Precast Planks + Cold Formed Steel (CFS) Load Bearing Walls

[srazahz]

Hello,

My question is regarding the connection between precast planks and cold formed steel (CFS) load bearing walls.

If we have an 8" precast plank sitting on a CFS wall (studs at 16" c/c), also bearing a similar CFS wall on top, on the third floor of a 6-story building, what would be the best way to connect the plank to the walls above and below it considering the walls are only taking gravity load?

Would 2 tapcons per wall stud (both top and bottom) be be enough for stability, or would we need to put in through bolts that connect the bottom track of the top wall and the top track of the bottom wall together?

 

[MIStructE_IRE]

There was a thread about this form of construction recently?

It makes me nervous even just looking at this stuff!!

 

[milkshakelake]

This is a pretty specialized type of design and a lot of liability involved. I would be careful of every detail. There are a lot of lawsuits (at least in east coast USA) regarding CFS design.

My detail on a 6 story building, use at your own risk:

For facade and edges, it's something you have to coordinate with the framer. Usually it's subcontracted to a cold formed steel company that has their own practices, and they all have different ways to do things.

 

[MIStructE_IRE]

How do they deal with the camber? The load won’t ever be as uniform as you think leaving huge concentrations potentially over one stud. And as we all know, the contractors never shim and grout properly!

 

[milkshakelake]

I span the plank from one stud wall or beam to the other, so the camber is in the center of the span.

 

[Ceinostuv]

There are a lot of lawsuits (at least in east coast USA) regarding CFS design.

Hey milkshakelake, I do quite a bit of CFS design on the west coast and there doesn't seem to be much litigation regarding CFS design, maybe I'm just oblivious. I'd be curious to hear more about the lawsuits you're talking about, would you be open to me getting in touch with you via e-mail or something?

Judgement-In-Training

 

[XR250]

Might want to spec Hilti Kwik cons if you are going that route. Buildex Tapcons like to break in higher strength concrete

 

[Teguci]

Here's a crazy idea. I wanted to provide some kind of bearing pad to allow slip on the tension side of the slab and also attempt to provide for some load redistribution at the top of the bearing wall for minor elevation differences. For 6 stories of load the pad will need to be a rigid korolath or similar. For less loads an elastomeric might work if you can torque down on it enough. Could consider voiding the bottom half of the joint to force the bottom to close instead of allowing the top of the joint to open when the slabs rotate under moment.