QueticoBill wrote:Just for bending strength, a channel will be stronger than a square tube that weighs the same per foot. Consider a C3 x 4.1 is a 3" channel weighing 4.1 plf and has a moment of inertia - the property that determines bending in the X axis - of 1.66. A TS 2x2x3/16 weighs more at 4.32 plf but has a moment of inertia of 0.64 - less than half.
My opinion is there are advantages and disadvantages of each that are far more important to consider than just the bending strength per pound of steel, especially for the relatively short spans in tiny trailers.
On galvanized, I believe nasty to weld and you still have to protect the welded area, but I'm old and there may be newer ways to solve that than were available when I learned welding - in 1969-1970.
Now look up 2x3 .085, its 3.7 pounds a foot, and is stronger than 2x2 3/16.
C channel is strong enough until its not and it fails dramatically. Watch the video posted above by Mick.