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Joints and Spacing in Concrete Tank?

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Thanks for the reply, Acie.

I've been able to get my hands on 2 separate plans for similar 
aeration basins. Both are much, much larger in scale than the one I'm 
doing, but the premises should be the same.

Aeration Basin #1:
This one is similar to the one you described. They are showing joints 
in both the slab and wall at 60' OC. The horizontal rebar is 
continuous thru the joint with a 1" premould material and 1'-6 smooth 
dowels at 12" OC and continuous water stop.

Aeration Basin #2:
The slab and wall joints are shown at about 70' OC and all rebar is 
broken at the joint. A 1" premould material is also shown and a 
continuous waterstop is present. A sealant is present on the upper 
slab portion and the interior face of the wall.

The detail used in #1 seems the most logical to me, but couldn't the 
premould material be problematic? Both seem to be more in line as 
expansion joints and not construction joints.

Your thoughts?

Thanks! 

Jeremy

On 8/2/05, Chance, Acie <AChance(--nospam--at)lacsd.org> wrote:
> Jeremy
> 
>     I know of two different approaches to joints in sedimentation and aeration tanks.  The first is to use "construction joints" not "expansion joints" at 30 feet +/- on center.  These joints use waterstops and the horiz. steel is continuous.  The second is to use no joints and epoxy any cracks which leak.  The first method is usually used by consultants as it shows you are doing something.  With both methods you stand a good chance of injecting when you are done.
> 
> 
> Acie Chance
> 
> -----Original Message-----
> From: Jeremy South [mailto:jslist(--nospam--at)apt38.com]
> Sent: Tuesday, August 02, 2005 1:52 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Joints and Spacing in Concrete Tank?
> 
> 
> I'm designing my first rectangular concrete tank (aeration basin) for
> a wastewater treatment facility. The tank is approximately 100' feet
> long with circular ends. There is a free-standing wall on the inside
> of the tank that separates the tank into 2 - 12' wide ditches. The
> tank will be an above ground tank approximately 12' deep.
> 
> I'm familar with the PCA guide for the Design of Rectangular Concrete
> Tanks (5th Ed.)
> 
> I have designed the side walls as cantilevers using the appropriate
> factors discussed in the ACI codes. The walls are 12" thick with 2
> layers of steel. I feel very comfortable with the design.
> 
> However, I am still confused regarding the joint layout and spacing.
> The design guides I've used so far don't provide much information
> regarding joint spacing for the main walls.
> 
> The PCA information I've found generally recommend limiting the joint
> spacing in the walls to about 20'-0 OC max. I have seen other similar
> tank wall designs where they push the joint spacing up to 50 or
> 60'-0...this seems excessive to me.
> 
> Given the design aids in the PCA publication, I'm looking at joints at
> about 35' OC for the T&S reinforcement I'm using. However, I'm still
> confused about whether to use expansion joints, construction joints
> only, or a combination of the two.
> 
> Generally, what is the recommended spacing or "rule of thumb" for
> spacing of joints both in the vertical side walls and slab?
> 
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