2, 12ft gates 260 lbs Proper depth help.


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Old 04-26-18, 07:31 PM
J
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2, 12ft gates 260 lbs Proper depth help.

Hey all first time here,

Been working away making my own driveway gate last few months finally got them done. 12 ft long and almost 4 foot high K brace style gates. 2 of them and each weighs about 250 to 280 soaking wet from the lumber from store. With that in mind i have been sold on the idea of using instead of wooden beams as posts to anchor the gates to i found these slightly used 6 x 6 inch Steel I Beams 12 ft long. No rust too! Now i am going to assume that the beam is going to support the weight of 1 leaf like a champ. So what i had planned on doing was to bury the I beams in cement as my anchor point. Couple things i am still milling around in my head i cant seem to find many answers to are ...
1.. Rust proofing the I beam in the cement. Do i go with a Zinc Primer and couple coats of acrylic paint? or would Taring the living snot out of it work too? Tar would be cheaper i think they do not give that zinc primer away.
2.. The beams are 12 ft long. I plan on burring them 5 feet deep. (Wisconsin winters frost line is about 4 ft to be safe) Now I plan on pouring a small 3ft x 3ft pad 4 inches deep to set the beam on. Then i had planned on making a 3 ft x 3ft x 5ft high form brace it and have the cement truck come and fill the 2 beam areas. about 3 yards of concrete i figure with rebar scrap fence wire the works. After it cures remove the forms and back fill the pillars packing the dirt. I guess my question is, is 5 feet deep overkill in a big way? is the concrete pillar 3x3 ft enough? too much?
The hinges are going to be about 6 inches off the ground and about 3ft 6 inches off the ground on the beam. Heavy duty gate hangers 3/4 pins etc. So there will be a bit of beam going above the gate and most of the weight will be centered near the ground. For extra good measure i am using 2 H braces on each side of the driveway One for when the gate is open and one for when its shut. (Fenced in my 5 acres last year all the way around got good practice at it lol) So should be supported from just above the top hinge to the H brace post behind it.

So will this play? Does anyone have any ideas on the post placement that i might be missing? Thanks again!!
 
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Old 04-26-18, 07:38 PM
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A concrete pier is only going to be as strong as the backfill around it. If your hole is made with an auger that does not disturb the soil around the concrete... and you use the ground as your form... yes, that should work. But your gate posts will likely still need a guy wire to keep them from leaning inward over time. The ground will move and the concrete pier will tip otherwise.

If you backfill soil around the piers, that's just a disaster, imo. Backfilling with a good backfill... a crushed limestone mix, for instance... that would probably be okay.

Zinc primer is nice. Aluminum paint might be another idea.

A wood gate that's 4x12? That's bound to sag unless you have cables and turnbuckles to square it. Are they similar to this?
 
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Old 04-27-18, 01:22 AM
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Thanks for the quick reply X.

Good call on the back fill. To get the depth i needed i could not use my 3 point auger so i just used the bucket to dig down about 6 feet about 4 foot wide plan on making the pier inside that in forms then removing the forms and refilling with the fill we have here. It is a shale/limestone mixture good stuff.. might even rent a compacter for it.

Yes xsleeper that is a very similar design. I beefed up some of the wood and used 3/8 bolts and glue at every junction where wood meets wood. They are over in the shop right now but there is 4 12ft sections going horizontal. and 5 vertical supports. All the corners are notched out and recessed fitted, glued and bolted. Then of course there is the full length angle board. and smaller angle board underneath all notched glued bolted as well. I will try to get over there and get a picture tomorrow. The I beam will be 7 ft out of the ground so i figured that might be a good spot to put a cable/turnbuckle in the future if needed. Even has holes already in the top for an eye bolt.
 
 

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