Concrete anchor bolt loading with standoff

[ewans]

Hoping you can help me with a simple bolt load question.

I have a poured-concrete foundation wall covered with 2" rigid foam insulation (extruded polystyrene), and I need to secure a 4'x4' plywood panel to the wall. Approximately 250lbs of heating equipment will be mounted to the plywood panel. I recognize that, due to the 2" foam 'standoff', using concrete sleeve anchors or Tapcon-type fasteners to attach the panel to the wall will result in applied bending loads on the fasteners.

My proposed approach is to use rigid spacers or sleeves between the concrete wall and the backside of the panel at each fastener location. Assuming the spacers are rigid with minimal bolt clearance and the anchors can be sufficiently pre-loaded, will this approach eliminate the applied bending loads and result in simple shear and tensile loads on the fasteners?

Please advise if I have not chosen the appropriate forum in which to post.
Thanks in advance.

 

[SlideRuleEra]

If the spacers/sleeves were large enough (diameter) they would help some, but it is probably not worth the troubled. The load that you are talking about is not unreasonable. Perhaps you can use multiple, somewhat oversized anchors bolts (say 0.5" diameter or so). Also try to get as much embedment in the concrete as practical.

 

[fepc]

The applied loads are still present. Check combined stresses. I would use a seat angle two or three inches long at the bottom of the panel in two or three locations to take the vertical load if this is permissable. Anchor the seat angle to the wall with expansion bolt.

 

[ewans]

Thanks to all for the replies so far... much appreciated.

fepc,
I assume you're suggesting I clear-off the foam in the seat angle locations so the vertical leg of the angle bears directly against the concrete wall; correct?

 

[civeng]

Hi everyone,

I'm with fepc, thats the method we always use. Even if you use sleeves, the bending reaction is still applied to your fastners.

Have a good one guys.

 

[fepc]

ewans,
Yes.The vertical leg will be behind the panel.

 

[ewans]

Thanks to all for the advice.

Regards.