Robert Maillart (February 6, 1872 - April 5, 1940) was a Swiss civil engineer who revolutionized reinforced concrete with
such designs as the three-hinged arch, the deck-stiffened arch,
and the mushroom slab.
Education
Maillart attended the Federal Institute of
Technology in Zurich. He studied under Wilhelm Ritter, who
was another accomplished Swiss civil engineer. Maillart did not excel in academic theories, but understood the necessity to mate
assumptions and visualize when analyzing a structure. A customary train of thought
prior to the 1900’s was to utilize shapes that could be analyzed easily using mathematics. This overuse of mathematics annoyed
Maillart, as he greatly preferred to stand back and use common sense to predict full-scale performance. Also, as he rarely tested
his bridges prior to construction, only upon completion would he verify the bridge was adequate. The testing of Maillart's
designs were often performed by Ritter himself. This attitude towards bridge design and construction was what provided him with
his innovative designs.
Personal Background
A major challenge Maillart had to overcome was the Communist Revolution in Russia. Just before the revolution, Czarist Russia
had begun to industrialize. Maillart's firm prospered by working on large projects there.[1] However, Maillart was unaware of the start of World War I and was stuck along
with his family there. [2] In 1916 his wife died and the Communist Revolution caused him to lose his entire fortune. Maillart and his three
children returned to Switzerland as refugees. They were penniless, but happy to be alive.[3]
Development and use of reinforced concrete
The first use of concrete as a major bridge construction material was in 1865. It was used
to form a multiple-arch structure on the Grand Maître Aqueduct in France. The concrete was cast in its crudest form, a huge mass without reinforcement. Later in the nineteenth
century, engineers explored the possibilities of reinforced concrete as a structural material. They found that the concrete
carried compressive forces, while steel bars carried the tension forces. This made concrete an even better material for
structures.
Joseph Monier, from France, is credited with being the first to understand the
principles of reinforced concrete. He embedded an iron-wire mesh into concrete.
However he was a gardener, not a licensed engineer, and sold his patents to contractors who built the first generation of
reinforced concrete bridges in Europe. He also perfected the technique of pre-stressing concrete, which leaves permanent
compressive stresses in concrete arches.
By the early twentieth century reinforced concrete became an acceptable substitute in construction for all previous structural
materials, such as stone, wood, and steel. People like Joseph Monier, had developed useful methods for design and construction,
but no one had invented new forms that showed the full aesthetic nature of reinforced concrete. Robert Maillart had an intuition
and genius that could entirely exploit the aesthetic of concrete. He designed three-hinged arches in which the deck and the arch
ribs were combined to produce closely integrated structures that evolved into stiffened arches of very thin reinforced concrete
and concrete slabs. The Schwandbach Bridge (1933) and the Salginatobel Bridge (1930) are classic examples of Maillart’s deck stiffened arch bridges and
three-hinged arch bridges. In 1991, the American Society of Civil
Engineers declared the Salginatobel Bridge a Historic Civil
Engineering Landmark. In 2001, the British Trade Journal, “Bridge – Design and Engineering,” voted the Salginatobel Bridge
the most beautiful bridge of the century [citation needed].
These designs went beyond the common boundaries of concrete design in Maillart’s time. Both of the bridges mentioned above are
great examples of Maillart’s ability to simplify design in order to allow for maximum use of materials and to incorporate the
natural beauty of the structure’s environment.
Analytical methods
By the second half of the nineteenth century, major advances in design theory, graphic statics, and knowledge of material
strengths had been achieved. As the nineteenth century neared its end, the major factor contributing to the need for scientific
design of bridges was the railroads. Engineers had to know the precise levels of stresses in bridge members, in order to
accommodate the impact of trains. The first design solution was obtained by Squire
Whipple in 1847. His major breakthrough was that truss members could be analyzed as a system of forces in equilibrium.
This system, known as the “method of joints,” permits the determination of stresses in all known members of a truss if two forces
are known. The next advance in design was the “method of sections,” developed by Wilhelm Ritter in 1862. Ritter simplified the
calculations of forces by developing a very simple formula for determining the forces in the members intersected by a
cross-section. A third advance was a better method of graphical analysis, developed independently by J.C. Maxwell (UK) and Karl Culmann. (Switzerland).
Robert Maillart learned the analytical methods of his era, but he was most influenced by the principles developed by his
mentor, Wilhelm Ritter, mentioned above. Maillart studied under Ritter, who had three basic principles of design. The first of
these was to value calculations based on simple analysis, so that appropriate assumptions could be made based on common sense.
The second was to consider carefully the construction process of the structure, not just the final product. The last principle
was to test a structure always with full-scale load tests. All these principles are an adaptation of the available techniques,
but with an emphasis on the careful study of previously built structures.
At the time of Maillart and Ritter, other designers preferred that their designs evolve from previously successful structures
and designs. German engineers and scientists had developed elaborate mathematical techniques, and were confident that they did
not need practical load tests of their designs developed using those techniques. However, these techniques did not encourage
designers to think of unusual shapes, because those shapes could not be completely analyzed using the available mathematical
techniques. Ritter’s principles did allow for uncommon shapes.
Other bridges
References
- ASCE, Notable Engineers - Robert Maillart, History and Heritage of Civil Engineering, undated
- Bill, Max, Robert Maillart Bridges and Constructions, Verlag für Architektur, Zurich, 1949
- Billington, David P., Robert Maillart: Builder, Designer, and Artist, Cambridge University Press, 1997
- Billington, David P., Robert Maillart’s Bridges: The Art of Engineering, Princeton University Press, 1978
- Billington, David P., Robert Maillart and the Art of Reinforced Concrete, Architectural History Foundation, 1991
- Billington, David P., The Art of Structural Design: A Swiss Legacy, Princeton University Press, 2003
- DeLony, E., Context for World
Heritage Bridges, ICOMOS and TICCIH, 1996
- Molgaard, John, The Engineering
Profession, lecture to Faculty of Engineering and Applied Science, Memorial University of Newfoundland, 1995
- Laffranchi, Massimo and Peter Marti. Robert Maillart's curved concrete arch bridges. Journal of Structural Engineering
123.10 (1997): 1280 Academic Search Elite. 8 February 2007
- Robert Maillart
information at Structurae
Notes
- ^ Billington
- ^ Bill
- ^ Laffranchi & Marti
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