Ast in Short Column?

[TonyES]

I've been doing a lot of steel buildings lately where the prefab steel column sits on a pier (short column). ACI 10.9.1 says I need .01Ag of steel. Well my client is saying that his other engineer specifies half the reinforcement that I do. Is there some provision I'm not seeing or is the other engineer in the fault??

 

[frv]

See section 1.1.5.

A pier is more along the lines of a continuously supported column and does not behave as a column.

We use them all the time.

The 1/2% min reinforcement is a very common geotech recommendation (unless you need more for uplift)

 

[WillisV]

ACI 10.8.4 effectively allows 0.5% reinforcing in low seismic.

 

[TonyES]

WillisV; I read that part too, however I'm right on a fault line and definetely high siesmic.

frv; I agree, often times these piers are even connected to a foundation wall, however, are you familiar with any part in the code that allows this?

thanks for the quick responses.

 

[frv]

TonyES..

I don't think it's so much a matter of the code "allowing" this as it is a matter of the code (318 anyway) not dealing with it.

The commentary will point you toward publications that deal with piers and piles (to this day I don't know the difference).

I have no idea how this would be affected by being in a seismic zone, but I can tell you from experience the 1/2% is very common in non-seismic zones.