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• To: <seaint(--nospam--at)seaint.org>
• Subject: Re: DeVere (vs. Madden)
• From: "Bogdan" <prodomus(--nospam--at)mail.dntis.ro>
• Date: Fri, 3 Dec 1999 16:07:49 +0200

```Dear Mr. DeVere,

I would appreciate very much if, in answer to my message, you could tell me
the principles (theory) on which american calculations regarding foundation
beams are based ; I doubt they are entirely "strange" of "these authors"
I've mentioned.
However...:
JEMOCIKIN is the (russian) author of this calculation method based
on the hypothesis of "elastic semi-infinite space (or plane)", being
considered only vertical forces on beam (plate); this calculation method
involves the sharing of beam in a finite number of "panels", every one being
supported by a spring; problems: does this model (very much like a fem
model) describes correct the curves of displacement? Is it possible to have
a correct definition (value) for spring's constant ?
FUSS-WINKLER is a method developed considering a continuous link
between beam and ground, involving the equivalence of ground and beam
displacement for every point; it is established the formula p=Ks*y, where Ks
is the rigidity coefficient for the ground and "y" is ground defformation;
practical calculation is based on the differential (4-th degree) equation of
an infinite beam deformed axis on ground. In order to transform the infinite
beam to a finite one (usually having both ends free), the beam is elongated
at both sides with virtual pi/4 distances, on wich are applied known virtual
forces choosen in such manner to respect end conditions imposed by real
problem (usually null end bending moments and shear forces). All
calculations are very accurate IF Ks is well defined (i.e., for uniform
granulation sand Ks=5.52...13.8, meaning more than double !!!)
UMANSKI-KRILOV method is also known as "initial parameters method"
being recommended for "finite length" beams (alpha*L<5); it is also based on
4-th degree differential equation of an infinite beam, where for every
constant of integration is given a phisycal meaning; the results are also
very accurate, but more easy to obtain by manual calculations, who can be
made for any desired section (the method can be assimilated to "Ritter
section" method for girder poles).
Even if both UK and FW methhods use the same initial equation, the
results are (sometimes) very different; I have found UK being the most
satisfying method because its simplicity and range of applicability.
But WHY these differences for some ACCEPTED calculation methods? Where
is the calculation accuracy reflected in solutions? In these condiyions, I
could simply meka a choice for some no matter what dimensions, looking for
the appropriate method of calculation AFTER !
The same thing can be done in case of using differential or FEmethod
(due to necessity of defining of Ks).
Do you know any method to define it correct?

Bogdan Dumitrascu - no title

Mr De Vere replied to a personal message of Mr.Madden:
>
> I have been able to find only brief citations of these authors in the
> foot notes of my reference books. Books by the authors seem to have been
> published in Russia circa 1935.  Would you be willing to share this
> information with us?   Your efforts will be greatly appreciated.
>
>
> Best Regards,
>
> Peter  De Vere
> devere(--nospam--at)asme.org

```