Beijing National Stadium (Bird's Nest)
Beijing National Stadium is also known as Bird's
Nest. The Stadium costs US$428 million. The design was originated from the
study of Chinese ceramics, implemented steel beams in order to hide supports
for the retractable roof; giving the stadium the appearance of Bird's Nest. The
retractable roof was later removed from the design after inspiring the
stadium's most recognizable aspect. Ground was broken on 24 December 2003 and
the stadium officially opened on 28 June 2008.
Bird's Nest Stadium Facts
Height: 69.2m (227 feet)
Length: 330m (1082 feet)
Width: 220m (721 feet)
Steel Used to Construct the Outer Shell: ~42,000
tons
Total Weight of Construction Materials (including
concrete
seating bowl): ~110,000 tons
Seating Capacity: 80,000-91,000
Design Life: 100 years
Architecture Firm: Herzog & de Meuro
The Beijing National Stadium, located at the south
of the centrepiece Olympic Green, is a stunning landmark building, which staged
the 2008 Olympic Games from 8 August to 24 August 2008. The opening and closing
ceremonies and athletic track and field events of the 29th Olympiad took place
at the stadium.
The stadium has a gross volume of three million
cubic metres and is considered to be the world’s largest enclosed space. It is
also the world’s largest steel structure with 26km of unwrapped steel used. The
innovative structure was designed by Herzog & De Meuron Architekten, Arup
Sport and the China Architecture Design and Research Group, and has been
nicknamed the "bird’s nest" due to the web of twisting steel sections
that form the roof.
As well as designing a modern stadium, the team was
challenged with creating a venue that was part of the culture of China and
would put Beijing on the map.
The 91,000-seat stadium was designed to incorporate
elements of Chinese art and culture. The National Stadium’s main structure is
an enormous saddle-shaped elliptic steel structure weighing 42,000t. The
stadium extends 333m from north to south and 294m from east to west, with a
height of 69.2m. The stadium design included demountable seats of 11,000.
Beijing National Stadium structure and design:
The stadium has two independent structures, a red
concrete seating bowl and the outer steel frame around it at a 50ft distance.
As this was an Olympic venue, there were many standards that the design
consortium had to conform to. Everything from the width of the track to the
size and location of the long and high jump pits needed to satisfy the
requirements set out by the International Olympic Committee (IOC) and the
International Amateur Athletics Federation (IAAF).
The architects and engineers also had to satisfy the
requirements laid down by the National Stadium Company in order to create a
bold, stand-out, world-class stadium and to design it with as much flexibility
as possible for future use.
The circular shape of the stadium represents heaven,
but has been described as a bird’s nest, with its pattern inspired by
Chinese-style crazed pottery. A series of cantilevered trusses has been
designed to support the roof, shading the seats. While designing the stadium,
architects and engineers also ensured comfortable seats and optimum view for
all spectators.
Focus was also given to designing the stadium in
such a way that it should be able to withstand earthquakes without much damage
as the stadium is located in one of the world’s most seismic zones.
The concourses are wide and spacious for making the
refreshment and merchandising stalls easily accessible. There is also a large
mixed-use retail development beneath the stadium featuring shops, restaurants,
cinemas, a health club and parking.
The football field of the stadium with an area of
8,000m² provided enough space for the underground pipes of the geothermal heat
pump (GHP) system, through which ground-source energy is collected. In winter,
the system absorbs the heat from the soil and helps heating the stadium, while
in summer the coldness from the soil is stored which cools the stadium.
Computational fluid dynamics (CDF) simulation based
on the Games-time situation has been used to calculate the temperature and
airflow speed at each angle of the structure and optimise all ventilation
facilities accordingly.
Finance:
The China International Trust and Investment
Corporation (CITIC) consortium, which raised 42% of the finance for the project
in return for a 35-year tender after the Olympics were finished, comprises the
CITIC Group, the Beijing Urban Construction Group, the Golden State Holding
Group of the United States, and the CITIC Group affiliate Guoan Elstrong (a public,
private partnership arrangement).
The remaining 58% is funded by the Beijing Municipal
Government and this has been entrusted to the Beijing State-owned Assets
Management Co Ltd as the city government’s representative.
National Stadium ‘Bird’s Nest’ architecture:
The team wanted an optimum balance between making
sure every spectator had a good view, creating a good atmosphere and designing
an elegant building. It also needed to be aware of the different uses of the
stadium; for example, when used as an athletics stadium, the most important
view is at the finish line of the running track but when used for football, the
best views are at the centre line.
Getting everyone close enough in such a big venue
was a real challenge and getting the calculations right was an immense task.
For example, changing the height of the first row of seating by just 100mm
would make the stadium significantly larger and higher and increase the cost by
several million pounds.
To achieve the optimum design, the team relied
heavily on parametric design software. This helped to work out the sightlines,
the bowl geometry, airflow to keep the grass in good condition, seismic studies
and the design of the external envelope.
While the surface of the structure is simple, the
geometry is complex – the calculations were so numerous and complicated that
they could not be solved manually. Software was needed to make sure that the
web of twisting steel sections fitted together, as they have to twist and bend
to follow the surface accurately.
The main elements support each other and converge
into a grid formation. The stand of the stadium is a seven-storey shear wall
system with a concrete framework. The upper part of the stand and the stadium
steel structure are actually separated from one another, but both of these are
based on a joint foundation.
The "nest" structure, however random it
might look, follows the rules of geometry and contains 36km of unwrapped steel.
The shape of the roof was inspired by yin yang, the Chinese philosophy of
balance and harmony.
The roof is covered with a double-layer membrane
structure, with a transparent ETFE (ethylene tetrafluoroethylene) membrane
fixed on the upper part of the roofing structure and a translucent PTFE
(polytetrafluoroethylene) membrane fixed on its lower part. A PTFE acoustic
ceiling is also attached to the side walls of the inner ring.
The spaces in the structure of the stadium are
filled with inflated ETFE cushions. On the façade, the inflated cushions are
mounted on the inside of the structure where necessary, to provide wind
protection.
Since all of the facilities – restaurants, suites,
shops and restrooms – are all self-contained units, it is possible to do
largely without a solid, enclosed façade. This allows natural ventilation of
the stadium, which is the most important aspect of the stadium’s sustainable
design.
To keep costs down, all the structural elements of
the stadium are contained within it, so there are no towers or cable nets. The
bowl of the structure is split into eight zones, each with its own stability
system, making each zone effectively as its own building.
Entrance to the stadium is controlled by tripod
barriers supplied and fabricated by Kaba Gallenschütz of Germany. The project
involved the installation of 138 of these units at the 12 entrances to the
stadium.
Construction:
Construction of the stadium proceeded in several
distinct phases, the first phase involving the construction of a concrete
supporting structure upon the concrete foundations laid for the construction
site. This was followed by the phased installation of the curved steel frame
surrounding the stadium which is largely self-supporting. This phased
installation involved the interconnection of sections of the curved steel frame
which were constructed in Shanghai and transported to Beijing for assembly and
welding. The entire structure of interconnected sections was welded together as
the primary means of interconnection used to assemble the entire surrounding
nest structure. Upon removal of the supporting columns used for the purpose of
expediting the assembly of the interconnecting sections, the completed nest
structure as a whole settled approximately 27cm to attain full stability before
the interior design and construction of the stadium could be installed and
completed.
Completion:
Ground was broken, at the Olympic Green, for Beijing
National Stadium on 24 December 2003. At its height, 17,000 construction
workers worked on the stadium. All 121,000 tons of steel were made in China. On
14 May 2008 the grass field of 7,811 square meters was laid in 24 hours. The
field is a modular turf system by GreenTech ITM. Beijing National Stadium
officially opened at a ceremony on 28 June 2008.
