: For seismic design, understanding the mass distribution is key. The mass of a structure directly influences its seismic response. A well-distributed mass can lead to a more stable structure under earthquake loads.
Seismic forces are calculated based on mass. If your story mass is off, your base shear and lateral forces will be incorrect. This table allows you to: Verify the self-weight of slabs, beams, and columns. etabs mass summary by story better
| Column | Description | Engineering Significance | |--------|-------------|--------------------------| | | Floor level | Check mass jumps between stories | | UTotal (or UX, UY, UZ) | Translational mass (same in X & Y for symmetric buildings) | Lateral seismic mass: dead + appropriate live load + partition + equipment | | RTotal (or RX, RY, RZ) | Rotational mass moment of inertia about vertical axis | Affects torsional response (accidental eccentricity) | | Self Mass | Mass from element self-weight | Based on assigned materials | | Additional Mass | User-defined mass (shell uniform load, point masses) | Often missed – check carefully | : For seismic design, understanding the mass distribution