What if I added static stresses on doing Respon Spectrum Analysis?

- June 23, 2020 at 1:57 pm
  
  alwidias
  Subscriber
  
  Greetings, I am going to do the Response Spectrum analysis Ship Unloader Crane on Ansys Workbench 18.2. The schematic project is:
  
  Static Structural -> Modal Analysis -> Response Spectrum Analysis
  
  The question is the RSA only calculates the structural stress? what if I add some static stresses like the container, machine room, etc on Static Structural?
  
  Because the crane must be on the operational condition while I simulating the earthquake (response spectrum)
  
  Thanks in advance
- September 24, 2020 at 4:43 pm
  
  dlooman
  Ansys Employee
  
  The stiffening effect of the static loads will be included in this set up, but not the static stresses. These need to be added to the spectrum results by a load case combination. Since the spectrum results are unsigned, the static results should be added by an SRSS combination or by first taking the absolute value of the static stresses. Otherwise negative static stresses will cancel out the positive spectrum stresses which is unconservative. n