Connection to concrete - distance from the column edge

[Fynch]

I have a connection for a flood gate that needs to be attached to a concrete pillar.

Logically - it seems that the connection needs to be further away from the concrete edge to avoid cracking, than that you would calculate if it was a rebar and nominal distance.

Therefore, how do you calculate the distance from the column edge?

 

[JoelTXCive]

I'm not following your question.

Many gate frames that I have seen have anchor bolts placed about 4" to 5" off the edge. The manufacturer should have a cut-sheet showing their frame geometry.

If you assume any rebar in the column has 1 1/2" to 2" cover; then a 4" offset will get you on the other side of the first bar.

When I do these; I calculate the head on the gate to figure out tension/compression load per anchor. Also calculate a shear load per anchor for the gate weight.

Then, I use the free hilti software and an initial assumption that there is no rebar for anchor reinforcement.

Sometimes I get lucky and it works right off the bat. I don't even have to worry about the rebar helping.

 

[KootK]

Therefore, how do you calculate the distance from the column edge?

You'd use your jurisdiction's code/standard provisions for anchorage to concrete. Or, I suppose another jurisdiction's provisions if your own jurisdiction doesn't have such a thing. Most of the modern versions of this stuff seem to be based on the information collated in the book shown below. Certainly, Canada's and the US's are.

 

[kostast88]

You need to keep enough distance from the edge to prevent concrete edge failure.

This varies according to the type of anchor you are using (mechanical,resin anchor) and often the country of application, but in principle the theory behind it is the same.

I have a clear preference for chemical anchors in almost all cases. For European guide, refer to EOTA TR 029:
Link

The relevant paragraph is 5.2.3.4. Make sure all other conditions/failure modes are satisfied.

Alternatively you can use HILTI Profis Anchor or a similar software to do the checks for you.

On the practical side of the project, do consider whether the pillar is existing, often they require strengthening and if you don't know its foundation and reinforcement consider doing site tests (ferroscan,trial pit and/or ground penetration radar). I've dealt with a couple of these in the past and tests are usually worth having a better look at these pillars.