). In ETABS, earthquake forces are directly proportional to the building's mass.
Unlocking Precision: Why "Mass Summary by Story" is Better for ETABS Analysis
| Story | U1 (X) ton | U2 (Y) ton | U3 (Z) ton | | :--- | :--- | :--- | :--- | | Roof | 150 | 150 | 1000 | | 3rd Fl | 250 | 250 | 1200 | | 2nd Fl | 250 | 250 | 1200 | | Base | 200 | 200 | 1500 |
For firms working on 50+ story towers, manual checking fails. Use the ETABS API to extract the mass summary and automatically compare it against an external gravity spreadsheet. If deviation > 5%, the script halts and flags the story. etabs mass summary by story better
I can provide tailored steps to extract and verify your specific seismic mass data. Share public link
Select "From Self and Specified Load Patterns" and create a custom combination:
: If your model uses diaphragms, also include the Center of Mass and Rigidity table to show eccentricity. 3. Verification & Quality Checks Use the ETABS API to extract the mass
If you use From Self and Specified Loads , the self-weight multiplier is typically 1.0 . But if you accidentally set it to 0 , you lose the entire slab and beam mass. Double-check this.
Display > Show Tables > Analysis Results > Structure Results > Centers of Mass and Rigidity CSI Knowledge Base
: Mass moments of inertia about the global axes, critical for torsional calculations. Share public link Select "From Self and Specified
Calculate the tributary area of a typical floor, multiply it by your expected dead load per square foot, and compare it to the table's Mass X value. The numbers should align within a 5% to 10% margin.
ETABS provides three primary ways to define the seismic mass:
Torsional effects and accidental eccentricities are calculated relative to the center of mass at each story.