Council on Tall Buildings and Urban Habitat
 

CTBUH Young Professionals Committee
Hosts Shanghai Tower Presentation in Chicago
May 22, 2013
See more about the Young Professionals Committee

CHICAGO - The designers of Shanghai Tower presented to a capacity crowd at the Chicago Architecture Foundation May 22, at an event hosted by the CTBUH Young Professionals Committee (YPC). More than 150 people attended a detailed multidisciplinary presentation by Grant Uhlir, Gensler (architecture); Dennis Poon, Thornton Thomasetti and CTBUH Trustee (structural engineering) and Christian Von Holten, Cosentini Associates (MEP engineering).

The 632-meter, 128-story Shanghai Tower will be the world’s second-tallest upon completion in 2014. While achieving “supertall” height always presents a design challenge, in this case it was compounded by silty soil, stringent seismic and fire codes and the desire to achieve maximum sustainability, the presenters said.

Delegates network in the Santa Fe Building lobby before the lecture
Uhlir began the presentation, noting the scale of the effort across multiple global offices and disciplines. Seventy-five people at Gensler and 180 design professionals total have been working on the project since 2008. A considerable amount of design effort went into winning the work in the first place, let alone verifying the integrity of the design. The process involved countless BIM models and a $300,000, seven-meter (23-foot) scale model tested in one of the two wind tunnels in North America large enough to accommodate it.
Sergio Valentini, YPC Chair, welcomes attendees
Grant Uhlir, Gensler, presents on the architecture

The tower’s twisting shape, in addition to providing visual interest, helps mitigate vortex shedding and other undesirable wind effects, Uhlir said. This design move reduced the amount of structural material needed to withstand eccentric wind events by 24 percent when compared with an orthogonal tower of the same height, saving the project $58 million in construction costs, Uhlir noted.

Poon detailed the structural concept of the tower, which is deceptively simple. “Our objective was to create the most efficient functional shape with a very clear structural path,” he said. Consisting of nine stacked zones of approximately 14 floors each, the tower’s concrete core rises in a vertical line, while its floor plates, supported by a megaframe at the perimeter, and its outer glazing, hung from outrigger structures at each sky lobby, twist and taper from a diameter of 76 meters at the base to 60 meters at the top. In plan, the floor plates resemble guitar picks revolving about a nine-box core reminiscent of a tic-tac-toe game, Poon explained. The extent of the outrigger and radial trusses provide wide, double-deck platforms that serve multiple purposes: as curtain-wall hanging points, as base floors for light-filled atria, as mechanical floors and as points of refuge in case of fire.

The full house listens to the presentation on Shanghai Tower

More elaborate structural moves occurred below grade: the ground under the site has a high water table and is comprised of sand and silt to a depth of more than 120 meters. As a result, the structural team designed an 18-foot (5.4-meter)-thick mat foundation, supported by 955 cast-in-place piles of 70 meters’ length. This meant staging the longest continuous pour of concrete in history – 1,000 cubic meters per hour for 60 hours straight, producing a line of cement trucks 2 kilometers long, Uhlir said.

Dennis Poon, Thornton Thomasetti and CTBUH Trustee, presents on the structural engineering Christian Von Holten, Cosentini Associates, presents on the MEP engineering

From an environmental engineering standpoint, the tower’s shape again played a vital role, said Von Holten. Characterizing the outer skin as a “wedding dress” that made the tower behave like a “thermos,” Von Holten explained that the atria between the inner and outer glazing, aided by enthalpy wheels and heat humps, regulate temperatures inside the tower, reducing reliance on mechanical cooling, for an overall energy reduction of 7 percent per year. The tower is pre-certified LEED Gold, Von Holten said.

Splitting the tower into a series of 14-story buildings also helped limit the need to run extensive MEP services through the full height of the structure, which would have sacrificed rentable floor space and used more energy, Von Holten said. This did, however, make the placement of chillers, pipes and water tanks amidst the diagonals of the mechanical-floor outriggers a challenge only BIM could solve.

“We never would have convinced the clients to accept this design without Revit,” Von Holten said.

Future Shanghai skyline showing Shanghai Tower as the tallest of the "Three Brothers"

In all, the Shanghai Tower will serve not only as a symbol of China and Asia’s ascendancy in the world economy, and as a triumph of design, but also as a case study of interdisciplinary collaboration worth sharing with other professionals, noted Aleksandar Sasha Zeljic, Shanghai Tower Façade Design Director at Gensler.

“This was great opportunity to expose both the efforts of the YPC workgroup, as well as to start up an event series of high caliber by our group for the future,” Zeljic said. “We are fortunate to live in the city full of great firms and their great projects. At Gensler, TT and Cosentini, we believe we should share our knowledge with our professional community so that the entire community can learn and become better. I think with this lecture we have set a precedent for others to do the same.”

The event was organized by:
Steven Henry, Design & Production Manager – CTBUH
Sergio Valentini, YPC Chair – Jahn
Aleksandar Sasha Zeljic, YPC member - Gensler
 
Sponsorship was kindly provided by:

For more information on the group, and to stay up to date with planned events, visit the Young Professionals Committee webpage.

View the full presentation here: