Hi there,

Here is just an opinion:

At THIS time, B31 Code Occasional Stress qualification are not correlated with B31 Displacement Stress Range (e.g. thermal expansion/contraction stress) check. Occasional and Sustained stresses are not self-limited stresses and are related to plastic collapse failure, while displacement stresses are considered self-limited stresses and are related to fatigue failure mechanism.

A conservative approach that would provide a safe envelope for B31 Code Occasional Stress qualification, would be to define a MAX SUS Load Case as MAXimum between actual SUS and Alt-SUS cases, and to perform then the ABS (absolute) summation between this MAX SUS case and the individual OCCasional (OCC) load cases.

A more expedite approach would be to perform the ABS summation between MAX SUS and MAX OCC (latest case as MAX between all individual Occasional load cases - might be efficient if you have many Occasional load case - WIND, SEISMIC, Slug Flow, etc.). But such approach might be overly conservative indeed.

Personally, this is the approach I use to employ. If it fails, then we need to go to deeper/more accurate investigations....

Regards,