct, however I would double check the designation
of the SG for Douglas Fir.
My reference book on this is "Modern Timber Engineering", and Table L in
that document shows the
SG for Doug Fir as 0.51, which would mean your multiplier would be 1.25,
resulting in a maximum
load of 250 pounds (200 x 1.25) in the configuration you described .
It's sort of interesting, in looking at the table I noted, there are
only two types of wood with an SG
less than 0.35, and all of the others are larger, suggesting the values
in the tables are most likely to
be increased when applying this modifier. The lower SG types are
Northern White Cedar (0.32),
Western Red Cedar (0.34).
PARSLEY CONSULTING
Ken Wagoner, SET
760.745.6181 voice
760.745.0537 fax
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> e-mail
www.ParsleyConsulting.com <http://www.ParsleyConsulting.com> website
Bob Knight wrote:
Good morning,
I was asked a question a couple of days ago about the specific gravity of
wood in relation to FIGURE 9.3.5.9.1. I think I understand what is being
shown, but I would like verification. The tables within this figure showing
through-bolts and lag screws in wood has a footnote that states the specific
gravity of 0.35 was used in the table. It then states that a multiplier
can be used for other types of wood. So, here in the west Douglas fir is
the wood of choice. It has a specific gravity of 0.45. If I grasp this
correctly, this allows me to use a multiplier of 1.17 to adjust the
allowable loads found in the figure. For example a 1/2" through bolt in
wood with a length of 1-1/2" is allowed 200 lbs when using angle C.
Applying the multiplier increases that allowable load to 234 lbs. Do I
understand this correctly? Thanks for your help.
Bob Knight, CET
(208) 495-2057
[EMAIL PROTECTED]
www.firebyknight.com
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