Etabs Mass Summary By Story High Quality Today
While the main table focuses heavily on translational masses ( Mass X and Mass Y ), ETABS also calculates around the vertical Z-axis (often labeled as MMI or found in the Centers of Mass and Rigidity table). Rotational mass is critical because it dictates how much the building will twist under accidental or inherent eccentric lateral loading. Step-by-Step Verification and Troubleshooting
In the realm of structural engineering software, CSI ETABS (Extended Three-dimensional Analysis of Building Systems) stands as a cornerstone for the analysis and design of building systems. Among the myriad of output tables and log files it generates, one of the most critical—yet often overlooked—is the .
The center of mass for the entire structure from that story upward. 3. Why This Data Matters A. Seismic Base Shear Verification
In the realm of computational structural engineering, the "Mass Summary by Story" table is not merely a ledger of weights; it is the quantitative biography of the building. While ETABS provides a plethora of complex output displays—from moment diagrams to shell stress contours—the Mass Summary remains the fundamental diagnostic tool for verifying the physical integrity of the analytical model. It serves as the bridge between the architectural intent and the structural reality, translating volumetric geometry into the inertial forces that govern seismic response.
In ETABS, the is one of the most critical outputs for structural engineers. It provides a concise breakdown of how weight is distributed across the height of a building—a factor that directly dictates seismic forces and dynamic behavior. etabs mass summary by story
: Total translational mass active in the X and Y directions.
(Translational Mass): The mass resisting lateral forces in the global directions, typically measured in units like UZcap U sub cap Z
Seismic design codes (such as ASCE 7, Eurocode 8, or IS 1893) calculate the design seismic base shear ( ) using the total effective seismic weight (
These represent the total mass considered for horizontal motion in the X and Y directions. In most cases, these values are identical unless you have assigned specific directional mass properties. While the main table focuses heavily on translational
Whether you are performing a seismic analysis (Response Spectrum or Time History) or simply checking vertical load distribution, understanding the Mass Summary is non-negotiable. This article breaks down what this summary tells you, where to find it, and how to use it to validate your model.
The values in the mass table are not arbitrary; they are derived from the defined in ETABS. The mass source defines what makes up the "weight" of the building, which includes:
Extracting this table is not just a bureaucratic step in documentation; it is a fundamental quality control and regulatory requirement. 1. Verification of Base Shear
Once you have defined your Mass Source and run the structural analysis, you can view the story-by-story mass breakdown by following these steps: Among the myriad of output tables and log
-Mass) against the center of rigidity helps you identify inherent eccentricities that cause amplification of torsional responses during an earthquake. Troubleshooting Common Discrepancies
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
The in ETABS is a critical output table used to verify the mass distribution of a structural model, ensuring that seismic and dynamic analyses are based on accurate data. Overview of Mass Summary by Story