Is it possible to perform a dynamic analysis of the initial deflection of a structural component in RFEM or RSTAB?

Answer

Yes, it is possible by using the RF‑/DYNAM Pro - Forced Vibrations add-on module. This application also allows you to use time history. It is available for both solution methods (linear Newmark analysis or modal analysis), but the procedures are slightly different.

The procedure is as follows:

  1. Define a load case containing a load that causes the desired initial deflection.
  2. Activate the time history method of time diagrams in RF‑/DYNAM Pro, and define a new time diagram that has a multiplier of 0 over the entire time.

    Figure 01 - Time Diagram with Multiplier 0

  3. Then, select the defined time diagram in the dynamic load cases (it is irrelevant which load case you combine it with as it multiplies the load by 0). You can then import the load case defined in the first step as the initial condition (or only the initial deformation in the modal analysis). Thus, the conditions from this load case are imported at time t = 0 and released immediately afterwards.

    Figure 02 - Activating Initial Condition/Deformation in Dynamic Load Cases

Use this procedure to simulate a vibration after the initial deflection. To illustrate this, you can find an example file under Downloads where this method is shown on a single-mass oscillator.

Keywords

Forced vibration Single-mass oscillator Initial deflection Initial deformation

Reference

Downloads

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RFEM Main Program
RFEM 5.xx

Main Program

Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements

Price of First License
3,540.00 USD
RSTAB Main Program
RSTAB 8.xx

Main Program

The structural engineering software for design of frame, beam and truss structures, performing linear and nonlinear calculations of internal forces, deformations, and support reactions

Price of First License
2,550.00 USD
RSTAB Dynamic Analysis
DYNAM Pro - Forced Vibrations 8.xx

Add-on Module

Dynamic and seismic analysis including time history analysis and multi-modal response spectrum analysis

Price of First License
1,120.00 USD
RSTAB Dynamic Analysis
DYNAM Pro – Nonlinear Time History 8.xx

Add-on Module

Nonlinear dynamic analysis to external excitations

Price of First License
1,120.00 USD
RFEM Dynamic Analysis
RF-DYNAM Pro - Forced Vibrations 5.xx

Add-on Module

Dynamic and seismic analysis including time history analysis and multi-modal response spectrum analysis

Price of First License
1,120.00 USD
RFEM Dynamic Analysis
RF-DYNAM Pro – Nonlinear Time History 5.xx

Add-on Module

Nonlinear dynamic analysis to external excitations

Price of First License
1,120.00 USD