I've been planning on building me another shed to park tractors in. With the crazy price of lumber lately, I've been wondering about maybe using poured concrete poles instead of wood 6x6. I've formed and poured concrete fence post before, but never something like support post for a building. I'm wondering if anybody has ever done this before and will they hold up without cracking? 

I know you said you were going to do it yourself, but they have premade concrete posts that you bury in the ground and have some above ground and then attach post to. They're called perma-column I believe.

Slenderness Ratio -----------

Edited by steve(ill) - 22 Dec 2020 at 9:08am

Then the huricanes hit the south and the lumber price made another jump up by it should settling down now 

It's been a few years since I saw it but in Fl. not very far from where the Florida Fly Wheelers grounds is a place that makes very large concrete power poles. They tapered and hollow. 

Edited by Dusty MI - 22 Dec 2020 at 8:04pm

Edited by jaybmiller - 23 Dec 2020 at 10:50am

Concrete in structural form is used every day in building both in columns,  floors, walls , and even poles .  Might check with a pre-stressed concrete supplier on what is out there . 
 I did several house basement excavations where superior wall product was used , precast concrete with nailer's set in concrete and insulation cast into it also - bolt flanges on end of each 8' section to join to next section . these were set on a trench or compacted rock so no footing except rock trench . 
 Full building both below and above ground portions use similar systems . 
Another building I worked on used 8' x 20' x 6" prestressed concrete slabs stood vertical on a concrete footing so the slabs were buried 3' into ground so interior ceiling was set on bar joists allowing 16' height inside . .
  My tuck under garage on this house has a prestressed concrete ceiling that is also the floor to the room above interior of the garage is free span of 25' with the 3' planks topped with 3" of concrete . 

Current pricing for treated 6x6x16 is $100 each. A 6x6x16 concrete post contains 4 cubic feet. I can mix my own concrete for less than $50 per yd. So that means I can make a 6x6x16 concrete post for less than $10 in concrete plus rebar. I’ve got a pile of rebar I got off a job they were going to throw away. That is what got me to thinking about it.

well, there are a dozen movies on you- tube about building concrete posts... almost every one is from overseas... and they tend to be 10 ft or shorter.... but here is the idea.. cheapest version seems to be a wood form ..... oil the inside ( or have screwed together so you can take it apart) ... put down 1 inch concrete, drop in a couple rebar... add 4 inches concrete... more rebar.. and an inch of concrete on top... as Coke said, you need to put a wood knock off form on the top to eventually set a rafter onto, etc..

YEP..... concrete has very little STRENGTH in bending... Only in compression ( down ward force)... Its the REBAR that does all the STRENGTH part.

You can also laminate the post.. build them out of 3 or 4  2 x 6.. PT in the ground, above  ground can be pine.