Etabs Mass Summary By Story May 2026

ETABS provides a cumulative total from the top down. This is useful for checking overturning moments and total base shear.

Appendix: Step-by-Step to Extract Mass Summary in ETABS

A very specific topic!

In ETABS, a popular software for structural analysis and design, the "Mass Summary by Story" feature provides a detailed report of the mass distribution of a building model, broken down by story (or floor).

Here's what it entails:

What is Mass Summary by Story?

The Mass Summary by Story report in ETABS summarizes the mass properties of a building model, including: etabs mass summary by story

Why is Mass Summary by Story useful?

This feature is useful for:

How to access Mass Summary by Story in ETABS?

To access this feature in ETABS, follow these steps:

The Mass Summary by Story report will display, showing the mass properties for each story in your building model.

Do you have any specific questions about using this feature or interpreting the results? ETABS provides a cumulative total from the top down

ETABS does not simply add up the dead load. The program follows code-specific load combinations to determine seismic mass, typically:

Seismic Weight = Dead Load + Applicable Live Load (Percentage) + Partition Loads + Equipment Loads

You control this via: Define > Mass Source.

The most common mistake engineers make is forgetting to define the Mass Source. By default, ETABS uses only the self-weight of the structure. You must manually add superimposed dead loads and a percentage of live load (e.g., 25% for parking, 50% for office storage as per ASCE 7).

Author: [Your Name] Course: Structural Engineering / Computer-Aided Design Date: [Current Date]

Objective: Verify that the total seismic mass matches the design calculation. Appendix: Step-by-Step to Extract Mass Summary in ETABS

Input Data:

ETABS Mass Summary Output:

Check: Expected $5 \times 600 = 3000 \text kN$. Error = 0.07% → Acceptable.

Conclusion: Mass summary matches hand calculation. Modal analysis can proceed.

  • Weight: This is the Total Mass converted back into force units (Weight = Mass × $g$). This is the number to check against your manual dead load take-offs.

    • Create a formula: Total seismic weight = Σ (U1 Mass * g). Compare this to your hand-calculated building weight (Sum of areas * (DL + LL + partitions)). They should match within 2%.

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