Modal Analysis Add-on
Compared to the RF-/DYNAM Pro - Natural Vibrations add-on module (RFEM 5 / RSTAB 8), the following new features have been added to the Modal Analysis add-on for RFEM 6 / RSTAB 9:
- Preset combination coefficients for various standards (EC 8, ASCE, etc.)
- Optional neglect of masses (e.g. mass of foundations)
- Methods for determining the number of mode shapes (user-defined, automatic - to reach effective modal mass factors, automatic - to reach the maximum natural frequency)
- Output of modal masses, effective modal masses, modal mass factors, and participation factors
- Tabular and graphical output of masses in mesh points
- Various scaling options for mode shapes in the result navigator
Seismic Analysis in RFEM 6 is possible by using the modal analysis and the response spectrum analysis add-ons. As a matter of fact, the general concept of the earthquake analysis in RFEM 6 is based on the creation of a load case for the modal analysis and the response spectrum analysis, respectively. The standard group for these analyses are set in the Standards II tab of the model’s Base Data.
Different Natural Frequencies Without Consideration (left) and with Consideration of Tension Members (right)
In RFEM, three powerful eigenvalue solvers are available:
- Root of the characteristic polynomial
- Method by Lanczos
- Subspace iteration
In RSTAB, two eigenvalue solvers are available:
- Subspace iteration
- Shifted inverse iteration
The selection of the eigenvalue solver primarily depends on the size of the model.
- How can I perform an earthquake analysis in RFEM 6 and RSTAB 9?
- How can I display mode shapes in RFEM 6 and RSTAB 9?
- Why do the results in a modal analysis differ between the initial prestress and the surface load?
- What is the meaning of the superposition according to the CQC rule in a dynamic analysis??
- There are two different add-on modules for a response spectrum analysis in RF‑/DYNAM Pro. What can be the reasons for the different results of both add-on modules?
- RF‑/DYNAM Pro - Forced Vibrations and RF‑/DYNAM Pro - Equivalent Loads perform the multi-modal response spectrum analysis. What are the differences?
- How can I adjust the number of decimal places in the standardized table values of a mode shape?
- How can I display the results of the RF‑/DYNAM Pro add-on module in the printout report?
- In RF‑/DYNAM Pro, the Rayleigh damping is available. How do I determine and use these factors?
- There are two solving methods for a linear time history analysis available in the RF‑/DYNAM Pro add-on module. What is the difference between them?
The Modal Analysis add-on allows you to quickly and conveniently analyze natural frequencies and mode shapes for member, surface, and solid models.
The Modal Analysis add-on allows you to analyze natural frequencies and mode shapes for member models quickly and conveniently.