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Rethinking the Ubiquitous Shipping Container

By Kevin Wilcox

A new building designed for a trendy Minneapolis neighborhood will be built modularly from repurposed shipping containers.

May 27, 2014—The new mixed-use building under design for 506 Fourth Street North in the gentrifying Minneapolis neighborhood of North Loop embraces recycling to an extent few projects can claim. The 15,000 sq ft structure will be constructed from 62 repurposed international shipping containers.
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A new mixed-use building in Minneapolis is reusing robust steel shipping containers arranged into a 100 by 100 ft rhomboidal donut shape for its structure. Some of the containers will be cut at angles of 30 or 60 degrees to form dramatic points, and windows will be added with carefully designed support systems. © LOT-EK

The containers, each 40 ft long, 8 ft wide, and 9.6 ft tall, will be arranged into a 100 by 100 ft rhomboidal donut shape. Some of the containers will be cut at angles of 30 or 60 degrees to form the dramatic points of the structure. One half of the three-story building will be raised off the ground by one story, creating open access to a central courtyard.

This innovative design is the work of the New York City-based architecture firm LOT-EK, with structural engineering provided by Robert Silman Associates, also of New York City. The dramatic shape of the building forms a sharp point at the street corner. "It [is] extremely pronounced visually, while also creating these interesting terrace and landscape areas to the side and underneath the raised portion," said Eytan Solomon, P.E., A.M.ASCE, LEED-AP, an associate of Robert Silman Associates, who wrote in response to questions posed by Civil Engineeringonline.

Standardized shipping containers came to prominence in the 1950s as a way to speed the intermodal transport of freight. In the United States, thousands of these weathering steel shipping containers are discarded each year after approximately 15 years in service. Trade imbalances cause some to be discarded sooner. But the containers remain exceptionally robust structures even at the end of their working lifespans, having been designed to support a load of more than 29 tons.

"The containers are indeed recycled from the shipping industry," Solomon said. "While some may see heavy use, most are used just once, so are in excellent shape. For the most part, since they are functional in industry, they can easily be adapted for architectural use.

"We not only call the containers 'recycled,' but we often call them 'upcycled,' meaning we are taking this resource ... and making a quantum leap in its productive use through a creative design process," Solomon added.

Engineering a modular building from shipping containers presents the design team with several engineering challenges, Solomon said. Because the containers are designed to stack and nestle together, welding them to each other and to lower steel-support structures is often straightforward. However, the addition of windows and doors creates the need for careful reinforcement.

"The containers 'work' structurally by the side walls acting as deep beams spanning all the way between the far-end casting supports," Solomon explained. "The roof deck braces the tops of the deep-beam walls and the floor joists span between the bottoms of the deep-beam walls. So when you start cutting those elements to make usable spaces, reinforcement starts to become required to make sure there is a competent load path."

Structural steel is welded onto the steel of the container to maintain these load paths. Care is taken to keep these new structural elements within the original dimensions of the container so the work can be done off-site and the containers transported to location by truck when the work is complete.

"One advantage ... is that the [International Organization for Standardization] ISO standards require containers in industry to be designed for huge live loads and many other different load and support cases, so that they can be loaded, lifted, swung around, stacked, and transported on a rocking boat or rattling train or truck," Solomon said. "So there is this robustness already inherent in them, which we can cleverly take advantage of when we go to use them literally as a building block for architecture."

There is an existing parking structure on the Minneapolis site that will extend beneath one half of the building. Steel framing at the base of the new structure will transfer loads onto approximately eight columns in the parking structure below. That parking structure's original engineer, Ericksen Roed & Associates, of Minneapolis, is on the design team to ensure that the load transfer is handled smoothly.

The other half of the new structure—the elevated section—will employ similar steel framing to transfer building loads to exposed columns that will be supported by new foundations, Solomon said.

The mixed-use structure will house the offices of a data-driven communications agency, with retail space and a restaurant occupying the lowest level. Construction of the modular structure is expected to move swiftly, with project completion slated for 2015.


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