Plain Concrete Pole Foundation Question
Plain Concrete Pole Foundation Question
(OP)
Hey all, new to the boards, and looking for some guidance here.
We've been asked to design some pole foundations for a sign company, and the client has requested that plain, un-reinforced concrete be used to save on costs. He provided us with old drawings that another firm has provided him for pole foundations in the past, and there is a note that reads:
"No steel reinforcement is required in cube or auger style footings where the support column is embedded directly into the bottom of the footing." Whoever designed the foundation has the sign pole embedded into the concrete foundation with zero reinforcement.
Is this acceptable? Backed by code? I have looked through IBC and ACI trying to find a justification for this, but no luck. Any help is much appreciated! Thanks!
J
We've been asked to design some pole foundations for a sign company, and the client has requested that plain, un-reinforced concrete be used to save on costs. He provided us with old drawings that another firm has provided him for pole foundations in the past, and there is a note that reads:
"No steel reinforcement is required in cube or auger style footings where the support column is embedded directly into the bottom of the footing." Whoever designed the foundation has the sign pole embedded into the concrete foundation with zero reinforcement.
Is this acceptable? Backed by code? I have looked through IBC and ACI trying to find a justification for this, but no luck. Any help is much appreciated! Thanks!
J






RE: Plain Concrete Pole Foundation Question
In summary, I am not a fan and wouldn't want to use it. The crazy thing is how much does ten #3 hoops @ 1.5' diameter really cost?
RE: Plain Concrete Pole Foundation Question
I RECOMMEND THAT FOR WHATEVER FOOTING CONFIGURATION YOU ARE LOOKING AT, MAKE SURE YOU JUSTIFY IT BY CALCULATION (INCLUDING CONFINEMENT.
RE: Plain Concrete Pole Foundation Question
I don't necessarily like it however, if you embed the post down to the bottom of the hole I would consider the concrete the as a sleeve that just widens the effective area pushing on the soil. I wouldn't account for the concrete in a strength aspect but when I was checking the required post depth I would use the radius of the concrete when doing the calculations. ASAE 486 I think.
If that makes any sense,
RE: Plain Concrete Pole Foundation Question
RE: Plain Concrete Pole Foundation Question
RE: Plain Concrete Pole Foundation Question
Now I'm not one to side with the contractors typically but I once had a reasonable guy that said to me "Sure what's the cost of that little extra rebar on this one job, I do 1000 of these little jobs in a year, it adds up to me, even if it doesn't add up for one project"
Sure it's maybe $100 in rebar, but if the sign company is busy and profitable that's $1000 every 10 sign posts. If they try to factor that into their pricing they lose the bid.
Depending on the size of the sign I would be willing to consider it at the very minimum.
RE: Plain Concrete Pole Foundation Question
Here's a really good article on plain concrete for walls and footings for buildings that summarizes how confused this issue can get:
http://www.buildersengineer.com/assets/images/blog...
http://www.buildersengineer.com/assets/images/blog...
As for a sign pedestal in the ground it appears that ACI 318 shrugs that off with 22.2.2 unless it's precast. I didn't look through the IBC but it sounds like you couldn't find anything there either.
As Eric said; does this really save much money?
Maine EIT, Civil/Structural.
RE: Plain Concrete Pole Foundation Question
I have to say, valid point jayrod12 on the adding up over multiple jobs; however this can be said for many things we specify and require as engineers.
RE: Plain Concrete Pole Foundation Question
Would I prefer to have rebar in the concrete? Of course.
If the sign is small enough will I at least take a look at the possibility of plain concrete? Sure, if the numbers don't work then so be it. But if you can rationalize it then make a contractors day.
Off topic but if you want a tough one to justify, re-analyze an existing pole barn and get the numbers to calc out. They do not, I repeat do not, work on paper in any way shape or form without voodoo. But yet they stand the test of time.
RE: Plain Concrete Pole Foundation Question
I've seen people worry less when the void around the pole is to be filled with tamped crushed stone instead of concrete.
Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin
RE: Plain Concrete Pole Foundation Question
RE: Plain Concrete Pole Foundation Question
Maine EIT, Civil/Structural.
RE: Plain Concrete Pole Foundation Question
RE: Plain Concrete Pole Foundation Question
Maine EIT, Civil/Structural.
RE: Plain Concrete Pole Foundation Question
RE: Plain Concrete Pole Foundation Question
They are also simple to design for moment of the pole to concrete and the concrete to soil. You just have to use enough concrete to make the numbers work. I have seen where engineers have welded (in shop) rebar to the poles to get the design to work easier.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.