Help with a Pad for Bronze Statue

What is the depth of the frost line at your location? You have to account for heave.

If you have no frost line considerations, how are you going to keep the statue from toppling over when the wind really blows? I do not a believe a flat slab by itself will do.

I had planned to set two piles in the underside of the pads, with all the rebar tied in to the grid in the slab. frostline is four foot of depth here the pile will be deeper for stability.

We attach our statues to a steel plate and the plate to the pad.

I would just place the rebar at 12"....You might go to 5" to be safe....imo

If you need a building permit for the work, the Director of Code Enforcement may dictate the design depending on how his prejudices are aligned.

Personally I'd be wanting to avoid piling. I've never had to deal with frozen soils so my opinion may be ambitious.

If you do go for a thicker slab it would only be for stability rather than strength.

Try to convince your higher ups that the cost of engineering design might easily be offset with a more economical build. that's the trouble with empirical designs, you end up putting in redundant safety margins.

The mass (thickness) and kerf (overhang) of the slab needs to resist toppling moments (wind loading), if it isn't pinned to the ground, and the dead weight of the statue with consideration for the soil's load bearing capacity.

I erect telecom towers for a living but frozen ground is outside of my experience.

I believe that the windloading will be the dominant design consideration here.

How do freezing soils impact designs (too lazy to google this myself) I wonder? What is this "heave" I've heard mentioned?

Who are these "higher ups"? Noah managed (or so the story goes) to build a container ship off the cuff but I figure his "higher up" was a bit different.

Heave is a very big problem here in Michigan. As the ground freezes, it expands. I have seen poured slabs raise as much as 6" due to this. With our frost / freeze cycles in the spring, concrete gets destroyed. (This is why Michigan's state animal is the orange barrel )

I used to run a foundation crew for a large concrete company and if I was going to build this pad, I would use a 4" trencher and trench 42" deep around the entire slab, tie it all in with re bar and pour it monolithically with the slab being 6" thick. Even when digging post holes for a deck, our concrete is required to be 42" deep by code here.

Check local codes, but as heavy as the thing is, I think it should be on a foundation.

First things first, if your area experiences freezing weather during the Winter months (assuming you're in the Northern Hemisphere), then you would need to have a foundation down deep enough to resist Frost heave.

Also, the foundation depth will aid in resisting overturning of the statue due to wind or earthquake (if your area is prone to earthquakes).

At a minimum, I recommend a 6-inch thick slab and a full perimeter haunch to a depth greater than the frost penetration depth. Reinforcement requirements will be dictated per structural design & analysis. Rebar placement and size requirements may be much higher, depending on the design forces...

Please keep in mind that most state building codes include the safe design & erection of statues...therefore you will most likely be required to obtain a building permit from the municipality having jurisdiction.

In this case I would strongly recommend hiring a Professional Engineer to design a proper foundation and anchorage for such a massive statue. Last thing you would want to happen is that the statue gets blown over and crushes/flattens a small child and his mommy. Think of the liability issues, and it will scare you into the proper action, and that includes the powers that be ("highers up"). Two sides for every coin: Initial costs spent on proper structural design vs. future liability (incl. future maintenance headaches).

===signed,

CaptMoosie, Ph.D, P.E.

Civil, Structural, environmental & Forensic Engineer

IMHO with something this size & weight it would be advisable to get an engineer to design the footing to guarantee it is secure, especially if the public is able to be any where near it. I know it's not made to climb on but you have to allow for the idiots that will try to

You say "I know I should call in an engineer, but I'm getting major resistance from the higher-ups"

My argument to the higher-ups would be, what will be more expensive, paying an engineer to design the footings or the legal expenses & personal injury compensation pay out they will face if it falls over & some 1 is injured. If they have not made it to meet or exceed relevant safety standards & local regulations they will be liable but if an engineer puts his signature onto it then he's liable it's sort of like an insurance policy lol

You could build it up by including a step like we did here. This base is 12 inches thick.

Morning everyone,

Thanks for all the input, suggestions, and reminders on frost heave, and stability.

I have contacted a Civil Engineering Tech, and will be taking an overbuild approach in the Slab.

My 'Higher ups' are the administrators of a non-profit society, and as such are very tight with the purse strings. Weighing liability vs. cost makes a pursuasive argument.

I'll post pictures to the forum after the slab has cured, and the Bear is in place.

I really appreciate the help on this one.

consult an engineer! there are too many variables. it's money well spent considering your losses if there's future problems.