INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!

*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.

Jobs

Analysis and Design of large mat foundations supported on soil using FEM considering soil -structure

Analysis and Design of large mat foundations supported on soil using FEM considering soil -structure

Analysis and Design of large mat foundations supported on soil using FEM considering soil -structure

(OP)
Large mat foundations are usually modeled using plate elements and the boundary conditions at soil – foundation/structure interface is idealized using winkler springs assigned with sub-grade modulus of soil (using plate mat with compression only springs in STAADPro to establish and take into account the loss of contact, if any). Needless to say, such an analysis is non-linear in nature and time consuming as it involves several iterations spreading over the entire set of load combinations in order to obtain convergence of results in each case.

For service level load combinations, foundation sizing is carried out based on the maximum bearing pressure, stability ratios (overturning and sliding) & estimating / limiting the contact area thus obtained.

Usually, the above sized foundation is then re-analyzed using strength level load combinations to obtain bending moments & shear forces at the sections of interest, in order to design the concrete thickness and reinforcement required.

Now, the point of discussion here is, should such foundations be re-analyzed in STAADPro (or any other analysis software) using the strength level load combinations in order to obtain the design forces?

OR

Should the internal forces obtained using service level load combinations above be simply magnified with strength level load factors to arrive at the strength level design forces?

Thanks and Regards
Sunny

RE: Analysis and Design of large mat foundations supported on soil using FEM considering soil -structure

In these circumstances, when non-linear effects are explicitly considered, each load case must be analysed separately as the boundary conditions of the FEM model change with the load magnitude and distribution. In this way, service level load effects can't just be magnified by a load factor. It is the same as in the non-linear analysis of laterally loaded piles.

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!


Resources


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