I’m not a very good writer and my English does not help me much, but I will try to give you an answer.

The code requirement is that you must check the primary stresses and secondary stresses.

How you can do this? This is the main issue. The same issue is the lift-off problem.
It is very difficult to know this when you deal with non-linear and complex systems.
You must segregate the various stresses types. This is clear for everybody the only problem is that is not really easy to know how.

We can only do this by identifying various operating scenarios (system state) then to isolate components.

There is a time when the force and temperature are coincident, but when force will stop acting, the system will still be hot, so you still have L2 and L1 and you should consider that L2-L1 is the net effect of the F1. If these two scenarios (L1 and L2) are real then is the F that “moves” the system from state L1 to L2 or L2 to L1 so this we must consider.

At least following the L2-L1= (W+P1+T1+F1) – (W+P1+T1) = F1

Take a look of the two images. If you rotate the first and replace F with W it will be about the same with the lift-off problem.

At this point there are a lot of different opinions so I will stop for now.

Regards,