"Rob Stokes" wrote in message
s.com...
Depends on the load, but I'm assuming you mean under deflection. If so,
the
square post is stronger as it has a larger surface area associated to the
top and bottom chords. This assumes all corners have been broken for
stress
concentration relief. If you mean a load under tension, it's strictly a
matter of cross sectional area (assuming a consistent modulus of
elasticity
across the section) thus the square section again would win...as it would
under compression.

Rob

Have to be a little careful with compression of a post. A lot depends on
the support conditions of the column, but you don't have to get a very
slender column (i.e. long in relation to cross-section) before buckling
becomes the primary failure mode. In this case, moment of intertia, not
cross-sectional area, will be the deciding factor. It still favors a square
cross-section over a round one, just not as much as the cross-sectional area
alone would lead you to believe.

todd
(gotta use that materials engineering education for something these days).