. Double-check that your Mass Source definition reflects your local code.
Accidental double-modeling of slabs or beams. etabs mass summary by story
Analysis Results > Structure Results > Mass Summary > Mass Summary by Story 2. Understanding the Columns etabs mass summary by story
The sum of the mass of the current story plus all stories above it. This is useful for checking the total "weight" of the building at any level. etabs mass summary by story
Ensure you have assigned diaphragms to your floor shells. ETABS calculates story mass properties most effectively when floors are constrained as diaphragms. Mass Source: Most modern codes require Mass = StorageLiveLoadcap S t o r a g e cap L i v e cap L o a d
The geometric coordinates where the story mass is concentrated.