The vertical mass. This is critical if you are running a vertical time-history or vertical frequency analysis.
table to ensure the applied un-decomposed loads match the calculated reactions. Common Pitfalls to Avoid
The "Mass Summary by Story" is a tabulated report in ETABS that lists the calculated mass (or weight) at each floor level based on the defined Mass Source .
Lump Lateral Mass at Story Levels is crucial. If this is not checked, ETABS might distribute masses to individual nodes (mesh points), which can cause inaccuracies if meshing is inconsistent. D. Validate with Manual Calculations etabs mass summary by story better
As a structural engineer, you know that the soul of a seismic analysis lies in how you define your building's mass. While ETABS offers various ways to view your model's weight, the report is often the gold standard for high-accuracy design.
Accounts for specialized joint masses and line masses without extra tracking.
If you have a and are struggling with unexpected mass distribution ,g., concrete, steel, residential, commercial). Whether you are using rigid or flexible diaphragms . Any non-structural elements you are trying to include. YouTube·Computers and Structures, Inc. TECH TIPS: Mass Source Definition in ETABS The vertical mass
Before looking at specific ETABS tables, it is important to understand why mass tracking is critical. Dynamic analysis relies heavily on the mass matrix of the structure.
Confirm the density of concrete/steel in the Material Properties .
The primary advantage of the "by story" summary is its direct alignment with seismic code requirements. Most international standards, such as ASCE 7 or Eurocode 8, define lateral loads based on floor levels. By summarizing mass at the story level, ETABS provides a clear snapshot of the for each floor. This allows engineers to verify that the program is correctly calculating the mass source—including self-weight, superimposed dead loads, and the appropriate percentage of live loads—ensuring that the resulting base shear is physically realistic. Efficient Error Detection Common Pitfalls to Avoid The "Mass Summary by
Mention if manual meshing was used for walls and slabs, as auto-meshing can sometimes lead to lumping errors CSI Knowledge Base Diaphragm Check: Confirm that Rigid Diaphragms
The story-based mass summary provides a high-level overview perfect for peer reviews and senior principal approvals.
The Mass Summary by Story report in ETABS is a detailed analysis that presents the mass distribution of a building across its various stories. This report includes several key components: