Alexandre Sarrasin (1895-1976) et l'esthétique de l'ingénieur

Alexandre Sarrasin (1895-1976) studied at Zürich Federal Swiss Institute of Technology (ETH) from 1913 to 1918. Despite First World War's conflicts surrounding the neutral Switzerland, the intellectual climate inside ETH was cosmopolitan and liberal. As unique educational institution directly depending from the Federal government, the ETH played an important role in shaping modern Switzerland where country planning and infrastructure building were the central power's main tasks. Engineers were important figures of this process of modernization. They embodied the values of the industrial revolution: rationality, efficiency and the huge power of transformation of the country and its society. Sarrasin opened an engineer's office in Lausanne in 1921 and in Brussell two years later. He established himself in the capital of Belgium in 1927 while ruling at the same time his office in Lausanne. He came back to Switzerland when the German army invaded Belgium. The office in Bruxells was maintained up to the early 1960's. Branches were opened in Sion and Geneva during the 1950's. Sarrasin's work concerned foundations, buildings, bridges and some dams also. Nearly all these constructions works were made of reinforced concrete, his favorite material. This thesis is dedicated to the construction works, especially the bridges in Valais, Sarrasin's native district, and the aesthetic question in engineer's design. Of the bridge of Branson (1924- 1925) near Fully, his first important commission, he wrote that "The elegance of the design is due to its simplicity. The quietness of its lines is fully harmonized with the landscape. Nothing was planned for the decoration. The bridge is the simple realization of a mathematical truth". This quotation highlights the issue of form for engineers and especially in Sarrasin's works: the affirmation of simplicity and "mathematical truth", that is to say the expression of the structural mechanics, as the engineer's aesthetic's fundamental the relation with the landscape The question of form was not only thought of in terms of efficiency and economy, or lack of decoration. The development of structural mechanics as engineer's science gave new conceptual tools allowing new designs. The first professor of civil engineering at the ETH, Karl Culmann (1821-1881), was the graphical static's father. This applied science was inspired by descriptive geometry and graphical calculation methods developed in France during the 18th and 19th century. To the construction's classical point of view distinguishing between elements bearing weight (for example pillars) and others being supported (for example lintels), graphical static opposed a spatial vision of forces interactions into the structure. New materials allowed bringing these forces into play with tensed cables, compressed or extended frames. At the beginning of the 20th century, reinforced concrete appeared as modern material along side with iron and steel. Created by builders in the 1