Design Resistance of a Fillet Weld (European Standard)

The weld size is determined according to Eurocode EN 1993-1-8: 2002, Paragraph 4.5.3.

The weld tractions are resolved into weld throat coordinates as shown. The weld throat area is concentrated at the root.

Free body diagram of weld joint
Free body diagram through weld throat
For transverse loading in weld joint coordinates For transverse loading in weld throat coordinates
The forces transmitted by a unit length of weld are resolved into components parallel and transverse to the longitudinal axis of the weld, and normal and transverse to the plane of the weld throat.

The resistance of a fillet weld is sufficient if the following formulas are both satisfied:

where:

  • fu is the ultimate tensile strength of the weaker part joined
  • βw is the appropriate correlation factor according to this table.
  • γΜ2 is the partial safety factor according to this table.
  • is the normal stress perpendicular to the throat
  • is the shear stress (in the plane of the throat) perpendicular to the axis of the weld
  • is the shear stress (in the plane of the throat) parallel to the axis of the weld
  • is the normal stress parallel to the axis of the weld. It is not considered when verifying the weld resistance.