Better — Etabs Mass Summary By Story

Ensure you haven't modeled a slab over a slab, which doubles the mass in that specific story.

Check if superimposed dead loads (SIDL) are applied correctly.

For better results, your "Mass Source" definition should follow these industry standards: etabs mass summary by story better

Ensure you are checking the "Include Lateral Mass" option for seismic analysis.

Cumulative mass from the top down; used to check total building weight. Ensure you haven't modeled a slab over a

The Center of Mass coordinates; compare these to the Center of Rigidity. How to Improve Your Mass Source Setup

Confirm the inclusion of the appropriate percentage of live loads. etabs mass summary by story better

Architects often provide cladding as a line load. Ensure these are applied to the perimeter beams and that the mass source is set to include "Specified Load Patterns."