First, you need to model enough underground routing in order your model get- at UG/AG points -the appropriate figures as displacement under pressure and UG temperature. Doing in this way, the AG part will see that imposed displacement, but also temperature, pressure and inertial seismic as you define in your model.

In case your concern about seismic is the UG part, CII is not a tool to evaluate this subject because the inertial forces are not really of interest for UG.