Maximum Reinforcement Ratio for Micro-pile Design?

[Stillerfan]

I was wondering if anyone knew of a code specifying the maximum reinforcement ratio for a Micro-pile socketed into bedrock? I did not find anything in FHWA-SA-97-070 or ACI 318. Currently I have one (1) #18 Grade 75 full length in a 6-inch rock socket (7-inch cased section).

 

[PEinc]

But, micropiles are not the same as reinforced concrete columns.

 

[kslee1000]

ACI provisions mentioned above (maximum reinf) are applicable to all kind of concrete "Compression Members". The limitations are considered good practices to avoid congestion and brittle failure mode.

However, I won't and didn't mention code required minimum, for which may not feasible, or is un-necessary for small diameter micro piles encased in steel casing - a composite member.