John, John - I fear you are attempting to "over-engineer" your trailer
project. The working loads imposed on a highway trailer are more complex
than the "relative load bearing characteristics" you seek. Simply stated,
it is impossible to anticipate in advance what the actual working loads will
be -- think of rough roads, sudden braking stops, overloads, joint design
etc and even if you are a skilled structural engineer, you will eventually
have to pull some of the unknowns out of the air. I suggest that you
examine an existing unit that has proven satisfactory under similar loading,
and use that for a preliminary design. Safety should be an important
consideration, and thus an overdesign makes good sense. The cost of a
failure would be far higher than any savings from a cheap design. Cheers,
Dave


"John Allen" wrote in message
...
Does anyone know of a good site which perhaps has a calculator on it for
determining the relative load bearing charastics of small (50mm x 50mm x
3mm) HRS and Equal Angle steel sections. I have some plans for a trailer
which shows using 50*50*5 equal angle and would like to know what
size/section of HRS would provide the equivilant load bearing and overall
strength charastics.

Tks John Allen