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I have a stock of surplus i-beams (aluminum) and am trying to build a structure where they are not always parallel. I understand i-beam is designed to be aligned vertically and optimized for strength in that direction.

What is the strongest way to connect i-beams at that are not parallel?

enter image description here If you bolt plates onto the sides there is a gap behind the plates and you either need a spacer behind or need really long bolts which may be harder to find. Also you are bolting into the web which seems less strong to me.

enter image description here If you have a bracket plate (red is welded) on the inside of the angle you can bolt into the Flange - this seems stronger also your bolts don't need to be super long.

enter image description here Having an plate bolted to the inside of the web?

Assume you have the option to cnc custom plates / add bolts / or weld... which is best in terms of layout and where to bolt to?

stackzz
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  • "I understand i-beam strength is strongest when aligned vertically." Care to rephrase that? Not all loading is vertical. – DKNguyen Aug 30 '21 at 01:24
  • Can you weld aluminum? Or is the plate in example 2 another material? – mart Aug 30 '21 at 07:08
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    Yes - can weld aluminum – stackzz Aug 31 '21 at 02:43
  • rephrased "I understand i-beam strength is strongest when aligned vertically." to "I understand i-beam is designed to be aligned vertically and optimized for strength in that direction." - Thank you @DKNguyen – stackzz Aug 31 '21 at 03:09

2 Answers2

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Increasing the size of the gusset plate is a bit deceiving first thought. But a disproportionally large gusset can cause stress concentration and even section failure right at the point of termination of the gusset.

There are strong joint connections that are designed to be tough and ductile at the same time, this is one example.

The stiffeners make the joint tough and give it ductility to absorb a lot of energy even if loaded beyond the plastic range.

apex joint

kamran
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This is what I might do, with or without the gusset plate. If you use a gusset plate, chop off the corner to allow for continuous welding.

enter image description here

r13
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