|Structural Design of the Water Cube of the 2008 Summer Olympics in Beijing|
If you watched Michael Phelps rewrite history during the 2008 Summer Olympics, you definitely couldn't miss the impressive design of the Water Cube, the venue for the swimming and diving events where Phelps won an unprecedented eight gold medals. Inspired by Kelvin's "Foam Theory," the National Aquatics Center—commonly known as the Water Cube—was another star of the Olympic Games in Beijing, China. Designed to resemble soap bubbles, the rectangular shape of the Water Cube was intended to coordinate with the circular design and philosophy of the neighboring National Stadium (Bird's Nest).
On October 29, 2008, over one hundred people came to the Helen Mills Theatre in Midtown Manhattan to listen to Professor Xueyi Fu, director and chief engineer of China Construction Design International, discuss the building concept, behavior and geometry of the polyhedron frame structure, structural analysis and research, geotechnical conditions, and the unique construction of the National Aquatics Center. The Water Cube was selected as the winning entry of an international design competition and was submitted by a consortium consisting of China State Construction Engineering Co. (Beijing), China State Construction International Design Consultant Co. Ltd. (Shenzhen), PTW Architects (Sydney), and Ove Arup PTY. Ltd. (Sydney).
Back in 1887, physicist Lord Kelvin questioned how a three dimensional space could be divided into cells of equal volume with minimal surface area, such as a natural formation of soap bubbles. Kelvin proposed a "foam" consisting of tetrakaidecahedra, a 14-sided polyhedron with six square sides and eight hexagonal sides. It wasn't until 1993 that Weaire and Phelan discovered a more efficient array consisting of two 12-sided polyhedrons and six 14-sided polyhedrons. The steel space frame structure of the Water Cube is essentially the Weaire-Phelan answer to Kelvin's question with a slight twist. To create a more natural look, the template for the space frame was cut out from a rotated array of polyhedrons.
The steel members were encased by a "film" of some 4,000 ETFE (ethylene-tetrafluoroethylene) cushions filled with low-pressure air. ETFE is a special polymer that is one percent the weight of glass and can also transmit more light through its surface. A total of 100,000 square meters (1.1 million square feet) of ETFE were used in the Water Cube. The ETFE cushions improve energy efficiency by allowing solar energy to heat the pools, protect the steel members from the high levels of condensation in the swimming pool environment, and are illuminated by LEDs for impressive displays of changing colors at night.
A variety of software programs were used to evaluate the substructure, superstructure, and overall structure of the Water Cube including ETABS, MIDAS, MST, SAFE, SAP2000, SATWE, STRAND7, and TAT. The steel structure was optimized to make it as strong but as light as possible, accommodating dead loads, roof loads, wind loads, earthquake loads, and temperature effects. Bending moments were reduced in high stress areas and different stress levels were developed for the walls and roof to achieve a strong-column, weak-beam design to achieve good seismic design.
The design of the pile foundation for the Water Cube needed to account for differential settlement rates between the pools and main structure. Two design load cases where analyzed: one with the pools filled with water and another with no water in the pools. As there would be an uplift effect when pools are emptied for cleaning, compression piles were used below the main structure, tension piles were used below the pools, and compression and tension piles were used below the boundary areas.
The Water Cube accommodates a competition pool, diving pool, and warm-up pool in the 177 m x 177 m x 31 m (580 ft x 580 ft x 102 ft) structure. The venue held 17,000 spectators during the Olympics and its capacity will be reduced to 6,000 when the temporary seats are removed and interior parts of the building are converted a fitness and recreation center that is open to the public. No changes will be made to the main structure after the Olympics.
|Tuesday, May 28th, 2013|
8:00 am - 5:00 pm
ASHE/ASCE 8th Annual Golf Outing
|ASCE National Website|
|Air Transport Group|
|CEs in Government Group|
|Forensic Engineering Group|
|Future City Competition|
|Government Affairs Committee|
|History & Heritage Committee|
|Long Island Branch|
|Lower Hudson Valley Branch|
|LHVB Younger Member Group|
|Younger Member Forum|