I have been asked by an EOR to design a 24ft long boxed header with light gage framing. This member will be laterally unbraced in a curtain wall assembly. Are there any practical limits to the span of such a header in a 6" wide wall? The loads are only in the 200lb/ft range vertical. Horizontal loads are less.
The "Standard for Cold-Formed Steel Framing - Header Design" by AISI only states length limits for L-shaped headers. Header calcs in this standard only address bending, shear and web crippling. I don't believe that the AISI main spec will adequately model a long-span composite assembly.
I would like to either find a conclusive way to design this header or prove that it is not practical.
Thanks in advance.
Jim Wilson, PE
Stroudsburg, PA