cold-formed box beam lintel

[RWW0002]

When calculating capacity for cold-formed steel box beam lintels(2- light gauge channels, toes facing inward, with track running along the top and bottom) I have been using the full lintel width for the unbraced length of the lintel (under gravity loading) and have calculated the capacity of the lintel as 2x the capacity of a single channel member. This works fine with relatively small openings, but gets pretty tough once openings get up to around 10'. I am wondering if I am being too conservative in the un-braced length asumption. In talking to other engineers, they have recommended running the lintel as fully braced, justified by the use of the flexural strength of the track at the top and bottom of the beam as lateral bracing.

Any thoughts?

 

[DaveAtkins]

A cold formed steel header is a box shape, not two individual C-shapes. Therefore, it is fully braced along its length.

DaveAtkins