Sonotube Tie Reinforcement

[bigmig]

I have designed sonotube piers for many years for light use residential decks basically, where
the reaction is around 2500 lbs, the sono tube is 10 inch diameter and extends 3 to 4 foot into the ground
where it is supported by a pad footing. We never used ties. The guy who taught me never used ties.

ACI requires that concrete piers have minimum longitudinal and tie reinforcement (.0025 % for vertical steel)
I have seen requiremenst for 4 bars min, and ties at a spacing of 16 bar diameters.

I seldom see engineers or builders put ties in these type of concrete supports.

I know that code says do it.....is there somewhere in the code that gives an exception? I can't seem to find it.
It seems like overkill; I know I know....follow the code. I'm just trying to see if practicality has caught up to the code creators.

 

[XR250]

I never specify them.

 

[driftLimiter]

Whether anchored at the top, or embedded I always specify (2) ties in the top 5". ACI says this is for when Anchors occur at the top of a column, but the embeded condition seems worse to me so I use it for both.

Ref: ACI-318 14 10.7.6.1.6

 

[JAE]

Might these fall under the ACI Plain Concrete specifications perhaps?

 

[phamENG]

Might these fall under the ACI Plain Concrete specifications perhaps?

This. I design deck footings to plain concrete standards. No rebar needed.

Now, if there's any uplift or lateral load on those foundations I'd want some sort of rebar. 10" dia x 4'-0" tall is likely to crack, neutering any uplift or lateral resistance you may have wanted. But if it's all gravity and the length is only for frost depth, I wouldn't be too worried.

 

[jerseyshore]

This. I design deck footings to plain concrete standards. No rebar needed.

Now, if there's any uplift or lateral load on those foundations I'd want some sort of rebar. 10" dia x 4'-0" tall is likely to crack, neutering any uplift or lateral resistance you may have wanted. But if it's all gravity and the length is only for frost depth, I wouldn't be too worried.

Same. Some building inspectors will ask the contractor to put rebar in just because, but if it's a regular deck footing I design them as plain. If it's a pergola or something with uplift then adding some vertical bars is a good move.

 

[Enable]

Circular ties in residential where there is no other major reinforced concrete element warranting a proper rebar supplier / detailer? Best to leave them out if you want any prospect of repeat work. If you are doing a monster custom home with suspended concrete elements / shop drawings / the works? Add them if you need but otherwise plain concrete will work sans uplift / lateral as mentioned above.