Meyerhof Bearing Capacity Factors

[Happy]

In the CERM, Table 36.3, For the Meyerhof Factors, there is Nc, Nq and Ny & Nyb

Nc - Bearing Capacity due to cohesion

Nq - Bearing Capacity due to surcharge

Ny - Bearing Capacity due to friction

How do you know when to use Ny or Nyb? In the CERM practice problems, question 3c uses Nyb and question 4c uses Ny, but no explanation is given for this.

 

[sac_engineer]

There are different factors for bearing capacity for shallow foundation that are square, circular, or strip versus a rectangular foundation. I don't have the CERM practice problems to see what the questions are asking, but the shape of the foundation will determine which factors to use.

 

[Happy]

I think you're talking about shape factors. But what I'm talking about is the bearing capacity due to friction factor prior to applying the shape factor.

Look at Table 36.3 in the Cerm. There are two columns, one has it as Ny, one has it as Nyb. (by y I mean gamma).

My question is, when does one use one or the other?

 

[sac_engineer]

I think you're talking about shape factors. But what I'm talking about is the bearing capacity due to friction factor prior to applying the shape factor.
Look at Table 36.3 in the Cerm. There are two columns, one has it as Ny, one has it as Nyb. (by y I mean gamma).

My question is, when does one use one or the other?

Honestly, you're probably spinning your wheels a bit hard on this one. Because there are different approaches to bearing capacity, I would rely on the exam to provide you these values rather than looking them up. You would only need to know which equation to use to solve the question which may ask the minimum size for square footing given the necessary parameters.

Just remember, sandy soils mean that there's no cohesion (c = 0), and you divide the ultimate bearing capacity by the factor of safety for the design capacity.

 

[CivilEngMatt]

Don't worry to much about the actual factors. These ifactors will be given to you on the exam, given there a several factors that apply to the same type problem.