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Pre-stressed modal / response spectrum analysis

    • Chris David



      I have been trying to learn to perform response spectrum analysis for preloaded structures using a simple cantilever beam model.


      To understand the affect of pre strees I have applied a point mass at the free end of the beam, which produces a 15mm deflection in a static structural analysis. Having performed modal and response spectrum the maximum deflection in the response spectrum analysis is 2mm. My question is what does this value tell me, is this a maximum displacement from the prestressed deflected position, or is my model setup incorrect? 


      Many thanks

    • Surya
      Ansys Employee

      Hi Chris,

      The deformation that you get in Response Spectrum is the maximum response that you obtain when you provide the Spectrum load. The deformation in Static Structural Analysis is the normal state of the model (as per my understanding) - due to which the mode shapes will vary. We cannot compare these two deformation results.

      I would suggest you refer to this video on how to perform Response Spectrum Analysis -


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