Etabs Mass Summary By Story ((top)) Official

: Always double-check your units (e.g., kg vs. tonf-s²/m) to ensure the values align with your manual seismic weight calculations. table directly to for further reporting?

: The translational mass of the floor in the global X and Y directions.

This article explores what this table means, how it is generated, its components, and why it is indispensable for seismic design. 1. What is the ETABS Mass Summary by Story? etabs mass summary by story

In most standard buildings with symmetric floor layouts, UX and UY will be equal or very close. Differences between UX and UY may indicate mass irregularities, eccentricities, or that the mass source is not defined consistently.

Compare modeled weight against manual calculations to meet quality assurance requirements. : Always double-check your units (e

The calculated gravity load associated with each level, derived directly from your defined mass source. Why is the Mass Summary Table Important?

ETABS automatically calculates the mass of structural elements (beams, columns, slabs) based on their geometry and material density. It also includes any manually assigned point, line, or area masses. : The translational mass of the floor in

The total weight from the roof down to that level. 💡 Pro-Tips for Accuracy

Once you have defined your Mass Source and run the structural analysis, you can view the story-by-story mass breakdown by following these steps:

Note on RZ: represents the torsional mass moment of inertia. This value dictates how the building twists during a seismic event and is critical for evaluating accidental eccentricity and torsional irregularities. Step-by-Step Mass Verification Workflow

For the practicing structural engineer: take the time to verify this table. When the Mass Summary by Story matches your hand calculations, you have confidence that the rest of your dynamic analysis—base shear, story drift, and member forces—rests on a solid foundation. And that, ultimately, is the difference between a software output and a reliable engineering decision.