2017 Tehran (12 October 2017)

Relations between Materials and Structures in
the Architecture of the 19th and 20th Centuries
Prof. Arch. Massimo Corradi
Lab.MAC
Laboratory / Atelier of Applied Mechanics
dAD
department of Architecture and Design
Polytechnic School - University of Genoa

The relationship between Materials and Structures resumes an existing
relationship at a higher level between Architecture and Mechanics, in the most
general sense that can be attributed to this term, namely between art and science
of building.
Catedral Metropolitana Nossa Senhora Aparecida in Brasilia (1958-70),
Oscar Niemeyer (1907 – 2012).
Relations between Materials and Structures in the Architecture of the 19th and 20th Centuries

Dichotomy between Art and Science
between Feeling and Reason
« The habit of considering above all the aspect of the static problem, the
impersonality of the rigid mathematical formulas through which the science of
constructions gives the illusion of being able to understand the static behaviour of
structures, the need to quickly prepare many young people to the structural
practice and the very rapid growth of activity in the world of construction (...) has
today removed the art and techniques, indivisible elements of each architecture
work » [Pier Luigi Nervi, 1945].
2003 : Curved Bridge, Chris Burden (1946 - ).

The Science of constructions
synthesis between Strength of materials, Mechanics of solids and structures
or
The Art of Structures
1955 : Assembly Hall (Chandigarh, India),
Le Corbusier (1887 – 1965), Iannis Xenakis (1922 - 2001).

Index of topics covered.

1  Historical compendium on the evolution of structural engineering and
Science of constructions before the twentieth century.
2  The structural design and the “new materials”.
3  Scienza o arte del costruire? ( Science or art of constructing? ) [Nervi, 1945].
4  The reinforced concrete: the bridges of Robert Maillart, the three-
dimensional curved surfaces and their structural characterization.
5  The steel: the membrane structures and the reticular systems in three
dimensions.
6  Composite materials: pre-tensioned membrane.
7  Conclusions.

1. Historical compendium on the evolution of structural engineering and
Science of constructions before the twentieth century.
1.1 The “industrial revolution”
Engineers’ science vs. Science of constructions

New « actors » occupy the scene of construction science
tension and deformation
1743 : machine «
divulsoria
», i.e. device for studying
the resistance of materials
Giovanni Poleni (1683 - 1761) used it to determine the
tensile strength of iron bars that will then be used in the
consolidation of the dome of St. Peter in the Vatican.
1660 : experimental apparatus used by
Robert Hooke (1635 - 1703) to describe the law of elasticity
of the materials.

The use of «new» materials:
cast iron and iron, then steel and reinforced concrete,
…
there will be a « liberation » of the formal variable
1900 : Paris, Exposition Universelle, the monumental gate (René Binet, 1866 – 1911).

The main stages of architecture and engineering of metal structures until the early twentieth
century:
•  1779 : Coalbrookdale Bridge, the first large metal bridge ever built. Project by
Thomas Farnolls Pritchard (1723 – 1777) and Abraham Darby III (1750 – 1791)
•  1801 : pont des Arts by Louis-Alexandre de Cessart (1719 – 1816) and Jacques Vincent de Lacroix
Dillon (1760 – 1807)
•  1811 : the dome of Halle-au-blé (Paris Stock Exchange) by François-Joseph Bélanger
(1745 – 1818)
•  1847 : workshop by James Bogardus (1800 – 1874) in New York
•  1847 : Galerie Royales Saint Hubert in Bruxelles by Jean-Pierre Cluysenaar (1811 – 1880)
•  1850 : Bibliothèque Sainte-Geneviève by Henri Labrouste (1801 – 1875)
•  1851 : Crystal Palace in London by Joseph Paxton (1803 – 1865)
•  1852 : Grand Halles in Paris by Victor Baltard (1805 – 1874)
•  1889 : Galerie des machines in Paris by Victor Contamin (1840 – 1895)
•  1889 : Tour Eiﬀel, by Gustave Eiﬀel (1832 – 1923)
•  1871 : Meunier mill in Noisiel by Jules Saulnier (1817 – 1881)
•  1885 : Home Insurance Building in Chicago by William Le Baron Jenney (1832 - 1907)
•  1887 : the Paderno Bridge on the Adda River by Jules Röthlisberger (1851 – 1911)

Architecture and Engineers.
1775-79: bridge over the Severn to Ironbridge near Coalbrookdale (Abraham Darby III, 1750 - 1791).
An unusual use of cast iron: the main ribs (in the number of five, about 30.5 meters in length) were fused on
silhouettes made in one piece sand, a semi-arch, then transported by river to the place where the bridge had to be
built, and placed in work, joined at the top without nails or bolts.

« Proved to be a catalyst for the growth of Sunderland »
1796: bridge over the Wear River between Sunderland and Monkwearmouth (Rowland Burdon, c. 1757 –
1838; Thomas Paine, 1737 - 1809).
Cast iron is treated like stone. Six-arched structure, side by side, each made up of 125 cast iron blocks joined
together by means of forged iron nails (72 meters of free light).

The architecture of engineering.
Architecture becomes an experimental and frontier art.
1801: McConnell & Kennedy Mills, factory with seven floors in Manchester, draft by Matthew Boulton
(1728 – 1809) and James Watt (1736 – 1819).
The Boulton & Watt company was founded by Matthew Boulton and James Watt in 1755 to build engines at
Soho factories in Smethwick near Birmingham, England.

The steel-glass-concrete trilogy replaces stone, brick and wood in new architecture and
universal exhibitions will play a major role in experimenting and diﬀusion of iron
architecture.
A technical revolution allowed Henri Labrouste (1801 - 1875) to build the high and light
coverage of the Bibliothèque Sainte-Geneviève (1842-50).
1842-50 : Bibliothèque Sainte-Geneviève, the reading room.

« Du fer, du fer, rien que du fer ! »
( Iron, iron, nothing but iron ! )
Baron Haussmann (Georges Eugène Haussmann, 1809 - 1891)
1854-74 : Halles centrales, printed by E. Bourdelin, represents the ancient Halles centrales in Paris, Victor
Baltard (1805 - 1874) and Félix Callet (1791 - 1854).

« Ce point du monde où l'on embrasse à la fois (...) l'Institut, le Louvre, la Cité- et les quais aux
bouquins, les Tuileries, la butte latine jusqu'au Panthéon, la Seine jusqu'à la Concorde », La
marche à l'Etoile (1943), Vercors (Jean Marcel Adolphe Bruller, 1902 - 1991).
1801-1804: Pont des Arts in Paris, Louis-Alexandre de Cessart (1719 - 1806) and Jacques Vincent de Lacroix
Dillon (1760 - 1807).
Wood carpentry « à la Delorme » is reclaimed and applied to cast iron. The current bridge was rebuilt between
1981 and 1984 « à l'identique » according to the designs of Louis Arretche (1905 - 1991), which has decreased the
number of arcs (seven instead of nine), and this has allowed the alignment with the pont Neuf, but nevertheless he
resumed the appearance of the old footbridge.

The charm of the ancient, in opposition to the elegance of modernity.
1802-06: Pont d'Austerlitz in Paris, Louis Becquey de Beaupré (1760 – 1849) and Corneillé Lamande (1776 -
1837).
Iron bridge, toll-free, inaugurated in 1807. The bridge is supported by four masonry pylons and five cast iron
arches made of imitation stone blocks. In 1854 the bridge was rebuilt, wider, and with brick arches, retaining the
pylons of the previous bridge. In the years 1884-1885 it was rebuilt a second time and it is what we see today.

The « ronds de serviette » (napkin rings).
1823: Pont du Carrousel (Antoine-Rémy Polonceau, 1778 - 1847).
Bridge made with three arches having a span of about 48 meters compounds of cylindrical segments in cast
iron interleaved with the blocks (voussoirs) having the function of putting in tension the arches themselves.

The iron carpentry of the dome of Halle-au-blés (1806-11) it sets itself as a
technical and architectural model.
1806-11: The Halle-au-blés after the project of Bélanger and Brunet.
A dome of 39 meters in diameter closed at the top by a large glass door, François-Joseph Bélanger (1745 -
1818) and engineer François Brunet.

Wrap the Nature with iron.
1833 : Jardin des Plantes
By Charles Rohault de Fleury (1801 – 1875).
1844-1848 : Decimus Burton (1800 – 1881) and Richard Turner (1798 - 1881),
Palm House in Royal Botanical Gardens in Kew, Surrey (England), before Joseph Paxton.

Wrap the Architecture with iron.
1818-58: Church of Saint-Isaac in St. Petersburg.
Dome of Saint-Isaac (1818-58) in St. Petersburg by Auguste Ricard de Montferrand (1786 - 1858).
1823 : Gabriel Lamé (1795 - 1870) and Benoît Paul Émile Clapeyron (1799 – 1864)
Mémoire sur la stabilité des voûtes et Supplément au Mémoire sur la stabilité des voûtes,
“Annales des Mines”, Tome VIII, livr.4, 1823, p. 789-810, 811-818

Factories and palaces with iron skeleton.
1885 : Home Insurance Building in Chicago, by William Le Baron Jenney (1832 - 1907).
1871 : Workshop mill Meunier in Noisiel by Jules Saulnier (1817 – 1881),
The originality of this metal construction comes from its visible structure that seems to draw the skin of the
building. The Noisiel workshop is the meeting point between art and architecture at the end of the 19th century with
its industrial functionality.

Arches and iron beams.
1887-89 : The Paderno Bridge on the Adda River by Jules Röthlisberger (1851 - 1911).
Iron arch bridge: span 266 meters, total length 150 meters, height 37.5 meters, height of the sloped from the
river surface, maximum total height of 85 meters.

Around 1840, special constructive systems of iron flat roof plate were realized
using composite beams, with flat and angular flanges, welded together, to form
single and double-beams. This type of plate will become common in buildings in
starting in 1860, and will know many typological developments until the advent
of reinforced concrete in the years around 1890.
1836: industrial production of double beams T to be used in flat slabs instead of wooden beams.
Composite beams made up of a set of compound elements, a soul made with a plate and wings made with
four angular to L to form a double-beam formed T. These systems were used in France since 1845 (the first angular L
and T iron bars are marketed since 1820) and are metal beams similar to those already patented by John Birkinshaw
(19th century). These were used by Eugène Flachat (1802 - 1873) for the construction of plate floors for the
Compagnie du Chemin de fer de Saint-Germain, while the first T-slab floors date back to 1849.

The plate floors: the iron thin plates.
1863: Simple thin iron floor: patent of Jolly et Joly; Jolly et Joly (César Jolly et Théophile Joly. Études pratiques
sur la construction des planchers et poutres en fer, avec notice sur les colonnes en fer et en fonte. Dunod, Paris, 1863).

1.2 The architecture made with the “new materials”: the use of cast iron and
iron (from the end of the 18th century) to the introduction of steel and
reinforced concrete (from the late 19th century).
1810: «Vue sur le ponte des Chaînes inventé per James Finley», William Strickland's Wood Print (1788 –
1854), Architect, The Port Folio [Magazine], June 1810.
James Finley (1756 - 1828) is universally recognized as the first builder of modern suspended bridges.
Although not specifically identified, Chutes du Schuylkill (1808) this suspended bridge is likely to be one of its first
bridge.

The first collapse of suspended bridges.
« On Monday evening last at 5 o’clock, the iron bars connecting the cables and the right hand anchor
of the Newport and Covington Suspension Bridge, on the Newport side, gave way and the entire
structure fell with a tremendous crash into the Licking, a distance of 70 feet ! » (Covington Journal,
Saturday, January 21, 1854, p. 3).
1850 : The collapse of the Basse-Chaîne Bridge in Angers.
1852: bridge de la Roche Bernard on the river Vilaine.
1852: the first bridge de la Roche Bernard on the river
Vilaine, 1839-1852.

In those years, numerous suspended bridges were built that will mark an
important road in the history of iron and steel constructions.
1819-20: Bridge over the Tweed River, Northumberland, Captain Samuel Brown (1776 – 1852).
The carpentry of horizontal plane is supported by twelve chains formed of rings of 5 centimetres in diameter,
with a width of 4.5 meters, for a span of 129 meters. This was the first suspended bridge in the world that was
crossed by motor vehicles.

1819-26: Menai Bridge by Thomas Telford (1757 – 1834).
Menai’s suspended bridge: cable suspended bridge (sixteen chains of suspension, each consisting of 935 bars of
iron): length 417 meters, main span 176 meters, width 12 meters, height 30 m. Materials: forged iron and stone. In
1940 the main suspended structure was replaced by an identical cable steel.

1836-64: Bridge over the Avon River in Bristol (Isambard Kingdom Brunel, 1806 - 1859), also called Clifton
Bridge.
Cable suspended bridge, length 412 meters, main span 214 meters, width 9.4 meters, height 74 meters.
Materials: masonry and iron (forged iron cables are those of the cable-stayed bridge built on the Thames, near
Charing Cross Station in London - Hungerford Bridge - replaced in 1859).

The Brooklyn Bridge has prompted its builders a great insight and a great
ability to dominate this technology.
1867-83: Brooklyn Bridge in New York (John August Röbling, 1806 - 1869).
On this bridge, we have a double horizontal plane, the top of the road and the lower railway: The structure is
realized by a diagonal lattice (reticulated) beam with vertical and diagonal connecting elements, ensuring rigidity to
support great accidental loads (central span is about 488 meters, lateral spans measure about 284 meters each).

1.3 Developments in science of construction in the nineteenth century.
An extremely “aristocratic” scientific adventure: the birth of solid mechanics and
structural mechanics.
vs.
the « science of engineers »
The foundation of great schools of engineering:
1747 École royale des pontes et chaussées
then (1775) École nationale des pontes et chaussées
1748 École royale du génie de Mézières
then (1794) École d'application de l'artillerie et du génie
1794 École centrale des travaux publics
then (1795) École Polytechnique
It establishes a closer relationship between physico-mathematical sciences and
technical applications.

The fundamental steps of the development of a
modern science: the science of constructions.
In 1826, Claude-Louis Navier (1785 - 1836)
published the first edition of his Résumé des
Leçons ... sur l'application de la mécanique, which
will mark an important milestone in 19th
century scientific literature and engineering.
A bridge is thus thrown between the technical
processes of the structural conception and the
theoretical results obtained by the great
mathematicians of the Enlightenment.
Navier publishes, and enriches with notes, old
treatises like the Traité de la Construction des
pontes by Émiland Marie Gauthey (1732 –
1806), La Science des ingénieurs (1813) by
Bernard Forest de Bélidor (1698 - 1761) or
L'Architecture Hydraulique (1819) by the sane
author.

The main essays that represent the foundations of the new Galilean science
can be summarized as follows:
•  1821 – Claude-Louis Navier: Mémoire sur le lois de l'équilibre et du mouvement des solides
élastiques, “Mémoires de l'Institut National”, 7 (1821), pp. 375-393, 1827; a famous work, in
which the basic equations of the mathematical theory of elasticity are made explicit.
•  1823 – Augustin Louis Cauchy (1789 – 1857): Recherches sur l'équilibre et le mouvement
intérieur des corps solides ou fluides, élastiques ou non élastiques, “Bulletin des Sciences per la
Société Philomatique”, pp. 9-13, where the great Cauchy theorem is exposed [ Le «grand
théorème» ](definition of equilibrium equations of an elastic solid).
•  1828 - Augustin Louis Cauchy: Exercises de mathématiques, in which the author writes the
basics of the mathematical theory of elasticity.
•  1833 - Siméon Denis Poisson (1781 – 1840) publishes the second edition, revised and
increased, of his Traité de Mécanique (first edition at1811).
•  1837 - George Green (1793 – 1841): On the laws of Reflection of Light at the common surface
of Two Non-crystallized Media, “Transl. Camb. Phil. Soc.”, 7 (1837), pp. 1-24, 113-120,
1839; definition of elastic bond equations.
•  1842 - During the construction of the bridge over the river Verebija, on the Saint
Pétersbourg-Moscou train line, Jourawski (Dmitrii Ivanovich Zhuravskii, 1821 – 1891)
comes to the definition of the relationship expressing resistance to the shear of a beam
[published in “Annales des pontes et Chaussées”, 12 (1856)].
Dmitrij Ivanovič Žuravskij (1821 – 1891)

•  1847 - Adhémar-Jean-Claude Barré de Saint-Venant (1797 – 1886): Mémoire de l'équilibre des
corps solides et Mémoire sur la torsion des prismes; “Comptes Rendus”, 24, pp. 260-63, 485-488,
847-849; where the author addresses and solves the problem of bending and torsion of prisms.
«Les perfectionnements que les formules de Monsieur de Saint-Venant
ont apportés à la mécanique pratique, de même qu’à la mécanique
rationnelle, ont été si importants que beaucoup d’entre eux sont déjà
passés dans l'enseignement, et ont été exposés, notamment, dans le cours
de notre académicien Monsieur Poncelet à la Faculté des Sciences».
Jugement de Augustin-Louis Cauchy (1789 – 1857) (“Comptes Rendus”, 17, pp. 1234-1236).
Adhémar-Jean-Claude Barré de Saint-Venant

•  1857 - Benoit-Pierre-Émile Clapeyron’s (1799 - 1864) Solution to the Problem of the Continuous
Beam (Calcul d'une poutre élastique reposant librement sur des appuis inégalement espacés, “Comptes
Rendus”, 45, pp. 1076-77. The solution of Clapeyron to the problem of the continuous beam is
the tool that will revolutionize the physical-mathematical calculation of structures especially in the
design of continuous bridges.
•  1864 - Adhémar-Jean-Claude Barré de Saint-Venant publishes his Résumé des Leçons de Navier
and enriches it with notes and appendices fundamental to the development of discipline.
•  1864 - Karl Culmann (1821 - 1881) publishes his treatise on Graphics Static (Die graphische
Statik) which will give great impetus, inter alia, to the calculation of reticular structures by means
of simple graphical methods.
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Benoit-Pierre-Émile Clapeyron (1799 - 1864)
Karl Culmann (1821 – 1881)

The Castigliano theorem is the fundamental tool for solving problems related to
hyper-static elastic structures. The Castigliano theorem is the basis of many
methods of calculating structures. It is based on an energy relationship and allows
a relatively simple calculation of the specific values (eﬀort or displacements) in
elastic beams.
•  1879 - Alberto Castigliano (1847 - 1884): Théorie de l'équilibre des systèmes élastiques et ses
applications.
•  1883 – Adhémar-Jean-Claude Barré de Saint-Venant publishes his Théorie de l'élasticité des corps
solides de Clebsch, with notes and additions.
Alberto Castigliano (1847 - 1884)
The partial derivative of the work (U) of the external forces in
relation to a force (F) is equal to the displacement (δ) of its
application point according to the force line of the force itself.

1.4 Iron bars and concrete masses: the reinforced concrete.
Towards the middle of the nineteenth century, some inventors have imaginated that he
could put together two very diﬀerent materials: concrete masses and iron bars, based on an
insight into their material qualities, and following an empirical study of their resistance
characteristics, and not on the basis of an in-depth knowledge of their physical-mechanical
characteristics.
Joseph Monier (1823-1906), a gardener and inventor, is considered to
be the inventor of reinforced concrete for which he has dealt numerous
patents, among them in 1867 a patent for the construction of concrete
crates and iron for horticulture.

The invention of reinforced concrete
The concrete boat (1848) by Joseph-Louis Lambot (1814 - 1887) is the first work made in
reinforced concrete. Joseph Monier’s flower pots (1849) (1823 - 1906) are the first
examples of the application of this new material. François Coignet (1814 - 1888) develops
agglomerated concrete, François Hennebique (1842 - 1921) develops new systems for the
construction of floor planes.
Armand Considère (1841 - 1914) invented the « fretté béton » (1901) and in the 20th
century Eugène Freyssinet invented pre-compressed concrete that will open new design
horizons.
1855: In Paris at the Universe Exposition in 1855, Joseph-Louis Lambot exhibited a small boat made with a metal
net drowned in a thickness of 4 centimeters of concrete.
Lambot: Patent filed on January 15, 1855.

•  1859: François Coignet pioneered reinforced concrete and prefabrication in
France. He studies how to increase the strength of the concrete by using iron
bars. His son, Edmond Coignet (1856-1915), makes the construction of
reinforced concrete a technology with precise calculation rules, which will be
partially reproduced in the first French regulations of 1906.
In 1854 Coignet patented a cement clinker and opened a factory in Saint-Denis in the Paris region. He constructed a
building made of artificial concrete blocks (1853) near his factory with architect Théodore Lachez (? - 1884). This
construction will be visited in November 1855 by a commission comprising 14 architects and chaired by Henri
Labrouste (1801 - 1875). In the report drawn up by the Commission it is written that « tous les travaux ont été
exécutés en béton pisé, moulé et massivé. Coignet a fait usage de mélanges de diﬀérentes matières de peu de valeur, avec la
chaux soit grasse, soit hydraulique ».
The fountain (1873) of the Grand Army Plaza in New York, made by architect Calvert Vaux (1824 - 1895), using the
Coignet cement with iron reinforcements.

François Hennebique has had the merit of being able to apply and spread the
technique of reinforced concrete when theoretical research was not yet based on
sound scientific bases.
1909: silos on pilotis, Roye, Somme.François Hennebique (1842 – 1921).
1894: First reinforced concrete bridge in Viggen or Wiggen (Suisse).

•  1879: first use of reinforced concrete by Hennebique.
•  1886: Hennebique suggests to support the tensile forces by suitable
reinforcements arranged in the concrete mass.
•  1892: Patent on concrete registered in Brussels.
•  1894: First concrete bridge in Wiggen (Suisse).
•  1896: Hennebique publishes the newspaper “Béton armé”.
1895: Hennebique system.

1921-23: Hangar for airships in Orly, by Eugene Freyssinet.
Hangars are made of reinforced concrete parabolic arches: 60 meters wide, 90 meters high, 300 meters long;
destroyed in 1944.

1.5 The Impact of “New Materials” in constructive systems of the late
nineteenth century, with particular attention to the new theory of elastic systems.
imagination and « sensitivity » Static
vs.
the availability of rigorous calculation and verification methods
1896 : Bridge of freedom, Budapest.

1845: Bridge over the Conwy River (Robert Stephenson, 1803 - 1859).
Forged tubular bridge, double on two separate tubes. On the same river in Conwy, not far away, there is the
suspended bridge of Thomas Telford, which is one of the world's first suspension bridges. The suspension is made of
forged iron cables. The towers supporting the bridge suspension cables were conceived in the style of those of the
nearby castle.
“Tubular bridge”.

1844-50: Britannia Bridge on the Menai River (Robert Stephenson).
An 1868 engraving shows Robert Stephenson (sitting in the centre) with the engineers who designed and built
the Britannia Bridge.

1844-50: Britannia Bridge on the Menai River (Robert Stephenson).
The Britannia Bridge has been designed on the continuous beams structure consisting of two 144-meter
central spans and two 74-meter lateral spans resting on two supporting structures. It is a railway tubular bridge, made
of rectangular shaped forged iron tubes, tubular elements were assembled on the ground, then placed on barges
before being placed in their final position.

1854-59: Royal Albert Bridge, railway bridge over the Tamar River (England), between Plymouth and Saltash.
Lenticular iron bridge over two 138.7-meter-long span, lenticular beams are 30.5 meters high, designed by
Isambard Kingdom Brunel.

The technique of iron railroad bridges soon arrives to create an iron age and
conquers its formal consecration with the industrial revolution, delivering results
of an impressive boldness and extraordinary elegance.
The construction of iron bridges becomes a showcase of the capabilities of
science and technology. Engineering becomes architecture, iron architecture.
1830 : Iron bridge in the park of El Capricho (Madrid).
This small bridge was built in the ancient park of El Capricho by the Duchess of Osuna María Josefa Pimentel,
(1752 - 1834). It is one of the last buildings built in the garden; was started in 1787 and ended 52 years later in
1839. It was built in the 1930s, when the iron architecture, applied to road engineering, was not yet widespread in
Spain.

1877: Bridge Maria-Pia on the Douro River in Porto (Gustave Eiﬀel e Théophile Seyrig, 1843 - 1923).
Materials used: cast iron and steel; total length: 563 meters; beam width: 6.0 meters; arch span: 160 meters; height
above water level / bottom of river: 61.20 meters.

Iron Giant.
1880-84: Viaduc du Garabit (Gustave Eiﬀel & Léon Boyer, 1851 – 1886, e Maurice Koechlin, 1856 - 1946).
Forged iron bridge: length 564.69 meters, width 20 meters, height 122 meters. The Garabit viaduct consists of
a metal lattice supported by seven high iron pylons up to 80 meters high. The three spans form an arc that has an
amplitude of 165 meters and a height of 52 meters. The metallic structure is connected to two north and south access
viaducts, built in masonry, of 46 meters and 71 meters in length, respectively. The project is by Léon Boyer (1851 -
1886), inspired by the example of the bridge over Maria Pia on the Douro river (Portugal), a viaduct built by Eiﬀel
and Seyrig in 1877.

1882-90: Bridge over the estuary Firth of Forth (William Arrol, 1839 – 1913, Benjamin Baker, 1840 – 1907,
and John Fowler, 1817 – 1898).
The reticulated bridge, extremely rugged and specially designed to withstand the most violent winds: total
length 2,528.7 meters, span 520.3 meters, height 100.6 meters, free height 46 meters.

1889 : Principle of the cantilever deck
Illustration appeared in a newspaper article The Illustrated London News of October 1889. The man at the center of
the photo is Kaichi Watanabe (1858 - 1932), head of the construction site.

Universal exhibitions, organized to present the industrial accomplishments of
the diﬀerent nations, represented the technological and industrial showcase of the
participants, witnessing the progress achieved with the industrial revolution.
Panorama of the 1878 Universal Paris Exhibition.

1851: London Exhibition: The Crystal Palace (Cristal Palace) by Joseph Paxton (1803 – 1865).
Quick execution and complete recovery of the construction elements after dismantling, thanks to a complete
prefabrication.

1851: London Exhibition: The Crystal Palace, Planimetry.

1854-66: The «Halles» market in Paris (Victor Baltard, 1805 – 1874).
Illustration in Monographie des Halles centrales de Paris, construites sous le règne de Napoléon III et sous
l'administration de M. le B[ar]on Haussmann, sénateur, préfet du département de la Seine by Victor Baltard and Félix
Callet (1791 - 1854), Paris: A. Morel, 1863, plate 1.

1889: Paris Exhibition, «Tour Eiffel» (Gustave Eiffel).
The tower is resting on the ground on a 125-meter-wide square. Height: 1st floor 57.63 meters, 2nd floor
115.73 meters, 3rd floor 276.13 meters, total with antenna 324 meters. Total weight 10,100 tons, metal carpentry
7,300 tons. Materials: Pompey (Lorraine) steel mills ironed. Number of iron elements: 18,038 metal pieces and
2,500,000 rivets. Company: Gustave Eiffel & Cie, Maurice Koechlin’s (1856 - 1946) and Émile Nouguier (1840 -
1898) project.

1887-89 : The Eiﬀel Tower (Gustave Eiﬀel) was built in 2 years, 2 months and 5 days of work:
January 28, 1887 - March 31, 1889

1889: Paris exhibition, Galerie des Machines (Ferdinand Dutert, 1845 – 1906, Charles Léon Stephen
Sauvestre, 1847 – 1919, Victor Contamin, 1840 – 1893, and Édouard Charton, 1807 - 1890).
The large three-hinged reticular arches form an immense metal and glass rib, its width was 115 meters, its
height was 48,324 meters and its length was 420 meters with an immense hall without backing inside.
Galerie des Machines is considered to be the most beautiful among the pavilions of the Paris Exposition of
1889; it is designed by Architect Ferdinand Dutert. Its main nave is 110 meters wide for 420 meters long, it was
the most important metal structure in Europe until it was demolished in 1909. The art and industry pavilion also
highlighted the emergency of the industrial revolution.
The writer Joris-Karl Huysmans (1848 - 1907),
enchanted by his beauty, imagined it as a cathedral of
the nineteenth century:
« Mais une galerie des machines belle,
immense, possible seulement avec le fer, l'ogive
alors éclatée, formidable - ça n'est pas mal -
quant aux machines, elles ne sont points posées
ou ne fonctionnent pas »
(Lettres inédites a Arij Prins 1885-1907, Genève, Libraire Droz, 1977.
Lettre 79: 14/5 '89).


Iron is the most used material in civil engineering and industrial applications.
The use of iron, and later steel, becomes the practice of manufacturing and in a
few years it will extend to civil engineering and architecture, particularly in the
United States of America.
a) b) c) d) e) f) g) h)
a) 1889-90: New York World Building, b) 1893-94: Manhattan Life Insurance Building, c) 1896-99: Park Row Building
d) 1893-1909: Metropolitan Life Insurance Company Tower, e) 1910-13: Woolworth Building, f), 1929-30 40 Wall
Street, o Trump Building, g) 1928-30: Chrysler Building, h) 1929-31: Empire State Building.

During the early twentieth century, the Empire State Building became the
symbol of the new structural system.
1929-31: Empire State Building.

2. The structural design and the “new materials”
In the twentieth century, the tormented alternative between art and science of
construction is increasingly highlighted
« constructive structuralism » vs. « mathematical structuralism »
1908: Experimental plate without ribs - load test on a template with punctual supports
(Robert Maillart, 1872 – 1940).

Research becomes a search for the poetic dimension of architecture within an
ostensibly rational work that deals only with the static aspect of construction.
1935: Frontón Recoletos, Madrid (Eduardo Torroja, 1899 – 1961).
Cylindrical shell made of reinforced concrete: length 55 meters, width 23 + 9.5 meters. The building was
destroyed during the Spanish Civil War.

The will to achieve a fruitful integration between technique and architecture,
between the boldness of construction and beauty, between rationality and
intuition.
1940: Palace of water and light, project for the Universal Exhibition of Rome (Pier Luigi Nervi, 1891 – 1979).
A bold but rigorous architecture with a deep structural conception.

•  Technological innovation
•  Research on new structural and architectural forms
•  Expressiveness of forms
1951: Gatti Workshops (Lanificio Gatti), Rome (Pier Luigi Nervi)
Ribbed plate with ribs where the ribs follow the isostatic curves.
Geometrical configuration - pillars and ribbed slabs. The configuration of the plates follows the trend of the lines of
minimum and maximum eﬀort.

The poetry of the concrete goes beyond engineering,
and it greatly influences the architecture.
« Mon béton est plus beau que la pierre.
Je le travaille, je le cisèle […],
j'en fais une matière qui dépasse en beauté
les revêtements les plus précieux »
(Auguste Perret, 1944).
1913: Théâtre des Champs-Élysées (Auguste Perret, 1874 - 1954).

The spatial influences, free and sensual, thanks to the use of reinforced concrete.
1943 : Church of Saint-François d'Assise, Belo Horizonte, also known as Iglesia de Pampulha (Oscar Niemeyer,
1907 - 2012).
The architectural conception of the church is for Oscar Niemeyer, as is structural analysis for Brazilian
engineer Joaquim Cardozo (1897 - 1978). The structure of the church is made of reinforced concrete self-supporting
times. Materials are used with great formal and structural abilities, and this is the central theme of architectural work.
« Une église est un hangar de Dieu sur la terre » Paul Claudel (1868 – 1955).

The poem certainly does not lack in the work of Niemeyer.
« I have no enthusiasm for rationalistic architecture and its functional limitations, its
structural rigidity, its dogmas and its theories. Architecture is made of dreams and
fantasy, generous curves and large open spaces (...) reinforced concrete allows
architecture to express itself in poetry. We need to know how to invent using all the
techniques that are at our disposal. Why submit to rules, intangible principles? »
1957 : Palácio da Alvorada, Brasilia.

1958 : Palácio do Planalto, Brasilia.
Niemeyer’s architecture becomes the « architecture of sensuality».
« It's not the corner that attracts me. Neither the straight line, hard, inflexible. What
attracts me is the sensual curve found in the perfect woman's body.
“When I started my career, functionalism was dogma: it counted only the use of the
building, all that was ornament was banished. I wanted to reverse the proposition, do
not do an architecture from the inside out, but first imagine its outward appearance
and adapt it to the rest ».

Niemeyer has become the promoter of structural fantasy: architectural fantasy .
« The first thing I do when I approach a job is to start by reducing the number of
supports. When the supports are reduced, architecture becomes more audacious. The
spaces become more generous and architecture can then create a new architecture,
which makes astonishment and can become a work of art ».
1962 : Palácio da Justiça, Brasilia.

1958-70 : Catedral Metropolitana Nossa Senhora Aparecida in Brasilia (Oscar Niemeyer).
This structure is a hyperboloid with a diameter of 70 meters, obtained by assembling 16 reinforced concrete
columns of 90 tonnes each, representing hands joining in the direction of the sky.
The design of the structure is transformed into art and poetry of architecture. The
architecture is tactile and sensual, but also hard and poetic, sublime and sensitive,
at the heart of the rules and techniques, the true magic of reality.
« Only plastic beauty is dominated by a permanent message of grace and poetry ».

3. Scienza o arte del costruire? (Science or art of building? )
[P.L. Nervi, 1945]
The question is asked to the architects, so that they try to use the advantages of
the technique understood as the study and interpretation of the divine laws of the
physical world: « [and] get special in imagining and knowing the game of forces
(actions and reactions) that develop in the diﬀerent parts of the resistant structure, as
muscle fatigue is the property of a large living organism ».
1930 : Municipal Stadium, Florence (Italy).

New instances of architecture emerge :
•  materials technologies
•  theory of structures
•  structural forms
•  static problems are dealt with from a mainly mathematical perspective
•  the rigid impersonality of the mathematical formulas goes ahead
but it does not establish the superiority of the structural conception on intuition
1939-41: Hangar for airplanes in Orbetello near Rome (Italy)
(Pier Luigi Nervi).

The need to create spaces that can take into consideration new intellectual or
symbolic instances.
The origins. 1863: Dome of the New Synagogue in
Berlin (Johann Wilhelm Schwedler, 1823 – 1894).
Developments in the 20th century. 1950: Konrad Wachsmann
(1901 - 1980), Hangar, United States. Wachsmann conceives
the first three-dimensional space structure made of steel.

These new lines of research know a fundamental stage with flat and three-
dimensional reticular structures.
•  Johann Wilhelm Schwedler (1823 – 1894)
•  Vladimir Grigorievitch Choukhov (1853 - 1939)
•  Walther Bauersfeld (1879 – 1959)
•  Franz Dischinger (1887 – 1953)
•  Richard Buckminster Fuller (1895 – 1983)
•  Ulrich Finsterwalder (1897 - 1988)
•  Konrad Wachsmann (1901 – 1980)
•  Zygmunt Stanislaw Makowski (1922 – 2005)
•  David Georges Emmerich (1925 – 1996)
1921 : Radio Antenna Chabolovka, from the Komintern emitter in Moscow
(Vladimir Grigorievitch Choukhov, 1853 – 1939).

Minimal use of materials for maximum structural performance.
1923: Skeleton of the first Dywidag dome built on the roof of Zeiss à Jena, Germany, by Walther Bauersfeld.
In this case, we can observe the extraordinary stability of the metallic reticular structure, very light, with a
weight of only 9 kilograms per square meter of dome surface. The structure, which constitutes the initial skeleton of
the dome 16 meters in diameter, is a reticular structure destined to be further embedded in a cast concrete of only 6
cm in thickness. This structural system allows to describe a flat surface formed by elementary geometries: triangles
and flat polygons.

4. The reinforced concrete: the bridges of Robert Maillart, the curved
surfaces in three dimensions and their structural characterization
« [reinforced concrete is] the most beautiful constructive system that mankind has
available today because the possibility of creating an artificial stone through a jet, no
matter what shape, capable of resisting traction, has something magical »
[ Pier Luigi Nervi ].
1910 : Warehouses in Zürich (Switzerland) by Robert Maillart.
First use of mushroom-shaped pillars in an industrial building
(cast-iron masonry slabs, flat slabs). The novelty is the disappearance
of the beams: all the floors are treated as a plate that becomes a
uniform bearing surface in length and width.

4.1 Robert Maillart’s Bridges: to choose the most aesthetic form, from all the
most rational possible ones.
1905: Bridge in Tavanasa on the Rhine (Graubünden, Switzerland).
Length 51 meters. The static system is that of a three-hinge arc. Maillart realizes for the first time a monolithic
structure integrating the load-bearing arch with the deck in each unitary structure.

Thin structural elements, non-massive joints, smooth cross-sectional passages, very light
metal skirting, and the curve of the skirt contribute to Schwandbach’s extraordinary
aesthetic bridge [ Daniel Imhof ].
1933 : Schwandbach bridge in the canton of Bern (Switzerland).
This bridge was made on a curved plane by forming a flat plate and curved plate system. The static system is
an arc, supported by punctual supports, to which a continuous beam is superimposed on multiple supports.

« La théorie est dangereuse, les normes sont trop restrictives, les essais à échelle réelle
sont décisifs et la sécurité peut être garantie » [ Robert Maillart ].
1936-37: Bridge over the river Arve (Vessy bridge, Switzerland).
The Vessy Bridge is a three-hinged arch bridge. It consists of three parallel arcs with U-shaped section and the
vertical supports of cruciform shape (X) section that allows to realize a hinge joint; length of the span 56 meters,
height 11.7 meters.

Nervi’s judgment is significant:
« Maillart’s bridges are an exaltation of the construction technique,
elevated to pure architectural expression » [Nervi, 1945].
Schwandbach Bridge: Sketch of Santiago Calatrava (1951 - ).

4.2 Three-dimensional curved surfaces and their structural characterization.
« The lines and surfaces are always linked to mathematical and physical laws that fix
their property. Only with a perfect knowledge of these laws and reflecting on their
consequences can we make perfect works (...) The artist must never forget that
aesthetics (...) is closely related to geometrical and analytical, mechanical and of the
resistance of these surfaces that delimit the mass of the building. Each mathematically
defined line possesses its intrinsic truth, expresses a law, represents an idea, it carries the
merit of virtue. To deny these things means closing yourself in the blind and selfish
retreats of laziness and ignorance » [Torroja, 1957].
Multiple curved surfaces: z = x2 sin (y)

The search for minimum thickness, the optimization of forms due to a static
“economy” that promotes material resistance, the claim to combine strength and
lightness, strength and agility, play a fundamental role in the development of the
architectural idea and in the aesthetic choice.
1956: Warehouses Celestino in Mexico City (Felix Candela, 1910 - 1997).
Felix Candela is one of the pioneers of the new structural forms built in reinforced concrete in the 20th
century. His contribution was to create new geometric-structural forms using multiple curvature surfaces.

Felix Candela found in the geometry of these surfaces the way to optimize not
only the “beauty” of a building, but also at the same time, and inevitably, its
structural behaviour and the simplicity of its construction.
Felix Candela, load test on a « umbrella » flat surface on a single central support in the mid 50’s.

These architectures built by reinforced concrete, using surface in the shape of a
hyperbolic paraboloid ( “striped” surface ), can be realized by means of simple
wooden carpentry made of straight planks arranged along the lines of the surface.
1957-58: thin reinforced concrete vault in Xochimilco park, cafe-restaurant « Los Manantiales », Mexico City
(Felix Candela e Joaquin Alvarez Ordoñez).
Monolithic surface in flower form.

1958-59: Chapel of Cuernevaca (Mexico) (Felix Candela).
Thin vault in reinforced concrete.
In this way, it is possible to optimize the shape, size, thickness of the heavy sections up to
the thickness of a few centimeters, and to make surfaces of minimal weight (minimum
surfaces) with free edges, and give them spatial and pure uniformity geometric shape.

The lightness of reinforced concrete.
1963-67: Viaduct on the river Polcevera in Genoa, Italy (Riccardo Morandi, 1902 – 1989).
It is a fenced beam bridge, where the vertical elements are easels consisting of two superimposed V sections; a
V has the task of widening the central area where the clamping beam is supported, while a downside V supports the
upper tie rods.

Significant work of the relationship that binds between matter / shape / structure.
1967-76: Thin shell surface, bridge over the river Basento, Potenza, Italy (Sergio Musmeci, 1926 – 1981).
Four-span bridge of 70 meters of light each, made of a slim 30 cm thick shell that - seamlessly formally and
structurally - loads for points on the ground and at same mode it supports the horizontal plane of the deck.
The project has been conceived as a pure structural form: the form of the structure is not a priori, an assigned form
where it is necessary to verify the structural safety factor but is derived from the “process of optimizing its static
behaviour” [Musmeci, 1977].

Antoni Gaudì (1852 – 1926).
Suggestive representations of three-dimensional shapes.
1925: Roof of the parish school of the Sagrada Família
[Barcelona, Spain] - hyperbolic paraboloid (‘striped’ surface).

Antoni Gaudì.
The constructive idea in architecture: organic and hierarchical.
1905-07: Parabolic arch structure supporting the roof of the Casa Milà (Barcelona, Spain)
.

Antoni Gaudì : matter and structure.
1898-1915: Chapel of Colonia Güelle in S. Coloma de Cervellò (Spain).
Gaudi prepares for this project a pattern of the vault formed by a continuous surface suspended by cables; the
cables are weighted proportional to the loads that must be borne by the main structures; the so-determined balance
polygons, on the contrary, allow to describe the lines of strength according to which the material must be arranged to
support the forces acting on the structure itself.

5. Steel: tensile structures and three-dimensional reticulated systems
The exaltation of mathematics as a tool for the interpretation of the mechanical
behavior of the structures, the numerical calculation as the sole means to
understand the complex system of equations that describes the balance, the
stresses and the resistance of structural systems are the formal research objectives
and material.
1948-50: Raleigh (Dorton) Arena, Matthew Nowicki (1910 – 1950), William Henley Deitrick (1895 - 1974)
and Fred N. Severud (1899 – 1990).

Lightness and innovation in the construction of roofing systems.
1976: Palace of Sport in Milan, Italy (Palasport of San Siro).
Elliptical shapes, the main axes have the following dimensions: 144 and 146 meters in length. The central
cover follows the form of an anti-clastic surface (hyperbolic paraboloid) and is formed by a tense structure (tensile
structure) measuring 128 meters in diameter, supported by 38 steel supports, positioned from the outer edge to the
(Gilberto Valle, 1935 - Tommaso Valle, 1934 - Giorgio Romaro, 1931); construction demolished today.

« The dome is the ultimate expression of art, perfect synthesis between sculpture and
architecture to dominate space. The dome is the most natural of the shapes, the man-
made vault in the image of the celestial vault »
[ Michelangelo, 1475 – 1564 ].
1967: Exhibition of Montréal, Canada (Richard Buckminster Fuller, 1895 – 1983).
United States Pavilion at Île Sainte-Hélène: The Biosphere.

To overcome the problems of excessive deformability or aerodynamic instability,
three-dimensional geometric shapes that can be described with two or more
interconnecting cable families are used to produce a shape stabilizing eﬀect based
on external stresses.
1972: Olympic stadium roof, swimming stadium and Münich Sports Palace, Germany (Frei Otto, 1925 - ).
Frei Otto is best known for designing minimal surfaces (minimum weight for maximum strength): light
structures inspired by organic shapes. Frei Otto is considered one of the precursors of bionic architecture.

Transparent Architecture and Mathematics.
Negative Gaussian curvature surfaces and anti-clastic surfaces.
« Minimal surfaces »
Minimal surface
made by Frei Otto with a soap film.

6. Composite materials: pre-stretched membranes
The study of pre-tensile membranes finds its origin in three-dimensional reticular
structures (lattices structures).
•  open systems, where the inner or outer supports of the membrane, in general, absorb traction and
compression eﬀorts. These eﬀorts are directly absorbed by tethered anchors in the ground or
attenuated through perimeter edge beams;
•  closed systems, which provide for anchoring the membrane to a frame independent of the support
surface. All the stresses are absorbed by the structure (linear or curved) and the anchorage of the
ground membrane occurs with a generally continuous line.
Example: hyperbolic paraboloid
HOD, FOB : guidelines
hi, …, hn : generatrix line (1st system)
ii, …, in : generatrix line (2nd system)
XOZ, YOZ : reference system
GOC, EOA : main parables
OZ : axis of the hyperbolic paraboloid
ω : corner between the plans of the guidelines

The pioneers of lightweight membrane architectural structures.
Frei Otto e Walter Bird (1912 – 2006), David Geiger (1935 - 1989) and Horst Berger (1928 - ).
1983-86: King Fahd International Stadium, Geiger Berger Associates (Horst Berger), Ian Fraser, John Roberts
and Pertners.
Membrane structure supported by struts and tie rods. Seated seats: 60,000; surface covered by the 51,000 m2
membrane, PTFE-covered fiberglass membrane (polytetrafluoroethylene). Contrast between the lightness of the
membrane and the heavy mass of the earth-masonry: in the background the wonderful skyscrapers of Shibam
(Yemen).

Frei Otto’s utopia: a new architecture.
1957: Coverage of a pool for water games in Cologne, Germany (Frei Otto).

The pneumatic structures.
The pneumatic structures, the contrast between lightness and weight.
1962: Telstar dome, Maine (United States).
At the time of construction, it was the largest pneumatic structure in the world: the diameter of the dome 64
meters, height about 50 meters.

Membrane domes or « tensegrity ».
« This curious structure, assembled with three bars and seven tie rods, was
manipulated with an eighth stretched cable, and showed that the set is indeformable.
This self-configurable configuration is very similar to a system of three self-tensioning
bars and nine tie rods of our invention »
[ David Georges Emmerich, 1925 – 1996 ].
1949: Structural prototype of Tensegrity.

Stretched membranes.
1970: Exhibition of Osaka (Japan); telecommunications room.
Cover material: Aluminium, Vinyl, PVC.
Main dimensions and geometric shape: the covered surface is 4,000 square meters, the maximum height is 20 meters,
the geometry of only one element is that of an anti-clastic surface, the whole structure geometry is hybrid.

7. Conclusions
In the twentieth century, the theme of structural conception will have new
meanings. New computer tools, such as the finite element method, help designers
of structures, new materials face the construction world, new technologies are
used in the construction site, new architectures materialize on paper or on a
computer screen, formal, material and structural research of new horizons that
have become subject to study and experimentation.
1988: The Pyramide du grand Louvre (Ieoh Ming Pei, 1917 - ).
Glass and steel pyramid: The structure rises up to 21.64
meters on a square base of 35.42 meters on the side. The
pyramid consists of 603 losanges and 70 glass triangles.

•  The twentieth century saw the dawn of a new architecture?
•  The answer to this question is complex and requires new research prospects .
•  The constructive idea ( l’idée constructive ) of architecture, therefore, remains
the synthesis of the Vitruvian triad: form, material and structure .
1989: The «Nuage» of the Grande Arche, Paris (Johann Otto von Spreckelsen, 1929 – 1987; Ove Nyquist
Arup, 1895 – 1988; Peter Rice, 1935 – 1992).
Johann Otto von Spreckelsen and Erik Reitzel (1941 - 2012) conceive the Arche de la Défense (Paris) as a 20th
century version of the Arc de Triomphe de l'Étoile: the Arch has about the shape of a cube of 112 meters long, 106.9
meters wide, for a height of 110.9 meters.
The «Nuage» of the Grande Arche of the Défense is a stretched canvas or membrane suspended for cables fixed to the
side walls. The membrane is a glass fiber with a surface of 2,300 square meters.

However, to conclude, I would like to mention the introduction
of Eduardo Torroja to his book Razón y ser de los tipos
estructurale (1957), which, in my opinion, summarizes the
intimate relationship between materials and structures :
« Every material has its own specific character and each
form implies its own static behaviour.
« The natural solution of a problem of construction - the
fruit art without artifice - which responds to the conditions
imposed in a comprehensive manner, aﬀects how a revelation
and meets at the same time the technical conditions and
requirements of the artist .
« The birth of a structural complex, the result of a
creative process, the fusion of art and technique, ingenuity
and research, imagination and sensitivity, goes beyond the
realm of pure logic to overcome the mysterious boundaries of
inspiration.
« Calculation schemes are preceded and dominated by the
idea that shapes the material in a durable form and fits its
function ».

Thanks for your attention
1919: Vladimir Tatline (1885 – 1953),
Monument to the Third International (1919-1943).
‫متشکرم‬ ‫شما‬ ‫توجه‬ ‫از‬

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Thanks for your attention
‫متشکرم‬ ‫شما‬ ‫توجه‬ ‫از‬
Lab.MAC
Laboratory / Atelier of Applied Mechanics
dAD
department of Architecture and Design
Polytechnic School - University of Genoa

2017 Tehran (12 October 2017)

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