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Roads, Bridges, and Buildings

The Lagrange Laboratory, a European Research Group for Civil Engineering

From designing flexible bridges to building with cables, or restoring historical monuments, the projects of the Laboratory for Civil Engineering Problems (Lagrange Laboratory) are above all the sign of three years of Italian-French collaboration.

dessins d'avalanche


Another way research looks at things: click on the picture to see three images of a rock slide in a valley. The boulders fall and collect in the bottom of the valley. Some of the material does not make it over the lip and are stopped before they can continue to fall.

A hundred or so research scientists from France and Italy work together in the context of the Lagrange Laboratory on such problems as protecting roads against avalanches, better ways to drive piles, using resin to glue huge blocks of concrete, finding new construction faults through infrared, or drying porous materials.
This European Research Group* (GDRE), founded in July 2000, is “above all a place of scientific exchange and shared endeavor”, according to Michel Frémond, researcher at the Central Laboratory of the renowned engineering school “Ponts et Chaussées” (LCPC) and coordinator of the Lagrange Laboratory. Participating laboratories in the Lagrange are Laboratoire central des Ponts et Chaussées (LCPC), Ecole nationale des Ponts et Chaussées (ENPC), Université Montpellier II and CNRS on the French side and, from the other side of the Alps, Italy's National Research Council, Tor Vergata University in Rome and the University of Ferrare.

Venerable sites and architecture of the future
“Our Italian colleagues are very active in the preservation of old buildings such as the Pantheon or Saint-Peter's cupola”, Dr. Frémont points out. And with such venerable structures the trick is to shore them up in very discrete fashion, with no visible struts or supports, using low-impact and reversible methods.
Lightness is also the key concept in contemporary architecture. René Motro is a researcher at the University of Montpellier II who studies tensegrity structures, assemblies of rods and stretched steel cables whose equilibrium derives solely from their configuration.
An 85 sq. m. grid one meter thick was erected in 2000 to demonstrate the feasibility of such a structure, whose advantages are many, including lightness with 12 kg per sq. m. as opposed to 15 to 20 kg/sq. m. for a standard steel rod grid, and autonomy since it is a self-contained unit not requiring the many points of attachment of spider-web cable structures.
Interestingly, one of the difficulties associated with these structures is too much choice; the shape of the final structure depends a great deal on the tension applied to the cables (up to 2.5 tons!) as equilibrium is sought. “The next step”, according to Motro, “is to optimize the materials used in order to reduce weight even further, and to look at the idea of being able to fold these structures up.”
Tensegrity structures may prove quite useful for building in high-risk earthquake zones since these structures absorb the energy of vibration. This is an aspect that is of particular interest to the Italian researchers at the Lagrange as they study the best way to build the bridge floor of the planned bridge over the Messina Straits. This bridge may turn out to be the longest in the world, with a span of three kilometers, and conventional suspension bridges are flexible and therefore susceptible to a high degree of oscillation. The bridge floor of the Normandy Bridge can rise as much as a meter in the middle of a span. In 2003, Lagrange researchers, both French and Italian, studied the construction underway of the viaduct of Millau in the Midi, some of whose pillars will rise higher than the Eiffel Tower.




Michel Frémond
Coordinator of the Laboratory Lagrange
Laboratoire central des ponts et chaussées (LCPC)

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Franco Maceri
Chair of the management committee of the Laboratory Lagrange
Université Tor Vergata (Rome)

René Motro
Laboratoire de mécanique et génie civil (LMGC)

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