Vibration measure on a structure with a vacuum pump 2

[Navid.Nik]

I am designing a cold-formed structure on which there is a vacuum pump is going to be mounted. The motor data is as follows:

rotation speed= 2000 min^-1
noise characteristic= 86 dB
Vibration characteristic= 20 µm

From the rotation speed, I can say the frequency is about 2000/60= 33 Hz. I am trying to reinforce the structure on the area that the motors are mounted, but I am still worried about the possible vibration problems caused by these motors. Could anyone suggest a reliable method to assess the structure or add any especial measures that can help to damp the vibration, such as vibration isolator etc.

Thank you.

 

[WARose]

This is a pretty opened ended question. I typically use some type of software package (like STAAD) for any time-history work.

 

[271828]

Frequency tuning is probably your best bet for design. Keep your floor natural frequency far from the operating frequency. That won't be too hard for 33 Hz. You probably couldn't get your floor frequency up to that if you tried. However, as the pump ramps up, it will pass through the floor natural frequency and cause a short resonant build up. If the occupants are sensitive, then that could be a problem. In that case, you would want to look at spring or other isolators for the pump or a structural separation.

If you want to predict the acceleration of the floor using time history analysis then you'll need a forcing function for the vacuum pump. You could contact the manufacturer to see if they have one. Chances are they don't. I've seen these kinds of situations quite a few times over the years and have been able to get loading functions only a few times.

 

[ALK2415]

USE THESE BELOW AND DONT WORRY TOO MUCH

 

[JoshPlumSE]

I don't think you're going to need a TH analysis for something that sounds pretty small. I was the project lead for RISA's addition of Time-History Analysis. I spent a lot of time talking to customers and researching what sort of projects structural engineers were really using this feature for.

Attached is a chapter from the Training Manual that I wrote that summarized the very basics of supporting vibrating equipment. You might want to read through this (and/or the ACI document that I referenced) to understand some "simplified" methods you can use to assess how serious your issue is.

https://files.engineering.com/getfi...19-cb94c0e2cb7c&file=Vibrating_Equipment_.pdf