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RE: 3/8 inch shear panels

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-----Original Message-----
From:	John Rose [SMTP:jrose36(--nospam--at)earthlink.net]
Sent:	Thursday, September 03, 1998 20:15 PM
To:	seaint(--nospam--at)seaint.org
Subject:	Re: 3/8 inch shear panels

...The UBC requires that all nailing spaced 2 in. o.c. must be in staggered 
rows; e.g., two rows with nails
spaced 4 in. o.c. in each row.  Splitting of framing is avoided with this
pattern....

[Bill Cain]  With all due respect, John, this is good theory. However, in 
practice, the contractors either meet the 2" spacing or stagger so much 
that they don't meet the edge distance requirements.  Either way you will 
often end up with toothpicks!  I can't count the number of times I've had 
to require the framing be replaced because the studs were so badly 
butchered.  Since I've stopped using these tight spacings, I've had few 
problems.

Eph Hirsch's caveats about the hold downs for a heavily loaded panel are 
important.  If you've ever seen Ed Zacher's videos of how plywood pulls 
loose at the corners under cyclic loads (which is also evident in pictures 
I've seen from Northridge), you understand that, although Simpsons's hold 
down tests (done on a steel jig BTW, not a wood post) show a large 
capacity, in reality, the eccentricity of the load for a single hold down 
at a corner and the resulting deformations and bending of the post due to 
the P/A + MC/I (in addition to bolt hole oversizing, crushing of the wood, 
etc.) effect will not give you the performance you are counting on. 
 Simpson makes great products if they are used with a little common sense 
and attention to basic mechanics.  And their catalog warns the designer 
about these effects (although I would prefer to see it a little more 
prominently presented).

Regards,

Bill Cain, SE
Oakland, CA