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RE: Concrete Load Brg Wall with Conc Beams

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The true fixity at an exterior wall will be almost zero. The wall will crack
in flexure before the beam will, creating something closer to a pinned
joint. The joists (do you really mean beams?) should be designed treating
the wall as a simple support anyway. The negative steel will only provide
crack control for any nominal stresses occurring.

Note that the negative steel needs to satisfy ACI 12.12.3 and the positive
steel needs to satisfy ACI 12.11.3. For your 12" wall, assuming your joists
are deeper than 12", this means you will need to provide hooks for both your
top and bottom joist bars. But that will be all that is required.


-----Original Message-----
From: James Lane, P.E. [mailto:jamesalane(--nospam--at)hotmail.com]
Sent: Friday, July 19, 2002 2:30 PM
To: seaint(--nospam--at)seaint.org
Subject: Concrete Load Brg Wall with Conc Beams




A 12 inch thick load bearing wall multiple stories. Heavily reinforced 
concrete beams on grid coming into bearing wall. Is it ok not to develop the

beam bars (not enough wall thickness. Wall must satisfy ACI 14.4.

I say negative steel should be developed by a haunch or something similar 
and design wall for additional haunch moment. Looking for other engineers 
comments regarding development of beam steel in exterior walls.

I have heard one response that does not develop the beam steel and treats it

as a partial fixity letting the negative steel yield and redistributing beam

moments. If you do not develop the beam steel how can you be sure that the 
end moment does not pull out the partial developed bars causing failure?



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