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RE: Fastening of Steel Stud Walls to Foundations

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Yes, I would agree that contractor's definitely prefer PAF's  for bottom
track anchorage.  This is very common in the construction world.  First
of all, all PAF manufacturer's have a value for installation into
concrete with a minimum embedment length of 1 1/4" to 1 3/4".  Most of
your metal stud manufacturer's will have values that have been approved
for attachment of their track to concrete based on NER or ICBO approvals
(based on gage of track and dia of pin).  I am not aware of any values
that have been tested for the use of anchor bolts with track (please let
me know if it exists).  The shear value would then be required to be
calculated based on Fy, gage of the steel, diameter of the bolt (typical
bearing type failure).  With a big enough diameter washer, you might not
have to worry about bearing failure but instead you need to check web
tearing or web buckling.  In a nut shell, this is a pain in the a__.
Besides, contractors can install hundreds of shotpins per hour compared
to having to install AB's and then drill bottom tracks or worse yet,
having to install expansion or epoxy anchors.  If the wall is a shear
wall, simply calculate the number of PAF's per foot.  You can be
guaranteed that no matter how many PAF's are required, it will still be
more economical than installing AB's.  It is also much easier to design
with PAF's and justify your design than if you used AB's.  

Construction industry is finally publishing material on the allowable
design values when using steel studs.  I began designing residential
structures with steel studs in 1991.  For years the municipalities and
code organizations refused to accept any design values for steel studs
until the testing was completed. We were designing shear walls with
pretensioned x-bracing even though the entire structure was sheathed
with plywood.   It may still be to early to expect them to accept the
capacities of anything in steel studs without completed testing
approval. 

-----Original Message-----
From: Dan Huntington [mailto:huntingtondj(--nospam--at)kjww.com]
Sent: Tuesday, August 17, 1999 12:40 PM
To: seaint(--nospam--at)seaint.org
Subject: Fastening of Steel Stud Walls to Foundations


I'd like to hear people's thoughts on anchoring bottom tracks of
exterior
steel stud walls to the foundation.  The stud walls being the back-up
system
to the cladding and either bearing or non-bearing.

I don't believe code requires the use of anchor bolts for this type of
construction.  Our office prefers anchor bolts (either cast-in of
expansion), but contractors are quite vocal about preferring
powder-actuated-fasteners (PAF's).  What are other offices specifying
and is
there a code requirement that I'm missing?

Dan.
-------
Daniel J. Huntington
Structural Engineer
KJWW Engineering
623 26th Avenue
Rock Island, IL 61201
PH: (309) 788-0673
Fax: (309) 786-5967
e-mail: huntingtondj(--nospam--at)kjww.com
Web: www.kjww.com