Lt. gauge Track on Structural Steel

[StrEng007]

I have a 6" exterior lt. gauge stud wall that will sit on a structural steel perimeter beam. If the track is 6" wide, what is the minimum width of beam flange I must provide (aside from strength and deflection, etc.)? I don't want to create an instability by having something like a 4" wide flange supporting a 6" wide track... although this would be pretty close to a pinned-pinned stud connection at the top and bottom.

 

[DaveAtkins]

I think a 4" wide beam is fine for a 6" wall above.

DaveAtkins

 

[XR250]

4" is fine for most cases that I can imagine

 

[StrEng007]

Great! Thank you.

 

[StrEng007]

One more for you... if this was a HSS and not a W-beam, what would you limit the workable flat to?

 

[XR250]

Depends on the loading on the track. Shear, gravity, uplift, torsion?

 

[StrEng007]

Shear from out-of-plane wind loading.

 

[271828]

I'm going to go against the grain.

Presumably the beam is short or else you wouldn't be looking at sections with 4 in. flanges.

A W10x22 is only about 10 plf heavier. Unless you have a lot of these, the weight increase for switching to W10x22 is nothing compared to making this issue go away entirely.

 

[StrEng007]

I've got bi-directional loading and the primary demand on the supporting beam is lateral (weak direction bending). This has resulted in me reaching for the HSS beam... Not a huge fan but it's lighter than using a W-beam.
I'm trying to get away with simple HSS beam to HSS column connections. Got this detail from the Steel Tube Institute:

Anyway, those pesky HSS have somewhat limiting workable flats, takes away even more of the bearing surface for the track.

 

[271828]

I would go with 6 in. wide and not worry about the workable flat.

 

[Aesur]

This post somewhat confuses me, if I understand correctly, you have a 6" stud wall that you originally were sitting on a wide flange beam, you were worried about the beam width being narrower than the track supporting the studs. Then you changed to an HSS beam and have a connection detail consisting of a beam seat.

Based on the information I can gather from this post, the beam is acting as a lateral header type member, in which case I would rarely if ever use a wide flange beam as they suck for weak axis bending without bracing, not to mention torsion you would be placing on the wide flange. An HSS would be your best option. If we are truly talking about about a header type scenario, I would make the header the same width as the steel studs to better control horizontal deflection (weak axis of the HSS from I presume wind loading). For the connection to the column, assuming the column is really a jamb stud column, I would directly weld to a sim width column and call it a day, I don't see a reason to provide a seat and angle as you show, unless the loads are such that you need additional capacity of the connection because the beam is less wide than the column and the column web is too thin?

 

[StrEng007]

Aesur,
You got it. I'm sorting out my options and was considering a W-beam upon request because GC doesn't prefer HSS to HSS connections. However, like you mentioned the weak axis is lousy and the HSS performs much better. When it was initially mentioned that a 4" W-beam flange would be appropriate, I wanted to get the opinion about workable flats for this scenario so I'm well prepared to use an HSS if that's the better choice (which it is). Sorry for the confusion, the train of thought changed fast.

If I do end up using HSS, I was trying to get away from using same width HSS beam to HSS column due to locations where two beam join at a corner.

I agree a full perimeter weld is more simple. However, I thought I was doing a solid by providing a seat to place the beam during welding?

 

[DanKile]

I know it will make for some messy connection details, but you could look at doing a wide flange with a cap channel.

 

[bones206]

One way to simplify the HSS connection you show is to replace the stiffened seat with a 6" wide clip angle (shop welded to column). They would drop to HSS beam on the clips then connect the beam to clip angle flare bevel welds along the sides. Top clip angle is then field welded as currently shown in the detail. No welds directly from HSS beam to HSS column.