What a beam will hold (yield) isn't the only conderation. A small beam will hold a lot but can be very bouncy. A truss would be a lot cheaper. Check with a steel building manufacturer that builds trusses like http://www.kbuildings.com/spotlight.asp

This company would hang a corvette from one of their trusses at the Farm Science Review to get attention.



"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge." Stephen W. Hawking