Post Installed Anchors Due to Anchor Misplacement

[HDStructural]

Hello all,

I am working on a small project where we are replacing a few anchors due to anchor misplacement. We will be using an adhesive anchor system. The problem that I am having is that the anchors are only off by 3/4" or so, and are in the way of where the new anchors would be.

Is it possible to do a large core drill of the concrete area (maybe 2" or 3" diameter) that would contain the existing anchor rod. Then epoxy in a new anchor? The issue I see is that the whole would be way too large.

Could I have them roughen the surface around the hole then fill it with concrete/grout and just place the anchor bolt in? Due to the left/right eccentricity of the anchors, we cannot just slot the base plate holes.

What have been your best solutions for these situations?

 

[Greenalleycat]

Definitely not equivalent to cast in - there's a potential critical interface that wouldn't exist with a cast-in solution
This is outside the realm of engineering calculations - it relies on the manufacturers having products that they recommend for certain applications
If engineering surety is required then proof testing is your only option IMO

Your engineering pathway is "identified suitable product that is rated to develop interface bond -> tested a representative sample and all samples met design criteria therefore confidence is ok"

 

[dik]

My experience was with Hilti re 500 v3 epoxy

I think you are limited to 1/8" thickness.

 

[Tomfh]

How do we know that the anchor isn't going to pull out as a plug of epoxy mortar 3" diameter?

Check the shear interface.

Note that sika 212 isn’t epoxy mortar. It’s cement grout. Personally I prefer epoxy mortars for this, as they stick much better.

 

[Just Some Nerd]

How do we know that the anchor isn't going to pull out as a plug of epoxy mortar 3" diameter?

Need something with a good capacity for bond stress, and I'd shoot for less than half of what they rate....can't trust the actual install to be as per their testing

 

[dvd]

For the record, modifying the baseplate does seem like the simplest solution.

The following is moot regarding grouted anchors since the baseplate is being modified, but it seems like this addresses driftLimiter's question (although not citing any ACI scriptures, this is from the Chockfast literature)