## Small-strain vs. large-strain shear modulus - General Bearing Capacity Equation

## Small-strain vs. large-strain shear modulus - General Bearing Capacity Equation

(OP)

The general bearing capacity equation requires a check of the foundation's rigidity index (I

_{r}) against critical rigidity (I_{rc}). Shear modulus (G) value is required to determine I_{r}. Is it the small-strain or large-strain shear modulus that should be used?
## RE: Small-strain vs. large-strain shear modulus - General Bearing Capacity Equation

## RE: Small-strain vs. large-strain shear modulus - General Bearing Capacity Equation

"The general bearing capacity equation' to me is Terzahgis bearing capacity (modified by Meyerhoff or others), I have never seen G in a bearing capacity calc?

## RE: Small-strain vs. large-strain shear modulus - General Bearing Capacity Equation

## RE: Small-strain vs. large-strain shear modulus - General Bearing Capacity Equation

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## RE: Small-strain vs. large-strain shear modulus - General Bearing Capacity Equation

https://www.up.ac.za/media/shared/124/ZP_Resources... (Archer's masters thesis - see below for paper)

https://pdfs.semanticscholar.org/b639/5a1b6f8bb053... (paper by Archer)

## RE: Small-strain vs. large-strain shear modulus - General Bearing Capacity Equation

EireChch: General BC Eqn. only works for the failure mode of "general shear failure." To check against other failure modes i.e. "punching shear" and "local shear failure," most codes require a check of the foundation's rigidity. I have seen 2 methods to undertake this check; 1 from Braja M. Das and 1 from Harry Poulos.Okiryu: I understand why you prefer l-s G over s-s G. After consulting with Harry Poulos, I decided to use an average value. Normal ‘working’ load value, as being representative of somewhere between elastic and fully plastic behaviour. The large strain value would approach zero, while the small strain value would relate to the early part of the loading process.Okiryu: This post is talking about footings not piled foundations. It refers to the rigidity index of footings. Not the cavity expansion theory for piles. Interestingly, Vesic addressed this issue i.e. the rigidity of footings and associated failure modes. If you have "Principles of Foundation Engineering" (2016) by Braja M. Das, refer to Figures 4.2 and 4.3.BigH: Thanks for the links!!! Very pertinent. Thank you.