Floating and transparent: The roof of the Olympic Stadium
The Olympic Stadium in Munich was built for the Summer Olympics 1972; today it is one of the city’s landmarks. The tent roof made of PLEXIGLAS® is the most extraordinary part of the stadium which even covers parts of the surrounding Olympic Park.
At the time, the tent-like roof of the Munich Olympic Stadium was an architectural sensation the likes of which had never been seen before! The transparent roof was to symbolize airiness and openness, as well as provide a structural separation between the second Summer Olympic Games in Germany and those of National Socialist times. The transparency of the roof also made it possible for the Summer Olympics and the matches of the 1974 FIFA World Cup (which Germany won) to be televised in color, a technology which was still in its infancy at the time.
Not enough room for sports fans
When Munich won the bid in 1966 to host the Summer Olympics of 1972, it soon became clear that a new stadium was needed. The largest stadium in the city until then, was the Städische Stadion an der Grünwalder Straße, had 45,000 seats and was clearly too small for the expected number of spectators. Neither was the “Grünwalder” large enough at this point for the two biggest soccer clubs in the city, FC Bayern Munich and 1860 Munich. Ticket requests frequently exceeded the stadium’s capacity which led the City of Munich to organize an architecture competition for planning the construction of a new stadium.
The main requirement was that the roof of the new stadium should be transparent. After all, the organizers of the Olympic Games wanted to broadcast the event on color television, which had just been launched at the time and required as much light as possible. A wooden or concrete construction was therefore out of the question.
An unusual idea
The design of the stadium was submitted by the architecture firm Behnisch & Partner from Stuttgart. They presented a model which was based on the tent-like roof designed by architect Frei Otto for the German pavilion at the World’s Fair in Montreal 1967. There, Otto had already designed a tent roof made from a PVC-coated polyester tarpaulin. This type of roof was now to be constructed in Munich as well. However, the design by Behnisch & Partner was dismissed by the jury at first as the idea seemed too risky and unfeasible. Their model was unconventional too: wooden sticks represented the steel construction and the roof was imitated using nylon stockings. After a long selection process and the intervention of one of the jury members, they were finally awarded the contract. The model won over the jury with the landscape architecture around the stadium in addition to the extraordinary tent-like roof.
Unlike many other stadiums, the Munich Olympic Stadium harmoniously fits into its surrounding rolling landscape of the Olympic Park thanks to its curved tent roof. The tent-like roof not only covers the main grandstand of the Olympic Stadium but also extends across the Olympic Hall, the Olympic Pool and the paths connecting the buildings. To make this possible, a complicated rope construction was necessary, for which the architects took inspiration from natural structures such as spider webs and diatoms. A net of steel cables was woven on the ground and then lifted up and fastened on masts which are secured with more cables.
The roof is constructed
Stadium façades made of PLEXIGLAS®
As was done in Munich in 1972, PLEXIGLAS® is now used in sports stadiums and other large buildings around the world. After all, its material properties of light weight, weather-resistance and safety make it the ideal material for public buildings.
The PLEXIGLAS® sheets are placed on the cable construction with room for movement, allowing them to yield to wind and snow. The entire roof area amounts to about 88,000 square meters. When looking at the enormous curved surface, it seems like a miracle that the construction remains intact at all. The Olympic Stadium in Munich is anything but ostentatious when compared to many other sports stadiums as the combination of PLEXIGLAS® and steel lets it appear light and airy.
Impressive material properties
The Olympic construction company conducted extensive tests to determine which material should be used for the roof panels. Glass-fiber reinforced polyester resin was out of question due to its unfavorable fire behavior. PVC-coated polyester tarpaulins, like the ones used at the World’s Fair in Montreal, were not to the construction company’s liking either. They would have been cost-effective but were not transparent enough and would have been too difficult to install on the steel cable grid. Ultimately, the Olympic construction company chose transparent, four-millimeter-thick PLEXIGLAS® GS sheets. The brand acrylic glass won them over with its incomparable translucence and by being in the “B1 – Flame resistant” fire class. Some of the PLEXIGLAS® sheets were colored a light gray for better protection against the sun.
In the end, the stadium opened right on time for the Summer Olympic Games 1972. Since then, it has fascinated visitors with its extraordinary roof structure. Many soccer matches have taken place under the tent-like roof as well, including the final of the 1974 FIFA World Cup in which Germany beat the Netherlands. In addition, the Olympic Stadium was home to the FC Bayern Munich and 1860 Munich soccer teams for many years. Today, open air concerts and sporting events are the main events taking place under the roof made of PLEXIGLAS® sheets.
Open and timeless design
During the Summer Olympics 1972, visitors streamed into the Munich Olympic Stadium and sat on the main grandstand under the tent roof made of PLEXIGLAS® sheets.