Slab Design for pump station 1

[PowerRanger]

Hi Fellows

I am designing a slab for a pump station. I am considering the anchor depth and the vibration effect when the pump is operating. I talked with the pump manufacturer, but not much help from them.

I would like to ask how should I deal with the vibration problem in concrete (Say concrete harden).

Thank you for your time

 

[cvg]

depending upon the type of pump and liquid you are pumping, you may not have a lot of vibration. If you do, there may be a problem with the installation or design of the equipment... You need to worry more about thrust during startup and shutdown. If you are in earthquake country, anchor it for seismic forces.

 

[archeng59]

I recently worked on a pump station project. The MEP provided data sheets with forces at the base of the pump. the pumps were mounted on pedestals and the pedestals were designed as a cantilever column to resist a moment and horizontal thrust in addition to the pump weight. As cvg stated, it is my understanding that those forces were greatest during startup. I don't know if all pumps are that way, but that's my experience.

 

[PEStructural]

You must check that the natural frequency of your slab is at least 1.5 times the RPM of your pump or you will have vibration problems with resonant frequency. Usually the pump cut sheet has the operating RPM of the pump.

How are you designing the slab? By hand, program, FEA?

 

[PowerRanger]

Thanks PEStructural.

Design By hand.

 

[PEStructural]

Do you have a copy of Roark's Formulas for Stress and Strain? If so, what version?

 

[bjb]

What about vibration isolators?

 

[cvg]

assuming this is a basic water pumping station, I haven't seen one yet with vibration isolators. vibration is generally not a big issue as these pumps run very smoothly. If they are vibrating, you a bigger problem with your pump than you do with the slab

 

[dicksewerrat]

For water pumps, when they vibrate theya re ready to fail. Usually by throwing the impeller through the side of the casing.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[PEStructural]

The issue with pumps on concrete is not an issue of the vibration of the pump. It's the circular frequency of the rotating mechanism. It's the same idea as the Tacoma Narrows Bridge failure in Washington. The wind vortices (i.e. RPM of the wind shed) created a frequency that matched the natural frequency of the bridge. When the two frequencies fall within a certain range, it creates a resonant frequency and shakes the structure apart. It's also the same idea as a woman's voice shattering a crystal glass. The frequency of her voice matches the natural frequency of the glass (therefore resonant frequency) and it vibrates enough to shatter.

I've seen applications of pumps on weak supports that the vibration was a real problem. It was not the pump vibrating, but the frequencies matching. We stiffened up the support and the vibration went away.

Just my $.02