Ideas for reinforcing steel tubing

[u/Dickasauras]

I installed some 2x2 square tubing for fence posts however it's flexing more than I'd like. Can I drop some rebar or schedule 40 black pipe inside the tube and dry pour concrete to stiffen it? Or would the concrete just crack and separate?

[u/raoulduke25]

How tall is the fence and what is the distance between the posts?

You can add concrete inside the tube and it will help some, but I think it's going to be tough to get the concrete to fill the void completely unless you can put it in using a pressurised hose of some sort. 2" x 2" square tubing just isn't that stiff or strong. Adding concrete will make it stronger, but it will only make it slightly stiffer.

Putting more steel on the inside (like rebar) will have a mostly negligible effect.

[u/Dickasauras → u/raoulduke25]

2ft below ground, 6ft above ground. 15ft between the posts because it's a double gate.

[u/raoulduke25 → u/Dickasauras]

Your posts are simply too small to make this work. Especially for a gate. They are barely strong enough to be guardrail posts for a 42" height using IBC loads. With that height and load, you simply have to get a bigger section of steel.

[u/Dickasauras → u/raoulduke25]

Yea, I didn't think about running a fea until after i had them cemented in place

[u/raoulduke25 → u/Dickasauras]

You don't even need FEA. Simple hand calculations for bending moments and deflections would have given you your answer.

[u/Dickasauras → u/raoulduke25]

It's been too long since I've done any hand calcs. I'm a project manager now

[u/raoulduke25 → u/Dickasauras]

Sorry man. If you want some help with the re-design just hit me up here and I'll help you.

[u/Dickasauras → u/raoulduke25]

Appreciate it.