Changing Beta Angle of a Member


  
 Applies To 
  
 Product(s):STAAD.Pro
 Version(s):All
 Environment: N/A
 Area: Postprocessing workflow
 Subarea: N/A
 Original Author:Bentley Technical Support Group
  

I am analyzing a large 3D structure. I changed the beta angle of one of the members to 90. I expected the MY and MZ for the two scenarios ( beta =0 and beta=90) to get interchanged. However that does not seem to happen. Why ?

The Mz and My would not simply get interchanged when you apply a beta angle to 90 for every situation. The same would be true if you are analyzing a beam in isolation without considering any effect from the rest of the structure. However when a beam is part of a bigger structure, the beam’s local stiffness in each direction would affect the global stiffness of the structure along each DOF. Depending on that there will be a redistribution of the forces which would result in different moments/shears.