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RE: Wood "Nailed" Moment Connection

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There is a reference to moment connections in the “Wood Engineering and Construction Handbook” by Faherty and Williamson (McGraw-Hill).  They have two different cases, a multiple steel plate connection and a rigid steel plate connection.  The single rigid plate can cause splitting of wood due to restrained shrinkage.  The multiple plate anchorage minimizes that problem.  For similar conditions to yours, but a steeper slope, I’ve used plywood gussets at the ridge (no ceiling in the space, so no collar ties were available) in residential construction. 

 

Eric

 

-----Original Message-----
From: Rand Holtham, P.E., Sigma Engineers [mailto:rand(--nospam--at)sigmaengineers.com]
Sent: Friday, May 16, 2003 9:02 AM
To: seaint(--nospam--at)seaint.org
Subject: Wood "Nailed" Moment Connection

 

Robert, Is there a ceiling joist in this situation? If so then there is no moment at the ridge only shear. It's a simple one bay truss. otherwise you would have the max moment at your splice in which you'd have to calculate you force couple in the nail group. I'd doubt that if you could hold much load at the 18 foot span. A collar tie could help you develop continuity at the ridge by spreading out you moment arm.

 

Rand Holtham, P.E.  

 

 

 

I'm sure many of us have seen wood beams that have been "scabbed
together".  I have a rather unique situation where two rafters are
sloping gently (about 1/2" per foot) to the peak of a low-slope roof and
are nailed together (at the peak) with some nails & plywood "scabs" on
either side.  There is no ridge beam, and the total span is about 18
feet (two 9 foot rafters abutting each other at the peak).  I have tried
to envelope the analysis by considering it as a simple beam (with max.
moment and no shear) as well as it being a rigid frame (nailed down at
each end) inducing shear, moment, and axial compression into the
rafters. =20
=20
Problem is, I have been unable to find any information about "nailed"
moment connections.  Nothing in AITC, nothing in Breyer's book (4th
Edition) and nothing after scouring the net......
=20
Anybody out there who can enlighten me on this subject matter
(transferring moment via a nailed "scabbed" connection) ?