Mass (Load)

Property	Value
Default Short Command	LMASS
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For dynamic, vibration shape and seismic effect calculations (especially for frame structures), masses can be defined optionally as point loads or automatic conversion of load cases to mass.

Masses are not participants of load cases, load combinations and load groups.

Concentrated Mass

Definition steps

1. Start the  Mass command from   tabmenu.
2. Set the mass value according to the current unit (that can be set at Settings > Units).
3. Place the mass just by clicking in the required point.
   The mass will be displayed on the Masses object layer assigned in green color by default.

Optional steps:

4. Modify the mass value with the  Properties tool of the Mass tool palette.
5. Set the display settings of masses (Load Display Settings).

Figure: Definition of concentrated mass

Load Case-Mass Conversion

With the  Load case-mass conversion command of Loads tabmenu, you may convert load cases to masses by assigning factor values to them. All conversions are done just before dynamic calculation.

Typing 1 into the Factor field means that the loads (of the load case) with their original value will be converted to mass. Typing 0 value removes predefined conversion of a load case (as a result you will get the "--" symbol again).

Figure: Mass definition by conversion of loads (load cases)

The following point, line and surface force types can be converted to masses:

  Plate module: force with global -Z direction: mz = -Fz/g

  Wall  and  Plain Strain modules: force with global -Y direction: mx = my = -Fy/g

  3D Frame and  3D Structure modules: force with global -Z direction: mx = my = mz = -Fz/g

Moments, support motions, thermal loads cannot be converted to masses.