No uplift while doing Response Spectrum Analysis

While analyzing a structure for response spectrum seismic loading the response(base reactions, member end forces, etc.), comes to be in absolute value.

This is due to the fact that the responses coming out of several modes are combined by using some predefined methods like SRSS or CQC & thus the result is always +ve or absolute value.

Actual push-pull of support reactions, coming out of horizontal loading on structure, does not come into the picture.

While I check the reaction, the support only shows up compression value, and no tension /uplift is generated.