Etabs Mass Summary By Story

The distribution of mass across stories directly dictates mode shapes and periods. A top-heavy model will produce longer periods and higher overturning moments. By reviewing the summary, you can quickly spot if a penthouse or water tank mass was accidentally omitted.

ETABS generally "lumps" masses at the floor levels to simplify the analysis into a Multiple Degree of Freedom (MDOF) system. Mass - CSI Knowledge Base etabs mass summary by story

Create a formula: Total seismic weight = Σ (U1 Mass * g) . Compare this to your hand-calculated building weight (Sum of areas * (DL + LL + partitions)). They should match within 2%. The distribution of mass across stories directly dictates