Concrete anchorage under wall element

[jwatso33]

I have had some conversations about a concrete anchorage breakout with another engineer. The issue is (for example) you have anchorage into large footing or other large concrete mass and you have a solid concrete wall that sits on the projected failure area, how does it affect your breakout calculation. I am more inclined to ignore it myself but this has come up between us more than just a few times. I would love to hear some thoughts/references on the matter. Thank you.

 

[KootK]

I think about this often. Undoubtedly, the effect is beneficial. I expect that a concrete strut would form between the anchor and the source of external compression (wall). If you had the necessary tie elements to form a strut and tie mechanism, you could probably forgo breakout altogether. Otherwise, I'm not sure how one would set about quantifying the improvement.

The common situation that gets me wondering is base plates with moment and deeply embedded anchors. I suspect that a concrete strut connects the anchor head and the compression block under the baseplate such that tension breakout isn't nearly as bad as it would at first seem.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.