Hi
eccentricities in response spectrum analysis are eliminated in SAP2000 V14!
Also Base on my experience, There is a bug with SAP2000 V10 response spectrum analysis. As you know the mass eccentricities can be set for diaphragms in static and dynamic analysis. With static analysis everything goes right, but in dynamic analysis when I set zero or another values for eccentricity in settings of response spectrum analysis, it does not affect analysis results.

For your info and according to SAP2000 help, I have done all the settings For diaphragms including:
1- rigidity of diaphragms, 2- the coordinates are global, 3- associated axes are Z, 4- assignment to the joint objects are done. Furthermore, I have tested both methods of defining diaphragms eccentricities: first applying a unique eccentricity ratio to all diaphragms and second utilizing override eccentricities individually, but unfortunately none of them worked out correctly.

Also eccentricities in response spectrum analysis are eliminated in SAP2000 V14.

Your consideration in this regard by answering is greatly appreciated.

Warm Regards