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Sill plate anchor bolts

StrEng007

Structural
Aug 22, 2014
510
What are the best practices for constructing sill plate anchor bolts along the edge of a slab on grade with monolithic footing (i.e., not a stem wall foundation)? Is the best practice to cast these bolts using a manufacturer's anchor? Post install these with epoxy anchors? What is the typical bolt diameter. I got 1/2" minimum from the applicable building Code. I wasn't sure if 5/8" is more common.

I'm using a 2x6 wall, and anticipate setting the bolts 2 3/4" from the edge of concrete. I would like to use one of the product shown below, but their slab edge details account for an additional "ledge" built into the foundation. Where I'm located, we typically use the footing shape shown below.


Simpson "SB" anchor bolt that I'd like to use:
Screenshot_2024-10-22_090445_ehyrer.png


Edge distance detailing for this anchor bolt. Note the additional ledge with providing (1.75" + 1.5") 3.25" cover from the bolt centerline:
Screenshot_2024-10-22_090425_dyatqo.png


Intended footing shape. Ignore the anchor bolt type (refer to question above):
Screenshot_2024-10-22_090733_y7pkjt.png
 
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Usually try to go for cast-in anchors but shy away from proprietary anchors so just a standard hex head bolt checked using ACI/NDS.

I also like to get that continuous top bar on the outside face of the anchor, feels better having it in the knuckle of the bar bend and also on the free edge side of the failure cone.
 
No reason to use a holddown anchor for sill plate connections. With wood sills use 5/8"Ø cast-in bolts with 7" min. embed min. 1 3/4" for edge, etc. following 1905.1.8.
 
Celt83 said:
I also like to get that continuous top bar on the outside face of the anchor
I know this is really splitting hairs... I'd like that bar on the outside as well. But with exposure to earth, weather, I use 2" cover for these top bars. That cover with bolt placement offsets the bolts from the sill centerline. Does that even matter? I know that none of these things come together perfectly anyway.

No reason to use a holddown anchor for sill plate connections.
That was a residual detail. I've got 165 MPH winds to deal with, some of my built up studs require this.
 
Like Celt83, I prefer to use cast in place, standard heavy hex head anchor bolts, rather than post-installed or proprietary. Regarding the placement of that top edge bar, I think if you draw the hooked bar to scale, you will find that placing the edge bar in the "knuckle" will have it nowhere near where Celt83 seems to think it will be.
It would probably end up about where you are currently showing it.
 
And I would use 1/2" bolts unless you need larger bolts.
 
I try to keep anchor bolts in the middle third of the sole/sill, but if you have those horseshoe straps you don't have to worry about developing cross grain tension from the uplift load path. You can put it anywhere in the sole plate so long as the connection meets NDS and ACI requirements. (Min edge distance, etc.)
 
My approach was to use embedded bolts and run the analysis without any tensile or breakout reinforcing in the slab. The top bars that runs parallel to the length of the wall is going to be positioned as shown, so I'm not counting on any reinforcing to help me do the trick.

 

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