At 07:20 AM 1/25/00 -0600, you wrote:
>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.
Agreed. For a while the architectural guys in our office were putting
control joints on each side of every window. Thus the brick load supported
was always assumed to be the full load because they would not be shored
during brick laying.
>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.
The insert data sheet I am using has prorating formulas for anything other
than the standard 2" horizontal distance and the distance from the centre
of the bolt to the underside of the angle. They also factor in concrete
strength and the SF is shown as 4.
>SDS Architects, Inc
>205 N. Dewey Street
>Eau Claire, WI 54703
>From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com]
>Sent: Monday, January 24, 2000 9:39 PM
>Subject: RE: brick veneer support deflection
>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,
>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)
David Handy, P.Eng.
The Thompson Rosemount Group, Cornwall, Ont. Canada
Opinions expressed are personal only.