Using Modified Stiffnesses for Dynamic Calculations

Technical Article on the Topic Structural Analysis Using Dlubal Software

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In RFEM, it is possible to modify stiffnesses for materials, cross -sections, members, load cases, and load combinations in many places. In order to consider these modifications when determining the natural frequencies, there are two options in RF-DYNAM Pro.

In the present example, the stiffness of the reinforced concrete columns is to be reduced in order to simulate state II.

The reduction with the factor 0.6 is carried out at the level of the "Rectangle 300/300" cross -section.

In order to consider these modifications of the cross -section when determining the natural frequencies, you have to select the second option under the calculation parameters under "Stiffness changes".

Due to the reduced stiffness, there is thus a lower natural frequency for the first mode shape.

Author

Dipl.-Ing. (FH) Frank Sonntag, M.Sc.

Dipl.-Ing. (FH) Frank Sonntag, M.Sc.

Sales & Customer Support

Mr. Sonntag coordinates the Dlubal Software office in Leipzig and is responsible for sales and customer support.

Keywords

Stiffness Modify stiffness Natural frequency

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  • Updated 27 April 2021

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