quote from prodigyrf:
"Nooooooooo!!!! Hanging beams are specifically designed to reduce ceiling joist spans taking into account light ceiling loadings NOT floor joist dead and live loading spans."
Correct, STANDARD hanging beams are for supporting ceiling loads only, however in this case the new members would not just be standard hangers, such as with 'counter strutting roof beams' that (for the "layman") are combined ceiling hanger AND roof strutting beams (no big deal and are commonly used in many pitched roofs). Despite their dual use, they are still commonly called a hanging beam.
AS I SAID, anything that the original poster wanted to do needed to be designed by an engineer or a qualified tradesman / builder who, like myself and other qualified persons, uses the relevant span tables and codes when calculating framing member sizes, loads and spans.
So instead of bombarding the OP with a whole lot of technical jargon that a "layperson" or that someone who is "faint hearted" wouldn't understand, I kept it basic to show that, yes you can (where's Bob the builder) install a attic ladder and create storage space in the roof cavity but it needs to be done properly, by someone who actually does know design and spans and loads and the difference between a trimmer, hanger, joist, rafter, purlin, strut, collar tie, flyer, top and bottom chord, web, gang plate etc etc etc. I hope that's not too laypersonish for you is it?
Noooooooooooooooooooooooooooooooooo!!!!! Its spelt AVOTROL.