Motor/Pump Base Design

[JD P.E.]

I am tasked with designing a motor/pump base for a 200HP motor and centrifugal pump. I have generally left the concrete/rebar design to others, but I'd like to get more involved in it and understand how to design it. I found the ACI 351.3R Foundations for Dynamic Equipment and ACI 351.2R Foundations for Static equipment. These are helpful in understanding the forces involved, but I have little knowledge on concrete especially relating to rebar requirements. I have a decent understanding of steel design.

I attached a snippet of a detail I've seen on a similar project and was wondering if anyone has any guidance or a direction I should go to understanding rebar/dowel requirements.

 

[desertfox]

Hi

Just have a look at this:-

Thread507-496618

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[JD P.E.]

Thanks. I went through that thread and it has a lot of good information. However, it doesn't really help me with the concrete/rebar design aspect of it unfortunately...

 

[desertfox]

Hi

Have a look at this reference then:-

https://www.theseus.fi/bitstream/handle/10024/169097/Belovolova_Arina.pdf?sequence=2&isAllowed=y

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[JD P.E.]

Since most concrete bases for equipment are generally wider/longer than they need to be just based of strength design would it be a reasonable approach to treat the base as a deep, short column, do some sort of minimum required reinforcement and call it good? Since we are really going for mass differential here, I know the strength of the base would in no way govern any of my designs.

Fair approach?

 

[Tmoose]

Have you investigated/confirmed any details of the floor slab construction?

Was a pump mounted there previously?

Some pump and fan manufacturers have good details for mounting their equipment.
Although the mounting plate provided by some as standard assumes/wishes filling with grout is a magic wand.

 

[JD P.E.]

Yes, this is a replacement task not new installation. So I am not too worried about floor slab given that so likely will tie in with #5 dowels or something similar just to tie into the foundation.

 

[Tmoose]

Is the slab on grade?

Is the replacement stuff larger/heavier/taller than the old stuff?

Did the original stuff run very well for years, including the last 6 months of service?
Is there some detailed vibration history of the original installation?

Sometimes slabs develop problems over time. Under floor erosion. Soil compaction, possibly even from the demolition of the old pedestal.

I think making a good concrete pedestal is relatively easy.

Do you have engineering drawings and pictures of the base plate that will provided with the new pump and motor?

 

[JD P.E.]

Current Pumps run below our vibration parameters we are replacing due to sole plate corrosion and concrete damage (spalling, fork lift traffic, etc).

These pumps pump from very large concrete chests (MM gallons), so foundation design nearby is not a concern of mine. Likely a mixture of slab on grade with deep piers.

I can design a base based solely off of rules of thumb and experience from concrete guys but what I’m trying to do is develop a more analytical approach that can be used for future projects. I am looking for knowledge specifically on pedestal concrete, rebar, and tie in to slab below if that makes sense.

 

[desertfox]

Hi JD P.E.

This might shed some light on how the concrete bases are designed.

https://pdfcoffee.com/pump-foundation-designpdf-2-pdf-free.html

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein