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?

 

[jayrod12]

My concerns are similar to yours, but in that same breath we specify continuous weld plates for steel deck with nelson studs into bond beams all the time. So might just be making a mountain out of a mole hill. Often concrete grout for these is quite high slump, so the contractor sequencing is the most concerning in my mind.

 

[KootK]

...but in that same breath we specify continuous weld plates for steel deck with nelson studs into bond beams all the time.

Ditto. I'm not sure if that's done more because:

a) It really works or;

b) The scale of the application is usually such that we don't care about the result all that much. Usually just roof deck at stair shafts.

The channel in question here is the lowest steel member in a steel braced frame that turns into a masonry shear wall. I don't love that setup in general but, alas, it is what it is at this point. Moral of the story: this thing is meant to see some real axial load.

Another option that I wouldn't mind would be studs on intermittent plates and then plug weld the channel to that. I could see the hole location coordination being a problem though.

 

[Enable]

How long are the channels and what is the approximate weight? If the sections start to get heavy for two guys to easily finagle I would give little chance of this thing going in as planned. However, if it's nice and light I wouldn't see that much of an issue as long as the grout has quite a high slump (probably max it out before you start getting into SCG range or even use SCG assuming we have a nice level bond beam here). I wouldn't count on the bond beam being vibrated FWIW.

 

[Brad805]

They do not need to be wet set if you let them blow some holes in them with a torch. Much easier to install that way since you do not have to lug a heavy piece of steel into place. If you are against holes, then you are at the mercy of the contractor.

 

[KootK]

How long are the channels and what is the approximate weight?

C180X22 x 25'

I wouldn't count on the bond beam being vibrated FWIW.

Is it supposed to be vibrated? I'm not clear on that.

They do not need to be wet set if you let them blow some holes in them with a torch. Much easier to install that way since you do not have to lug a heavy piece of steel into place.

I'm not opposed to holes. I don't think that I understand what you're proposing though since, even with holes in the channel, it would still be a long heavy piece to lug into place. The only weight savings would be the material removed in the making of the holes? Can you elaborate?

 

[Klitor]

Set the channel before grouting. Grout trough holes in channel?

 

[Celt83]

This option keeps the trades separate mason can set the threaded rods and the steel guy can come in later and slap it on.



I'm making a thing:

http://www.thestructuraltoolbox.com

(It's no Kootware and it will probably break but it's alive!)

 

[KootK]

Set the channel before grouting. Grout trough holes in channel?

Yeah, that's being considered. Are we not concerned about grouting quality that way though? Seems to me that would be rife with potential for voids and poorly consolidated grout. If I'm wrong about that, I suppose that's precisely what I need to know.

 

[KootK]

@Celt: that's clever but, even with the slotted holes, is that still not likely to be a coordination challenge?

 

[Celt83]

It will still be a coordination challenge however in my opinion it's less so than having a mason wet setting the channel. Most the time I see the grout slammed down with a 2x4 instead of vibrated as well so the threaded rod gives me more piece of mind for the attachment if this is a critical piece of the lateral load path.

I'm making a thing:

http://www.thestructuraltoolbox.com

(It's no Kootware and it will probably break but it's alive!)

 

[jayrod12]

I would think if you have a reasonable contractor, with oversized slotted holes and site measured anchor locations, a decent steel sub would be able to knock those holes into it from dimensions and it be on site the next day. And be close enough to tolerance that it's not an issue.

However, if going to that much hassle, may as well just do the screw anchor post installed solution you were originally planning.

 

[Enable]

Yikes! That's getting upwards of what 370lbs? I see that as being a real struggle to get into place during the pour.

MasonryGeek may have more insight but as far as I know the positions of the NCMA, and generally speaking, all grout needs to be aided in its consolidation unless it is SCG. If the pour is less than 300mm it can either be mechanical or by puddling, but beyond that it must be mechanical. I don't know of any exceptions for bond beams on this.

MSJC commentary on Masonry Structure Building Code Requirements

 

[Brad805]

My idea is below.

 

[dold]

What does the connection between the channel and braced frame look like? If it's what I'm thinking then I'd be more inclined to weld a plate to/through the column and weld some A706 bars running into the bond beam, maybe use a 16 or 24" bond beam depending on how much steel you need. Doesn't solve the wind girt problem, but the headed studs will have less demand on them.

 

[Deker]

Another option that I wouldn't mind would be studs on intermittent plates and then plug weld the channel to that. I could see the hole location coordination being a problem though.

This option gets my vote, especially if you can use 10" plates with an 8" channel or 8" plates with a 6" channel so that fillet welds would work. Alternatively, maybe you could hold the top two courses down and form the bond beam so that it can be grouted though "windows" in the forms. Or maybe form one side and shotcrete from the other...each of these options with the channel in place, obviously.

 

[KootK]

This is a thing that we tend to do at school gymnasiums up here. Ball on wall durability and all that.

I'm not sure how they deal with the weight of the channel but they seem to.

If the loads work, does anyone see any drawbacks of using the HUS screw anchors as I proposed earlier other than the weight thing? A little bolt slop, separate trades, no coordination, sequencing friendly...

 

[GC_Hopi]

If the tolerance requirement are tight then embed anchor bolts by mason, steel plates bolted on top of the wall, then field weld channel to plates. A lot more steps but you can tighten the tolerance at each step.

 

[dold]

Gotcha. Well then. I like Brad's idea with the grout holes. I'm not a fan of wet setting anything. In grout or concrete. I also like the top two courses as a cast in place/formed "closure" beam after steel is in place.

Or just insist on the post installed anchors. Surely they can suffer an hour's labor of drilling.

 

[Deker]

For that arrangement, I'd probably lower the work point of the braces and block out the ends of the wall for the gussets. Lap the wall reinforcement with the gussets and weld.