Etabs Mass Summary By Story !full! (360p)

The table exists in two primary forms in ETABS:

Calculate the dead weight of a typical floor by hand (tributary area

The mass moment of inertia about the global X, Y, and Z axes.

In a dynamic analysis, ETABS calculates the participation factors based on this mass. A critical check involves verifying that the modal participation mass ratios sum to near 100% (

Here is a detailed guide on how to extract, interpret, and troubleshoot the Mass Summary by Story in ETABS. Why Story Mass Matters in Seismic Design etabs mass summary by story

Next she compared imposed loads used to compute masses. The mass summary reminded her of the live load reduction she’d applied per code: residential floors used a reduced live load factor, but the rooftop mechanical area still used full live load. That explained a spike at Story 11 where the plant room sat. She adjusted the live load assignment—moving some equipment to a lower floor—and watched the mass numbers settle into a more uniform gradient.

To get a clear picture of how your building’s weight is distributed, follow these steps in ETABS. This summary is essential for verifying your seismic mass and ensuring your model’s gravity loads make sense. How to Find the Mass Summary

The ETABS Mass Summary by Story is not just another output table; it is your model's . Before you invest hours interpreting drift ratios or designing rebar, spend two minutes reviewing this summary.

Alternatively, you can find it in the output text file ( .OUT ) generated after analysis. The table exists in two primary forms in

Below is a drafted report structure for presenting this data. Structural Mass Summary Report 1. Project Overview ETABS 2026 Model Status: Analysis Completed Mass Source: Defined as [e.g., Self Mass + 25% Live Load] 2. Mass Source Definition

The values in the summary table are derived directly from the definition ( Define > Mass Source ). ETABS calculates mass based on three primary settings:

The coordinates of the center of mass for all stories combined from the top down to the current level. 5. Step-by-Step Verification Workflow

In the model explorer or top menu, navigate to > Show Tables . In the Choose Tables window, expand Analysis Results . Expand Structure Results . Check the box for Mass Summary by Story . Click OK . Troubleshooting Common Errors in Story Mass Summaries Why Story Mass Matters in Seismic Design Next

The table provides the exact coordinates of the Center of Mass (Xcm, Ycm). Comparing these coordinates with the Center of Rigidity (CoR) allows engineers to calculate . If the distance between the CoM and CoR is too large, the building will experience significant twisting moments during an earthquake. 3. Diaphragm Mass Check

Once you have successfully run your analysis in ETABS, follow these steps to view the data: Navigate to the on the left-hand side. Go to Tables > Analysis > Results > Structure Results . Double-click on Mass Summary by Story .

) across all stories multiplied by gravity should equal your total seismic weight (

The total mass from the top of the building down to that specific story. Why the Mass Summary Matters 1. Seismic Base Shear Verification The total seismic weight (