A new concept in bridge design in the 19th century: Ithiel Town's timber bridges

The work aims at documenting the first applications of Navier’s bending theory to structural design. Two cases are presented in the paper, which are described in the 1841 and 1842 volumes of the Annales des Ponts et Chaussées: both cases refer to temporary wood bridges built in France according to the structural layout patented by Ithiel Town in 1820. A brief description of the two lattice bridge patents by Ithiel Town is provided. In these examples, Navier’s bending theory is applied to the bridge beam with the purpose of checking dimensions. In both cases, only the bending behavior is considered, even if in the second example the importance of extending consideration also to deformations is evident. These are the first documented examples of the application of structural analysis to design. No reference is made to the shear behavior, for which a theoretical formulation will be developed by Jourawski about ten years later.