Combination of Several Loading Time Diagram Sets for Time History Analysis
Tips & Tricks
To simulate an excitation that is varying not only over time but is also changing its position, you can combine several loading time diagrams in RF‑/DYNAM Pro - Forced Vibrations.
In RFEM/RSTAB you define several load cases containing the loads at the desired position. In RF‑/DYNAM Pro - Forced Vibration you define the same amount of time diagrams. And in dynamic load cases you combine all those together.
The loads in load cases can be of nearly any type: nodal, member, surface, free or generated loads. Time diagrams can be defined as periodic, transient, or directly as function. The figure shows the example of walking on an simple supported beam.
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Calculation with consideration of a damping ratio (or Lehr's damping) is not possible in the direct time step integrations. Instead, the Rayleigh damping coefficients must be specified by the user.
In technical literature, the given damping ratio for specific construction forms is in many cases only a rough approximation of the real damping ratios. In RF-/DYNAM Pro - Forced Vibrations, it is possible to use the value of damping ratio to determine the Rayleigh damping. This may occur at one or two natural angular frequencies defined by the user.
Frequently Asked Questions (FAQ)
- Why do I only obtain the seismic loads calculated in one direction in the case of design with RF‑/DYNAM Pro?
- During the check in RF‑/DYNAM Pro, I get the message "No natural vibration case or dynamic load case has been selected for the calculation." Why?
- How can I enter or read out a response spectrum via the COM interface in DYNAM Pro?
- Which time step should I select for the calculation of the time history analysis in the RF‑/DYNAM Pro add‑on module?
- After running a time history analysis, I am not able to see all results on surfaces. Is there a possibility to show them?
- Is it possible to perform a dynamic analysis of the initial deflection of a structural component in RFEM or RSTAB?
- Is it possible to consider the static zero position in a time history analysis?
- In RF-/DYNAM Pro, I get the error no. 1759: "The Microsoft Excel Worksheet 'Acceleration Data' was not found." What could be the reason?
- Is it possible to display or export certain results over a period of time from the time history calculation in RF‑DYNAM Pro - Forced Vibrations?
- I have used the RF‑/DYNAM Pro add-on module to generate the governing result combinations of seismic loads. What is the next procedure to perform the design of the individual structural components?
Dynamic and seismic analysis including time history analysis and multi-modal response spectrum analysis