Etabs Mass Summary - By Story Better Best

Why is the mass in my penthouse higher than the roof? Why is the mass contribution from diaphragms different from my dead load takeoff? Why does the seismic weight not match my hand calculations?

Stop Guessing: How to Actually Use the ETABS Mass Summary by Story

Tracking your model's inertial properties using the is a significantly better method for structural verification. Extracting your mass metrics story-by-story helps you catch hidden modeling mistakes, satisfy strict building codes, and ensure your dynamic and lateral wind/seismic simulations are completely accurate. Why Is the Story Mass Summary Approach Better? etabs mass summary by story better

Properly add Load Patterns (Dead Load, Superimposed Dead Load, Partition Load) with a multiplier of 1.0.

Mastering Seismic Analysis: Why ETABS Mass Summary by Story is Better for Structural Engineers Why is the mass in my penthouse higher than the roof

Let’s fix the default output. Follow these steps to generate an accurate, plan-check-ready mass summary.

The mass distribution directly determines story shears and the total base shear ( V ), which is the total horizontal force the earthquake exerts on the structure. The base shear is a function of the effective seismic weight, W (the total mass from your Mass Summary by Story , converted to weight). You can find this in the program's printed summary. Stop Guessing: How to Actually Use the ETABS

Always verify the active units (e.g., kg, kN, or kips) before exporting the table to Excel to avoid catastrophic scaling errors.

Beyond basic interpretation, using the mass table strategically can drastically improve your analysis results.

: Briefly describe the structure, including the number of stories, heights, and general building type.

definition. To align with most seismic codes (like ASCE 7-16), ensure you include 100% of Dead Loads and a percentage of Live Loads (typically 25% for storage or specific occupancy). Unit Conversion