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Re: X Bracing for Metal Buildings

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> From: "Chance, Acie" <AChance(--nospam--at)lacsd.org>

>      I am remodeling an old metal building and need to add additional X =
> bracing.  Is the standard material for X bracing used in the metal =
> building industry ASTM A 311 Class A Grade 1018.  If not what is =
> normally used?

I'm not familiar with that spec.

Normal use depends on each individual manufacturer. Anything from ASTM
A36 up to ASTM A572 Yield 50 ksi is typical for rods. Cables are
commonly spec'd inappropriately and inadequately and just make my skin
crawl in general.

If you are trying to determine the existing, call the manufacturer. If
the manufacturer is defunct, assume that the braces were maxed out to
start and back calculate probable Fy and Fu. If you want to spec new,
use whatever you like.

I suggest that you concentrate on getting stiffness appropriate to suit
the new load redistributions so that you don't accidentally overload the
existing bracing.

Also, many buildings have reinforced bracing load paths that are not
easily found, visibly. Ensure that your redistribution does not overload
elements that weren't considered for the bracing loads (e.g. eave strut
connections outside the braced bay).


> From: "Stuart, Matthew" <mstuart(--nospam--at)schoordepalma.com>
 
> I would be more concerned about how you are going to reinforce the =
> adjacent columns and foundations for the vertical component of the new =
> X-brace.

Depending on the magnitude of the bracing forces in the original
building and the fondation configuration, it is possible that all
foundation locations are equally competent wrt bracing.

Regards
Paul

-- 
R. Paul Ransom, P. Eng.
Civil/Structural/Project/International
Burlington, Ontario, Canada
<mailto:ado26(--nospam--at)hwcn.org> <http://www.hwcn.org/~ad026/civil.html>

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