Innovation: Sydney Opera House
Location: Sydney, Australia
Architect: Jorn Utzon
Structural Engineer: Ronald Jenkins with Ove Arup and Partners
Construction Managers: Civil & Civic
Since the Sydney Opera House was completed in 1973, it has become one of the twentieth centuries most distinctive buildings, earning Utzon the Pritzker Prize in 2003. The distinctive silhouette of the building was Utzon’s interpretation of sailboats over the water and was therefore originally designed as a composition of many unrelated shapes. However, it was soon realized that building individual casts for each concrete shell would be extremely expensive, so the design team was forced to come up with a more economical solution. After a period of uncertainty, Utzon came up with the idea of giving each shell the same curvature, meaning that the dimensions of each large shell had to be derived from the same circle. This method would require only one mold for all of the panels. These panels could then be manipulated by adjusting their angles to accomodate the design. Once this decision was made, 2400 precast ribs (used to support the roof) and 4000 roof panels came together with the help of an innovative adjustable steel truss system to form the iconic roofline.
The solution to the roof challenge probably would not have been found if this team hadn’t propositioned the use of a computer for one of the first times in the field of structural engineering. They also designed a very complex glass curtain wall and achieved huge spans by designing intricate beams that changed their cross-sectional shape along their length.
Innovation: Los Manantiales Restaurant
Location: Xoxhimilco, Mexico
Architect: Felix Candela
Structural Engineer: Felix Candela
Felix Candela has designed and built many thin shell concrete structures, but one of his most famous works is Los Manantiales Restaurant. Candela used his signature hyperbolic paraboloid geometry, which is a surface that is curved along two planes at once, to create a seamless concrete structure, which sometimes is as thin as only 1 inch. These concrete vaults are not made of precast concrete, but of concrete mixed and poured on the spot over a temporary wooden support structures with wire mesh interlacing the concrete for structural support. Candela utilized hyperbolic paraboloids frequently in his work because they create a geometrically complex yet symmetrical shape, and their formwork is so easy to build. By rotating pieces of wood around a central point and cyclically undulating the far end up and down, you can create this shape.
The structural engineering that Candela did for this building was very complex. The groins between each parabola conceal a steel-reinforced V-beam, which lends the shell of the structure to be called a groin vault. This V-beam is designed to address temperature effects within the concrete to keep cracks from forming and propagating, not to add additional structural support. `
Innovation: Seagram Building
Location: New York City, New York
Architect: Ludwig Mies van der Rohe, Philip Johnson
Structural Engineer: Severud Associates
As an example of functionalism and modernism, the Seagram Building has been very influential on American architecture. Mies van der Rohe loved the aesthetic of exposed structural elements and utilized them as external decoration on this building. However, these exposed vertical I-beams aren’t actually structural. The structural steel frame had to be encased inside concrete in order to meet building codes, so Mies added decorative bronze-cladding to an additional set of steel beams on the surface to mirror the inside structure. These beams were welded to the tinted glass curtain wall, markedly the first true curtain wall, providing floor to ceiling lighting and establishing a view of the expansive granite plaza in front of the building.
This building set the standard for skyscrapers in America. At 38 floors, it was the first tall building to use high strength bolted connections, vertical truss wind bracing system, and it was the first to employ a composite steel and concrete lateral frame. Upon completion, the Seagram building became the most expensive skyscraper per square foot at that time.
Innovation: TWA Terminal
Location: New York City, New York
Architect: Eero Saarinen
Structural Engineer: Amman and Whitney
The construction of The Trans World Airlines Terminal, which was designed by Eero Saarinen as part of the JFK International Airport in New York, began in 1956 and was completed six years later. Saarinen’s abstractly bird-shaped design was intended to celebrate the spirit of flight that everyday citizens had just recently begun to enjoy. The most prominent feature of Saarinen’s extremely futuristic design was the 1.4 acres of reinforced concrete that formed the thin shelled roof of the main volume of the building. In his original plans, this expansive roof was one continuous, undulating slab, but engineers from Amman and Whitney suggested that he separate the roof into four separate slabs connected by joints, because of the shrinking that would inevitably occur in the concrete. This shrinking occurs in large concrete applications due to a temperature difference between the initial layer and each subsequent layer of concrete as older layers begin to cool off . This structure is only supported by four pillars, which gives the form an even more discernible connection to flight.
The TWA Terminal didn’t only look futuristic. It was the first terminal to have enclosed passenger jet ways, baggage claim carousels, electronic schedule boards, baggage scales, and a central PA system.