#4 Tie
#4 Tie
(OP)
I have a 24" diameter drilled pier. It is 6" to 1' above grade and 3' below grade. I'm using #6 verticals and #4 circular ties to confine it.
Question:
Do the #4 ties require the same lap calculation as a straight bar? Is it considered confined because it is circular? Or is it unconfined because it *IS* the confining element? OR???
What is the lap requirement for it?
Question:
Do the #4 ties require the same lap calculation as a straight bar? Is it considered confined because it is circular? Or is it unconfined because it *IS* the confining element? OR???
What is the lap requirement for it?






RE: #4 Tie
RE: #4 Tie
RE: #4 Tie
http://www.dfi.org/qaforum.asp?class=ACIP&sid=...
RE: #4 Tie
RE: #4 Tie
7.10.5.4 — Where longitudinal bars are located
around the perimeter of a circle, a complete circular tie
shall be permitted. The ends of the circular tie shall
overlap by not less than 6 in. and terminate with
standard hooks that engage a longitudinal column bar.
Overlaps at ends of adjacent circular ties shall be
staggered around the perimeter enclosing the longitudinal
bars.
In other words the simple lap splice is no longer allowed. (Kudos to Hokie). I read an article earlier that it was only for seismic areas. But this ACI excerpt indicates no such exception. The reasoning was that too many circular piles and piers were spalling on the outer layer. This reduced the required cover to the point where the laps no longer provided any tension capacity.
So, hooks it is.
@Slick,
This may be the reason why your contractor thought 6".
RE: #4 Tie
I have never used spiral ties. How are we supposed to terminate the end of a spiral tie? With a hook?
RE: #4 Tie
RE: #4 Tie
"I have a 24" diameter drilled pier. It is 6" to 1' above grade and 3' below grade. I'm using #6 verticals and #4 circular ties to confine it."
This seems like a very shallow foundation, unless it is into rock. Also, the longitudinal bars will not really develop along the length of the pier. Will the bars extend into an element at the top of the pier?
RE: #4 Tie
RE: #4 Tie
It is a shallow foundation. It doesn't need to be any deeper. Very little load. It would be shallower if the soil allowed it.
#6 has a development length of 29". We're at least that height.
There is no true column or beam action. To me it is a reinforced pedestal. But we have a standard detail that needs to cover instances where the T.O.C. will be a foot or two above grade.