Etabs Mass Summary By Story Here

ETABS reports the coordinates (X, Y, Z) of the center of mass per story. This is essential for calculating accidental eccentricity and torsional irregularity (per ASCE 7 Section 12.8.4.2).

To ensure your Mass Summary by Story is flawless, follow these rules:

After analysis, open the .log file or the .f2k text file. Search for STORY MASS. This raw data is useful for scripting or batch verification. etabs mass summary by story

Cause: You have rigid floor diaphragms, but your walls are modeled with "Pier" sections that are not tied to the diaphragm, or you have a "soft" story with no diaphragm assignment.

Symptom: The "Base" or "Story1" (below ground) shows U1/U2 mass > 0. Problem: You applied floor loads to the foundation level, or the base slab is modeled as a flexible diaphragm. Fix: Delete loads at base or assign the base points to a fixed support with no mass source assignment. ETABS reports the coordinates (X, Y, Z) of

Engineers must define a Mass Source via Define > Mass Source:

Incorrect mass source is a leading cause of erroneous dynamic results. After analysis, open the

Loads like lateral wind or soil pressure are forces, not masses. The summary will only include loads that have a vertical component and are assigned to the mass source. Review your diaphragm assignments to ensure mass is correctly lumped at the center of rigidity.