New Amazon DC being Built in Tulsa Sets Record for Tilt Up Panel Height, as New Technologies were Required to Make it Work in Scheduled Time

It no secret distribution centers are getting taller, to provide more effective space for a given square footage of ground real estate used.

In late December, for example, real estate firm CBRE said its research showed that new US DCs on average had a "clear height" of about 32 feet, up from 28 feet 6 inches about 10 years ago.

Supply Chain Digest Says... The resulting tilt-up composite panels are an amazing 81-feet tall and 13 inches thick, with two 5-inch concrete layers. What do you say? Click here to send us your comments Click here to see reader feedback

What's more, in some popular distribution areas, where square footage is hard to acquire and is expensive, some developers are deciding the answer is to go up, with multi-level DC designs.

For example, in 2017 SCDigest reported on how warehouse developer Prologis broke ground on a new 590,000 square-foot facility that will have three levels and be located two miles from the Port of Seattle and five miles from Seattle's downtown.

Such multi-story DCs are already becoming popular again in parts of Europe and Asia. In fact Prologis says it has built more than 50 multistory facilities in Japan and China.

But even more topically, the focus on ecommerce and rapid deliveries in urban areas is naturally pushing distribution companies to consider going vertical in places where land is difficult or find and/or very expensive.

All of which led Amazon to tell financial analysts that it may change the way it reports its fulfillment center assets.
In its recent Q3 earnings call, Chief Financial Officer Brian Olsavsky said that Amazon could start using cubic feet, instead of square footage, to measure its fulfillment center footprint. That would change the measurement from one of sheer size to one of volume, and give a clearer picture of how Amazon is becoming more efficient or not as its inventory grows.

"We are debating whether the dynamics of the warehouse are changing, so that square footage may not be the main indicator - it might be cubic feet," Olsavsky said. He said that if the company makes a change it will provide more detail to investors, but he didn't say when a decision will come.

And that actually makes a lot of sense – cubic feet really does provide a more accurate metric of capacity than does square footage.

But it looks like Amazon is going even higher.

In June of 2018, local news sources reported the city of Tulsa was negotiating with Amazon to construct a distribution center in the Tulsa metropolitan area.

A preliminary site plan presented to the city identified the development property as "Project Dylan" and showed the footprint of the building to be 640,000 square feet. The plans were initially said to be for a four-store building, making the effective space over two million square feet, though if it was to be a true multi-story building or simply rise that high to handle say automated storage and retrieval systems was unclear.

(See More Below)

Just recently, an article in a construction magazine Engineering News Record (ENR) reported that a new DC being built in Tulsa would require "tilt up" composite exterior wall panels that reach a record 81 feet in height, requiring use of an unusual bracing system and a lot of careful pre-planning.

"It was originally designed in precast, but they couldn't do tall enough panels," Jeff Cannedy, a project manager at construction firm Clayco, which led the development of the new DC.

Clayco said the steel-frame building was also too tall for stacked panels to be used. While lower panels could be braced to the ground, the upper panels would have to be held up by a crane until the steel connections were made, which the consruction schedule did not allow for.

"But a full-height panel can be braced to the ground and not just the steel," Cannedy added. The resulting tilt-up composite panels are an amazing 81-feet tall and 13 inches thick, with two 5-inch concrete layers.

Amazon's requirements drove the unusual approach, says Karen Hand, structural engineer with the project's structural wall panel designer, Needham DBS. "The reason we have these panels so tall is many ecommerce logistic centers are going toward having multi-floor spaces to increase their efficiencies," she says.

The key component that allowed the tilt-up process to work was a Super 62 brace, anchored to the ground and to an embedded insert in the panel. At 62 feet long, 9 inches in diameter. and 950 pounds, it's no ordinary brace. "The Super 62 can accommodate panels up to 90 feet tall. It's really new to the [tilt-up] industry to go to those heights," Mike Wolstenholme, project executive with brace manufacturer Meadow Burke, part of the design team, told ENR. He added that "This [Super 62] brace was created just for this project, it was the first project in the country that a brace of this nature has been used."

Amazon is said to be in the midst of a similar project in Beaumont, Calif. With seismic codes and regional differences in construction methods taken into account, the designers went with a modified version of the massive tilt-up panels used on the Tulsa project. On the Beaumont job, referred to there as Project Cherry, structural wall panel designer HSA & Assoc. went with a load-bearing tilt-up panel that allowed for the perimeter steel to be taken out of the design used in Tulsa. "It's the same building, same design, just a different [structural] design solution," Cannedy said.

"The thing about this is that the height limitation [for concrete tilt-up] has been overcome," says Clayco's Cannedy. "Panels in general have never extended much beyond 60 feet to 65 feet, but both of these projects have 70-ft to 85-ft panels. You'll see the limitations being overcome in projects across the country."

How high will we see DCs go? What do you think of this construction strategy? Let us know your thoughts at the Feedback section below.