Hi
when I try to use Bar.Deconstruct.Modify for a single beam, it shows number of bars as 1,number of curve as 1, however section number as “2”. How it is possible?
This discrepancy creates mess when I use “cull pattern” to split the curves based on section to reconstruct an existing FEM model. Please help
Hi @Arun_N_Dinesh 
welcome to the community page!
The output shows 2 sections as FEM-Design can handle tapered beam where the start and end sections are different. In your case, you can probably use a list item and select the first one 
Hi Marco,
Thank you for the quick response. It really helps me sort things out quickly 
From what I understand, if my model has multiple sections (without any tapered sections), I can use a list item and call the alternate items—probably the odd numbers—to match the section numbers with the curve or bar numbers. Please let me know if I’m wrong. Thanks in advance!
ehi @Arun_N_Dinesh
The best way to use the output data structure is to work with DataTree.
I highly encourage you to start using them when possible. As you can see in the picture below, every bar/curve/identifier has the same tree branch. It means that if you can select branch {8} from the different output, you will get the information for the selected index beam.
Hi @MarcoPelle
Thank you for the DataTree suggestion. I’m wondering why all the curves are assigned the same section (1500×1200) for all bars after deconstructing. Doesn’t the Deconstruct tab automatically map the curves to their corresponding sections in the existing FEM model? If not, it creates a lot of DataTree/cull pattern work to retrieve the actual model. Don’t we need that?
It is bit unclear what you are trying to do in your grasshopper script.
However, bar.deconstruct will return the properties of the bar that belong to the model that you are trying to deconstruct. It is not necessarily the one open in FEM-Design.
As a suggestion, always try with a small model which you can investigate the script.
Hi @MarcoPelle
Sorry to hear it wasn’t clear. Yes, I’m working with a small model.
Here’s what I’m trying to achieve:
The issue I’m facing is that
It’s hard to see in the picture it seems like the flat curve list is culled but not the section list? Are they equally long? If not, are the first 88 sections in that list 600x2000?
Hey Arun,
If I understand correctly, you’re trying to deconstruct certain bar elements and modify their section properties — in this case, the 600×750 elements.
However, in your current workflow, I don’t see any step where the sections are actually being updated. It looks like the script only retrieves the sections rather than modifying them.
Additionally, the overall data flow has some issues. The inputs and outputs aren’t properly controlled, which causes the script to return incorrect elements — most likely you have multiple overlapping elements in the same location in your model.
Have a look at my brief explanation below:
In case you want to change a certain section with another, take a look at a simple example below:
Of course, if you’re working with a large amount of data (beams/columns) with different sections, materials, or even tapered sections, using a DataTree structure will give you a clearer and more reliable workflow.
I hope this helps 
Hi @Arun_N_Dinesh!
I’ve created an example file showing how to use the Bar.Deconstruct.Modify component with data trees, and included some explanations of how data trees work. I hope this little example can help you or anyone else who is new to data trees.
Basics-of-using-data-trees-with-BarsDeconstructModify.gh (68.7 KB)
However, Andrei’s answer is very detailed! Thanks to him! 
Hi @anLor Thank you for the detailed explanation and the concise script. I had intended to produce similar output, but due to my busy schedule, I couldn’t find the time. I truly appreciate your effort and support! 
@AndreiM Thank you for providing the snapshot and the data tree example 
This has been extremely helpful in enabling me to view the information in a more structured and organized manner. I sincerely appreciate the time and effort you invested in preparing this.
@MarcoPelle Thank you for adding me to the community link and solving the issue. I’m truly impressed by the active engagement and quick responses from other members into my post—it’s great to see such collaboration! I’ve never experienced this level of quick responsiveness in other developer communities.
As I’m new to FEM design, this support is highly motivating and encourages me to explore FEM design tools further. I particularly appreciate the detailed and reliable outputs from Strusoft Eurocode elemental design, which is why I’m working on deconstructing an existing model that involves several section and design iterations during the project stages.
