## Design of stirrups for column

## Design of stirrups for column

(OP)

hello pals,

im designing a column which confused me very much, some of my collegue says that desingning stirrups for column does not have great importance as long as you will provide.

i dont a agree, though im trying hear to find some answer.

from the books i have read that if the actual shear Vc, is greater than 0.85Vc/2, the procedure of designing the beam stirrups may be used.. the problem is how can we find the actual Vc where Vs is unknown?

thanks for reply in advance, God Bless...

fratrowie

im designing a column which confused me very much, some of my collegue says that desingning stirrups for column does not have great importance as long as you will provide.

i dont a agree, though im trying hear to find some answer.

from the books i have read that if the actual shear Vc, is greater than 0.85Vc/2, the procedure of designing the beam stirrups may be used.. the problem is how can we find the actual Vc where Vs is unknown?

thanks for reply in advance, God Bless...

fratrowie

## RE: Design of stirrups for column

If 0.75Vc/2 < Vu then you have to design the stirrups for strength just like you would a beam (as you mention above).

I don't understand your final question of how do you find the actual Vc if Vs is unknown. Please elaborate.

Are you in a seismic area?

In any event, designing stirrups IS IMPORTANT!!

## RE: Design of stirrups for column

## RE: Design of stirrups for column

## RE: Design of stirrups for column

MYerges because from the book i read it says that the actual shear is Vn = Vc + Vs, i completely confused which is which the actual shear and the ultimate shear, if its so that the actual shear is Vn then the Vs should be known to find the Vn... im in a siesmic zone, the structures is symmetrical.

thanks for enlighten me with this, and to you metchilon and henry2..

and oppss... ultimate shear is the shear due to lateral force times half of the column height in a particular level?

fratrowie

## RE: Design of stirrups for column

## RE: Design of stirrups for column

## RE: Design of stirrups for column

## RE: Design of stirrups for column

## RE: Design of stirrups for column

Hmm...well, please read 9.3.2.2 where using spiral reinforcing instead of standard ties lowers the Φ factor and thus increases the column capacity. Also, ACI doesn't use "allowable" stresses except in the appendix.

I agree with you that shear isn't usually a big issue in most columns.

## RE: Design of stirrups for column

## RE: Design of stirrups for column

The ACI commentary in chapter 7 has this statement:

"Limited tests on full-size, axially-loaded, tied columns containing full-length bars (without splices) showed no appreciable difference between ultimate strengths of columns with full tie requirements and no ties at all."

The reference is to this article:

Pfister, J. F., "Influence of Ties on the Behavior of Reinforced Concrete Columns.", ACI Journal Proceedings, V. 61, No. 5, May 1964, pp. 521-537.

## RE: Design of stirrups for column