Portable rigging formulas

[jemawalton]

Is there a formula for aluminum I beam load ratings based on width of supports? For example if I have an I-beam rated for 2000lbs at full span and I move the supports in, how do I calculate the new rating for the beam? I know I have seen a formula for this somewhere but can't seem to find it now (when I need it of course).

[pjgmfs]

If this is a gantry rated at 2000 lbs.But has an adjustable span.The overall rating of the gantry will still be 2000 lbs.Due to the legs and casters which are all rated as an assembly.

[jemawalton]

I was thinking more along the lines of an A-frame with interchangeable heads and beam. I know I would be limited my the rating of the legs but if I decrease the span on the beam I should be able up the rating on the beam to match that of the legs. I am working with an A frame right now with leags rated for three tons but an 8" beam rated for one ton at a span of 12'. I don't need to pick three tons but with a shortend span i should be good for more than 2000lbs. I would like to be able to calculate it and pick with confidence.

[Lash]

http://www.bookmarki.com/SearchResul...FRoSFQodpjsTRw

Too many variables. I have my book at work. If you give me what type, height, width, and thickness of beam it is I can check it out for you on monday.