Drilled Pier/Caisson Reinforcement

[dmitriy555]

I am analyzing a guyed tower that rest on a 6' diameter by 50' deep drilled caisson. The major forces applied to the foundation is the down force and some minor shear force. The pier has only (18) #6 bars, which is not even close to 0.5% required by ACI, but since there is virtually no moment in the caisson but just a compressive load, do I still need to provide a minimum of 0.5% of steel reinforcement?
Thanks.

 

[FixedEarth]

You are more than adequate. Last week I had similar pier geometry (6 ft DIA., 45 ft embedment with 14 #7 bars). The PhiMn value was 3,600 k-ft and PhiPn value was 1,600 kips. The vertical capacity was 500 kips & uplift was approx. 220 kips.

 

[JAE]

ACI 318 doesn't apply to drilled piers.

I don't recall if ACI 336.1 (drilled piers) requires the 0.5% but I don't believe it does.

 

[dmitriy555]

Is there a minimum reinforcement requirement for drilled piers or as along as PhiMn value is greater than PhiPn value than I should be o.k.?