{"id":7799,"date":"2025-03-17T13:51:28","date_gmt":"2025-03-17T12:51:28","guid":{"rendered":"https:\/\/ingenius.ecoledesponts.fr\/?p=7799"},"modified":"2025-07-29T16:23:32","modified_gmt":"2025-07-29T14:23:32","slug":"felix-candela-and-the-heritage-of-the-french-concrete-shell-pioneers","status":"publish","type":"post","link":"https:\/\/ingenius.ecoledesponts.fr\/en\/articles\/felix-candela-and-the-heritage-of-the-french-concrete-shell-pioneers\/","title":{"rendered":"Felix Candela and the heritage of the French concrete shell pioneers"},"content":{"rendered":"\n\n\n
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Fernand Aimon\u2019s aircraft hangar project for the French Air Ministry (1934) using a system of \u201cumbrellas\u201d formed by an arrangement of hyperbolic paraboloids (ENPC archives).<\/figcaption><\/figure>\n\n\n\n

Shells are extremely effective technical objects from a mechanical point of view, setting themselves apart with their double-curved geometry (i.e., curvature in two different directions) enabling the bearing of forces exerted on the structure without practically any flexing. This means shells enable the minimal use of material. Their utility has been known since antiquity but reinforced concrete, \u201cthis liquid stone\u201d, caused an architectural revolution by freeing builders of the need to master the art of stone-cutting (stereotomy) and enabling the structure, thanks to reinforcements included in the concrete, to withstand tractive forces.<\/p>\n\n\n\n

If F\u00e9lix Candela, a Mexican architect born in Spain (1910-1997) is now world-renowned, it is for the concrete shells that he designed and built in booming 1950s Mexico. His equally economical, effective and elegant building work is a fine example of Structural Art<\/em>, the poetic expression defined by engineer David Billington to refer to the full extent of creativity that can be involved in structural design. To better understand why, this article looks back at the scientific and technical personalities who inspired F\u00e9lix Candela (particularly Fernand Aimond (1902-1984) and Bernard Laffaille (1900-1955), and what sets him apart from his contemporaries: Ren\u00e9 Sarger (1917-1988) and Nicolas Esquillan (1902-1989).<\/p>\n\n\n\n

Torroja, Dischinger and Freyssinet: forever first<\/h2>\n\n\n\n

The first reinforced concrete shells were works of corporate project engineers who developed technical know-how as well as theoretical tools to understand them. Eduardo Torroja (1899-1961), whose Zarzuella racecourse building site in Madrid Candela visited during his studies, began his career at Hidrocivil<\/em>; Franz Dischinger (1887-1953), the German pioneer of revolving shells was an engineer at Dyckerhoff & Widmann AG<\/em>, and Frenchman Eug\u00e8ne Freyssinet (1879-1962), worked at Limousin et Cie<\/sup><\/em> where he built large conoid-shaped hangars before inventing prestressed concrete (concrete to which steels bars are added and tensioned, before or after drying to make it stronger), which he spent most of the rest of his career developing.<\/p>\n\n\n\n

Limousin et Cie<\/sup><\/em> \u2013 Proc\u00e9d\u00e9s Freyssinet \u2013 “Usine de la Compagnie nationale des radiateurs” at Damarie-les-Lys (Source : L’Architecture Vivante, Printemps 1931, \u00c9dition Albert Moranc\u00e9. Cr\u00e9dit : Archives ENPC)<\/p>\n\n\n\n

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Interior view<\/figcaption><\/figure>\n\n\n\n
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Exterior view<\/figcaption><\/figure>\n
Limousin et Cie<\/sup><\/em> \u2013 Proc\u00e9d\u00e9s Freyssinet \u2013 “Usine de la Compagnie nationale des radiateurs” at Damarie-les-Lys (Source : L’Architecture Vivante, Printemps 1931, \u00c9dition Albert Moranc\u00e9. Cr\u00e9dit : Archives ENPC)<\/figcaption><\/figure>\n\n\n\n

Limousin et Cie<\/sup><\/em> \u2013 Proc\u00e9d\u00e9s Freyssinet \u2013 Railway maintenance workshops at Bagneux (Source : L’Architecture Vivante, Printemps 1931, \u00c9dition Albert Moranc\u00e9. Cr\u00e9dit : Gallica)<\/p>\n\n\n\n

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Exterior view<\/figcaption><\/figure>\n\n\n\n
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Interior view<\/figcaption><\/figure>\n\n\n\n
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Interior view<\/figcaption><\/figure>\n
Limousin et Cie<\/sup><\/em> \u2013 Proc\u00e9d\u00e9s Freyssinet \u2013 Railway maintenance workshops at Bagneux (Source : L’Architecture Vivante, Printemps 1931, \u00c9dition Albert Moranc\u00e9. Cr\u00e9dit : Gallica)<\/figcaption><\/figure>\n\n\n\n

Straight lines for formwork<\/h2>\n\n\n\n

The conoids built by Freyssinet form part of a family of surfaces called ruled surfaces. The particularity of these surfaces is that they can be traced by moving a straight line along two curves. This remarkable geometric property is an advantage both to calculate forces in the surface and also in terms of construction in order to build wooden formwork for concrete, as boards can be aligned directly according to the straight lines of the surface.<\/p>\n\n\n\n

Of the ruled surfaces, some like hyperbolic paraboloids (HP) and revolving hyperboloids have a particular characteristic: they feature two families of independent straight lines. They were particularly useful, firstly for design engineers who could develop an exact analytical solution for stresses in the shell when computers were still not very powerful and, secondly, for building engineers who could use the first family of straight lines for the structure and the second to set up the formwork.<\/p>\n\n\n\n

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