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Re: DeVere (vs. Madden)
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- Subject: Re: DeVere (vs. Madden)
- From: Peter De Vere <m-p.devere(--nospam--at)worldnet.att.net>
- Date: Fri, 03 Dec 1999 13:44:46 -0800
Bogdan: You are correct! I looked at the 4th edition of Bowles and found "The Winkler Foundation". The early edition of Fang & Winterkorn's FDN. Eng. Hnbk also covers this very well. Thanks for the information. Peter De Vere Houston, Texas devere(--nospam--at)asme.org Bogdan wrote: > > 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? > > Thanks in advance. > 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 > >
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