Expansion Load Cases

Dear Friends,

I need your assistance for one of my problem facing in current LNG project.

We have negative temperature,so we are following load cases as below.

L1 = W+P1+T1 (OPE)
L2 = W+P1+T2 (OPE)( -VE TEMP)
L3= W+P1 (SUS)
L4 = L1-L3(EXP) --> ALGEBRAIC
L5= L2-L3 (EXP) --> ALGEBRAIC
L6 = L4+L5 (EXP) --> ABS

CLIENT COMMENTED TO USE BELOW

L6= L1-L2 (EXP) --> ALGEBRAIC

To take thermal full stress range, we are taking load case L6 i,e in "ABS" combination method.

However, client commented to use L1-L2.

May I request to you all, please provide your suggestion, which method is correct one?

As per my knowledge, L1 & L2 are OPE and without selecting Appendix P, CAESAR not checking any stresses.

So, if I directly subtract as per client comment, is it correct way?

As per CODE it is mandatory to take "Full thermal stress range", So,I need to finalize the method of load case evaluation.

Thanks

DAVE

I would say the client's L6 fits better with CAESAR II's approach in calculating stress range when nonlinear conditions exist. This is similar to your current L4 & L5.

Your current L6 harkens back to the solution for purely linear analyses. I believe your L6 may produce more conservative results.

Check B31.3 Appendix S example 3 for more information.

Dear Dave,

Thanks for your guidance.

Yes, My proposed load case creates higher stresses than the client's suggested load case.

If, load cases wise, I will subtract, the output value should be same. But if "CAESAR RESULT" shows "L6" in both cases are different.

Is this due to Linear or Non-linear concepts of supports?

Regards
DAVE