These represent the total mass considered for horizontal motion in the X and Y directions. In most cases, these values are identical unless you have assigned specific directional mass properties.
In ETABS, the is one of the most critical outputs for structural engineers. It provides a concise breakdown of how weight is distributed across the height of a building—a factor that directly dictates seismic forces and dynamic behavior. etabs mass summary by story
Ensure you have assigned diaphragms to your floor shells. ETABS calculates story mass properties most effectively when floors are constrained as diaphragms. Mass Source: Most modern codes require Mass = StorageLiveLoadcap S t o r a g e cap L i v e cap L o a d These represent the total mass considered for horizontal