×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*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.

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

 Forum Search FAQs Links MVPs

## 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 (Ir) against critical rigidity (Irc). Shear modulus (G) value is required to determine Ir. 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

I would use the large-strain shear modulus for foundation design. My understanding is that small-strains are used mostly for seismic applications.

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

Which code requires this check?

"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

I am assuming that the OP is working on pile foundations and using the cavity expansion theory from Vesic...

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

Ok thanks, still I dont think there is a general bearing capacity equation for piles!

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

(OP)
Thanks for your responses!

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.

#### 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.

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

Click Here to join Eng-Tips and talk with other members! Already a Member? Login

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. 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:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!