I re-read your OP, I see that you mentioned there was positive axial movement in the thermal (T) case and negative axial displacement in the pressure (P) case. What about in the GT1P1 case? Is there displacement there?
Try not to focus on the individual T and P cases, focus more on looking at the displacement and forces occuring in the:
GR
GT1P1
GTXPX (where X is your alternate thermal/pressure conditions)
GTXPX+EX
GTXPX+WX
GTXPX+Snow
referencing the individual T and P cases gives you good data on where the loads and movements are coming from, but don't design a support based solely on the output from T or P. In the real world those cases are never going to occur as you will always have GR included and for 99% of processes, T and P will occur at the same time in the steady state condition.