Wuhan Greenland Center, China
|At a Glance|
|Project||: Wuhan Greenland Center, Wuhan, China|
|Architectural firm||: AS+GG Architecture|
|Engineer||: Thornton Tomasetti|
|Client||: Greenland Group|
|Height||: 606 m height|
|Start of Construction||: 2012|
|Estimated Completion||: 2017|
The Wuhan Greenland Center, at 606 meters (1,988 feet), is likely to become China's third-tallest and world's seventh tallest building, when completed in 2016. AS+GG Architecture in conjunction with Thornton Tomasetti Engineers won the design competition to build the 125 storey tower which comprises about 300,000 square meters of floor area, including about 200,000 sm of offices, 50,000 sm of luxury apartments and condominiums, a 45,000 sm five-star hotel, and a 5,000 sm, 27-meter-tall private club with spectacular views at the tower's penthouse level.
The tower features a uniquely streamlined form that combines three key shaping concepts-a tapered body, softly rounded corners and a domed top-to reduce wind resistance and vortex action that builds up around supertall towers. The building's extremely efficient aerodynamic performance will allow it to minimize the amount of structural material (and the associated embodied carbon) needed for construction.
Frame WorkThe major structural system of Wuhan Greenland Center Main Tower consisting of robust composite walls, giant slightly sloping composite SRC columns and curved belt trusses, is adopted to resist the lateral loads (wind or seismic) effectively. The locations and geometry of structural components have carefully been optimized to not only provide enough strength and stiffness but also to integrate with the architecture seamlessly.
The tower's three corners rise from its tripod-shaped base and taper upward, culminating in an arched tip above the dome at the top. The corners will be of smooth curved glass, contrasting markedly with the more textured curtain wall cladding the body of the tower. The curtain wall will enclose a composite concrete core with steel framing. Apertures in the curtain wall at regular intervals will assist in venting wind pressure against the tower; the apertures will also house window-washing systems and air intake and exhaust systems on mechanical floors.
Tower Crown StructureThe top of the Wuhan Greenland Center Main Tower is an expression of the project design philosophy. As the tower reaches into the sky, the cladding splits at the line between two architectural components known as the body and the shield. This separation was created to help alleviate tower top wind forces and thus significantly improve building behavior. This simple but powerful statement about the effectiveness of coordinating architecture and structure in Supertall building design has become the building's most iconic feature and is certain to create a landmark on the city skyline.
Rising from gently tapering tower wing tips, the taper steadily and continuously increases to the point that the tips converge on the tower centerline to form a unique 61m tall crown. Tapering of other building surfaces defines a 35m tall dome. Cleaning of the dome glass will be performed by equipment suspended from the crown above. Cladding of the outer crown is supported by a special tripod structural system. Because crown tripod leg framing is concealed within opaque cladding, support structural design was based on material efficiency and constructability. Each crown tripod leg, a half-arch in profile, is trapezoidal in cross-section or plan. The four faces of each leg are trusses following simple surfaces, with the upper/outer and side trusses triangulated for shear stiffness and the lower/inner truss a Vierendeel without diagonals. Pipes up to 500 mm diameter are used for truss chords and smaller diameter pipes are used for web members and braces. The inner truss Vierendeel configuration and the hollow tripod leg design without internal diaphragms were both selected to work with the window washing machine within. The side trusses taper nearly to a point at the crown base, landing on the super columns at wing tips and connecting directly to the embedded steel columns in the super column for secure load transfer.
The tower dome structure posed different design challenges. Dome cladding is transparent but substantial cladding support framing is required at long spans and high wind pressures. Viewing up through the peak of the dome is desired. Dome structural framing will be visible to visitors so a dramatic sculptural appearance is desired.
Sustainable ElementsThe tower has several other planned sustainable elements that include: Energy recovery using an enthalpy wheel integrated into the ventilation system; this captures energy from the building's exhaust systems and uses it to pre-heat or pre-cool air entering the building.
It will have a greywater recovery system which takes waste water from the hotel laundry, sinks and showers and reuses it in the building's evaporative cooling system. Water-conserving low-flow plumbing fixtures, has been selected for this building which reduce the total amount of potable water required as well as the associated pumping energy.
Besides these, a high-efficiency lighting system has been planned which uses low-energy-consuming ballasts and lamps to reduce required power consumption. It has also a daylight-responsive control system, which automatically turns off electric lights when sufficient daylight is available.
In addition, the AS+GG Interiors studio is developing the tower's fluidly sculpted interior public spaces, many of which reflect the tower's exterior silhouette. The conical silhouette is visibly echoed in the entrances to the primary elevator bank from the main lobby, as well as in the shapes of the elevator cabs and other public spaces. The lobbies and other amenity spaces within the tower also feature sweeping, fluid lines and a neutral blue-gray palette that recalls the reflective glass of the exterior wall. The transparency of the ground-floor lobby wall allows views from inside toward the entry canopy drop-off areas, establishing a seamless relationship between the interior and exterior.