Answer:
The RF‑/DYNAM Pro – Equivalent Loads add-on module works in the following way: It generates one load case for each eigenmode and each direction, which contains the generated equivalent loads. When the random torsion is activated, the number is doubled again.
Example: You have calculated 10 mode shapes and activated the X and Y directions. Now, the add-on module generates 20 load cases, and 40 load cases if the random torsion is activated. The number of the generated load cases increases significantly when increasing the mode shapes to be calculated.
Therefore, you should always make sure that you keep the number of mode shapes as small as possible.
However, it often happens that a mode shape with a high effective modal mass factor only occurs after many mode shapes with small effective masses. For such cases, there is the option in the "Dynamic Load Cases" → "Mode Shapes" tab to deselect shapes that have a small effective modal mass factor. The effect of this option is shown in the video.
We strongly recommend using this option in all models with many mode shapes. The limit value from which the shapes are canceled can be changed as desired and adapted to the specific situation.
