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RE: existg CMU

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Here is the situation: we had called for a bond beam at the top of all
masonry walls; the walls span vertically and we are using clip angles with
drilled-in anchors for top support attachment to a concrete beam above at
one structure. But we missed the callout for this detail at one of two floor
levels and the Contractor says he didn't include anchors at that floor in
his bid. 

Then a decision was made in the field (per contractor and engineer's
representative) to lower the bond beam by one course, since the concrete
frame was constructed first and the bond beam could not be practically
constructed in the first course directly below the concrete beam. (Hence the
question: could it have been built in the specified location? I have to
admit, I haven't come up with a "practical" method.) 

The contractor used standard hollow block for the top course; but our
drilled-in anchors are intended for grouted block or solid block. While I
don't mind the bond beam being lowered by one course, I would have required
a solid block at the top course to allow for the drilled-in anchors - but
now it is too late. So we are trying to find the most economical solution.
If we grout the cells where anchors are to be installed, the bond beam in
the course directly below will prevent flow of grout into cells below. The
walls are exterior CMU walls and the anchors must resist wind suction
pressure on the wall. (There is a gap between the top of CMU and bottom of
concrete beam to allow the beam to deflect and the clip angles have vertical
slotted holes to permit vertical movement.) 

William C. Sherman, PE
(Bill Sherman)
CDM, Denver, CO
Phone: 303-298-1311
Fax: 303-293-8236
email: shermanwc(--nospam--at)cdm.com

-----Original Message-----
From: Andrew Kester [mailto:akester(--nospam--at)bbma.com] 
Sent: Thursday, June 10, 2004 7:52 AM
To: seaint(--nospam--at)seaint.org
Subject: existg CMU

Bill wrote:

1. If I want to use a drilled-in adhesive anchor to attach to in-place
hollow concrete masonry units, is it practical to drill a hole into the open
cells and pump grout into them, in order to obtain a solid material to
anchor to? 
We have them do that all of the time. I prefer the entire cell to be filled,
but some engineers have them grout a foot or so above and below an anchor.
They can do this by slot cutting or drilling, which is quite easy in hollow
CMU (done it myself).

2. If a new masonry wall is to be constructed below an in-place concrete
frame, is there any practical way to construct a reinforced bond beam
directly below the concrete beam? 
What are you trying to accomplish with the bond beam? IF you need a lateral
brace in addition to the concete frame in place above it, then I would go
one course below the top and construct my bond beam. That way the last
course they are just sliding block into the gap and mortaring. IF you have
to have the bond beam right at the top of the wall, then it is possible but
they have to do some slot cutting and pressure grouting...

Andrew Kester, PE
Longwood, FL

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