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Need some help with Light Gauge Built-up beams

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Does anyone have a spreadsheet or MathCad template that I can use to calculate a built-up section of light gauge steel to act as a beam?
I am designing store soffits (entry's at mall stores) and the architects restrictions often result in spans upwards of 30 feet. The tributary area on the beam rarely exceeds 4 feet and the weight of the light-gauge framing is around 10-psf. There is no live-load, but I add 10-psf as I would a ceiling. The problem is that I don't believe that a built-up cold form section will make a 30 foot span when restricted to a 10" or 12" depth without an excessive amount of deflection. I have been using TS4X10X1/4" sections which provides a controllable amount of deflection for the span (compression flange braced at 16" on center by the 20 gauge framing that frames above the beams) that the contractor can tweak out in the field to insure that the bottom of the soffit (where a ceiling is attached) is level after loading.
The problem is that some of these steel sections are difficult to find in the timeframe that the contractor has to do the work and the amount of steel needed is relatively small.
I have two choices:
1. Design the beam as a cold-formed steel built-up section (if the depth is not excessive) OR
2. Specify sources of TS sections around the country that the contractors can order available sections from. j
I am not sure how to search out sources for the second option.
If any of you are doing similar work and can offer me some advice as to how to address the problems, I would greatly appreciate the help.
Dennis S. Wish, PE
(208) 361-5447 Efax