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RE: brick walls

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Jason,
How far is Kansas City from the New Madrid Fault? If I recall,  you are
on the West side of the state and therefore a low risk while I felt my
first earthquake in 1969 at Southern Illinois University in Carbondale
which is on the New Madrid Fault.
The point is that there is little risk to URM's in your area. If you can
confirm that you are in a low risk zone (since you are on the ICC side
of the Rockies) you will be able to construct the wall with a header
course probably every 7 courses. 

I understand Roger Turks rationale, but URM's are so common throughout
the Midwest where there has been little or no record of earthquake
activity in more than 100 years that the only real threat to these
buildings would be from Cyclones (Tornados) than from land movement. I'm
not sure what purpose a non-bearing interior reinforced masonry wall
would serve as long as the wall is braced from in-plane forces that
might bring it down and this is no different from Reinforced brick
walls.

Finally, the majority of cracking that you see in URM walls throughout
the Midwest (including Chicago) are due more to soil problems
(geotechnical) than from lateral demands. Once you get into any region
which is close to a mountain range (including those areas east of
Indiana, the risk of being in a region with a seismic history increases.

We in the Southwest know and rightly fear the force of a seismic event.
Roger's fears are real in Tucson (the San Bernardino Fault as Roger once
told me) and his words of advice might be weighted with mine to allow
your own engineering judgment to work.

Dennis S. Wish, PE

-----Original Message-----
From: Jason W. Kilgore [mailto:jkilgore(--nospam--at)leok.com] 
Sent: Tuesday, December 23, 2003 10:45 AM
To: seaint(--nospam--at)seaint.org
Subject: brick walls

I'm working for an architect who wants to build an 8" brick interior
partition wall.  The entire building is URM, and this wall is to match.
It
is "L" shaped (self-bracing), and is attached to the concrete floor,
soffit
of floor above, and existing brick (3-wythe URM) walls on each side.

The architect wants to know if reinforcing is necessary.  His argument
is
that the rest of the building isn't reinforced, so why should this wall
be?
My answer was that the wall *did* need reinforcing.  My arguments are
that
this wall is the partition around an exit corridor, and that since it is
new
construction it must meet new construction requirements.

My question is, how do you reinforce an 8" brick wall?  You
theoretically
have 3/4" of space between the two wyths.  Would #4 vertical bars in a
grouted cavity with horizontal mesh work? Can you grout a 3/4" cavity,
or
would you just use mortar?

My current plan is to use horizontal joint mesh at 16" o.c. with #4 bars
in
the cavity.  The cavity will be filled with mortar buttered on the back
of
each brick.  The #4 bars will be drilled an epoxied into the concrete
slabs
above and below for lateral stability.  I will perform a seismic
analysis to
determine the spacing of the bars.

I appreciate any input.

---
Jason Kilgore
Leigh & O'Kane, LLC
Kansas City, Missouri




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