Pierre-Simon Girard

Pierre-Simon Girard came from a Protestant family. Girard’s scientific talent was recognised at an early age, which enabled him to study at the École des Ponts et Chaussées, leaving in 1789 as a roads and bridges engineer. During the 1790s, Girard was involved in waterways and he published his first monograph on strength of materials in 1798 [Girard, 1798], which, however, was restricted to beam theory. In the first part of his book he presents the history of beam theory, but shows a preference for Euler’s non-linear theory, which is why Girard’s work contains complicated mathematical equations that are of little use in practice. Eytelwein would be the first to work with the linearised differential equation for bending in 1808 (see eq. 5-51), later Navier (see section 5.6.3.2), who based his practical bending theory on this. The second part of Girard’s book deals with a problem that was popular in the 18th century – the beam of constant strength. But the third part of his book is original and covers bending and buckling tests. Girard’s monograph on strength of materials is a focused demonstration of the initial phase of structural theory (1775–1825) and as such forms the historico-logical precursor to Navier’s synthesis of statics and strength of materials to form theory of structures. In the same year his book on strength of materials was published, Girard together with other engineers and scientists accompanied Napoleon on his expedition to Egypt. After his return, Girard dedicated himself to problems and projects in hydraulic engineering, especially canal-building.

Main contributions to structural analysis:

Traité analytique de la résistance des solides, et des solides d’égale résistance, auquel on a joint une suite de nouvelles expériences sur la force, et l’élasticité spécifique des bois de chêne et de sapin [1798] 

Source: Kurrer, Karl-Eugen The History of the Theory of Structures, Wilhelm Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH, Berlin (Deutschland), ISBN 3-433-01838-3, 2008; p. 733

Participation in the following structures & large-scale projects:

• Canal Saint-Denis
• Ourcq Canal
• Saint-Martin Canal