The Garabit Viaduct: A Historical and Structural Study

Abstract

This thesis investigates the Garabit Viaduct, providing a historical study and structural analysis of its truss arch. It aims to unravel the ingenuity behind the arch's elegant shape and design process. By examining historical plans and the memoirs of engineers such as Gustave Eiffel and Léon Boyer, this research uncovers the evolution of the viaduct's design and shape, revealing that the geometry of the arch was form-found using graphic statics. This study sheds light on the structural design hypotheses employed by Gustave Eiffel and Maurice Koechlin in sizing the members, providing insights into design practices of the late 19th century. Additionally, the study of the primary source documents left behind by the engineers suggests the method used for the arch's design may have influenced the shaping of the supporting piers, opening avenues for future research into the broader implications for Eiffel's later iconic tower.