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TikkaMasala12-Amethyst
12-Amethyst
January 20, 2012
Solved

Pressure below rigid footing

  • January 20, 2012
  • 3 replies
  • 6749 views

Hi,

I have struggled with this problem for a while now, so could someone help me with this.

The problem involves iterations between elastic and plastic pressure distribution below a rigid foundation.

When pressure exceeds plastic limit, the pressure at the elastig region should increase. The limiting step would be when the integral of pressure below the footing is the same as the loading on top of foundation or i.e. when the sum pressure below footing is same as footing load.

The calculation method which I try to get a match with is published here:

https://docs.google.com/viewer?a=v&q=cache:W9TL0BfeiiUJ:elearning.just.edu.jo/jjce/issues/paper.php%3Fp%3D37.pdf+new+elastoplastic+method+for+calculating+contract+pressure&hl=fi&gl=fi&pid=bl&srcid=ADGEESjxRUEhCCY8ZSL7UMUwhWtMzctefD5Nsk42h161klolaPhfFZlrSAYSLbi8boeqSfvRSWw7lGBepmqkRCWlCB2B0sbZ0MxXjw_CafJZ4-_Yp9sT0W0TuW3QCeVr3lMeLzcBVUeN&sig=AHIEtbRvjeZ0o1CAFn3K2U0cxU8H-7B27w

The formula 27 in the article(, which is hidden by an advertisement in the link above) can be found from the attached calculation sheet.

Thank you for your help.

Best answer by Fred_Kohlhepp

matti meili wrote:

Hi Fred,

I was hoping of modeling the soil using elasto-plastic model which is provided in the article.

I can't read your article. (My work computer blocks access to that site.)

I can solve your problem of finding where the integral sums to the load. (See attached.) But I don't think this is the right answer--the step change in stress doesn't make sense.

At any rate, you can express your stress as functions rather than tables of vectors and use them more effectively. Hopefully this will give you a place to start.

Addendum: By solving P1 as a function of the intersection point, you can get a solution that makes sense!

Good luck!

Fred

Message was edited by: Fred Kohlhepp

3 replies

A
AlanStevens19-Tanzanite
19-Tanzanite
January 20, 2012

Does the attached help?

Alan

T
TikkaMasala12-AmethystAuthor
12-Amethyst
January 20, 2012

Hi Alan,

Thanks for your help, but this wasnt' quite what I was looking for... the problem appears to be little bit trickier. I'm not sure if I have tried to solve the problem from correct angle.

F
Fred_Kohlhepp23-Emerald I
23-Emerald I
January 20, 2012

I'm don't know if you want another approach, but this is beam on elastic foundation.

T
TikkaMasala12-AmethystAuthor
12-Amethyst
January 20, 2012

Hi Fred,

I was hoping of modeling the soil using elasto-plastic model which is provided in the article.

F
Fred_Kohlhepp23-Emerald IAnswer
23-Emerald I
January 20, 2012

matti meili wrote:

Hi Fred,

I was hoping of modeling the soil using elasto-plastic model which is provided in the article.

I can't read your article. (My work computer blocks access to that site.)

I can solve your problem of finding where the integral sums to the load. (See attached.) But I don't think this is the right answer--the step change in stress doesn't make sense.

At any rate, you can express your stress as functions rather than tables of vectors and use them more effectively. Hopefully this will give you a place to start.

Addendum: By solving P1 as a function of the intersection point, you can get a solution that makes sense!

Good luck!

Fred

Message was edited by: Fred Kohlhepp

V
24-Ruby III
VladimirN24-Ruby III
24-Ruby III
January 21, 2012

Below I attached to the message specified article without a watermark. I've been using this software "PDF Watermark Remover": http://www.pdfwatermarkremover.com/ (it may be useful in the future).

T
TikkaMasala12-AmethystAuthor
12-Amethyst
January 23, 2012

Thank you Fred for your answers. This gives me definetely something to work with and the computations you provided at the bottom of the file makes sense. The distance of point from foudantion center line, where elastic behavior changes into plastic, match relatively well with the graph provided in the article in figure 6, but the pressure values doens't match with the figure. I need to take check this more carefully.

Thanks Vladimir for your tip regarding PDF Watermark Remover.

V
24-Ruby III
VladimirN24-Ruby III
24-Ruby III
January 23, 2012

matti meili wrote:

...Thanks Vladimir for your tip regarding PDF Watermark Remover.

No problem.

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