Ensure your model is fully analyzed (press F5 ).
ETABS uses these values to determine the for each diaphragm. The relationship between the CM and the Center of Rigidity (CR) determines the building's eccentricity and its susceptibility to torsion during an earthquake.
Are you encountering a between your manual calculations and ETABS? etabs mass summary by story
Before looking at the summary table, it is essential to understand where ETABS pulls its mass data from. This is controlled by the definition ( Define > Mass Source ). ETABS offers three ways to define mass:
ETABS automatically calculates the mass of structural elements (beams, columns, slabs, walls) using their geometric volume and material density. It also includes any lump masses manually assigned to joints or frames. Ensure your model is fully analyzed (press F5 )
: Automatically calculated from material density and member volume. Additional Mass
The calculated gravity load associated with each level, derived directly from your defined mass source. Why is the Mass Summary Table Important? Are you encountering a between your manual calculations
The center of mass for the entire structure from that story upward. 3. Why This Data Matters A. Seismic Base Shear Verification
Sometimes shown as UX Mass , UY Mass . This confirms the directional mass used for base shear calculation.
Go to Display > Show Tables > Analysis Results > Structure Output > Story Information > Mass Summary by Story . 2. Key Components of the Mass Table
Unusually high mass at a single floor could indicate a modelling error (e.g., duplicated elements or incorrect material density).
Ensure your model is fully analyzed (press F5 ).
ETABS uses these values to determine the for each diaphragm. The relationship between the CM and the Center of Rigidity (CR) determines the building's eccentricity and its susceptibility to torsion during an earthquake.
Are you encountering a between your manual calculations and ETABS?
Before looking at the summary table, it is essential to understand where ETABS pulls its mass data from. This is controlled by the definition ( Define > Mass Source ). ETABS offers three ways to define mass:
ETABS automatically calculates the mass of structural elements (beams, columns, slabs, walls) using their geometric volume and material density. It also includes any lump masses manually assigned to joints or frames.
: Automatically calculated from material density and member volume. Additional Mass
The calculated gravity load associated with each level, derived directly from your defined mass source. Why is the Mass Summary Table Important?
The center of mass for the entire structure from that story upward. 3. Why This Data Matters A. Seismic Base Shear Verification
Sometimes shown as UX Mass , UY Mass . This confirms the directional mass used for base shear calculation.
Go to Display > Show Tables > Analysis Results > Structure Output > Story Information > Mass Summary by Story . 2. Key Components of the Mass Table
Unusually high mass at a single floor could indicate a modelling error (e.g., duplicated elements or incorrect material density).