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Physical Members and Dynamics

Physical Members and Dynamics

Physical Members and Dynamics

I'm searching for other's thoughts on this subject.  When doing a dynamic analysis with self-weight of a physical member considered, will the result be different if instead individual members with the appropriate end release (fixed, no forces/moments released) are used?  I.E. will RISA find the center of mass for each individual shorter member seperately whereas the physical member will only have a single center of mass?  And will this affect the eigensolution frequency values and number of modes?

I apologize if this question seems fundamental.  I am simply trying to understand the software's solution method.

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RE: Physical Members and Dynamics

That's an excellent way to test the Physical member behavior.  So, I think it is a good exercise for you to do if you want to gain more confidence in what the program is doing with the Physical members.  

In the end, you will find that the frequencies and mass participations and mode shapes will be exactly the same. The program does split those physical members into smaller pieces (at each node location) before the solution.... It just pieces the member back together again after the solution. The main point being that the user can model the beam as it really exists and review the results for it as if it were one physical member.   

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