[Zumba]

Walter, I think you're spot on about needing reinforcements.

E/G and E/Q (I guess they're pretty much the same thing) have excellent rigidity at 5,000ksi (1/2 that of Aluminum, 1/6t that of steel).

But tensile strength is rather miserable at 2200psi according to the "Anocast" documents that were posted in this thread awhile back. Compare this to the yield stengths of carbon steel and aluminum - 36,000 and 60,000 psi, respectively.

I believe the 2200psi number for E/Q is ultimate strength. That stuff won't bend, so there is no yield strength number available. Those numbers for steel and aluminum are yield strength numbers. Ultimate strength is even higher, but since a bent piece of metal is useless, ultimate strength doesn't really matter in this case.

So yes, if you're not going to fill a steel tube, you should probably add rebar. One benefit of rebar is that it's so damn cheap, but I'd be cautious as to the mystery metals that might be in there. Perhaps it may be wiser to use 1018 rounds? Even those are pretty cheap from Enco with free shipping.

[LeeWay]

So yes, if you're not going to fill a steel tube, you should probably add rebar. One benefit of rebar is that it's so damn cheap, but I'd be cautious as to the mystery metals that might be in there. Perhaps it may be wiser to use 1018 rounds? Even those are pretty cheap from Enco with free shipping.

Part of the strength you get from rebar is in its gription. It doesn't slip easily through. Any smooth rod would not do as well. Threaded rod might work okay. Acme would be better, but rebar is hard to beat for its purpose and cost. You can always step it up in size if you are worried about its strength. Then again there are ratio's for that too. I do know that 1" rebar is some very strong stuff when surrounded by concrete.

[walter]

So yes, if you're not going to fill a steel tube, you should probably add rebar. One benefit of rebar is that it's so damn cheap..

Check out the rebar "cage" in post #404 on page 34.

I thought the 8020 idea was pretty good too.. We've got 8020, steel tubing, I beams, C channels.. You name it.

I should just go buy the 8' of C channel and encapsulate it with E/Q. That would be a good test..