topic Simply Supported Slabs and Beams – One-Way vs Two-Way Behaviour in Robot in Robot Structural Analysis Forum

Simply Supported Slabs and Beams – One-Way vs Two-Way Behaviour in Robot

ashley_calleja0806 — Wed, 07 Jan 2026 09:46:25 GMT

I am new to Autodesk Robot Structural Analysis and I am modelling a single-storey building with walls, columns, beams, and slabs. I want to model the slabs as simply supported and compare the results assuming one-way and two-way slab behaviour. I have tried:

Changing the Panel Calculation Model to the Simplified (trapezoidal/triangular) method for both one-way and two-way slabs
Applying linear releases along slab edges (I am still getting small moment peaks at the slab edges, and the slab behaviour does not clearly reflect the intended support conditions.)
Using orthotropic material properties to increase stiffness in one direction only.
Changing the slab model from Shell to Load Take-Down one-way and two-way (When using Load Take-Down, the beam results seem closest to what I expect for simply supported behaviour; however, in this case no slab results are available)

I also want to model the beams as simply supported, but end releases do not seem to fully remove continuity effects or moments at the supports.

Would appreciate some advice how to model this please. This is the model file for reference.

Thank you in advance for your help.

Re: Simply Supported Slabs and Beams – One-Way vs Two-Way Behaviour in Robot

Rafacascudo — Wed, 07 Jan 2026 12:09:26 GMT

To have slab results , you can not use simplified distribution of loads on calculation model. It has to be analytic.

So that´s it , perfect beam results for one/two way slab only if using claddings.

Acceptable results can be achieved using orthotropic slabs as you already know

Re: Simply Supported Slabs and Beams – One-Way vs Two-Way Behaviour in Robot

ashley_calleja0806 — Thu, 08 Jan 2026 09:45:26 GMT

Thank you for your response. So, to confirm my understanding: it is not possible to obtain both accurate simply supported slab results and simply supported beam behaviour within the same model?

Re: Simply Supported Slabs and Beams – One-Way vs Two-Way Behaviour in Robot

Rafacascudo — Fri, 09 Jan 2026 15:32:29 GMT

For one-way ,You can try Ortho +releases. Looks good to me