The Roof Shells? of Sydney Opera House

The Roof Shells? of Sydney Opera House 

As work progressed, no definite geometry for the roof shells had been established although Utzon was working on solving the geometry of the tiling, relying upon full scale mock-ups to solve the problem. Utzon noted that, as was often the case with the construction, the solution of one problem led to another. As work progressed the shells were developed on the geometry of a sphere – it was this spherical surface which led to similar curvature throughout.The Roof Shells? of Sydney Opera House

Utzon thought this ‘an elegant solution to a construction' which would otherwise have led to a lot of scaffolding and shuttering. The roof shells had to span large areas to accommodate the main hall and a smaller hall. The solution devised by Utzon and Ove Arup and Partners, the engineers, was to produce arched segments of varying curvature. The concrete shells were produced by cutting a three-sided segment out of a sphere. The roof shells and their vaulted concrete ribs were pre-cast and held together by pre-stressing steel tendons, an innovation at the time. (Sydney Opera House, Utzon Design Principles, May 2002)The Roof Shells? of Sydney Opera House