Shallow Foundations

[ktulu]

The only place I have seen shape factors mentioned and used is in the CERM. I have Coduto's book and he makes no reference to shape factors when discussing ultimate bearing capacity for shallow foundations..

I'm working the 6-minute solutions, and I got the "wrong" answer due to not using the shape factors. It would have possibly screwed me b/c the answer I came up with was a choice. Coduto's equation for square foundations does not have shape factors.

Question is: Are they necessary to input into the equation when not every text book mentions them?

Thanks,

ktulu

 

[Guest]

The only place I have seen shape factors mentioned and used is in the CERM. I have Coduto's book and he makes no reference to shape factors when discussing ultimate bearing capacity for shallow foundations..
I'm working the 6-minute solutions, and I got the "wrong" answer due to not using the shape factors. It would have possibly screwed me b/c the answer I came up with was a choice. Coduto's equation for square foundations does not have shape factors.

Question is: Are they necessary to input into the equation when not every text book mentions them?

Thanks,

ktulu

Oooh ... oooh .. you asked one I can answer :appl:

Terzaghi was the first person to develop shape factors based on failure surface at equilibrium. That analysis was later updated by Vesic (1973) after a number of field and laboratory studies were conducted to 'correct' the factors. I posted an image of the shape factor analysis/results from NAVFAC 7.02 below.



I use Braja Das', Fundamentals of Geotechnical Engineering. Chapter 11 is devoted to Shallow Foundations and lays out the theory for the shape factors. You can also find added discussion in NAVFAC 7.02 as previously mentioned (this document is free with google search).

In terms of the taking the examination, I don't think you will need to use shape factors unless there is something in the problem that says to use them because you have the 'original' shape factors and then the shape factors as developed by Vesic (1973).

I hope this helps. If you have any more questions, or need clarification, just post a follow-up question and I will do what I can.

JR