Answer:
The Sigma Delta stress determines the maximum difference between the normal stresses. This is used to display the existing difference between the stresses available in the different load cases. Therefore, the result tables only show an existing stress value, no corresponding load cases or design ratios.
If, for example, only members under pure tensile load are present, the difference between the lowest and the highest stress is given as an absolute value for Sigma Delta. Thus, it is possible to determine the difference from different load cases.
The Sigma Delta stresses can be used for fatigue design.
