Etabs Mass Summary By Story Better Official

The ETABS Mass Summary by Story provides the (typically in ton-sec²/mm or kip-sec²/in) used for modal analysis (eigenvalue extraction) and equivalent lateral force (ELF) procedures. Understanding it correctly prevents underpredicting seismic demands.

Which (e.g., ASCE 7, Eurocode 8) you are designing for?

Now, the exported table alone is still not great. Create an Excel pivot table that: etabs mass summary by story better

Seismic codes require a strict understanding of the Center of Mass versus the Center of Rigidity (COR) to calculate accidental eccentricity.

), which can cause catastrophic failures if not properly addressed. The ETABS Mass Summary by Story provides the

Mastering the table transitions your modeling from guesswork to verified engineering. By routinely checking this output against manual estimates, auditing your Mass Source inputs, and verifying torsional inertia, you ensure a rock-solid foundation for all subsequent lateral, dynamic, and seismic designs. To help tailor this guide further, let me know:

| Story | Mass DL | Mass 0.25LL | Total Mass | Seismic Weight (W) | Cumulative W | |-------|---------|-------------|------------|--------------------|---------------| | Roof | 850 | 50 | 900 | 8820 kN | 8820 kN | | PH | 300 | 10 | 310 | 3038 kN | 11858 kN | | 5 | 890 | 60 | 950 | 9310 kN | 21168 kN | Now, the exported table alone is still not great

: It helps identify if Superimposed Dead Loads (SDL) on null areas are failing to transfer to the seismic mass because a diaphragm wasn't assigned. How to Access the Report To get this better view of your structure’s data: Navigate to the Display menu. Select Show Tables . Go to Output > Other Output Items > Mass Summary by Story . Pro-Tip: The "Mass Source" Secret

: Ensure your model is fully analyzed (press F5 ). Open Output Tables : Navigate to Display > Show Tables .

The ETABS Mass Summary by Story table contains several distinct columns. Understanding what each column represents is crucial for proper interpretation: Column Name Description Structural Significance The specific level identifier. Tracks mass distribution vertically. Diaphragm The diaphragm assigned to that level. Shows if mass is lumped or distributed. UX / UY Translational mass in X and Y directions. Used to calculate translational kinetic energy. UZ Vertical mass. Critical for vertical seismic or vibration analysis. RX / RY Mass moment of inertia about X and Y axes. Influences the rocking modes of the building. RZ Torsional mass moment of inertia. Dictates the torsional response and period of the story. Step-by-Step Mass Verification Workflow