Text by Nate Berg
The twin towers of Jiangxi Nanchang Greenland Central Plaza, Parcel A, were about halfway built when Skidmore, Owings & Merrill (SOM) received a somewhat inconvenient request from the developer. Instead of the designed height of 289 meters (948 feet), the towers were to be adjusted, mid-construction, to reach 300 meters (984 feet). “Adding 11 meters to a building that’s already under construction is not necessarily an easy task,” says lead designer Mark Nagis, AIA, who is based in SOM’s Chicago office.
At that stage of construction, there weren’t a lot of options that would pencil out with the building’s existing engineering and load management design. Nagis and his team went back to the drawing board, then to the 3D printer, then to the wind tunnel. After testing the structural loads of their design alternatives, they found a solution in an elegant crown covered with gently angled glass panels. The panels add the desired height and open like vertical blinds to allow the prevailing east–west winds to blow through, load-free.
Completed in January at an official 303 meters (994 feet), the matching office towers are the tallest buildings in Nanchang, the capital of the Jiangxi province in southeastern China. The towers, developed by the Greenland Group, total 2.18 million square feet and anchor a brand new high- and mid-rise district just across the Gan River from Nanchang’s old center.
The towers are conspicuous in the new skyline, and not just for their height. Each one transitions from a rounded square base to a more tubular form in the midsection to a squished cruciform in the crown. Both twist slightly to maximize views over the growing district, a new park, and the old city.
The towers are enclosed in smooth glass held in place by a structural sealant. “It’s curving in two directions,” Nagis says. “So it’s a fairly complex surface.” When the project was first sketched out in 2008, SOM’s architects weren’t even sure manufacturers could produce the glass. “The design concept demanded that it be parametrically analyzed from the early stages,” says project manager Michael Pfeffer, AIA. “Our structural engineers were sitting side by side with us the whole time.” The geometry made the prospect of a smooth curtainwall especially tricky.