Etabs Mass Summary By Story Better [top] -

When you use ETABS for high-rise or complex structures, simply looking at the total mass isn't enough. You need to ensure the distribution aligns with the structural intent. Why Mass Summary by Story Matters

Interpreting between the Center of Mass and Center of Rigidity.

Seismic forces are calculated based on mass. If your story mass is off, your base shear and lateral forces will be incorrect. This table allows you to: Verify the self-weight of slabs, beams, and columns. 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."

Typically, use 1.0 for Dead/SIDL and 0.25 for Live Load (depending on your local building code). When you use ETABS for high-rise or complex

For better results, your "Mass Source" definition should follow these industry standards:

Cumulative mass from the top down; used to check total building weight. Seismic forces are calculated based on mass

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

💡 Always compare the Total Mass in the summary table to the Base Reaction for a dead load case. They should be identical. If they aren't, your mass source is likely missing a specific load pattern.

ETABS automatically lumps mass at the story levels. If you have significant mass between floors, consider adding dummy levels or intermediate joints. Troubleshooting Common Discrepancies