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RE: brick veneer support deflection

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Be careful in using a triangular load.  If you have expansion/contraction
joints in the area of the wall which would be considered the abutment for
the "arch" above the 45 degree triangle, you don't really have arch action -
caulk and a foam rod don't provide much restraint.

Another concern is relative deflection from one floor to another.  If one
shelf angle ends up deflecting .4" and the one below deflects .2", the joint
between them may suffer.

A big thing to look out for is what capacity you assign to the shelf angle
inserts.  The usual ones that I have seen provide test data for a brick load
at 2" from the face of the insert and a safety factor of 2 in computing
their allowable design loads.  I don't think either is realistic.  Halfen
Anchoring Systems make an insert that looks more expensive but at least on
one job where I compared them against a more standard insert, they were
cheaper.  (800) 323-6896.

Roger Davis
SDS Architects, Inc
205 N. Dewey Street
Eau Claire, WI 54703
715-832-1605
rdavis(--nospam--at)sdsarch.com


-----Original Message-----
From:	Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com]
Sent:	Monday, January 24, 2000 9:39 PM
To:	seaint(--nospam--at)seaint.org
Subject:	RE: brick veneer support deflection

David,

Remember that the lintel is only going to support a small triangular load
providing the lintel is shored while the brick is being installed.  I use a
45 deg. triangle, but know that with brick it will probably be much less.
Once the brick gets about a foot or so higher than half the span distance,
it
will arch (providing you have an adequate thrust block), regardless of
whether the lintel is shored or not.

BIA is Brick Institute of America.  I do the same thing that Harold Sprague
does in designing lintels in following the BIA recommendations.  The L/600
and 0.3" limits are to prevent the triangular cracking that would occur.

Hope this helps.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

David Handy wrote:

>>Also: This is very strict, especially the 0.3" in one case this would be
L/1100. Would it make sense to use shear studs on the perimeter beams to
increase stiffness??? I would likely use a lesser amount for lateral
support reasons anyway. I don't use shear studs too often; would the
increase in stiffness be considerable or marginal?
thanks again, David Handy

At 06:36 PM 1/24/00 -0600, you wrote:
>David,
>
>The UBC says to use L/600 for total deflection.  The BIA says the lessor of
>L/600 or 0.3".  I tend to agree with the BIA unless you can cut the masonry
>into smaller panels with properly detailed joints that can accommodate more
>movement.  I would recommend that you read the BIA Technical Note 28B.<<