: Ensure "Element Self-Mass" is checked if you want ETABS to automatically calculate mass from material density and volumes.
Checking the mass of every beam, column, and slab individually is virtually impossible in large models. Conversely, looking only at the total base reaction can hide localized errors. If a single story has an unusually high or low mass, the Mass Summary by Story table highlights it instantly. 2. Direct Alignment with Seismic Lateral Force Procedures
If you have ever run a seismic analysis in ETABS, you have likely stared at the table. It appears innocent enough: a simple spreadsheet showing mass, weight, and lateral stiffness. But for experienced structural engineers, the default output often raises more questions than it answers.
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
Ensure you are checking the "Include Lateral Mass" option for seismic analysis.
: It allows for a quick manual comparison against estimated building weights (e.g., Dead Load + % Live Load) to ensure no significant loads were missed.
. When viewed floor-by-floor, this allows the engineer to track the alignment of the building’s inertial center. If the COM shifts drastically from one floor to the next, it indicates a potential for high eccentricity and torsional shear, prompting a redesign of the lateral force-resisting system before the project advances too far. 4. Efficiency in Base Shear Calibration : Ensure "Element Self-Mass" is checked if you
In structural engineering, precision in mass distribution is the bedrock of reliable seismic analysis. While ETABS offers various ways to view model data, the Mass Summary by Story
The sum of all story masses in the Mass Summary by Story table does not match the total mass reported for Group ALL (the entire model). Causes & Solutions:
A better mass summary requires rigid or semi-rigid diaphragms. Go to Assign > Shell > Diaphragm and ensure: If a single story has an unusually high
The Story Mass Summary is essentially the "heartbeat" of your lateral force distribution.
Architects often provide cladding as a line load. Ensure these are applied to the perimeter beams and that the mass source is set to include "Specified Load Patterns."
Mass moments of inertia; critical for capturing torsional effects.