Orthotropic behaviour and nonlinear analysis of slabs


I’ve got this situation here about a certain problem, that I believe everyone may have ran into some time or another.
To begin with, I’m modelling an “area” type of an element which is supported by 2 beams on 2 edges. The problem begins with bending moment as this area element has bending stiffness that adds up with beams’ and creates a lower actual bending moment.

In this case, there is an option to create an orthotropic behaviour slab:

The results are:

You can see the difference in beam’s bending moments with reduced stiffness (bottom slab) and without slab stiffness reduction (middle slab).

Now this works linear analysis, however, nonlinear analysis doesn’t work on orthotropic elements. Any suggestions how to solve this? Or maybe there is another option to have slab’s bending stiffness reduced and also to be able to solve slabs in nonlinearity.

Thank you in advance

Dear Mr. Tomas,
If you want to use nonlinear analysis for othotropic elements, you can not use nonl. materials.
You have to use geometric nonlinearity (SYST PROB NONL).
Please have a look at our teddy examples. Available at Teddy/SSD Data - Examples - ASE - nonlinear_quad
For further informations I recommend our ase manual at Teddy/SSD - Help - Manuals - ASE - Theoretical Principles - Nonlinear Analyses and T-beam-Philosophy, for a better understanding of the interaction between beams and slabs.

Best regards,
Your SOFiSTiK Support Team