Thank you very much for your quick answer. Very appreciated it!
Yes, I've had the same concern about Miner's Rule (thinking that probably is quite forced in our case).
I think B31.3 is not so clear about what is permissive on the stress (range) from a single, one-time displacement, even some guidance is provided within. If a client insists to remain under B31.3, I have to follow (1d) "fifth power rule" also for this case, isn’t it?

Thank you again,
My best regards