Can minimum reinforcement in short concrete column go below 1%?? 2

[PostFrameSE]

As I read ACI 318, I don't see any provision for allowing less than 1% steel/concrete ratio. I understand the reasoning for that, however......if for reasons other than the structural load-carrying capacity of the column I want to make a larger column..........do I HAVE to reinforce it more heavily?

For example, I designed a 16" circular pier, with (6) #6 bars to carry my loads. Now the concrete guy wants to use a 24" x 24" pier. My loads haven't changed. Must my rebar?

Thanks.

 

[dik]

You used to be able to, and I'm not familiar with ACI. At one time you could effectively use a fraction of the physical column area to determine the area on which the percentage of steel was based.

Dik

 

[delagina]

i'm sure you can use 0.5% just dont have time to look at aci. look it up.

 

[delagina]

aci 10.8.4

 

[dik]

Thanks, there's still provision...

Dik

 

[DST148]

ACI 318 - 05, section 10.8.4 permits to base the minimum reinforcement and strength of a compression member on a reduced effective area Ag not less than one-half the total area. This provision does not apply in regions of high seismic risk.

To extend PostFrameSE's post further-----

How do we distinguish between a flexural & a compression member?
Typically we treat vertical elements as compression members. Should a vertical element with minimal axial load be treated as a compression member or a flexural member for determining minimum reinforcement?

Chapter 21 - special provisions for seismic designs, distinguishes a flexural member from a beam-column if factored axial compressive force on the member does not exceed
Ag.f'c / 10.
Any thoughts?

 

[PostFrameSE]

Thank you all for your posts!!! I glossed right over that section.