Ground and structure
Shell
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It is a very thin curved roof of concrete, brick or ceramic that resists through its form and not its thickness.
What it solves
It covers large spaces with very little material because the curvature carries the loads within the shell to the supports. It gives broad, high shade, good for the heat of the tropics.
Today
Fit the form to the calculation and not only to taste, because a small deviation changes how it works. Protect the top surface with a good slope and waterproofing against tropical rain.
Common mistake
Treating the shell like a slab and later drilling through it or loading it with heavy equipment.
Tomorrow
Reusable formwork and digital fabrication make the shell possible, and it saves concrete. With local brick and masonry skills it can be a low-carbon roof.
Fact The roof of Los Manantiales restaurant in Xochimilco is 4 cm thick.
Where it comes from
- 1First modern shells Jena, Germany, 1926
A 25-meter dome made of sprayed concrete on a mesh opened the way for concrete shells. - 2Reinforced brick Uruguay, second half of the 20th century
Eladio Dieste developed the Gaussian vault of a single layer of brick, which gains stiffness from its double curvature.
Masters
- Félix Candela Los Manantiales Restaurant, Xochimilco, Mexico, 1958
He joins four hyperbolic paraboloids 4 cm thick into an eight-sided vault beside the canals. He uses that form because its stresses can be calculated with simple equations. - Eduardo Torroja Zarzuela Racecourse, Madrid, Spain, 1941
He cantilevers the grandstand roof almost 13 meters with a curved concrete shell barely 5 cm thick at the tip. He teaches that form supports what thickness could not.
See also
Also in Ground and structure
Diagrams and texts by LDB Arquitectura. They are shared under the CC BY 4.0 license, which allows them to be used and adapted with credit to the source.