Drilled peir shear check and ties requirements

[BAGW]

Hi,

1) Have a drilled pier subjected to shear, should the minimum shear reinforcement be provided per ACI chapter when Vu > 0.5 phi Vc? Or should this be just treated like a foundation and just make sure that Vc > Vu and move on without checking the minimum shear reinforcement requirement. I could not find any document for the drilled pier design which mentions shear check.

2) If shear reinforcement is provided with circular ties, can one tie contribute to two legs of reinforcement like shown below?

 

[cec17]

I recently received a plan review comment that required us to design the ties in a drilled pier as transverse reinforcement in a special moment frame per ACI 318-19 Table 18.7.5.4.

It actually says in IBC 1810.2.4.1 that "deep foundation elements" are required to be detailed per ACI 18.7.5.2-4 in SDC D-F (this project was SDC D). It's a volumetric calculation (considering the area of your tie in plan) to find the spacing. It comes out a LOT closer than 12".

 

[EZBuilding]

Note - if you have net tension on your pile, the shear reinforcement must be sized to resist all of the shear demand.

 

[slickdeals]

You would consider it as a column and design as such.
Yes, one tie contributes to two legs. Similar to a circular column. You would use effective depth as 0.8 times diameter.

You can review ACI 336.3R or ACI 543R-12.