Etabs Mass Summary By Story -

If you modeled a concrete slab but forgot to assign Self Weight Multiplier = 1 (under ), ETABS will only include the superimposed dead loads (finishes, partitions) and completely ignore the 150 pcf concrete you just modeled.

ETABS doesn't just use "dead load." It calculates mass based on your load combinations. Specifically, for seismic analysis (per ASCE 7, IS 1893, or Eurocode 8), it typically uses: etabs mass summary by story

But when he ran the modal analysis, the building had massive torsion. He spent days adding shear walls. If you modeled a concrete slab but forgot

But here is a hard truth: