Etabs Mass Summary By Story Better May 2026
In ETABS, the Mass Summary by Story table is a critical output for verifying your building's seismic weight and ensuring your Mass Source is defined correctly. It provides a lumped mass per level, which is more intuitive for global checks than viewing individual joint or element masses. How to Access the Table
The primary benefit of the Story Mass Summary is its role in "Mass calculated manual" verification. By breaking down the weight floor-by-floor, you can easily compare ETABS’ output against manual calculations for: etabs mass summary by story better
Method C: Python Scripting via ETABS API
For large projects, manual checking is error-prone. Use the ETABS API (C# or Python) to extract: In ETABS, the Mass Summary by Story table
Step-by-Step (ETABS v18+):
- Navigate to Define > Mass Source.
- Select "From Load Cases" (not "From Self and Specified Loads").
- Add the following load cases:
5. Sample Summary Table (Better Format)
| Story | UTotal (ton-s²/m) | RTotal (ton-s²-m) | Verification Check | |-------|------------------|-------------------|--------------------| | Roof | 125.4 | 8,420 | ✅ Cladding + roof live 20% | | 5 | 210.2 | 12,150 | ✅ Partition added | | 4 | 210.5 | 12,140 | ✅ Uniform | | 3 | 210.3 | 12,160 | ✅ Uniform | | 2 | 211.0 | 12,170 | ✅ Slight increase from stair infill | | Base | 0.0 | 0.0 | ✅ No mass at fixity | Navigate to Define > Mass Source
The Mass Summary by Story table in ETABS is often considered "better" or more reliable than other mass tables because it provides a comprehensive accounting of all structural mass assigned to a level, regardless of whether a diaphragm is present. Why "Mass Summary by Story" is Often Preferred
