Steel structures - Pathology of steel structures

A building, whatever its purpose (residential, industrial, community, entertainment...) and its construction principle (material, type of structure), must be capable of resisting the forces applied to it. In the context of the subject of this article, this "resistance" role is performed by the steel framework or structure that forms the building's "skeleton".

The steel used in steel construction [1] has guaranteed characteristics. It is an isotropic, homogeneous material with ideal behavior according to the theory of elasticity, the basis of the laws of strength of materials. It is ductile, a property necessary for the proper distribution of forces in assemblies.

It can be welded, subject to compliance with the provisions specified in the project .

It is the material most commonly used in construction, offering the highest properties for the lowest weight.

The structure's main function is to ensure that external forces are transmitted to the solid foundations. Knowledge of this path is essential for the study of the structure's constituent elements and their connections (fasteners). The structure is stable if this transmission takes place without disorder.

Metal frames are generally "flexible" and made up of "slender" bars or thin elements. These specific characteristics need to be borne in mind when designing steel structures, as the problems of flexibility, buckling, tilting of bent beams and buckling of compressed elements are decisive in the justification and dimensioning of steel structures.

The current rules [2] allow steel structures to be justified by the theory of strength of materials in the elastic domain, with the possible inclusion of a plastic adaptation coefficient. The justification of structures taking plasticity into account, under certain conditions and precautions, has been codified since 1981 [3] .

Future structural steel design regulations currently in preparation [Eurocode 3, EC3-DAN (national application document)] will codify other design methods (non-linear analyses: geometry and/or material).

Compliance with the validity of these codes is essential and must be verified for each project.

Regulations are just one of...