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

Spring Support Generation in STAAD.Pro

Spring Support Generation in STAAD.Pro

Spring Support Generation in STAAD.Pro

I am checking a mat foundation that was modeled in STAAD using springs. The engineer used the PLATE MAT feature in STAAD where it "multiplies the subgrade modulus by the influence area of each support node to determine the spring stiffness". I can see how the influence area may be calculated but how do I verify the subgrade modulus for the soil?

RE: Spring Support Generation in STAAD.Pro

JE Bowles' book on Foundation Analysis and Design publishes typical values for some soil types.  By cross checking the soil you got against the published values you will have an idea where you stand.

Failing that do a load test on soil.

RE: Spring Support Generation in STAAD.Pro

For Mat foundations the Subgrade Modulus (k) can vary depending on the duration of the load.  To be conservative, as far as moments are concerned, you can look up the typical value for k based on your soil conditions and divide it in half.  For bearing pressure use the higher k, resulting in higher pressures.  Basically, you will have an upper and a lowere bound for your k.  If you don't have a soils report, this is about all you can do.

RE: Spring Support Generation in STAAD.Pro

Firstly, I use the same approach to compute my spring value. Secondly subgrade modulus (k in pci) should really come from the geotechnical engineer. It is a tricky number and lots of people assume it. I also encountered geotechnical engineers who would give different values for (k). I would suggest to use a seasoned soils engineer not one who copies numbers from previous reports (oops..  I hope this does not upset any one).

Good luck.

RE: Spring Support Generation in STAAD.Pro

Not me!

Lufti is on the mark - the geotechnical engineer should be providing those values - and if the structure is "significant", you should work together to iteratively improve them.  You see, there is no such thing as "the" k-value - it is a numerical convenience, not an intrinsic property.

Please see FAQ731-376  by VPL for tips on how to make the best use of Eng-Tips Fora.

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! Already a Member? Login


eBook - Integrating the Engineering Ecosystem
Aras Innovator provides multiple options for integrating data between systems, depending on the scenario. Utilizing the right approach to meet specific business requirements is vital. These needs range from authoring tools, federating data from various and dissimilar databases, and triggering processes and workflows. Download Now
Research Report - Simulation-Driven Design for SOLIDWORKS Users
In this engineering.com research report, we discuss the rising role of simulation and the paradigm shift commonly called the democratization of simulation. In particular, we focus on how SOLIDWORKS users can take advantage of simulation-driven design through two analysis tools: SOLIDWORKS Simulation and 3DEXPERIENCE WORKS. Download Now
White Paper - Industry 4.0 and the Future of Engineering Education
With industries becoming more automated, more tech-driven and more complex, engineers need to keep their skills and knowledge up to date in order to stay on top of this wave—and to be prepared for the Industry 4.0 future. The University of Cincinnati offers two online Master of Engineering degree programs designed specifically for practicing engineers. Download Now
eBook - The Design Gridlock Manifesto
In this eBook, you’ll learn 6 ways old CAD technology slows your company down and hear how design teams have put those problems to rest. “The Design Gridlock Manifesto” shares first-hand modern CAD experiences from 15 companies around the world. 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