Innovation: Pre-stressed concrete dome
Location: Belgrade, Serbia
By: Branko Žeželj and Milorad Pantović
The Belgrade Fair Hall 1 was the world’s largest dome between 1957 and 1965 and remains Europe’s largest dome, as well as the world’s largest prestressed concrete dome. It spans 109 m with a maximum ceiling height of 30.78 m and total area of 21,280 sq m. It includes an arena, ground floor, and three galleries which all serve as exhibition spaces, and it also houses office space in a basement level [1, 2].
The architects, Branko Žeželj and Milorad Pantović, used prestressed concrete to overcome the tension that results from a bending load. The process effectively balances out the bending loads, allowing for larger concrete beams and spans, producing a larger dome in this application. In addition to achieving such a sizable dome from concrete, the external exhibition walls are made of glass, indicating the strength and intricacies in the building’s structural design. As seen in the images above, the roof is not solid concrete similar to the Pantheon but rather many curved concrete beams, further lessening the load .
The Hall is a descendant of domes such as the Pantheon and is a forerunner of domes such as Cowboys Stadium, which currently holds the record for the world’s largest dome .
Innovation: thin-shell concrete used for complex designs
Location: Ciudad Universitaria, Mexico City, Mexico
By: Felix Candela
Felix Candela was instrumental in the development of reinforced concrete thin-shell structures. He explored the potential of reinforced concrete, which works extremely well in dome or shell shapes due to the elimination of tensile forces. Furthermore, Candela worked as not only an architect but also engineer and builder, and helped to define Mexican architecture .
The Cosmic Rays Pavilion was a project given by the Mexican government and has become a prestigious icon in the city. Its concept is based on the shape of a hyperbolic paraboloid. To achieve stiffness, strength, and stability, Candela employed a double-curved roof rather than a cylindrical one, working with Jorge Conzález Reyna. In addition, the Pavilion is extremely thin, with the thickest part of the cast at 5/8 in. The outside vertical walls are in a corrugated configuration and supported by three arches into the foundation. It is not only a highly technical structure, but also aesthetically simplistic .
Innovation: Tensegrity Structure
Location: London, England
By: Hidalgo Moya, Philip Powell, and Felix Samuely
Tensegrity, a term coined by R. Buckminster Fuller as the combination of tensional integrity, is conceptually seen with the Skylon Tower (upper left). By definition, all members are in either uniaxial compression or tension, and no bending moment. The steel spire therefore appeared to be “floating compression,” a term used by Kenneth Snelson .
The tower was made of six cables, three rods, and a large steel piece. The steel piece was vertical, with three cables at the top and three on the bottom. Each top cable paired with a bottom cable to attach to a rod, which held the structure to the ground. The result was a futuristic piece that appeared to float in the air, though it was in fact stable.
The Skylon Tower was designed by Hidalgo Moya and Philip Powell and made structurally possible by Felix Samuely. It was made to be a “Vertical Feature” at the1951 Festival of Britain, and was deconstructed in 1952. Once completed, the base was 15 m (50 ft) from the ground and the top about 90 m (300 ft) high. Structures similar to the Skylon Tower include Snelson’s Needle Tower in Washington, DC, 1968 (upper right) and the Kurilpa Bridge in Australia, 2009 (lower) .
Innovation: Fast assembly tower crane development
By: Hans Liebherr
Until 1949, cranes used in construction could lift vertically but had no horizontal movement, and materials were manually carried after being dropped. With Hans Liebherr’s innovation, the tower crane could not only swing materials horizontally, but also be transported in parts and fully assemble itself at the construction site. His design, the TK-10, was a machine that had the slewing unit on the bottom, allowing the entire crane to rotate, with a horizontal jib on top. It was presented at the Frankfurt Trade Fair in 1949, but new designs came to the market almost immediately after its unveiling.
The development of these new tower cranes came in time for the construction boom of the 1950s, when buildings were needed quickly and therefore cranes and other equipment were in high demand. This need was facilitated by increasing crane efficiency. The jib was modified to luffing jibs, which kept the material relatively level to the base while lifting. Self-climbing mechanisms allowed cranes to grow along with the building. In addition, the job radius of the jib increased. Altogether, the ease in transportation and assembly, as well as the increasing efficiency, contributed to the development of taller building structures .
Watch a video here of a tower crane building itself. `