Dear
I think you must not only look for the sign
-U and +U. You must also look for the direction U (Y direction) U (X direction) and
U (Z direction)in the static seismic analysis. And you must found the max. forces and moments for the restraints.
Look, the horizontial acceleration gives a load in a Guide restraint. When calculate
only U vertikal, then you becom no load
in horizontioal restraint!