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Define modal masses for an analysis model

Last updated March 12, 2019 by Tekla User Assistance tekla.documentation@trimble.com

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Define modal masses for an analysis model

Define modal masses for an analysis model

You can perform a modal analysis instead of a stress analysis. In the modal analysis, resonant frequencies and the associated patterns of structural deformation called mode shapes are determined. For the modal analysis, you can define modal masses to be used instead of static load combinations.

  1. On the Analysis & design tab, click A&D models.
  2. In the Analysis & Design Models dialog box, do one of the following:
    • To create a new modal analysis modelstructural model that is created from a physical model and used on the one hand for analyzing structural behavior and load bearing, and on the other hand for design

      Analysis model can be viewed in Tekla Structures in a model view.

      Analysis model that is made with Tekla Structures can be worked on in other analysis and design software or application.

      , click New.

    • To modify an existing analysis model, select the analysis model, and then click Properties.

    The Analysis Model Properties dialog box opens.

  3. On the Analysis tab, select Yes from the Modal analysis model list.

    This forces Tekla Structures to ignore static load combinations.

  4. On the Modal analysis tab, define the modal analysis properties and the load groups to be included as masses in the modal analysis:
    1. Enter the count of modes to calculate.
    2. Enter the maximum frequency to calculate.
    3. Select the appropriate Include self weight check boxes to indicate the directions for which Tekla Structures includes the self-weight of parts in the modal analysis.
    4. If suitable, click Copy seismic masses to include the same load groups in the modal analysis as in the seismic analysis.
    5. To move the appropriate load groups to the Included load groups table, select them and use the arrow buttons.
    6. For each load groupset of loads and loadings that are caused by the same action and to which the user wants to refer collectively

      Loads belonging to the same load group are treated alike during load combination.

      in the Included load groups table, enter a load factor and set the mass direction.

      In the Mass direction column, select either:

      • XYZ to include the load in all three directions.

      • Model default to include the load only in the direction of the load.

  5. Click OK.

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