By Story - Etabs Mass Summary

The center of mass for the entire structure from that story upward. 3. Why This Data Matters A. Seismic Base Shear Verification

Ensure your Dead Load pattern has a self-weight multiplier of 1, so the program automatically includes the weight of beams, columns, and slabs. 5. Exporting for Documentation

By comparing the from this table to the Center of Rigidity (CR) (found in a separate table), you can determine the structural eccentricity. High eccentricity leads to significant torsional (twisting) effects during an earthquake. 4. Tips for Accurate Mass Results etabs mass summary by story

Seismic codes (like ASCE 7 or Eurocode 8) calculate the base shear based on the total "Seismic Weight" (

, the total mass in your ETABS summary (multiplied by gravity) should match your hand-calculated dead loads and applicable live load percentages. B. Spotting Modeling Errors The center of mass for the entire structure

Whether you are checking for modeling errors or prepping data for base shear calculations, here is everything you need to know about the Mass Summary by Story table. 1. How to Access the Mass Summary Table

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 Seismic Base Shear Verification Ensure your Dead Load

Accidental double-modeling of slabs or beams.