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002062
2021-07-28

Multi-Modal Reponse Spectrum Analysis in RF-/DYNAM Pro

RF‑/DYNAM Pro – Forced Vibrations and RF‑/DYNAM Pro – Equivalent Loads perform the multi-modal response spectrum analysis. What are the differences?


Answer:

RF‑/DYNAM Pro – Equivalent Loads performs a multi-modal response spectrum analysis with the export of equivalent loads.

  1. The static equivalent loads are calculated and exported to load cases. This happens separately for each mode shape and each direction of excitation.
  2. The total earthquake forces can be determined easily for each mode shape.
  3. Accidental torsional actions can be taken into account automatically
  4. The load cases are calculated in the main program RFEM/RSTAB. Possible nonlinearities are taken into account; the calculation parameters of the load cases can be adjusted (for example, the calculation according to the second-order analysis, deactivation of nonlinearities).
  5. The stiffness modifications from the natural vibration cases (NVCs) are not transferred to the load cases automatically.
  6. The result combinations are generated individually for each excitation direction (combined modal responses with SRSS or CQC) and for the combination of results from different excitation directions (SRSS, 100%/30% [40%]).
  7. The sign-dependent results are available on the basis of the dominant mode shape, which results in unique RCs.
  8. The results can be reproduced step by step.

In RF‑/DYNAM Pro – Forced Vibrations, a multi-modal and multi-point response spectrum analysis is performed.

  1. A building can be subjected to the excitations by different response spectra at different supports and in different directions.
  2. The calculation and superposition are carried out within the RF‑/DYNAM Pro add‑on module. The calculation is linear; nonlinearities are not taken into account. The stiffness modifications from the ESFs are applied.
  3. Only result combinations of the superimposed results are exported.

Author

Ms. Effler is responsible for the development of products for dynamic analysis and provides technical support for our customers.

References
  1. Dlubal Software. (2020). Manual RF-DYNAM Pro. Tiefenbach: Dlubal Software.