1. Principles and behavior analysis

1.1 Foundation

Metal fabricators are very familiar with the optimization process involving the specialization of elements or sections (lattice, I for bending, tubes for compression or torsion).

As it happens, of the four pure stress modes (normal stress, tangent stress, bending moment, torsion moment), only the normal stress, in the case of tension, subjects the entire section to a constant normal stress in the elastic phase, if necessary at its admissible or limit value. Hence, with the aim of reducing the structure's own weight as much as possible, the search for a design and structural composition such that all components are, in fine, only tensioned (maximum stress, freedom from elastic instability), whatever the load case.

The existence...