Etabs Mass Summary By Story Better !new! Access
What is ETABS Mass Summary by Story?
Tips for Using Mass Summary by Story in ETABS etabs mass summary by story better
Centers of Mass (XCM, YCM): The geometric center where the story mass is concentrated. Common Issues to Watch For Center of rigidity - ETABS - CSI Knowledge Base What is ETABS Mass Summary by Story
- Dead Load (DL): Multiplier = 1.0 (Full self-weight)
- Super Dead (SDL): Multiplier = 1.0
- Live Load (LL): Multiplier = 0.25 (for ASCE 7 seismic mass, adjust per your code)
- Snow Load (SL): Multiplier = 0.0 to 0.2 depending on your jurisdiction
- Partition Load: Include if not already in SDL
where ( g ) = 9.81 m/s² (or 386.4 in/s² in imperial). Dead Load (DL): Multiplier = 1
Interpreting the table
- Columns typically include: Story name/level, Total Mass, Mass X, Mass Y, Mass Rotational (if shown), Cumulative Mass, Percentage of Total.
- Check that cumulative mass reaches an expected percentage (codes often require ≥90% modal mass participation in primary modes).
- Compare mass per story for unexpected peaks or drops—these may indicate missing elements or incorrect story heights.
- Look at the "Mass" column from top to bottom.
- Does the mass generally increase as you go down?
- If Yes: Good. Gravity is working.
- If No (Spikes): You may have a heavy mechanical unit on a random floor, or you forgot to model openings in a slab.