On Jul 24, 3:57 pm, Bruce L. Bergman

Much depends on what the ends are like. My pallet rack collection is
3" channel with perforated bars welded onto the ends to bolt them to
the columns. The bars are wider than the channel and don't fit well
together. I planned to bolt the sections end-to-end for sawmill track
but getting them flush, smooth and straight was too much effort, so I
sawed the end bars off and used them as lengthwise splices.

There is an 8' wide vehicle shed near here. The doors are hinged to
the side walls to maximize the opening, which makes that end unsteady,
and wind & snow loads have ripped the hinges off the doors. If you
welded the 4 corners it might be stiff enough, maybe. Upper corner
braces would help.