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Anyone use shipping container as concrete form?

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
As part of a shop addition this summer I want to build a tunnel that connects two buildings (yet to be built) that are 70 feet apart. There's a lot to consider. I have a large stockpile of 3" pandeck so I can form the walls conventionally and pour the pandeck in as the ceiling. If I use pandeck the tunnel would only be about 5 feet wide. However, doing the math on form materials to build the wall forms has me spending about what a couple nice 40 ft conexs would cost me delivered. Using containers would add about 20% to the concrete cost, but that's not a big deal.

What kind of internal wood bracing would I need in a shipping container to keep the walls from buckling from the pressure of 8" of concrete on the sides and 12" on the roof?
 

MaxPrairie

Hot Rolled
Joined
Jul 9, 2015
Have you looked into precast walls and planks?
Concrete weighs 150 pcf and your side load while pouring will be triangular.

< 0 FEET (GRADE) 0 PSF
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<<<<<<<<<< 10 FT 1500 PSF

If you choose to use the shipping container I would use jack posts like a guy would use in his basement for supports.
 
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Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
From this, 330lbs sq/ft: How much weight can a shipping container roof support? - Quora

And a Sq/ft of concrete 12" is about 135lbs, so you've got a ~2.4 safety factor.

No way it's that much. Most container roofs are just 20 gauge or so with ribs every foot. They are barely adequate to walk on. I think if a person jumped on the roof hard enough you could dent it in a few inches. They are not tough. The sides are pretty stout though.

If I form the tunnel from scratch I need to use plywood or 2x forms and have to build them in a way I can get them out without destroying the forms. I have actually constructed an underground concrete room in a previous shop I rented and getting the forms out was a nightmare so I want to be proactive in that area. The thing is- If I can brace inside a sea can with a bunch of random 2x lumber I can use up a ton of junk I already have and I can use a bunch of the lumber I'm going to use to build the buildings above the tunnel- I can likely reuse most of it or it's free. I don't need to spend a fortune on 3/4" plywood or metal forms that I can't re-use after the fact.
 

Milland

Diamond
Joined
Jul 6, 2006
Location
Hillsboro, New Hampshire
It's good to be cautious - how about doing a test with a bunch of improvised water load bags on a couple roof segments, to approach 150/lbs sq ft? See if you're comfortable or not with the settling.

[Might go with sand rather than water, given the drought out West]
 

MaxPrairie

Hot Rolled
Joined
Jul 9, 2015
No way it's that much. Most container roofs are just 20 gauge or so with ribs every foot. They are barely adequate to walk on. I think if a person jumped on the roof hard enough you could dent it in a few inches. They are not tough. The sides are pretty stout though.

If I form the tunnel from scratch I need to use plywood or 2x forms and have to build them in a way I can get them out without destroying the forms. I have actually constructed an underground concrete room in a previous shop I rented and getting the forms out was a nightmare so I want to be proactive in that area. The thing is- If I can brace inside a sea can with a bunch of random 2x lumber I can use up a ton of junk I already have and I can use a bunch of the lumber I'm going to use to build the buildings above the tunnel- I can likely reuse most of it or it's free. I don't need to spend a fortune on 3/4" plywood or metal forms that I can't re-use after the fact.

If you can find a deck profile similar to your shipping containers you can get an idea.

https://vulcraft.com/catalogs/Deck/Vulcraft-Steel-Roof-Floor-Deck-Manual-Aug2018.pdf
 

dalmatiangirl61

Diamond
Joined
Jan 31, 2011
Location
BFE Nevada/San Marcos Tx
A shipping container will not hold up to being buried in dirt, so I think its pretty easy to say it will not hold up to being used as a concrete form without a shload of interior bracing. The strength of a container is in the corners, and is only for a vertical force.

I'm not an engineer, or a concrete expert, but I have poured concrete in overhead applications, we used screwjacks spaced every foot, and a lot of prayers.
 

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
The church behind my sister built a long drainage tunnel. The dug a trench and poured a floor. No idea if they put in rebar for the walls and roof. They sat a metal tunnel on the floor shaped like a wagon top. Vertical sides, arched roof. it was about 6' long. Poured concrete over it and waited a few days. Then they winched the form forward another 6' and repeat.
Bill D
 

Chip Chester

Diamond
Joined
Dec 13, 2007
Location
Central Ohio USA
I see these ADS Storm-tech arches at various construction sites around town. They're designed to go under parking lots. They're not quite tall enough without a sidewall, and they are certainly not designed or rated for human traffic. But they look like lots o' fun.

https://www.adspipe.com/water-management-solutions/detention-infiltration/stormtech-mc-7200

Agree with above that the strength of shipping containers is in their frame and (sometimes) floors. If it weren't for the sidewall weakness, best approach would be to turn them upside down before use.

What does the roof have to support for this tunnel? Are we talking dump trucks and concrete trucks, or is it someplace it won't get driven on by anything bigger than a lawn tractor? If there's a pre-cast concrete company nearby, a few large vault structures end-to-end would get it done, for a fee...
 

wheels17

Stainless
Joined
May 10, 2012
Location
Pittsford, NY
If the concrete gets under the container, you are at risk of it floating right up. If the concrete is only 2 feet deep on the sides, a 20' container has a buoyancy force of about 50,000 lbs.
 

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
If the concrete gets under the container, you are at risk of it floating right up. If the concrete is only 2 feet deep on the sides, a 20' container has a buoyancy force of about 50,000 lbs.

It would only be on the sides. Every few feet some of the rebar from the bottom slab would be bent inward and welded to the containers to keep them in position.

I think I would be more worried about shifting the containers side-side during the first lift than the container floating up. I think the mud would tend to apply a down force to top of the beam at the base of the corrugated wall.
 

FredC

Titanium
Joined
Oct 29, 2010
Location
Dewees Texas
Anyone here done a house or a wall with Integrated Styrofoam Forms or seen it done? I have seen the forms, seem like that were 2 inches thick inside and out with plastic straps tying the sides together. I never have seen them filled with concrete but that 2 inch foam has to be weaker that the sides of a shipping container. Just guessing but the secret maybe is going around the structure and pumping in the concrete a foot or so at a time. By the time you get around the house the first concrete has probably partially set?

I was going to have my house done with the ICF walls for a time, but I dropped back and punted with cinder block walls with the Styrofoam glued to the outside.

The roof would need some thinking from what has been said, it will need rebar. Anything wrong with welding the first run to the roof with spacers to hold it off the roof?
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
Anyone here done a house or a wall with Integrated Styrofoam Forms or seen it done? I have seen the forms, seem like that were 2 inches thick inside and out with plastic straps tying the sides together. I never have seen them filled with concrete but that 2 inch foam has to be weaker that the sides of a shipping container. Just guessing but the secret maybe is going around the structure and pumping in the concrete a foot or so at a time. By the time you get around the house the first concrete has probably partially set?

I was going to have my house done with the ICF walls for a time, but I dropped back and punted with cinder block walls with the Styrofoam glued to the outside.

The roof would need some thinking from what has been said, will need rebar. Anything wrong with welding the first run to the roof with spacers to hold it off the roof?

Those have a strap thru the concrete, much like the industry standard of snap ties & Jahn clips.

The container form has no such bracing.
 

CITIZEN F16

Titanium
Joined
May 2, 2021
Looks like lumber prices that had fallen off are back up to all time highs, yikes! Do companies rent concrete forms?
 








 
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