Duct Bank Concrete Reinforcing

[JasonWrenn]

We are starting a new major 3 year project, apparently the EPC convinced my engineering team to allow the elimination of rebar reinforcing in the concrete for electrical duct banks to save money. We will have dozens of major duct banks. The EPC sold the idea that Fiber would work just as well. Please give thoughts or referencing on why this is a bad idea or should not be allowed. Located in Kentucky where freeze and thaw (frostline) is an issue, also will have potential truck loading over the duct banks. I am not finding much online. Thanks

 

[roger]

I did many duct banks in NC where the ground freezes and thaws and never had any problems with fiber reinforced concrete, in fact some with no reinforcement at all

 

[PaulMmn]

They use fiber reinforced for driveways. Not sure if they could use it for industrial driveways or not.
How deep will the duct banks be? Below the frost line??
How deep is required before truck loading isn't an issue?

 

[PD1972]

This is more of a civil/structural design question than an electrical question. Civil/structural engineers would have more insight on when reinforcement in a concrete duct bank is actually required.

Many times "standards" or "standard details" require things that serve no purpose, but are carried through because "this is how we have always done it" or "this bad thing happened once at this very specific location because of this very specific condition". I have seen concrete encased duct banks in the northeast (freeze/thaw, aircraft loading) without reinforcement, and to my knowledge those duct banks have not failed.

 

[ron]

We don't use reinforcement generally unless the ductbank is in expansive soils (Texas) or above the frost line.