Interior CMU partition foundation

[tw]

We typically specify thickened slab and dowelled rabar for interior CMU partition walls. We don't use a lot of CMU so it was never a big deal. Now we have an elementary school that is chock full of them. Has anyone ever used some type of post-installed shear connector that can be easily fastened (screwed) to our 5" slab?

Seems like this would be tons easier on everybody.

tw

 

[msquared48]

If all these are is partition walls and not shear walls, then there is such a thing as a concrete expansion anchor that can be installed, and the rebar threaded and inserted into it. But why do that?

It would be cheaper and quicker to epoxy the dowels 4" into the slab.

Mike McCann
McCann Engineering

 

[MarcbSE]

I have always used embedded doweles for interior CMU partition walls - even on very large schools.

I would agree with Mike though that epoxy anchoring the dowels would be better and easier for the contractor if you didn't want to use embedded dowels. I could see it being a nightmare trying to accurately locate and hold in place mechanical anchors in the slab during concrete placement.

 

[DaveAtkins]

Is there a structural reason for the dowels? Why not just lay up the CMU without them?

DaveAtkins

 

[msquared48]

MarcbSE:

I do not believe tw was referring to wet setting the anchor.

The anchor I was referring to still has to have a pre-drilled hole, and was made by "Red Head". It is termed a "non-Drill Anchor" and is covered in an ICBO report #1372 dated Feb, 1975. You can probably get the current, updated report online if they still make them.

Mike McCann
McCann Engineering

 

[msquared48]

Dave:

I would still put minimum reinforcing in the partition wall and tie it to the slab, but I am in a high seismic area too.

Mike McCann
McCann Engineering

 

[tw]

These are interior non-load bearing walls...so they have minimal lateral support requirements (5 psf). Seems to me you don't need mechanical connection with slab since wt of wall will hold it in place. Wall would be braced at top as well, of course.

I've never done it this way & that is really my question: Has anyone done it that way?

tw

 

[msquared48]

Better check your seismic requirements for "Parts" of a structure. Could work out to be greater depending on the wall thickness and grouting requirements, especially if any one is a firewall.

Mike McCann
McCann Engineering

 

[tw]

Yes, I'm still getting used to thinking seismic, good point.

Option I will likely use is to use some type of non-drill anchorage that will provide the connection & work with just the 5" slab.

thanks for the input
tw

 

[UcfSE]

What do you mean when you say "non-drill"? Even screwed anchors (not those that had a really bad day) have to have a hole drilled first.

Dur-O-Wal makes an interesting anchor, Dur-O-Wal DA8800 OCM Anchor. I've never specified it myself but it may be OK for interior walls. I would definitely use some sort of dowel instead of leaving them out. I would also provide a footing, even if only 8x16.

 

[msquared48]

A "non-drill" anchor is just that. The hole is predrilled with another tool, and the "Non-drill" anchor inserted. With some of the other Red Head anchor products, the anchor has a drill tip as part of the product, so it serves as the drill bit.

Mike McCann
McCann Engineering

 

[MarcbSE]

Mike,

You're right - a mechanical anchor could be set in drilled holes. For me though, if they're already drilling the hole why not just put the epoxy in there.

 

[msquared48]

Exactly.

Mike McCann
McCann Engineering

 

[NITTANYRAY]

We generally use 8" thick thickened slabs under non-bearing walls. We space the vertical bars at 48" c/c so the walls can qualify as intermediate reinforced masonry shear walls.This gives you an R factor of 3.5 vs 2 for ordinary reinforced shear walls. Our buildings are usually Design category B or C.