LG Top Track as distribution member

[DEL2000]

I was looking at using a light gage top track to distribute loads to load bearing stud walls, which I have never even explored before. In looking at deep leg tracks (user defined as 600T400-68 and 600T600-68 in the programs that I have), you find out that those types of tracks have all kinds of capacity in positive moment (legs of track in tension), which is enough to distribute the loads to the studs if the track would be put in place as a number of individual segments.
On the other hand, the negative moment capacity of the track (with the legs of the track in compression) is like 1% of the capacity of the positive moment noted above. Is there any way to neglect this in the design of the top track, since the positive moment capacity is enough to distribute the load to the studs. Or since you have a negative moment overstress you have a failure, causing the legs of the track to distort, etc.

Has anybody ever explored this.

Thanks for any input.

 

[JAE]

Usually you use a tube or angle of some sort to transfer the load to the nearest studs. Here's a couple of previous threads that discusses this subject:

thread507-99013

thread507-77098

Also, I believe that some light gage manufacturers have an "L" or "U" shaped member that laps over the top cap to assist in this transfer. Go here to see an example:

http://www.dietrichindustries.com/CAD/?p=Structural Wall Framing

click on the left side under "Load Distribution" and "TradeReady Header"

 

[DEL2000]

Thanks for the response. I am familiar with the TradeReady header (which would be the equivalent of a 600T800-68), but I guess my main question is how well a track would work in a continuous span condition, where there are negative moment failures at each stud support. I have a call in to Dietrich as well to ask this question, but it will have to wait till tomorrow since they are closed.

I was trying to avoid a regular steel angle or tube at the top of the wall if I could, as a tube might be pretty expensive and the angle will affect how they apply the wall finishes.

 

[UcfSE]

You can build a tube out of a nested stud and track and engineer that to work, or design a regular continuous box header. You can also detail the wall with a wood double top plate if you are permitted to use a combustible material.

I would not ignore the negative moment in the track even if the positive works. That might cause too many finish problems.

 

[JAE]

DEL2000,
One thing to consider is that if you use a continuous track, and the negative moment resistance is small compared with the positive capacity (i.e. the neg. buckling kicks in early at low loads), then in effect the negative moment regions form a sort of pin and you are back to a simple span condition anyway.