Etabs Mass Summary By Story Better !exclusive! Jun 2026

For response spectrum or time history analysis, the Mass Summary is your truth serum. Compute the from the modal analysis. The Mass Summary gives you the total mass of the building. The modal output gives you the effective modal mass.

Ensure that the sum of the effective modal masses in the X and Y directions equals at least 90% of the total mass listed in your Story Mass Summary. If they don’t match, your structure is either too flexible (need more modes) or your constraints (rigid diaphragms) are preventing proper mass participation.

Master the Mass Summary, and you will no longer wonder why your building twists unexpectedly or why your base shear seems low. You will know .

While global totals provide a "big picture" view, the is the tool of choice for the meticulous engineer. It bridges the gap between complex finite element modeling and the practical requirements of building codes. By offering localized clarity, simplifying error detection, and enhancing the reliability of seismic data, it ensures that the digital twin behaves as closely as possible to the future physical structure. etabs mass summary by story better

Display > Show Tables > Analysis Results > Structure Results > Mass Summary by Story Cumulative Mass X (Sum to N) Total Mass

| Story | Mass (kip-s²/in) | Lateral Stiffness | |-------|------------------|-------------------| | Roof | 1250 | 280 | | 5 | 900 | 310 | | 4 | 900 | 310 |

To view the mass summary data, you must first run a basic structural analysis. Once the analysis completes, navigate through the program using the following steps: Click on the menu at the top of the screen. Select Show Tables from the dropdown options. Expand the Analysis Results tree. Expand the Structure Results folder. Select Mass Summary by Story to open the data grid. Key Data Fields Explained For response spectrum or time history analysis, the

The ETABS Mass Summary by Story is an indispensable tool in structural engineering, providing critical insights into a building's mass distribution. By effectively interpreting and utilizing this information, engineers can design safer, more efficient structures that meet or exceed code requirements. Whether you're a seasoned professional or a student, understanding this aspect of ETABS can significantly enhance your structural analysis and design skills.

As you build upward, the people get lighter.

Display > Show Tables > Analysis Results > Structure Results > Centers of Mass and Rigidity CSI Knowledge Base The modal output gives you the effective modal mass

Instead of relying on ETABS’ automatic story grouping, define (e.g., Group-Roof-Beams , Group-Penthouse-Walls ). Then modify the Mass Summary by Group table. This gives you control to exclude non-structural masses that artificially inflate the story summary.

The translational mass active in the X and Y directions. In most standard buildings, these values will be identical unless you have directional mass modifiers.

Create a Mass Source that references load patterns ( DEAD , SUPER_DEAD , LIVE_REDUCED ). Never use the "From Self & Specified Mass" option unless you fully understand the lumped mass elements you've added. A clean mass source leads to a clean summary.

Mass should generally decrease as you move up the building. The roof level is typically lighter than typical floors because it carries lower live loads and lacks rising vertical elements like columns or shear walls.

Here are a few options for a positive review of the feature or report, ranging from professional to more enthusiastic. Professional & Precise