in this way i'm analyzing seismic acceleration on pipe (0.35g) separately from structure/piperack displacements.

Structure/piperack displacements are consequence of seismic acceleration on structure/piperack: civil department made calculation to calculate those displacement starting from acceleratio on structure/piperack. So i think (here my starting question) i have to consider seismic acceleration (on pipe) and displacements (on structure/piperack, consequence of seisimc acceleration on structure/piperack) ACTING AT THE SAME TIME. Here is my question.