Roof mass is 39% higher than typical floor due to penthouse and water tank weight being mis-assigned.
Expand Analysis Results > Structure Results > Mass Summary > Mass Summary by Story . etabs mass summary by story better
Manually post-processing joint data opens the door to human error. When engineers export joint mass, they often accidentally double-count mass at shared nodes, misclassify boundary condition joints, or leave out mass from null lines and area modifiers. Roof mass is 39% higher than typical floor
After updating the mass source and stories: misclassify boundary condition joints
Evaluating torsional eccentricities (Center of Mass vs. Center of Rigidity). Handling of Off-Diaphragm Mass Includes it flawlessly. Ignores it, leading to underreported building mass. Sensitivity to Meshing High; requires proper node alignment to lump correctly.