Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Meyrhof's Bearing Capacity equation

Meyrhof's Bearing Capacity equation

Meyrhof's Bearing Capacity equation

I'm a fresh graduate, not my first time here but my first time posting, so bear with me. Here's my problem I was trying to calculate the bearing capacity of a soil for a project, I was working on. The ultimate bearing capacity equation used was Meyrhof's. I noticed that the bearing capacity would drop as the width of the footing increased. This seemed contrary to what I have studied; therefore, I tried to plot Ultimate Bearing capacity Vs. Width for a square isolated footing resting on a soil with C = 0 KPa, Φ = 11°, γ = 18KN/m³ and foundation depth(Df)=3m. The result was a non-linear plot with Bearing Capacity decreasing with width of the footing. I have attached the plot and the python(numpy+scipy+matplotlib)code used to produce the plot. Now, my question is shouldn't ultimate bearing capacity of an isolated footing increase with increase in width?

RE: Meyrhof's Bearing Capacity equation

First off remember there are many different users here with different unit systems. You say nothing about that or show that bearing capacity usually is a pressure as unit of load per unit of area. So as you increase the area, by the abscissa, the total load increases and thus more settlement or tendency to shear results. And to keep that within failure limits, you reduce the unit pressure. Forgetting to designate what the numbers mean leaves you with the question.

I might add, to help clear this up to design a series of footings for equal settlement, the larger total loads require a larger footing area, but at a lesser bearing capacity than for smaller loads.

RE: Meyrhof's Bearing Capacity equation

jmcc3265 has presented a nice generalized graph - I developed similar graphs back in the 70s for Sarnia Ontario clays.

However, it irks me - perhaps not others, when geotechnical engineers refer "Allowable Bearing Capacity" - when, in fact, shear does NOT govern but settlement governs. In my view - allowable bearing capacity is a "shear/strength" issue; allowable bearing pressure would be best used if it is a serviceability issue. In this way there is no confusion.

RE: Meyrhof's Bearing Capacity equation

Hey BigH: Right on the money with that. In his classic paper in 1959 my old boss and college prof B.K.Hough uses the term "Soil Bearing Value" and he tied it to settlement. His first sentence of the abstract reads: "The value and practicality of rupture theory as the chief basis for bearing value determination is questioned. The paper title: "Compressibility as the Basis for Soil Bearing Value". It resulted in shaking up discussors such as Peck and Ireland.

RE: Meyrhof's Bearing Capacity equation

MathewosEndeshaw, the issue may be due to the depth factors values. Look at the term "Df/B". If you increase the width of your footing "B", you will be getting smaller depth factor values.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


White Paper - Effects of AIA Quick Guide to UL 489 or UL 1077
The function of a circuit breaker is to provide overload (thermal) and short-circuit (magnetic) protection to a circuit and its downstream components. A circuit breaker functions like an airbag in a car, protecting circuit components and people by tripping the circuit to interrupt the current flow if it detects a fault condition in the control system. Download Now
White Paper - Guide to Integrate Large-Format Additive
As with any new technology, getting into large-format 3D printing begins with investigation. The first question may be a simple one: what does “large-format” mean? For 3D printers, “large” is a relative term. Many extrusion-based (FFF) 3D printers are referred to as desktop machines, because they fit on table space. Some of these have very respectable build volumes – but when it comes to “large-format,” the machines will need their own dedicated floor space. Large-format 3D printers have significant build volumes and are most often found in professional settings, like manufacturing facilities and R&D centers. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close