FAQ 004947 EN

Helpful Questions & Answers

  • Frequently Asked Questions (FAQs)

After the calculation in the RF‑/DYNAM Pro - Equivalent Loads add-on module, the size of my file has increased significantly. The performance has worsened enormously. What could be the reason for this?

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. If activating the random torsion, 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 activating the random torsion. 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 the shapes that have a small effective modal mass factor. The effect of the option is shown in the video.

It is strongly recommended to use 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 special situation.

Keywords

Dynamic analysis Performance Load case Mode shape Response spectrum

Reference

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  • Updated 5 April 2021

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