[RSA 2023] Overlapping Panels from Imported Analytical Model

[DonBAE]

I am getting an overlapping panels warning in the attached model. The model was imported from Revit and is a two-way concrete slab with drop panels. I'm not sure if the warning is triggered by the fact that there are several interior panels for the drop panels or if perhaps there is some model inaccuracy from the import. 

Appreciate an help on this.

[okapawal]

Hi @DonBAE 

The drop panels overlap with the slab.  It is not recommended to use overlapping panels.

How the program should know which thickness assign to finite elements in overlapping zone if they are different?

It worked as you would expect, I guess, and assigned  in most places the bigger thickness.

I can spot mismatched thickness in panels 164 and 166.

I would recommend to define openings in Revit panels where they overlap with drop panels.

You can do it using Opening By Face and Pick Lines of the drop panel contour.

[DonBAE]

@okapawal 

Thank you for looking into this. Your reply suggest some disappointing behavior with the handling of panels in Robot.

"How the program should know which thickness assign to finite elements in overlapping zone if they are different?"

We would expect consistent behavior with industry practice seen in various other software packages either meshing based on panel draw order, panel thickness, or user assigned priority.

"I would recommend to define openings in Revit panels where they overlap with drop panels."

This is not a possibility in Revit as that fundamentally alters the documentation appearance and per industry standard drop panels must appear dashed. In Revit a single high slab must be modeled overtop of all drop panels for drafting consistency with industry standards.

"You can do it using Opening By Face and Pick Lines of the drop panel contour." 

Trying this procedure I am running into several locations where the applied opening cuts out both the primary slab panel and the drop panel leaving an actual opening. Could you please provide a video showing how to apply the opening to these locations such that the drop panel remains after the opening is cut:

[DonBAE]

@okapawal 

As a follow on question assuming one was building the model entirely in Robot what is the procedure to model drop panels in concrete slabs, the elements are extremely common? It does not appear that there are any tools built in to handle the modeling of these elements with any form of modeling efficiency. 

Additionally searching the forum I found conflicting information across various posts one of which made by Artur in which he showed modeling the panel for the drop panel overtop of the slab panel, as was done in this model but it seems somehow that did not count as an overlapping panel.

For complete model accuracy drop panels should also be modeled with a vertical offset from the primary slab and connected via rigid links the only efficient method I was able to find for this from searching the forums is the Spyder tool provided by another user. It seems it would be in the best interest of Robot and Robot's user for Autodesk to incorporate all of the features from Spyder, any reason this hasn't been done the tool seems to be several years old now? For slabs acting as diaphragms which can experience significant axial loading not modelling the offsets can lead to unconservative designs.

[Romanich]

Hi @DonBAE ,

Did you have a chance to try this approach?

https://apps.autodesk.com/RSA/en/Detail/Index?id=964813656627065816&appLang=en&os=Win64

[DonBAE]

@Romanich 

We have not given your Spider tool a try as of yet, we are vetting if Robot is worth further time and financial investment.

Can Spider handle overlapping drop regions, see below examples, we have these conditions very frequently with Architects pushing for more irregular column grids these days?

[okapawal]

I meant modification of analytical panels in Revit.  Once you create analytical panels for slab and drop panel at the same level, you can create openings in the slab over the drop panel contour.  This will create separate, not overlapping panels in Robot.

See the short video

Revit Openings by Face 

Alternative solution in Robot will be to generate local mesh on drop panels and freeze it.  Then you can generate mesh for the rest of the model.

See the short video

RAS local mesh  

[DonBAE]

@okapawal 

The Revit option only seems to be viable in Revit 2023 where the analytical model is disconnected from the geometric model. We are required to use earlier version of Revit to maintain file compatibility with our clients (this seems to be something Autodesk struggles to understand)

"Alternative solution in Robot will be to generate local mesh on drop panels and freeze it.  Then you can generate mesh for the rest of the model."

I attempted this as well but several other inconsistencies appeared the elevator core opening now gets meshed as slab and several areas where the 10" primary slab is meshed inside the 20" drop panel slabs.

[DonBAE]

@okapawal I have created this idea in response to the discussion here as well: https://forums.autodesk.com/t5/robot-structural-analysis-ideas/panel-mesh-priority-system/idi-p/1140...

[DonBAE]

@okapawal would it be possible for you to provide a short video illustrating the process of adding 8'-0" x 8'-0" drop panels at the column locations in the model attached to this post, without the use of Spider Pro?

The drop panel configuration should be similar to this sketch:

This could then serve as a tutorial video to be added to the knowledge resources.

[DonBAE]

@okapawal 

Would greatly appreciate a video showing how to apply drop panels to the columns in the model attached to message 10 in RSA 2023.

[DonBAE]

@Krzysztof_Wasik 
@tomasz.wojdyla 
@Rafal.Gaweda 
@Artur.Kosakowski 

@pawelpiechnik 

Would it be possible for anyone to provide assistance as requested in message 10?

There are a small number of posts on the forum regarding drop panels and @Artur.Kosakowski even suggested in one of them to just model the drop panel slab on top of the primary slab but in every test I have tried the results are inconsistent with the mesh occasionally generating elements of both slab thicknesses on top of each other. 

Can someone from Autodesk please outline the proper way to model drop panels in Robot, these structural elements are fundamental in two-way flat slab construction to limit long term deflection, reduce reinforcement demand over columns, and increasing punching shear resistance.