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Re: Dynamic design of machine foundation

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Is it a centrifugal compressor or a reciprocating one?
It is important to know which one it is. With a
reciprocating compressor both the first and the second
harmonic needs consideration. The operating frequency
of a modern day recip compressor is fairly high and it
will be a challenge to size a suitable foundation to
assure that the sytem frequencies are well separated
from the operating frequencies.

There must be a geotech report to enable you to design
this foundation. If there isn't one, please request
it.  This foundation is a critical component of the
machine foundation system and an improperly deisgned
foundation will create problems with the machine
performance.

The geotech company should be able to give you a range
of presumptive values for the dynamic shear modulus,
based on the soil log data. It is a key parameter in
the dynamic analysis and has a significant bearing on
system frequencies.

By the way, you need more literature than just the
book by Bowles.

Rajendran


--- Rich Lewis <sea(--nospam--at)lewisengineering.com> wrote:

> I am designing a foundation for a 130,000 lb
> compressor with dynamic
> loads.  The foot print of the equipment is over a
> 30X40 ft. area.  It
> will have a separate mat foundation below it.
> 
> I have done some research and it appears to me a
> dynamic l

oad such as
> this requires a special analysis to calculate the
> deflections based on
> the dynamics.  I found several references on this,
> one in particular by
> Bowles in the 5th ed., chapter 20.  He has a program
> to calculate the
> vertical, horizontal and rocking deflections due to
> the machine
> dynamics.  Is the method he describes in his book
> what is commonly used
> in practice today?  Is there an easier way to do
> this?
> 
> Bowles method requires the dynamic shear modulus. 
> Are there some tables
> with typical values for clay soil other than what he
> has in his text?
> Bowles uses primarily metric in this chapter and
> doesn't have an
> equation for English dynamic modulus.
> 
> I would appreciate any suggestion I can get for
> foundation design of
> dynamic equipment loads.
> 
> -------------
> Richard Lewis
> Lewis Engineering
> rlewis(--nospam--at)lewisengineering.com
>  
> 
> 
> 
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