Louis-Jean Résal

{{Short description|French civil engineer}}

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Jean Résal (22 October 1854, in Besançon – 14 November 1919, in Paris) was a French civil engineer. He was a professor of mechanical engineering at the École polytechnique, and designed several metal bridges in France, especially bridges above the Seine in Paris:{{Cite web|url=https://structurae.net/persons/jean-resal|title=Jean Résal (1854 - 1919) {{!}} Structurae|website=Structurae|language=en|access-date=2017-02-24}}

The career of the brilliant student of the École des ponts ParisTech was always an upward ladder: service in the Roads and Bridges Department at the Loire-Atlantique Département and thereafter in the shipping authority in Paris. Résal succeeded the student of Saint-Venant, Alfred-Aimé Flamant (1839-1915), at the Chair of Strength of Materials at the École des ponts ParisTech in 1892. Although Résal had already published a two-volume work on arch bridges together with Ernest Degrand (1822-1892), he concentrated on the theory and practice of steel bridges from a very early stage and had a profound influence on steel bridges at the transition from the discipline-formation to the consolidation period of theory of structures.

• Nantes Résal Bridge (rail), destroyed during the Second World War, rebuilt in concrete
• Road bridge over the Erdre (Nantes), appointed first bridge Barbin, then Pont du General de la Motte Rouge.
• Mirabeau bridge in Paris (road bridge, 93 m range)
• Alexandre-III Bridge (Paris) (highway bridge, 107 m range)
• Bercy bridge (Paris)
• Gateway Debilly (Paris)
• Bridge of Notre-Dame (Paris)

The bold steel arches of the Pont Général-de-la-Motte-Rouge (1885) in Nantes, Pont Mirabeau (1896) in Paris, Pont de l'Université (1899), Pont Alexandre III (1900) and Pont Notre-Dame (1914) in Paris set standards for steel bridges. All those bridges listed could only be built as a result of Résal’s research into elasticity and the strength of structural steels, work that he summarised in a monograph (1892). Furthermore, Résal made a lasting contribution to earth pressure theory (1903, 1910), which Albert Caquot would use successfully as his starting point.

The Résal effect is named after him.