How much weight will 2″ aluminum angle support?

Question by wskinn: How much weight will 2″ aluminum angle support?
I am building the benchwork for a portable model railroad. I would like to use 2″ aluminum angle bonded to the edges of 2″ thick x 24″ wide pink board insulation panels. How much weight can I put on a 5 foot span? Rough guesses are good, telling me where I can find aluminum angle span tables would be great!

Best answer:

Answer by Bomba
We could use some more information on the angle, but I will just pick one, a 2″x2″x3/16″ having a section modulus (Z) of 0.19.
Also I will presume the load from the table contents is uniformly distributed and not concentrated in the center, and that the span is simply supported. Annealed low alloy aluminum has a tensil strength of about 12000 psi. I will use half of that for the design stress. (I would use even less if it was a larger more serious structure.)
The bending moment “M” for that configuration is WL/8 where W is the total load. L=60″ so M is 7.5 W
The formula for bending stress is S = M/Z
6000 = 7.5W/0.19 so W is 152 pounds distributed across the 5ft length.
If the allowable load was indeed concentrated in the center it would be 76 pounds and the deflection downward would be about 1/8″
This is a bit on the conservative side so I would not be concerned with a 100 pound concentrated load directly on the angle.

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