Wedge anchor

[JStructsteel]

Generic question about wedge anchor, what amount of concrete would you want below your anchor? If I have a 5" slab, and try to set a anchor 4.5" deep, is that ok? I cant find anything from Hilti saying how much concrete you need below anchor. Thanks

 

[jayrod12]

2" minimum for me. And there is a reduction for concrete thickness in hiltis information.

 

[TehMightyEngineer]

Assuming the person on the tool can get the depth the accurate; the hammer drill will punch through about 1/4" of concrete. I'd go 1.5" min. and definitely recommend jay's 2" min. and comment about Hilti's recommendations.

Ian Riley, PE, SE
Professional Engineer (ME, NH, VT, CT, MA, FL) Structural Engineer (IL, HI)

 

[skeletron]

The modification factor (Annex D of CSA A23.3-14) kicks in for the shear loading if the depth of the member is less than 1.5 x the edge distance in the direction of shear. The projected area is also affected.

I would also try to provide some sort of minimum cover similar to reinforcing. The above recommendations (1.5 or 2 in) sound reasonable as a start.

 

[JStructsteel]

This is a hypothetical question,maybe I didnt explain myself. based on tension alone. Ignore any edge distance, shear, etc. If I have a 6" slab, and I use a 1" anchor, 6" embedment, hilti publishes a value. I dont see where its reduced due to slab thickness.

I was going to put it into PROFIS, but I see they have changed that to a subscription and are charging now. Great.

Maybe I'll try it in the Simpson anchor designer software.

 

[jayrod12]

The concrete thickness factor applies only to shear. Your tensile breakout cone starts at the anchor, so I wouldn't expect any change based on concrete thickness versus embedment.

That being said, check out this excerpt from the Canadian Hilti Kwik Bolt guide. It appears my 2" is correct for most cases and not enough for the higher embedment 3/4" and 1" anchors..

 

[JStructsteel]

Thanks, I am finding the same with the Profis (its free until August) that the anchor embedment changes if you change the thickness.

 

[jayrod12]

Profis here in Canada is free all the time. You have to pay for it? I feel as though this conversation has been had before.

 

[JStructsteel]

it looks like Profis is going to cloud based. Right now you have full access to the whole design package, after 8/1, looks like it goes to a bare bones package, and the bells and whistles is 25-35$ a month.

https://www.hilti.com/content/hilti...ral-engineering/profis-engineering-suite.html

 

[birneys]

My understanding is that the "bare bones" package is the same features that were previously available for the desktop product. The "bells and whistles" are the new features that are being added in this new release (they haven't been available before). That's how I read the feature comparison for the cloud version.

 

[TehMightyEngineer]

Meh, I just use Dewalt/Powers design software over Hilti's. The only thing I used to use Hilti for was their lap-splice capabilities.

For your hypothetical situation jrisebo I believe you'd be fine as long and the drilling or engaging the wedges didn't damage the concrete. That's a tall order for 1/2" of remaining concrete at the bottom of the hole but not impossible from the theoretical sense. I'd say you could theoretically have no reduction in capacity with that setup.

Ian Riley, PE, SE
Professional Engineer (ME, NH, VT, CT, MA, FL) Structural Engineer (IL, HI)