A “supertall” building is one which tops out at over 1,250 feet. Right now, there are 18 completed supertall buildings and 21 under construction. Chicago-based architects Skidmore, Owings, and Merrill (SOM) will break ground on Tuesday on the 1,740-foot-tall CTF Tower in Tianjin, China. It will be the tenth supertall building to begin construction for SOM, the most of any firm in the world. The building is a carefully-crafted design which deliberately merges structural challenges with program and form.

The mixed-use tower in the Tianjin Economic Development Area, an area planned for new growth, has retail at the base, topped with offices, 300 residential units, and a 350-room, 5-star hotel. “The functional aspects of program were integrated with the structure,” said SOM design partner Brian Lee. “And the form was also developed alongside the structural scheme.” Larger floor plates are needed for the office spaces, which are placed near the base of the building. Residential units with smaller floor plate are at the top.

The gentle curves of the building and the large, sloped, concrete elements form a “mega-column,” which acts as an external frame. Environmental conditions also affected the final design. Wind slots, a porous crown at the top of the tower, and a gradiated opacity toward the higher floors all help to decrease wind loads, and the corners are rounded to prevent a vortex effect on the back side of the building.