Light Pole Calculations

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eager2learn

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Mennifee,Ca
I have a project that I am doing for an HOA in California that involves exterior street pole light fixtures. The Poles were originally a gas lamp that were retrofitted some time in the 70's to electric. The manufacturer name was Welsbach. Anyways, the association wants to keep the existing poles and fixtures and have them powder coated. They also want to demo the existing base foundation for the poles because many of them are sinking and things of that nature. The existing pole is about 10.5' high with a base plate and bolt circle of 11.5" and a bolt square of 8.25" with a 5/8" hole. I'm having a hard time with the information that I have regarding the length of the anchor bolts. Any help would be greatly appreciated. I'm assuming that I will have to pour a concrete base at 24" round by 36" deep, what size anchor bolts do I need? Like I mentioned above the existing base plate has 5/8" holes
 
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eager2learn said:
... what size anchor bolts do I need? Like I mentioned above the existing base plate has 5/8" holes
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Hmmm....


...perhaps 5/8" :p


Kidding aside, the length would be dependent on the method of concrete reinforcement used and whether the anchor bolts utilize that reinforcement to aid in their integrity. As a WAG, I probably wouldn't use less than 10 inch L-bolt anchors
 
Smart $ said:
Hmmm....


...perhaps 5/8" :p


Kidding aside, the length would be dependent on the method of concrete reinforcement used and whether the anchor bolts utilize that reinforcement to aid in their integrity. As a WAG, I probably wouldn't use less than 10 inch L-bolt anchors
Click to expand...

If the OP's area of installation is in a siesmic rated zone there may be local, county or state requirements that govern the specs on pole foundations.
 
Is there an easy formula used to determine the size of the anchor bolt in relation to the height of the fixture, or perhaps, just a rule of thumb.
 
Calculate the moment and anchor holding force will be relative to anchor distance from the center of the pole.

10.5' high.
How much does the luminaire weigh?
How high is the luminaire?
How far from the center of the pole is the center of mass of the luminaire?
What codes do you have? Wind? Seismic? Snow? Anything I'm missing?
And you're putting in new foundations also, right? Who sized them? If you're going with what worked before, that didn't work before; that's why you're redoing it now. Suggest a bit wider then former foundations.
 
You should call your favorite structural engineer and get him to submit a proposal to the HOA. He will probably have some questions about the soil conditions. It might take him an hour or two. You might even be able to absorb it in your fee. If you are in a seismic zone, this is not a DIY proposition.
 
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