From the beginning of Stage Two, the construction of the vaulted shells, Sydneysiders began to get a sense of the iconic structure that would emerge into the symbol of modern Australia.
With the podium of the building complete, the construction of the superstructure – or roof – of the Sydney Opera House began in 1963, described as Stage Two of the project.
Space-age forms began to develop from the already sculptural appearance of the site and, because it was exceptionally photogenic, artists were drawn to Bennelong Point to document progress. The spectacle evoked a reverence and even awe more commonly associated with a cathedral.
A brief excerpt from the beginning of the 1968 film, documenting the construction of Sydney Opera House.
Building the Opera House was truly an exercise in working at “the edge of the possible”, as Arup engineer Jack Zunz described it. Individual rib components could not exceed 10 tons, as this was the maximum lift capacity of the three French cranes, at the time the strongest in the world.
Solutions to problems, which by today's standards would seem dated, were at the time inventive and completely novel. One of Arup’s engineers wrote a computer program that would help the surveying engineers accurately track the placement of the elements in space against their calculations. These calculations were done each night by General Electric computers and the results delivered back to the building site the following morning for the engineers to evaluate. At the time, this was indeed “the edge of the possible”.
The shells were constructed by Hornibrook Group Pty Ltd during Stage Two. Having developed a method of production that resulted in this on-site factory, Hornibrook manufactured the 2400 precast ribs and 4000 roof panels.
As Utzon reflected: “Initially, no definite geometry for the shells had been established, but, as work progressed, the shells were developed according to a spherical geometry and we suddenly had a common denominator, the same spherical surface to deal with, with a similar curvature throughout. This was an elegant solution to construction ... Now the shells could be sub-divided into ribs, which again could be divided into smaller elements, which could be cast within formwork representing the largest rib-entity. Thus it was possible to pre-cast the concrete-shells in smaller pieces and assemble these pieces on location.”
This excerpt describes how the method of construction was closely integrated into the design of the shells, and how computers were used to calculate the points in space that the various elements of the ribs would need to accurately occupy.
This excerpt describes the process of transporting and fitting the rib segments from the formwork to their final positions.
This excerpt describes the intricate job of the engineers who survey the position of each segment from different locations around the site and harbour. Physical positions were compared with positions calculated by computer.
Created by Sam Doust and the
Sydney Opera House GCI Team
State Library of New South Wales