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Re: masonry & wood

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Thanks, I wrote single wythe, didn't I. It is two wythe, 8" thick.
 
I'll hit the icbo website looking for the AC60 doc. If I don't find it you may hear from me again.
 
Mark
----- Original Message -----
Sent: Thursday, August 03, 2000 8:00 AM
Subject: Re: masonry & wood

Mark,
 
You can conduct your own testing program on adhesive anchors in the masonry of your project.  Use AC60, "Acceptance Criteria for Unreinforced Masonry " by ICBO Evaluation Service Inc. as a guide for the specs for the testing.  You'll need to pick through the requirements of AC60 to select the applicable requirements for your test program because it is more general than you will need, and it has some arbitrary minimum and maximum requirements for which you may want to make your own determination regarding appropriateness for your test program.
 
I believe that one of the reasons that 13" thickness of brick is the minimum thickness for which general approval has been granted for adhesive anchors is that it takes at least three wythes of brick to develop an effective "cone" of brick masonry around an anchor to distribute the anchor force into the wall.  Higher quality mortar is more likely to be effective in distributing the anchor force into a thin wall -- with low quality mortar, local bricks are more likely to be dislodged by a force on the anchor.  To take that effect into account, the reaction legs on the test apparatus should apply their load to the wall well away from the anchor and the adjacent bricks so that any tendency for bricks to become dislodged by the force is included in the data.
 
You may find that you can come up with reasonable capacities for closely-spaced anchors in two-wythe brick masonry.  My one attempt at anchoring single-wythe masonry has made me decide it just doesn't work, and I won't try that again.
 
Nels Roselund
Structural Engineer