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RE: vertical control joints in long CIP concrete shear walls

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Often, there are times when joints are not acceptable.  On those occasions,
some amount larger than the minimum steel is used in order to minimize the
cracks.  An example is contained in the ACI 350, where crack widths must be
predicted for proper performance.  If you are using the minimum steel, and
joints are acceptable, half the horizontal steel is cut as in the PCA and a
joint is formed in the concrete.  The obvious exception is at the chords and
collectors where the rebar is continuous.  

The same holds true in concrete masonry walls, except all the horizontal
steel is interrupted at the joint except the chords at the top.  And there
is no ACI 350 type guidance to eliminate the joints.

Harold Sprague

> -----Original Message-----
> From:	Dave Evans [SMTP:DEvans(--nospam--at)]
> Sent:	Wednesday, March 15, 2000 1:20 PM
> To:	seaint(--nospam--at)
> Subject:	vertical control joints in long CIP concrete shear walls
> Hello,
> PCA's "Building Movement and Joints" recommends cutting every 
> other horizontal bar at vertical control joints in above-grade, 
> exterior, cast-in-place concrete building walls, to help induce 
> cracking at the joints.
> In addition to crack-control considerations, other issues include 
> code minimum required reinforcement at the joints, vertical shear 
> transfer across the joints, and wall segment stiffnesses (for center-
> of-rigidity analyses).
> Assuming long (100' or more) cast-in-place building walls are (or 
> were) being designed by members of this listserve...  I'm interested 
> in whether cutting every other bar is (or was) standard practice, or 
> whether it is (or was) more common to terminate all bars except 
> chords and collectors.
> Thank you,
> D a v e E v a n s
> T N H,  I n c.