When considering the resistance to bending and the compression strength of square tube vs round tube, which is "stronger". I'll qualify that with an example; 3/4" X .065" square 6061-T6 aluminum vs. 3/4" X .065" round of the same material. How would they compair in bending and compression loads? Considering the round is +/-75% of the weight of the square, is the resistance to bending and strength in compression compairable, higher or less? Is the load comparison somewhat similar to the difference in weight? Tension I would expect to be reduced by the reduction in cross section area.

A second way to ask the question would be how do they compair on a Lb. for Lb. basis? Which would offer more bending resistance and handle a higher compression load, a round tube with thicker wall or a square tube, but with the same O.D., ie. 3/4" Sq vs. 3/4" Round, but weighing the same in terms of #/Ft.?

I was always under the understanding that # for #, round was the stronger shape compaired to square. Maybe the answer is different for torsional strength vs. bending or compression?

Square is certainly easier to use in fabrication since no "fishmouthing" has to be done to intersecting tubes. I'm more interested in getting the biggest bang/Lb.

As always, thanks in advance for input and answers.

Lynn