stone sign base

[AlpineEngineer]

I have a stone sign (5'wide x 4' tall above grade, 4" thick sandstone) that is being set for a subdivision entrance sign. The City has asked for a stamped and signed foundation for this thing. Bearing capacity and frost depth are easy to acheive. What concerns me is our wind loads (138mph) and how to make sure this thing is connected properly to the fndn so it doesn't blow over. I was thinking they could set the sign, form the foundation, and pour the concrete so its integral with the sign base. They had planned on having it protrude 16" deep into the foundation.

I had mentioned the thought of drilling holes near the bottom of the sign (in the fndn) every 16" and running a #5 bar through horizontally in order to help with the lateral loading, of course the contractor doesn't like that idea.

It would seem having 16" of the sign base embedded in concrete would be suffecient. I assumed I would calc wind load from ASCE 7-05 and make sure there is enough mass in the fndn to resist this overturning moment. I guess the failure would probably occur at the sign base by snapping the stone; this sandstone isn't the toughest stuff, but 4" thick is pretty tough.

Is there a better way to approach this? Any ideas? Am I making a mountain out of a molehill?

Thanks guys...

 

[msquared48]

Will they allow you to attach a couple of steel section vertical strongbacks to the backside of the sign that are embedded in the concrete foundation, then thru-bolt the sign to the strongbacks?

Mike McCann
McCann Engineering

 

[hokie66]

Embedding the sandstone into the footing should work fine, and 16" is probably overkill. The typical way I have seen it done is to cast the footing, leaving a slot for the panel, then set the panel and grout between the panel and concrete. But if they can hold the panel in place, casting it in is good.

 

[MarcbSE]

I would lean towards hokie66's solution with the block out slot in the footing. It would be much easier to cast the footing first without having to hold the sign in place while the concrete sets.

 

[AlpineEngineer]

Thanks Guys,
I can't put the strong backs in due to asthetics, both sides of the sign are etched. The contractor says he wants to wet set it, so I think that will work great and be stronger. I looked at wind loads and the OTM and the footer mass will resist the OTM and I think 16" embedded is plenty. I feel pretty good about it..
Thanks,

 

[csd72]

What stops the sign sinking further than 16".

I would call up a support pad/block under each end of the sign to hold it at the required height. Then you can run reo underneath betwwen the blocks and you know it is going to stay put.

csd