Bollard Foundation Design and Detailing

[oengineer]

I have a question regarding the design of bollard foundations for an ATM. The ATM is sitting on top of a 2'-6" thick slab that is 9'-0" x 5'-0". Based on the recommended location of the bollards show in the vendor data, the bollards will be located in the slab.

I am thinking that it would be best to have reinforced concrete blocks or piers located underneath each of the bollards and have them tie into the slab. I would make the depth of the block or piers 1/3 the height of the bollard. I don't think have the bollards embedded into the 2'-6" slab is enough.

Is this typical? Is there anything else I need to consider? Open to suggestions and comments.

 

[JAE]

Bollards are really only psychological barriers unless they are designed as impact resistant elements per actual impact testing.

We found some previously tested products online - specifically government designs for terrorism resistance.

For an ATM - I'd suggest just the psych barrier unless the client wants to positively stop moving vehicles from impacting the unit.

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[canwesteng]

I wouldn't have them be part of the slab. Drill a hole, stick the bollard in it, fill with concrete. Bollard should be encased in concrete and not in contact with soil. The bollard is there for impact and if something hits it hard enough it will break, better off not also breaking your slab.

 

[oengineer]

So would the 2'-6" thick slab be adequate for the psych barrier/bollards?

From the vendor drawing, it callas for 4" diameter bollards. The vendor drawing does not call out the height of the bollards, but I think 3'-0" would be a good assumption. Using 1/3 of the height, I would get 1'-0" embedment for the psych barrier/bollards into the 2'-6" slab.

This would eliminate the need for piers underneath/attached to the slab.

Does this seem adequate and/or typical?

 

[oengineer]

Also, does anyone happen to have a good example of a bollard foundation design calculation?