terzaghi83
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There is a slight difference in the ultimate bearing capacity equations for square and circular foundations as listed in variosu Braja Das and V.N.S Murthy texts versus the Equations in the CERM.
In the Das and Murthy texts, the terzaghi bearing capacity equation is modified for square foundations and circular foundations with the following changes:
For square foudnations:
c*Nc is multiplied by 1.3
the Ngamma term is multiplied by 0.4
compare this to the use of shape factors listed in CERM, for a square foundation the nc term is multipled by 1.25 and the Ngamma term is multiplied by 0.425 (.5 in strip footing equation multiplied by the shape factor of 0.85 in CERM.)
Similar differences are present in the circular foundation equation.
As far as I know, these are both terzaghi bearing capacity equations, although they are just listed as terzaghi equations in Das and murthy but the one with the shape factors is listed as terzaghi-meyerhoff in the CERM so perhaps this is the difference? Both are different from the general bearing capcity equation which can account for shape, depth, inclination factors from meyerhoff, hansen or Vesic.
If the exam asks you to solve a bearing capacity problem using terzaghi bearing capacity equations and factors what is one to do (method with shape factors in CERM or slightly different equations with shape factors "built in" as listed in Murthy and Das?
Using the Das equation to solve problem 15 of six minute solutions, the answer is 3553 psf. If you use the equation in CERM with shape factors you get 3857 psf. In some instances this may lead you to the wrong answer selection from multiple choice perhaps?
I'm looking for input from anyone who has taken the exam (or anyone else) about how to handle this situation.
thanks, and back to another wonderful weekend of studying!
In the Das and Murthy texts, the terzaghi bearing capacity equation is modified for square foundations and circular foundations with the following changes:
For square foudnations:
c*Nc is multiplied by 1.3
the Ngamma term is multiplied by 0.4
compare this to the use of shape factors listed in CERM, for a square foundation the nc term is multipled by 1.25 and the Ngamma term is multiplied by 0.425 (.5 in strip footing equation multiplied by the shape factor of 0.85 in CERM.)
Similar differences are present in the circular foundation equation.
As far as I know, these are both terzaghi bearing capacity equations, although they are just listed as terzaghi equations in Das and murthy but the one with the shape factors is listed as terzaghi-meyerhoff in the CERM so perhaps this is the difference? Both are different from the general bearing capcity equation which can account for shape, depth, inclination factors from meyerhoff, hansen or Vesic.
If the exam asks you to solve a bearing capacity problem using terzaghi bearing capacity equations and factors what is one to do (method with shape factors in CERM or slightly different equations with shape factors "built in" as listed in Murthy and Das?
Using the Das equation to solve problem 15 of six minute solutions, the answer is 3553 psf. If you use the equation in CERM with shape factors you get 3857 psf. In some instances this may lead you to the wrong answer selection from multiple choice perhaps?
I'm looking for input from anyone who has taken the exam (or anyone else) about how to handle this situation.
thanks, and back to another wonderful weekend of studying!