Is additional Tie Reinforcement required in concrete pedestal cross section?

[oengineer]

I have a question regarding a missing reinforcing tie in a concrete pedestal. The concrete pedestal has an opening in it that's 1'-0" diameter. Please see the image below.

Is it necessary to include the tie shown in RED in the cross section as well? Currently this tie shown in RED is not apart of the pedestal reinforcing.

From the elevation view it shows ties confining the vertical center rebars, but the ties stop as the pedestal begins to have the 3 layers of vertical reinforcing.

Initially I was thinking that the ties shown in RED are not required, but I am starting to reconsider.

Comments/suggestion are appreciated.

 

[phamENG]

I don't consider myself a concrete expert, but if those bars are considered in any calculation of the compressive strength of the section then yes the ties should be there. Otherwise those vertical bars are unbraced and ineffective if the concrete cracks. I welcome anyone who can correct me, of course.

 

[JoelTXCive]

I'm interested in the responses that OE will get.

Conceptually, I've always thought that if you have substantial section depth around a piece of rebar, then that serves as confinement. I've not seen an equation or methodology to account for this type of confinement though.

I bet that Koot, DIK, or SlideRule will know.

 

[HTURKAK]

Dear oengineer (Structural),

The excerpt implies that the bottom section of the pedestal has circular cross section while above the slab has square perimeter.

The bottom section has interior and exterior circular ties while the above suare section only has exterior square links.

IMO, the reinf. is for confinement and constructive rather than structural requirements.

I will suggest to extent the interior circular ties to upper portion.

 

[Lomarandil]

My vote is no, assuming that the bars don't carry any substantial compressive load.

The contractor is likely to include them anyway for constructibility and to avoid the appearance of error.

----
just call me Lo.

 

[JLNJ]

This looks like a flagpole footing or something of the sort. Surely the ties are not needed to develop the full compression capacity of the vertical bars. I suppose the whole thing would work unreinforced, but I imagine shear is the primary concern as the footing contains the "kick" force at the base of the sleeve.

I think I would arrange the inside bars in a square and then provide rectangular ties to make it all work together.

 

[bones206]

As HTURKAK pointed out, you have two different cross sections here. Could you show us each cross section separately?

 

[GC_Hopi]

IMHO, it appears like two separate section with the circular below the square section and the square is extending above grade. In that case you are trying to develop the vertical bars from one section to the other. You should provide circular ties at half spacing near the transition then provide a circular tie at normal spacing above the transition. Then circular ties at a nominal spacing above that to ensure the verts dont move during concrete placement.

 

[jgailla]

How are the rodbusters going to place the vertical rebar without the tie?

 

[oengineer]

As HTURKAK pointed out, you have two different cross sections here. Could you show us each cross section separately?

the 1st view is the plan view and the 2nd view is the elevation view. The more narrower portion in the elevation view is circular (which I have not included).

@Everyone

Based on the comments, the additional tie has been added. Thank you all.

 

[bones206]

I don't think you need to continue the red ties, but I agree with HTURKAK that the smaller diameter inner ties should continue full height.

 

[oengineer]

I don't think you need to continue the red ties, but I agree with HTURKAK that the smaller diameter inner ties should continue full height.

The smaller inner ties extend all the way up to the top of the pedestal. It is not clearly shown in the elevation view, but the rebar ties do continue.