Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: wood truss and glue

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Mark;
Up until 5 years ago, Salem was home to 'Rigid Truss', one of only two truss
fabricators in the US building trusses without MPC Metal Plate Connectors.
Though popular in their local area but not others (exception being the bush
country in Alaska where materials are flown in by small planes), the dominant
market is MPC trusses. Most repairs however are wood gussets, which are
typically nailed or screwed and, if glued, a reduction in bond strength taken
due to temperature control issues and bond to galvanized (oiled) steel if MPC
are gusseted over.

You might want to consider a specialty engineer that has experience in this
area.
By the time you investigate which empirical moment equations to design lumber
for using truss methodology,
the reductions to take for non-coincidental chord-web centerline forces,
gusset rotational forces due to glue area centroids being eccentric,
and plywood allowable stress reductions due to size,
it might be cheaper to pay $300 to a truss engineer and yourself act as project
EOR.
CTruax


----- Original Message ----- 
From: "Mark Miller" <milm(--nospam--at)chemeketa.edu>
To: <seaint(--nospam--at)seaint.org>
Sent: Thursday, June 24, 2004 11:42 AM
Subject: wood truss and glue- sorry second try


| Hello-
|
| I have a client that has built some wood roof trusses (normally I try to avoid
projects like this, but long story…..). The trusses look very reasonable in
their construction. I will have to analyze them for strength and deflection, but
before I put the time into doing this I was concerned with the way the plywood
gussets were glued to the truss members. They used Gorilla Glue and nails to
hold the joint tight while the glue cured. I was concerned with how Gorilla Glue
(one part polyurethane glue) compared with the resorcinol glue that we have used
in the past. I have contacted the makers of Gorilla Glue and they were very
helpful and pointed me to some tests done by the USDA Forest Service Forest
Products Lab. The shear strength, in these tests, looked as good or better than
resorcinol for use on doug fir. I am still concerned with the long term
performance and performance in a fire (high temp). This is in Oregon and under
the UBC.
|
| Does anyone have experience with this?
|
| What do you think?
|
| Thanks for your consideration.
|
| Mark Miller, PE


******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********