Eduardo Torroja

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Eduardo Torroja sketch

Eduardo Torroja y Miret, (27 August 1899 – 15 June 1961) was a Spanish structural engineer and a pioneer in the design of concrete thin-shell structures.


  • [El Instituto Técnico de la Construcción y del Cemento] had shown that it is possible in Spain to create organizations in which there exists a perfect harmony between different professions, between those above and those below; organizations in which everyone is able to live a life of high human rank, as gentlemen, a life of mutual respect and help and of maximum personal dignity.
    • Francisco Arredondo Verdú, La obra de Eduardo Torroja (1977) pp. 50-51, as quoted by Lino Camprubí, Engineers and the Making of the Francoist Regime (2014) p. 181.

Philosophy of Structures (1958)[edit]

English translation: J. J. Polivka, Milos Polivka.
  • The technical literature on structural engineering abounds with theoretical works of a mathematical nature, but few publications are concerned with the various kinds of structures or the fundamental reasons for their existence.
  • Structural design is... very much concerned with art, common sense, sentiment, aptitude, and enjoyment of the task of creating opportune outlines to which scientific calculations will add finishing touches, substantiating that the structure is sound and strong...
  • Mathematics is merely a convenient tool by which the designer determines the physical proportions and details of a planned structure in order to transform his ideas... to the actuality of a finished structure.
  • Before a man can successfully plan a structure... he must study, from every possible angle, the ultimate purpose of his building. Attention must be directed to the basic structural concept before the mathematical process of calculation is undertaken.
  • [E]very structure has a resistant function to fulfill... to ensure ...the static equilibrium of the structure for a long period of time.
  • [M]aterials should resist mechanical forces and other effects... starting with all types of loading and external forces... and with the mechanical properties of the materials... constitutes the part given most emphasis in technical books and schools.
  • Stone can effectively resist compression but is relatively weak in tension. Because of its mass and weight it may be used advantageously in structural types that can be made stable by the proper weight (dead load, gravity) and are but slightly exposed to lateral forces.
  • Construction methods are... variable for each specific material.
  • One should become so familiar with the structure as to have the feeling of being, in full vitality and sentiment, part of it and of all its elements. is necessary to achieve a sincere Einfühlung [empathy] of the process of resistence... through the deformation that is always essentially united with the process of stressing. ...[T]he comprehension of a structure requires intuitive knowledge of the ethology of its resistance and of its constituent materials.
  • Long before... our techniques of today, men could conceive and build structures adapted to the requirements of resistance... because he had observed... the branches of a tree bending under the weight of fruits and the tensioned cords of strings in which children have rocked from time immemorial...
  • [T]here are three different but interconnected conceptions to be considered in every structure, and in every structural element involved: equilibrium, resistance, and stability.
  • Equilibrium requires that the whole of the structure, the form of its elements, and the means of interconnection be so combined that at the supports there will automatically be produced passive forces or reactions that are able to balance the forces acting upon the structures, including the force of its own weight.
  • The equilibrium... in order to become static—should be steady, permanent, lasting. ...This type of equilibrium... is... independent of any scale. A reduced model will show the same effects as the proper structure. Experiments on models are simple and... instrumental for understanding such structural problems.
  • The material in all elementary parts of a structure must have the properties of resistence to all internal forces produced by general loading conditions and by the action of any exterior force.
  • [S]tresses in one direction produce not only a deformation along this direction but also transversally, the relation of both being expressed by the so-called Poisson ratio. However, the consideration... is of no great importance for the first, approximate judgement.
  • Stress phenomena are... not independent of scale, as was the case pertaining to simple external static equilibrium. ...with increasing dimensions of a structural element the volume and therefore the proper weight increases more rapidly than its cross-sectional areas...
  • [E]xperimental investigation of stresses in a plane structure is of great interest and merit as applied to shells with single curvature (barrel shells, pipes) and to shells with double curvature (domes, etc.). In these structures similar states of stress are produced and can be determined at any point as acting in a plane tangential to the center layer of the shell.
  • [M]ost of our structures in the past consisted of individual members having relatively small transverse dimensions as compared with their length, and in such members stress analysis is much more simple. ...[M]any modern structures consist of frameworks of this type, and frequently the word "structure" refers specifically to assemblies consisting of linear elements.
  • Even children know that drafting rule is easier to bend flat than across the edges; and... they will not be much surprised if told that for the same width of the rule its resistance is proportional to the square of the thickness and the deflection is inversely proportional to the cube of the thickness. Nevertheless some modern designers seem to be unaware... since they require... beams of such slenderness that they resemble springboards...
  • If you lean on a straight stick... [it] can resist your weight, despite its slenderness, as long as it remains straight; once it starts to bend, it will easily break. The danger of breaking increases with the deflection... [T]he danger of failure will diminish with the increased moment of inertia of the cross section, or if the same are of cross section should be maintained, by distributing the material in a hollow section.
  • In general, these phenomena are very easy to perceive and understand, but difficult to calculate. The danger of failure increases rapidly with decreasing depth or thickness of the structural member...
  • [C]onsider the danger of bulging and... counteract it by providing adequate anchorage, thus shortening the free length of the member and reducing its relative slenderness.
  • Adobe (sun-dried clay bricks) is a material usable in regions where sandy clays suitable for fabrication are found. Adobe masonry, is, however, useful only for walls and structural elements subjected to lower values of tension and compression, and is, therefore, of little interest as a structural material.
  • Clay masonry, like concrete, is a "plastic" material that permits the pouring in situ of large monoliths of any shape or form, with certain limitations and by using special methods. Its economical possibilities when used in walls of popular housing, its excellent heat and sound insulation, as well as its aesthetic possibilities, should not be underestimated. Its resistance and durability can be substantially improved by using modern techniques and methods, for example, admixture of small amounts of Portland cement in accordance with granulometric investigation, petrographic composition, and rheological behaviour of all constituents.
  • The variety of exterior forms in concrete is limited only by the cost of forming; and its thickness is limited only by the size of aggregates, gravel, and sand.
  • Concrete presents, besides a coefficient of thermal expansion, a coefficient of hygroscopic dilation which is more appreciable. While concrete is kept wet... it expands; and as it dries, it contracts, in inverse proportion to the hygroscopic degree of the ambient air. ...The shrinkage ...will vary with the porosity of the concrete and with the thickness used in the structural member. ...Shrinkage is much greater in structures consisting of thin elements subjected to intemperateness of dry climate, and disappears or becomes negligible in underground structures (e.g., foundations).
  • Lightweight concrete obtained with special admixtures producing bubbles throughout the mass shows lower resistance, which makes it less suitable for structural purposes; its practical application is limited to smaller structural elements adequately reinforced in which thermal insulation is required.

Quotes about Torroja[edit]

Eduardo Torroja's Algeciras market hall (1934).
Pier Luigi Nervi's design for the Norfolk Scope Arena (Norfolk, VA) recalls closely his Little Sports Palace (Palazzetto dello Sport), Rome.
  • Torroja was a specialist in stress analysis... and he wrote a... book on the mathematical theory of elasticity. This... led him to see a connection at Algeciras between the stresses in the shell and the reinforcement... but not to express those stresses in... visually evident ribs. We contrast... Nervi's Little Sports Palace... whereas Nervi sees shells as ribbed, Torroja sees them as ribless... since domes tend to spread, Nervi designed ribbed buttresses... whereas Torroja avoids buttresses by connecting vertical supporting columns with a... polygonal ring of horizontal ties... prestressed to counteract dead load and to lift the shell slightly off its scaffold... probably the first application of prestressing to a doubly curved shell. In the Nervi dome... the buttresses are supported below ground on a ring which carries the horizontal thrust and... transmits the vertical weight to the ground. ...[These] choices related to the [respective] local traditions in Italy and Spain.
    • David P. Billington, The Tower and the Bridge: The New Art of Structural Engineering (1985)
  • The grandstand for Madrid's Hipodrómo de La Zarzuela (the city's horse racetrack) is Eduardo Torroja's masterpiece and one of Spain's most important architectural works of the 1930s. The building complex was... designed by the architectural office of Carlos Arniches and Martín Domínguez in collaboration with internationally well-known civil engineer Eduardo Torroja, who with Robert Maillard, Eugene Freyssenet, and Pier Luigi Nervi is considered a pioneer in the design of concrete structures. The Grandstand for La Zarzuela Racetrack is the best-known work of Arniches and Domínguez, as well as Torroja's most important architectural work—among many other brilliant structures that he conceived—to the point that it is credited only to him.
    • Alejandro Lapunzina, Architecture of Spain (2005) Reference Guides to National Architecture
Mercado de Algeciras,
Andalucía, España      
  • Eight supports set into the foundations and a shell with some beautiful additions that nonetheless are structurally significant. These [cylindrical sheets] that hang over the building's doors add more strength to the shell roof. ...[T]his building is a spherical shell roof on eight supports. The roof is the most important part of the building. ...It's a roof with entry doors. That's all it is.
    • Rafael López Palanco, "Visita al mercado de Algeciras con Rafael López Palanco" (2014) 1:21-2:37.
  • This was absolutely cutting-edge... about 1932, 33, 34 there are no laminar structures. ...[T]his was a huge step forward in reinforced concrete and lamimar structures, and it is recognized as such. I compare it... with the Hipodrómo de La Zarzuela. They were absolutely original and absolutely original structures, not only in their originality but in how they were calculated and built.
    • Rafael López Palanco, "Visita al mercado de Algeciras con Rafael López Palanco" (2014) 2:37-3:17.
  • This is a span of nearly 50 metres. If it had been done with beams [they] would have had to be 80 or 90 cm thick. ...Torroja was able to do this with a thickness of only 9 cm.
    • Rafael López Palanco, "Visita al mercado de Algeciras con Rafael López Palanco" (2014) 3:24-3:47.
  • So how does the dome work? It is clear. The dome is always in compression, both in the direction of the meridians and in the direction of the parallels, up to a parallel when the meridians continue to provide compression and the parallels start to provide traction, so cracks would appear. So then what does Torroja do? ...[C]ylidrical sheets ...absorb the force from the membranes through the meridians, which continues through the cylindrical pieces.
    • Rafael López Palanco, "Visita al mercado de Algeciras con Rafael López Palanco" (2014) 3:47-4:41.
  • In the early twentieth century reinforced concrete was a new building technology. Its novelty inspired experimentation, both from architects, such as Le Corbusier, and from engineers, who dreamed up different applications for the new ferroconcrete. ...The German engineering firm of Dyckerhoff & Widmann['s]... design of the concrete dome for Max Berg’s Century [or Centennial] Hall in Breslau... in 1913... became the first modern building whose clear span exceeded Rome’s Pantheon. Other notable structures of this early phase are the elegant works of Eduardo Torroja in Spain, including the Algecira market hall (1934), and Freyssinet’s economical segmented system for an aircraft hangar at Orly (1921).
    • Michael W. Weller, "A Thin Shell Trolley Barn for Seattle's Water Front" (2010) thesis proposal, Master of Architecture, University of Washington, Dept. of Architecture.

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