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Re: Wood Moment Frame?

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This was my concern from the start.  I got involved with the project
because of an issue with a suspended concrete floor slab.  As I was
going through the plans, I noticed the narrow shear walls.  Out of
curiosity I called the EOR to find out how he justified it.

Apparently, the report that John Rose mentioned is about to be
published.  This is the response I got from Tom Skaggs:

    "The information that you request has recently been finalized in APA
Report
    T2001L-56 "Narrow Wood Portal-Frame Bracing Segments"."

I don't know when it will be available though.  He is going to mail me a
copy.  Thanks, John!

I think I have talked the EOR into using a Strongwall.  We'll see.
He did not perform a deflection check.  I doubt it would meet the
code requirements.  I've noticed that a few of the strongwalls have a
full height metal strap at the edge.  I wonder if this is to limit
deflection?

George Richards asked "Where is the life safety issue?"
If only we had to worry about life safety.  What do you tell the
owner/lawyer
when the garage door won't open after the big wind storm because the
garage is slightly out of plumb?

Thanks for all the input.
Dan Goodrich, P.E.


---- Original Message -----
From: "chuckuc" <chuckuc(--nospam--at)pacbell.net>
To: <seaint(--nospam--at)seaint.org>
Sent: Friday, November 30, 2001 11:31 PM
Subject: Re: Wood Moment Frame?


> The proposed wall has an aspect ratio of 5:1 and is not UBC compliant (see
> Fig. 23-II-I b)--and that should be the end of the discussion.
> It is certainly possible to build such a wall so as to meet the code
> required drift limits, but it is extremely difficult if the loads are
large
> (and you'd need lab tests to prove it).  Simpson (and a few others) have
> gone to great lengths to fabricate and test code compliant portal
> frames--tell your guy to buy some.
> The aspect ratio multiplies all the sources of deflection: construction
> slop, shrinkage, tie down deflection, fastener deflection, plate crushing,
> etc. 5:1 is a killer and the problem is not amenable to accurate
calculation
> even if you tried to control all the construction variables. (I don't even
> think Simpson's tests with green headers are accurate because they didn't
> allow their headers to shrink before they tested them.)
> Chuck Utzman, P.E.
>
>
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