Steel structures - Welded joints

The articles on assembly methods used in steel construction have been subdivided into several sections:

• [C 2 520] "Means of assembly;

• [C 2 521] "Assembly by mechanical processes".

This third article deals with welding assembly techniques.

Welding is a permanent joining process obtained by localized fusion of the metal of the parts to be joined in the joint area.

There are three main methods for creating the heat required for welding:

• oxyacetylene flame;

• resistance to current flow ;

• electric arc.

Each method produces a bath of molten steel that must be protected from atmospheric contamination, as the molten steel is likely to absorb gases from the air, which can render the weld porous and thus lead to mechanical and metallurgical problems. The method used to achieve this protection has a major influence on the characteristics of the operating procedure.

Oxyacetylene flashlights are more commonly used for cutting parts, although laser and plasma cutting processes are becoming increasingly common.

Resistance processes are used in spot welding of thin components.

The most commonly used methods for welding structural steel components are based on the electric arc.

This article begins by describing the various welding processes available in steel construction, and the many phenomena associated with them.

The second part presents the different types of welds:

• butt welds ;

• corner cords ;

• plug welds ;

• spot welding.

The third part presents the calculation of weld seams as defined in EN 1993-1-8. While butt welds generally require no specific dimensioning when they ensure the geometrical and mechanical continuity of the assembled parts, this is not the case for other types of weld...