Structural Engineers

Category: Buildings Made From Shipping Containers

No, You Can’t Bury Containers!

I get asked over and over again if you can bury shipping containers.  Fortunately, most people accept my answer, which is simply – no.  In fact, just the other day an architect I work for sent me a question about whether a container could be buried.  I answered, “no, it will crush like a beer can.”  He wrote me back – “thank you George” and that that was it.  I guess that since I am a licensed Professional Engineer with 35 or so years experience in construction, plus a Master of Science from Columbia University in with a heavy concentration of structural engineering convinced him that I know what I’m talking about.

Unfortunately, not all people are like that.  One one site I was quoted about this matter, and the answer came back from some fool that said,  “hey, they stack them like 30 high on ships, so they can be buried”.   Well, do your math.  A container is 9 1/2′ tall.  If you stack them like 30 high, that comes out to be 285 feet high.  That’s a 28 story building.  Have you EVER seen a 28 story high merchant ship?  A slight wind from the side would roll the thing over.  OK, let’s look at how incredibly strong containers are – for STACKING!  You can stand on top of a can of beer can and it will probably hold your weight (provided you aren’t too heavy).  Lay the beer can on its side and stand on it.  If you are stupid enough to do this experiment, do it in your living room on the carpet right after your mom cleaned it.  Because if you are this stupid you probably don’t have a job and you live in your mom’s basement.

Shipping containers have very little strength from the side.  They have 0.07″ thick steel on the side which is about 2 mm thick (that is the metric system for you out there that remain convinced you can bury these things).  That thin steel can take a bit of a beating from the random forklift hit, or someone hitting it with a hammer.  However, the pressure of soil at 9 feet deep is about 315 lbs/sf.  That’s a bit high for 2 mm of steel.

Now, one idiot called me and wanted to know if he could bury a container.  I told him no, its sides are too thin.  He said “but it’s made of Cor-Ten steel”.  Look, Cor-Ten steel is not a magical substance.  It is steel that is chemically formulated to not scale when it rusts.  The rust then provides a coating that protects the underlying steel, making it great for bridges and outside structures since you can save on painting them.  It isn’t any stronger than any other steel.

Every now and then I get an e-mail with a link to a You Tube video where they bury a container.  There usually is little commentary in the e-mail, I guess the sender figures I will watch the video and have a reaction like this:

 

Well, I don’t.  There are all kinds of You Tube videos.  So what?  I.  They need to do a video of that container three or four years from now when its sides have crushed in.

The next one I get is – “Well, what if I encase it in concrete?”  Yes, that is an excellent idea.  It will work.  Here’s another idea – why not just make a concrete vault and save the hassle of the shipping container?  Here in Georgia there are wall contractors that have metal forms that piece together and you can form a wall, pour it, and reuse the forms for another wall.  You could hire one of these contractors and save the hassle of entombing a container.  Unless you really, really like shipping containers.

I also get asked, “can’t I reinforce the container?”  Yes, with a lot of steel. Or, you can pour a concrete vault.  OR you can even build a vault from reinforced masonry.  Both are probably a lot cheaper and easier than reinforcing a container.  Also, neither will rust through. Cor-Ten steel is rust resistant, but I don’t know how well it will do in a buried environment, especially if you have corrosive type soils.

If you’ve gone this far, and need some more proof – look at this website!

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Why Don’t We Do Shipping Container Houses For Individuals?

I get e-mails all the time from people that want to build their own shipping container houses.  Some of them are actually quite belligerent as to why we won’t work for individual homeowners in designing these.  Some plead with us to make an exception, others ask for us to point them to a builder that they can go to that we will work with.  Let me explain our reasoning, and hopefully clear up some confusion.

First, we have done work for individuals in the past, and it didn’t work out well.  In most cases they had unrealistic ideas as to what this type of construction would cost.  If you are building a container house by yourself, I don’t care what the many other websites tell you, it will cost you about $150.00 a square foot.  Now, somebody will reply to this pointing out they “know a guy” that built a house for couple hundred dollars.  I’m not talking about a hermit living in a box in the woods.  I’m talking about a permitted legal house .  I’ve challenged people to come up with a specific house that has been permitted and follows all applicable codes that costs less – I need specifics.  If I get one of these, I will happily post about it here on the website.

Second, if you’ve ever built your own house you know what a pain in the neck that it is.  Shipping containers are not conventional.  Cutting them requires a skilled hand with a plasma torch or diamond saw.  Welding them requires a lot of tedious grinding to get rid of the epoxy paint, and a skilled hand at welding.  When you cut the sides off, the containers spring out of shape.  They have to be lifted by a crane.  This is more commercial type work, not residential.  I don’t care if you’ve built a wonderful wet bar in your basement, it’s not a DIY project. I know there are websites out there that say that they can be built as a DIY project, but there are also websites out there that say the moon landing was faked, and that the US Government has an Alien breeding program where aliens are cross bred with humans. Look, I worked for the Government, and we were too incompetent to fake a moon landing, and you would have better luck mating my parrot with my dog than a human with a species from another solar system.  You also would find building your own container house only marginally easier that mating the parrot with the dog, and would have better luck faking the moon landing.

Third is the liability.  “Liability” is often used as an excuse for poor service, but in this case it is real.  If you contract with us to design a house for you, and you run into all kind of problems as you find it’s sprung out of shape, you can’t get the floors to match up, you have problems stacking the containers, and the details have to be changed, you may get very angry instead of realizing you waded in over your head.  That’s how lawsuits begin.  It’s just not worth the risk for us.

Now, one other problem is that people that want to build a home for themselves with shipping containers get very angry when we don’t return their calls or e-mails. It comes off as impolite, but let me explain why this happens.  First off, we say in our contact information that we don’t do shipping container houses for individuals, we also say it again in this post.  So, if you are calling or e-mailing us, you probably had read that we don’t do work for individual homes, but you chose to contact us anyway.  That’s a red flag right there.

If we respond to an e-mail or a phone call, it almost always starts a bargaining session that can be very time consuming.  If you spend 15 minutes talking to me on the phone, it costs the company $50.00 in billable time.  That’s a lot of time to be spent to tell you “no”.  With e-mails, if I respond, it starts a flurry of back and forth e-mails, again trying to bargain with us.  Again, it is time consuming going back and forth on e-mails for projects that the answer will certainly be “no”.

If you really want a container house, what do I recommend you do? I don’t really have any recommendations on this.  This is something we just can’t help you with.

George

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Shipping Container House on the Weather Channel

The Weather Channel recently did a short video on one of  the shipping container houses we designed in Atlanta.  Glen Donaldson the owner/builder leads the tour.

[youtube]http://youtu.be/HRxA25AR4GA[/youtube]

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Pictures of Our Projects In Canada

These projects in Canada are in the northern part of Saskatchewan Province and were designed for 3Twenty Solutions.  3 Twenty Solutions provides prefabricated buildings for remote sites that are used by oil companies and mining companies.  These sites are inaccessible most of the year except by plane, and the only way to haul supplies up is during the winter over ice roads for many of the sites.  Since it is hard to get construction equipment to these sites, and the weather is far from perfect, as much as possible must be assembled prior to transport.  So, modified shipping containers fit the bill perfectly in most cases.

Inside a Typical Bedroom

 

 

 

 

 

 

 

 

 

 

 

Lifting Modules Into Place

 

 

 

 

 

 

 

 

 

 

 

Hallway View

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In the Kitchen – This was more difficult to design because of the open area.

 

 

 

 

 

 

 

 

 

 

 

End View of Completed Building

 

 

 

 

 

 

 

 

 

 

 

 

 

Another View of the Containers Being Lifted Into Place

 

 

 

 

 

 

 

 

 

 

 

Lifting Into Place – Note supports at ends.

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A Good Question Considering Shipping Container Structures

This question came in to me by e-mail considering shipping container structures.  It is from a graduate student that is doing research on the structural design and analysis of a shipping container building, and he is working on doing it by FEM (Finite Element Method).   Finite Element Method design is a very good way to model complex structures and lends itself well to computer analysis.  I’d like to share my answer with you all:

——– Original Message ——–
Subject: Dry Cargo Shipping Container Structural Integrity
From: “Shane xxxxxxxxxx
Date: Tue, February 21, 2012 2:13 am
To: georger@runkleconsulting.com

Dear Mr. Runkle,

I want to begin to thank you for taking the time for reading this email. I will try to keep short and clear.

I am a structural engineering graduate student at xxxxxxxxxx and I am involve in a multi-disciplinary team designing the next generation of innovative student housing at xxxxxx campus. The multi-disciplinary team has decided to design a high-performance sustainable green structure that will have a dome-mound of dirt as a green roof and the main structural system will be composed of repurposed shipping containers.

The reason why I am emailing you is that I was researching online about any structural analysis or finite-element analysis that has been done for dry cargo shipping container and came across your name at this website: (http://ronestudio.wordpress.com/2012/02/10/basic-container-design-structural-considerations/)

I wanted to kindly inquire if you know of any published information about the structural integrity of cutting walls and windows to dry cargo-shipping containers.

I have found several technical specification requirements from ISO that accounts for both static and dynamic loading but all are under the assumption that the load path is from the cargo floor>C-beam floor joist>Longitudinal C-beam>Corner fitting>Foundation (or the next lower shipping container column).

So far, roof-loading scenario of soil mound is 600lb/sq. ft. and ISO requires roof of shipping containers to handle 300lb/sq. ft. We are looking to reduce load by using alternative fill material but are still concern about combining 20′ shipping containers and cutting entire wall out. I have found one case study of a cabin that you advise by replacing entire wall with two 6″x3″x1/4″x19′ steel box beams welded the entire length of the containers. I believe this cabin did not have loading scenario as much as we have.

With that said, I kindly ask if you could share any information you have regarding structural integrity of a shipping container used as housing. I will be performing a finite-element model of our final design and I wanted to see what information is out there before I begin. Again, thank you for your time and I look forward to hear back from you!

 

Kind Regards,

Shane xxxxxxx Graduate Student

==============================================================================

Shane,

There is no published information about container strength when they are cut up, and because there is a huge number of configurations, a prescriptive type of guidance would not work.  You have to break the container down into its constituent parts and model it based on the sections of the parts.  I use a 3d FEM program (Bentley RAM Elements) and I have put all the parts in as sections.  For the sides, I use thin steel shells.  You have the following parts in a container:

1.  Rear posts – these are roughly steel angles.  It’s fairly simple to calculate the moment of inertia of these, or draw them in AutoCAD and let it figure the modulus with the MASSPROP command.

2.  Front posts – these are fairly complex members made from two different size channel sections.  The moment of inertia can be found by drawing these in AutoCAD and using the MASSPROP command.

3.  Bottom Rails – these are C sections, again fairly easy to calculate section properties.

4.  Top Rails – these are steel tube sections

5.  Side corrugations – these can be modeled as cold formed hat sections.

6.  Top corrugations – again, can be modeled as cold formed hat sections.

To get specific information on containers in the form of drawings, check out this site: http://www.isbu-info.org/

RAM Elements will automatically find all the section properties of the sections once you program them in.  The side corrugations are pretty easy, you can use existing AISI hat sections.  The other members take a bit of work using the LEO language that comes with the program.  Also, I’ve found that it is necessary to stiffen members as you make cuts in the container.  That takes again more work with the LEO language in RAM Elements to model the sections, or conversely you could calculate your section properties by hand (not recommended, too much chance of error), or a program such as AutoCAD.

 

You are right, the ISO testing is not applicable in any way.  It assumes the containers are not cut into, and is only applicable for their use as cargo carriers.  There is no way it can be used for building, although I did see it used by an engineer in his calculations.  In case of a failure, it would make for an interesting lawsuit against the structural engineer, he would lose big time.  I hope this helps.  A copy of this e-mail is going up on my blog, with your personal information removed, since your question is very good I’d like to share it with all.

 

George

George W. Runkle III, P.E., PEng, MIEAust

Runkle Consulting, Inc.

930 New Hope Road, Suite #11-145

Lawrenceville, GA 30045

678-225-4900 (US)

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www.runkleconsulting.com

 

 

 

 

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Video of Shipping Container House

This video shows a detailed view of the exterior of the 2nd shipping container house in Atlanta.

This video shows a rather limited view of the interior:

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