Hi
I am designing a rotating pump support steel structure. The pump has 3600 rpm at operating condition (or 60 Hz) and its weight is 5000 lbs. The C.G. of the pump is known. In staad, in order to find natural frequency of structrural steel, normally we input the pump weight in 3 directions (X, Y & Z) and use "modal calculation req" command with cutoff mode shape.
My questions are:
1. Do we have another way to find the natural frequency of the structural steel by input the pump frequency (60 Hz) in structural steel model? If yes, please explain how to input the pump frequency in staad model.
2. Could I use verification problem no 22, "steady state analysis" as example for this frequency calculation?
3. I got a license warning message:"Cannot execute Steady State Analysis! You may not have license to avail this feature" when I tried to run verification problem no 22. I truned on (green bullet) 4 licenses: US Design Codes (Standard); US Specialization Design Code; Global Design Code and STAAD.beava(Bridge Codes) in "License Configuration". Could you please let me know what license I am missing.
I really appreciate your help.
Staad123
The natural frequency calculation for the structure is based on a free vibration analysis. So you do not need to input the machine frequency for that. However you can find out the response of the structure to the vibrating machinery by carrying out a time history analysis. You will then be able to define the machine frequency as part of the harmonic loading input. You may use the application example 22 which is titled Time History Analysis for Sinusoidal Loading. The steady state would require the license for Advanced Analysis Engine, however the time history example would not need it. You are getting the warning as you may not have the license for the Advanced Analysis Engine. Try checking the box and if you see a red light for it, you either do not have the license or it is not available for your use.
Answer Verified By: Staad123