Owner Shanghai Tower Construction & Development Co. Ltd.
Contractor Shanghai Construction Group
Lead Designer Gensler
Architect of Record Architectural Design & Research Institute of Tongji University (Group) Co. Ltd.
Structural Engineer Thornton Tomasetti
MEP Engineer Cosentini Associates
Shanghai Construction Group ranks protecting the crews working 300 meters above grade and higher—especially while erecting the cantilevered steel structure and the curtain-wall bracing system—as the most challenging aspect faced during construction of the 632-m-tall Shanghai Tower. The 121-story megatower is China’s tallest building and the world’s second tallest—after the 828-m Burj Khalifa in Dubai.
Raising the cranes at extreme heights comes next in a long list of demands placed on the contractor. Installing the 20,000 glass curtain-wall panels was the third most difficult undertaking, followed by forming the core’s concrete tube, building the foundation and organizing the workforce, which peaked at about 4,000.
The project presented the design team with a task never before attempted: creating a record-height steel-and-concrete frame in a seismic zone, founded on very poor soft soil and sheathed in a thin glass skin. The tower also had to be buildable by local labor using easily procured materials and equipment.
The tower, called a vertical city, has a tapered shape and consists of nine stacked zones and 21 sky gardens. Locating the mechanical levels above and below each five- to 17-story zone avoided the need to import larger custom-designed equipment to distribute mechanical services longer distances, according to Cosentini Associates.
A major design element is the tower’s transparent outermost “second skin”—the glass curtain wall. Judges were impressed with the building’s “cutting-edge design” and the structure itself.
Separated from the twisting outer form, the structural system is orthogonal. It consists of a shear-wall core, with high-strength concrete connected to eight composite steel-and-concrete supercolumns by two-story outriggers at the mechanical levels (ENR 7/26/10 p. 24). The supercolumns are composed of concrete-encased, built-up steel plate, 100 millimeters thick. The building is the world’s tallest composite structure.
Once the orthogonal structure was established, the asymmetrical form—the tapered profile and rounded corners—became an asset, naturally resisting the typhoon winds common in Shanghai.
Other adjustments to the form, based on wind-tunnel tests on a 30-ft-tall model at wind engineer RWDI in Guelph, Ontario, lightened the structure and saved $58 million in materials over the original design, says Dennis C.K. Poon, Thornton Tomasetti’s vice chairman.
Different customs, cultures and languages complicated the work, though the U.S.-based designers had Chinese natives in major roles on the job and offices in Shanghai. “The Chinese style is adversarial and bureaucratic,” which made it difficult to get consensus, said one designer in the early days of the project. “In the U.S., we go forward like a jet plane. In China, we progress like a bicycle wheel,” he added.
To manage the labor force, the contractor says it kept the pace of construction uniform and “controlled human behavior” through education, training and supervision.
Adjacent to the 492-m Shanghai World Financial Center and the 421-m Jin Mao Tower, the Shanghai Tower, which contains the world’s fastest elevators and is linked at its base to the underground transit system, completes the city’s supertower precinct, which was first planned in 1990.