Shipping Containers 1

[XR250]

I have an Arch. who wants to design a structure using shipping containers. I have found information on the vertical load capacity of the roof and the horizontal load capacity of the sides, but nothing on the actual lateral capacity of the unit. It would seem that the solid end wall would provide stability for one end, but at the door end, what provides the stability? Is the framework surrounding the door acting as a moment frame or is it designed as an open ended structure?

Thanks

 

[Ussuri]

Taking a bit of a punt, as I have never designed one, but a common standard for offshore containers is DNV 2.7-1. It gives requirements for the design of containers. Quoting from the standard:

Clause 4.1.1 Structural design

Containers shall be designed as structural frames (primary structure), with non-load bearing cladding where necessary (secondary structure). Only the primary structure shall be considered in the design calculations.

Which suggests they are designed as a frame.

I am sure there are other standards for containers as well.

 

[XR250]

Thanks for the reference. I do not see anywhere in the standard that discusses lateral stability.
I wonder if this is ever explicitly addressed in the design?

 

[Ussuri]

This link may also help you, its from Lloyds Register and is related to container securing on vessels. It also gives some references to ISO standards for freight containers.

http://www.lr.org/sectors/marine/documents/175167-a-masters-guide-to-container-securing.aspx

They state that the racking resistance of the container is provided by the panels. They also state that the racking resistance of the door end is about 4.5 times less than the opposite end.

To me, the container frame must function as a moment frame at the door end, as I don't see how the doors can provide much in the way of resistance.

This might also be a useful link as it seems to suggest that lateral loads the container will be subjected to as part of its testing regime.

http://www.containerhandbuch.de/chb_e/stra/index.html?/chb_e/stra/stra_03_01_00.html

When stacked on vessels the containers are usually secured to the deck using diagonal tie rods, connected into the iso pockets on the corners. So there will be a horizontal load applied to container.

Not sure if this is much help though.

 

[XR250]

thanks!

 

[XR250]

The example shown shows a racking strength of 33.5k at the door end. That is a pretty significant load for a moment frame. My guess is that this is with the doors closed and they are providing the lateral stability.

 

[Ussuri]

http://www.iso.org/iso/home/news_index/news_archive/news.htm?refid=Ref1045

 

[Ussuri]

You do get some containers with plywood sides. In that case they would provide significantly less racking resistance than corrugated steel panels.

 

[bookowski]

This has become a popular idea with architects lately. We've been asked to look at it a couple of times but have run into obstacles that keep it from being a realistic structural system. It depends where you are located - but around here I've only seen it done for small structures, or where there is an independent system added to or built around the container.

Here we haven't had much luck with getting the building department to look favorably at using containers for anything substantial. They have a lot of questions/concerns, things like: fire rating - what UL assembly are you referencing, one developer had testing done to get a UL rating but was unable to pass the test, inspections/testing - who is going to sign off that a container meets your specs, containers are governed by a performance spec - i.e. Xkips at each corner, Ypsf pressure on side walls - but they may meet that with different geometry/materials, how will you relate that to building code requirements and reference standards. Connections are also an issue. For anything substantial we have redundancy requirements that require tension connections as a percent of gravity etc. - you need to start coming up with funky custom connections that take tension, shear etc. across the container joints.

I know that they have been used in some locations - might just depend how open your building department is to new/different systems.

 

[XR250]

Interesting...

"Containers that have one or both doors removed for the transport of special cargoes shall be assumed to have reduced racking strength and shall similarly be stowed within cell guides or in the uppermost tiers on deck"

so, clearly, the doors are acting as shearwalls.

 

[XR250]

@Bookowski

That echos my concerns. I decided to pass on this job.