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Anchor hole for 1/2" rod

Anchor hole for 1/2" rod

Anchor hole for 1/2" rod

AISC specifies the hold diameters for anchors, but starts at 3/4" with no apparent pattern I can easily detect. Maybe just a low morning - trying to determine appropriate hole size for 1/2" anchors to allow for fit up.

Anyone ever come across this?

You might be thinking...why 1/2" ? We have spacing requirements for anchoring a logo into a concrete parapet. Before everyone get's into a tizzy about the parapet (haha), the building isn't built yet - we are in design working with the building structural to mount this thing.

Normally I'd say just go with oversize holes in lieu of guidance, and since shear is necessary, field weld some washer plates once we are fit up, but perhaps someone has a "legitimate" hold diameter out there...?

RE: Anchor hole for 1/2" rod

Try specifying 7/8" diameter holes for 1/2" anchor rods.


RE: Anchor hole for 1/2" rod

Well, you are going to insert a 1/2 diameter anchor rod into finished (hardened) concrete, but how are you holding the anchor rod into the hole?

If using a two-part epoxy (my recommendation), then epoxy tube will have specific drill diameters, drill depths, cleaning rules, and hold times before applying weight.
If using a expanding-type insert, then screwing into the threaded insert to expand it into the concrete, you need to know the maker and style to find the drill diameter.

Can't just insert the rod into a hole.

RE: Anchor hole for 1/2" rod

Thanks Dave for the input.

Racookpe - I don't know whether I should be insulted haha (I'm not) or what, but it's a cast-in-place anchor rod. I was talking about the holes in the base plate itself. For fit up, due to variances in the field or whatever you want to call it, AISC allows for larger than "normal" bolt holes for the anchor rods. My apologies if that wasn't clear.

RE: Anchor hole for 1/2" rod

Why can't you use table J3.3? 9/16" standard hole or 5/8" oversized hole for 1/2" bolt. If you can control it, you can force field verification of anchor locations and then use standard holes, or you can provide oversized holes and weld a washer with a standard holes as required for shear transfer.

RE: Anchor hole for 1/2" rod

Good insight, and I "can" do that, but I just want to know if anyone has a value for 1/2" anchors as if they appeared on the table. Thanks for the post.

RE: Anchor hole for 1/2" rod

From my drawing notes(may have to be formatted):


(IN) (IN) (IN) (IN)
1/2 1 1-3/4 3/16
5/8 1-1/8 1-3/4 1/4
3/4 1-5/16 2 1/4
7/8 1-9/16 2-1/2 5/16
1 1-13/16 3 3/8
1-1/4 2-1/16 3 1/2
1-1/2 2-5/16 3-1/2 1/2

The post has spaces between the numbers that don't show up.


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