Ram Elements Dynamic Analysis

Hello, I have some questions regarding performing a Dynamic analysis in RAM elements to determine the natural frequency of a monumental stair. Following are the steps I have taken so far: 

  • I have rotated the model so that the Z-direction is "Up and Down" and the X-direction is "Sided to Side". 
  • Defined an X and Z direction dynamic load case in the load conditions module. For each load case I set the "Earthquake Scale Factor to 1.0, the damping ratio to 1% and set the direction to 0 degrees and 90 degrees for the X-direction and Z-directions respectively.
  • Added mass loads to the nodes in the Z and X direction. 
  • The dynamic analysis has been run with the CQC method, with 10 modal shapes and considering node mass only.

My questions are:

  1. Why are the mass loads not load case specific? The inputted masses appear to be included in all load cases?
  2. I am getting about 30 percent participation in the X-direction and 70 percent participation in the Z-direction. When I turn mass loads off in the X-direction I get 100% mass participation in the X-direction. How do I get 100% mass participation in each direction? 
  3. Is there a way to get the natural frequency (or period) for each modal shape in each direction? When I turn on Finite Elements Model and view the modal displacements and deflection I am given 10 periods, which do not appear to be direction specific.

Thank you

Parents Reply Children
No Data