The Thornton Tomasetti-designed frame consists of a shear-wall core with high-strength concrete connected to eight composite supercolumns by two-story steel outriggers trusses at mechanical levels. Smaller composite supercolumns are positioned between pairs of the larger supercolumns, opposite core corners, to halve the span between the larger columns. All columns slant 1.5° from the vertical.

Though the core extends to floor 67 of the eventual 121-story building, structural steel is at about the 50^th floor. Crews have installed about six levels of the flat glass units of the tower’s perimeter glass wrapper, beginning several levels above grade.

The core will top out at 580 m some time next year, said J. Marshall Strabala, founding partner of Shanghai-based 2Define Architects, which is serving as the tower’s chief architect for the building's quasi-governmental owner-developer, Shanghai Tower Construction & Development Co. Ltd, since 2010.

“Construction is going at a great pace,” said Strabala.

But the architect said the interfaces at the floor slabs, where the outer glass skin and the inner skin of the occupied tower meet, “is slowing the pace somewhat,” said Strabala. “There is so much going on there,” he added, including a sliding assembly and the need for a two-hour fire rating.

The goal of Shanghai Tower Construction & Development is to create a sustainable supertower. The building, which is targeting LEED Gold certification from the U.S. Green Building Council’s green-building rating system, is designed to contain 43 energy-conserving technologies, including a gray water recycling system, rainwater capture and more, according to the owner. “It is our hope that Shanghai Tower can be built into a green community,” said Jian Ping Gu, president of Shanghai Tower Construction & Development.

According to other green-building experts, Shanghai Tower’s sustainable features are symbolic of a national green-building movement. “China really wants to do something about the environment,” says architect Heller. “They have a national policy to make China green, which is telegraphed down through the smallest cities, and they really mean it.”

Editor's note: This is an updated file. An earlier version incorrectly stated that the Shanghai Tower would be the world's third tallest building when complete. It will be the second tallest.