Full Length Reinforcing in Large Diameter Pier?

[mrengineer]

For a 5' diameter straight shaft drilled pier, combination friction and end bearing, lengths 70-90', would you consider dropping off the vertical reinforcing at some point? Surrounding soils are capable of providing lateral support for the entire length of the pier.

 

[ChipB]

I always look at the bending moment from the lateral load analysis and take it past the curve. If there is uplift, you'll need to install a dywidag bar almost full length.

 

[jike]

We will generally will extend reinforcement 10 to 12 feet or until any bending moment might die out.

 

[Qshake]

For additional drilled shaft information check out the FHWA's publication on deisgn and construction of drilled shafts.

http://www.fhwa.dot.gov/engineering/geotech/library_arc.cfm?pub_number=1

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[JedClampett]

I once tried to optimize the reinforcing by stopping it part ways down the shaft. The Geotechnical Engineer caught it and notified me that he was counting on a fully reinforced shaft for uplift. It was right there in the Geotechnical Report if I would of been awake enough to notice it.
Anyways, another reason to be careful before you stop the reinforcing.