round opening at slab-on-grade

[cmrdata]

What is the rule of thumb in determining the maximum size of round opening at slab-on-grade that does not need any additional reinforcing, other than typical scheduled slab reinforcing?

 

[Ron]

Slabs on grade generally do not need structural reinforcement. Any "hole" in the slab needs to have consideration given to its impact on cracking in the slab. I know of no size, spacing or frequency prohibition for slabs on grade other than functionality.

 

[cmrdata]

Thank you, Ron.