Wet Setting Nelson Studs into Bond Beam 11

[KootK]

Got the situation below. I've pitched post installed anchors (Hilti HUS) for the fastening. There's a desire to use nelson studs but, presumably, those would be wet set. I'm concerned about the wet set nelson studs for these reasons:

1) Issues with wet setting anchors in general compromising capacity.

2) Not sure the grout will be well consolidated if there's a rush to get the channel on before it sets. Does bond beam grout get vibrated?

3) Contractor might not manage the sequencing and I'll be stuck detailing a post installed solution anyhow.

How do we feel about the viability of the nelson stud option?

 

[dik]

You can go to Hilti HAS and 270 glue...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[StrEng007]

Koot,
How much drag force are you trying to put into the wall? Do you have any option of using a concrete tie beam at the top of the wall in lieu of an 8"x16" bond beam?
Sorry if I've missed something, or if this has already been discussed; how about using intermittent plates that are 8" wide. This will provide enough room on either side of the beam to flare-bevel weld the channel to the top of the plate (assuming your channel is less than 8" deep).

Disclaimer: The issue I've usually seen with these sorts of studs is the side face blowout. With a tie-beam, you can provide (1) longitudinal bar at each face. The stirrups theoretically help you prevent the side face blowout, but whether or not the hooked bar of the stirrup develops is another question. I've mostly seen this being ignored for getting too "granular".

 

[KootK]

@strEng007: thanks for your very well sketched suggestion.

How much drag force are you trying to put into the wall?

Ostensibly 90k over 32'. I don't actually believe that the demand is anywhere near that high though and am working on lowering it.

Do you have any option of using a concrete tie beam at the top of the wall in lieu of an 8"x16" bond beam?

It would be a stretch aesthetically but isn't entirely off of the table.

The stirrups theoretically help you prevent the side face blowout, but whether or not the hooked bar of the stirrup develops is another question. I've mostly seen this being ignored for getting too "granular".

Yeah, it's tough building a career in a space where doing the right thing is considered being "too granular" per the MBA types.

@Everybody: we've got some great ideas to work with on this. Thanks to all who've contributed. I dare say that this is probably now the definitive thread on how one might attach a steel drag strut to a masonry wall.

 

[JLNJ]

We have used channels toed toward each other spaced at 7 5/8" out to out. Then fill the annular space with grout. You can even run the wall rebar up through if these channels are not at the top of the wall.

 

[phamENG]

JLNJ - so a steel face shell bond beam? Neat...

 

[KootK]

We have used channels toed toward each other spaced at 7 5/8" out to out.

That is neat. Do you make any attempt to make the two channels composite across the wall thickness? Studs? Some manner of capping plate maybe?

 

[JLNJ]

We did try to make them composite. We used studs along with running the rebar through.

It's been a few years, but if memory serves we had an architect punching windows all over the place in a tall wall. We could find only a few "bands" of continuity across the wall's width. We made those "bands" steel since the bands were too narrow to span horizontally.

 

[KootK]

@JNLJ: My only beef with the channels oriented strong axis, and with the toes turned in, is that I'd probably wind up with only 3.5"-ish worth of grout width (distance between flanges) available for shear transfer from the wall into the beam/girt. Or have you laid claim to shear friction between the grout and the flanges as well in the past?

 

[KootK]

How much of a badass would I be if I could pull this off? Consider:

1) There used to be an HSS on top of the wall before I got involved so, aesthetically, it might fly.

2) It's kind of an amalgamation of a lot of our ideas here:

a) I've got double, vertical channels per JLNJ. And a slick connection to the brace frame node to boot as a result.

b) I've got the concrete tie beam per Agent et all with stay in place formwork.

c) I've lowered the work point per Deker.

d) The channels could be craned into place and the wall built underneath, solving Enabled's concern for the man lifting of heavy stuff.

 

[jayrod12]

How do they wedge the 8" wall 2" into the channels if the channels are in place before the wall is erected? Do you need to have the 2" embed? Or is that just a feel good thing?

 

[KootK]

Do you need to have the 2" embed?

I don't. I was just trying to keep the tie beam out of sight and not have there be a formwork gap.

How do they wedge the 8" wall 2" into the channels if the channels are in place before the wall is erected?

Originally, I thought that one would build the wall up to the second to last course and then drop the topmost course in from the top, maybe with some prying apart of the channels if need be. I see now that I've neglected to consider the wall reinforcement which will make things harder. Oh well, maybe the channels still have to come after the wall. Thanks for the vett.

 

[jayrod12]

Forest for the trees sometimes. They could likely do that from the top idea.

How do the elevations work out with block coursing? Could you just have the channels 2" higher and they just caulk the joint between the channels and the topmost block row to create the formwork? Or a C10 in lieu of C12? few different ways to skin the cat in this regard.

 

[KootK]

How do the elevations work out with block coursing?

I don't know and am not planning to get that deep into the weeds on this.

Could you just have the channels 2" higher and they just caulk the joint between the channels and the topmost block row to create the formwork?

Perhaps. I'd have to run that by the other parties to see what is tolerable / desirable.