Spiral Reinforcing in Seismic Pile
Spiral Reinforcing in Seismic Pile
(OP)
I have a fixed pier in a high seismic zone, for which the geotech has specified 16" square prestressed piles. For the spiral reinforcing, I need 2" cover (marine environment) so I am left with a core diameter (Dc) of 12". Works fine with equation 21-2 (ps=0.12f'c/fyt), which calculates to #3 spiral at 3" pitch. But then ACI states "shall not be less than req'd by eq. 10-5"...and that equation seems to give huge unrealistic values for the spiral reinforcing - #5 spiral at 1.81" pitch! Seems like this is the case due to the ratio of Ag to Ach being much larger than it would be with square ties in a square column, but 16" square piles with spiral cage are very common, no? Am I missing something, or does anyone know how this is commonly handled? Much thanks...





RE: Spiral Reinforcing in Seismic Pile
RE: Spiral Reinforcing in Seismic Pile
RE: Spiral Reinforcing in Seismic Pile
RE: Spiral Reinforcing in Seismic Pile
RE: Spiral Reinforcing in Seismic Pile
Using 4000 psi for concrete and 60 ksi for spiral ties gives 0.0233 for ratio of spiral steel volume to total volume of the core, (12" x 12"x 12" length). Thus 40.3 cubic inches of spiral steel. 201.6 inches of #4 spiral length in 12" of column length at pitch of 2.93 in.