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I have a 2" square stock 1/4 thick hollow. It's 210" long. It's being supported on each end by 4". How much weight can it hold in the center

It's 1018 cold steel 1/4" rounded edges and hollow. I just need approximately how much weight it can hold in the middle. It is supported on both sides by 4". Total piece is 210". Just need an idea of weight it can hold not using this to live underneath it, it was just holding something up in the backyard shed just need an idea that soul can't hold 200 pounds 100 pounds Etc. It's also floating on cinder blocks 4 inches on each side

Tester101
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Mike Jacobs
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    Answers depend on the amount of deflection allowed (which is never zero) - so your question needs to include that information. Also it depends on the material: titanium, steel (what grade), aluminium, cheese? – RedGrittyBrick Apr 29 '16 at 12:52
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    need the following: 1) alloy, 2) wall thickness, 3) cold rolled, hot rolled or extruded, 4) cross sectional details or youngs modulus, 5) radiused or square edges, 6) how is the load going to be attached, 7) how are the ends supported (sitting on blocks, welded, bolted, free floating, etc. – personal privacy advocate Apr 29 '16 at 13:35
  • Doesn't this seem more like a physics or engineering question? Should it be moved to another forum? – Ben Welborn Apr 29 '16 at 14:09

2 Answers2

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2" at 17 feet - pretty much none. That's going to act more like a wet noodle than a beam.

The 2x2x1/4 load tables here (page 35 or 65) stops giving any load figures at 5 feet. While the steel type is probably not the same, the difference steel type makes is small compared to the difference geometry makes.

http://www.cousesteel.com/AndysPlace/Pdf/LRFDBeamLoadTables.pdf

Ecnerwal
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I want to thank ecnerwal for that link. I used the (little bit of) data avaliable from that info to create a formula/graph, extrapolating the weight that such a "beam" could hold. I found that the breaking point is about 8.88 ft.

So, it is interesting that you have a 17.5 ft piece. Since you have it supported on either end by concrete blocks, it makes me wonder how it is withstanding it's own weight.

enter image description here

Ben Welborn
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