As the assessment has to consider stress values within the welds, but only stress values within the joint plates are provided, the stresses of the elements need to be upscaled. For this a factor fw is used which describes the proportion of a weld cross section "a" to the sheet thickness "t", see the figure below.

The factor fw is calculated by:

The upscaling of membrane and bending stresses is done according to the following formulas: ,

The upscaled normal stress in the weld is then calculated according the following formula:


The quadratic upscaling of bending stresses is not performed in Eurocode assessments, because structural stresses are used for the evaluation according to the IIW recommendations as structural stresses already take the effect of stress enhancements within the weld into account.


In most weld joints this will be a conservative approach, since the force flow will not always go entirely through the weld.