Anchor Edge Distance New Concrete against Existing 1

[WiSEiwish]

Can new concrete be poured against existing concrete and bonded in such a way that post installed anchors into the existing concrete can consider the new concrete when determining required edge distances? I’m concerned that if it is not a homogeneous pour (new against existing) that I cannot consider the new concrete to add to the edge distance for the anchor.

 

[CANPRO]

regardless of the connection detail between the new and existing, I would still account for the edge reduction. If your post-installed anchors are close enough to the edge that you have to consider a reduction, can you just embed a plate/anchor in the new concrete?

 

[steellion]

I wouldn't count on the additional edge distance if it is just a cold joint between the new and existing concrete. I can't see the cone of failure crossing that joint. If the concrete was mechanically connected, such as with dowels, you may be able to make the argument for additional edge distance.

 

[WiSEiwish]

Thanks,

I was concerned that the cone would essentially stop at the joint between the new and the old. Are there ways to overcome this?

I'm looking at an existing pier for a column that was extended to allow for a new column to be attached. The extension just so happens to not be as big as I needed it to be due to the size and location of the new column. The column is offset a couple of inches and it gives me very little room to install fasteners. I was toying with the idea of demolishing half of the pier and installing a new one for the new column, or somehow building out the existing pier to be what I need it to be. I would prefer the latter as it seems like a better option to try to avoid demoing something that is still being used (half of it), but don't know how to overcome the new concrete joint.

 

[SLTA]

Call the folks over at Simpson Strong-Tie, and ask for the Engineering department. They have test results they won't tell the whole world, but you may be able to get closer to the edge using their anchors than the catalog says.

 

[Ron]

You can inject the cold joint with epoxy prior to installing anchors. Make sure the distance on either side of the anchor along the cold joint is larger than the anticipated failure cone. If you are using adhesive anchors, the failure is not typically conical, so as slta says, contact Simpson.

 

[hokie66]

Nothing much to add to the OP's question, but I am sometimes amazed at how much reliance you folks in the US place on some guy named Simpson.

 

[Ron]

hokie66...they are the only manufacturer we've seen that has valid, independent test data that they update reasonably often. Even Hilti doesn't seem to provide the test data Simpson is willing to provide.

 

[hokie66]

Ron,
I admit to ignorance of Simpson's products. They have only recently started marketing in Australia, probably because it is a relatively small market. I did note that Simpson and Bosch Power Tools have formed an alliance, so that may help in speeding up the visibility and acceptance of Simpson here.

 

[Guest262653]

Is his first name Homer?

 

[a2mfk]

Ron- I am sure you have been to Simpson in Jacksonville for one of their bolt seminars? I would highly recommend this to anyone, it has been a long time but they installed several bolts using different systems in concrete foundations and then did pull tests to failure. Fun for a structural engineer for sure...