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box tube strength

box tube strength

box tube strength

Looking for the amount of weight for a 2x2x1/4 box tube 20' long vertical with a 3'x2x2x1/4 box extension on top and base is 12" 2x2x1/4 box with 6x6 gusset on 2 sides of top extension and base, noticed alot of flex in the tubing because of the length but was wandering how much would it hold before bending or breaking ??

RE: box tube strength

I would look at buckling of the column as the first failure mode. Treat it as a complete column first and use Euler's formulae to give you the buckling load.

RE: box tube strength

Tube 2X2X1/4 is very slender member for the 20 foot height. I would never use suck a slender member. That may explain why it is so flexible.

I would be concerned with buckling more than bending as corus explained above. If you must use the same tube size, consider reducing its unsupported length/height.

Good luck.

RE: box tube strength

I agree w/ Corus and Lutfi - 2x2 and 20' in height? Even it would carry the load w/o failure, the servicibility of it will be a problem.  The deflection would be huge and the vibration (bouncing) will be a problem as well.

Anyway, if you are to use it, here;s a list of limit states whatI think you should check:
(1) Local Buckling of Plates in the tube, i.e. b/t ratio
(2) Overall Column Buckling

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