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RE: steel formdeck as shearwall?

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Thanks Ed, I think you're the definitive swing vote to make sure I get CMU for shearwalls.

Thanks for the seismic input.  I realize it can control, and a month from now, when the project is in my hands, it'll be checked as always for these conditions.  

IBC makes a roughly 4x change in seismic forces in the Birmingham area.  It would definitely control if that was what I was using.  SBC, maybe/mabye not.  The recurrence interval is now about 2500 years under IBC.  I'm not using that unless dictated by law.  If I was around Memphis or Charleston, heck yeah, I'll get into it.

John C. Jones, PE
Barnett Associates
Pell City, AL
205-884-5334
205-884-0099 (fax)


-----Original Message-----
From: Ed Tornberg [mailto:edt(--nospam--at)blazerind.com]
Sent: Thursday, October 30, 2003 5:46 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: steel formdeck as shearwall?


John,
We had to look into this on a few projects where it had to be
non-combustible and lightweight.  The options for steel stud walls came
out as:
 
1.  Hardy frames
2.  Light gauge "diaphragm" material, similar to form deck.
3.  Strap bracing
 
The hardy frames were excellent on a single story project where we
designed the holdown bolts to attach to structural steel channel serving
as a floor rim.  
 
The problem with steel siding is that the manufacturers really don't
understand what documentation we need to apply it as "sheathing"  They
sometimes could come up with an ICBO listing for roof diaphragms, but
not for walls.  In our case we were looking for something with a very
low profile - not B-36 or other heavy stuff.  We came close with some
material but the price for a small job was astronomical, and we nixed
it.  If you really want some leads on manufacturers contact me and I'll
try to dig up the notes.
 
Thus we ended up strap bracing on a couple of projects, which works but
oh what a pain to do the calcs when you're used to specifying sheathing.
You might as well have the fee figured the same as for doing CBFs, but
with many more braces, since they're relatively wimpy.  And they do
bulge out the walls, especially if you're using gussets at the brace
corners, which we had to do to make the connections work.
 

Ed Tornberg, PE 
Blazer Industries, Inc. 

Aumsville, OR
503-749-1900 

 

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