algorithmic modeling for Rhino

Here's a thread for questions and suggestions specific to the Geometry Gym addon to interact with SAP2000 Structural Analysis.  Note you can filter my blog for posts/examples specific to SAP 2000 using the tag cloud or this link here: 

First post relates to questions raised here:

SAP2000 uses slightly different terms to other structural analysis software (ie Load Patterns are  equivalent to Load Cases in most other software).  I am trying to do my best to ensure the GH plugin terminology matches, but still needs improving and this doesn't help with what connects to what.  If you spot something you think can be improved, please let me know.

I've attached my subtle changes to your GH def.  Note that at least one of the forces needs to be activated to true to get results to emit.

I had a request to report stress the other day, but when I went to check you can only extract the force using the API, so I need to find some time to do some additional coding to calculate these from the section properties.  Axial force you might be able to quickly calculate from the force using GH components.  

Note also I recently enabled the ability to nominate the SAP model units (ie Feet and kips) from a right click on the ssiBake button.  This should be done prior to the first exchange to SAP, so either save, close and restart Rhino, or disable the solver prior to first opening the model to make the change.

Hope it helps, look forward to hearing more.



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Replies to This Discussion

Hi Jon,

For the latest version of ggSAP (V18), the ggSAPCreateFrameProp component is not working properly. Is that a bug? It was working fine in your v16.1.

I have attached an example for your review.




I uploaded a new installer, maybe it's something I fixed in the past two weeks (but I don't recall).  If it still not working, email me and I'll help you troubleshoot.



Hi Qi

I wonder if your problem solved.

I had the same problem and found that it was because of incompatibility between the Sap2000 version and the ggSap plugin version.

Just want to share this here as for others!!:

ggSap Erro

Hi Jon,

I notice there is a ggSAPBuckling Load Case component for buckling analysis. But I don't see an input for connecting a load pattern component. And there is no buckling factor query or result decompose component either. Just want to ask whether the buckling function is still in progress. 



why do I get this error message? I do have sap2000 14 installed on my pc, I installed geogym, bulland ggsap and some other stuff. What do I do wrong?

Hi everyone,

I'm trying to explore ggSAP.

When I want to bake examples by first going on "Open Model in SAP", Rhino crashes.

If I click on "Bake model", nothing opens neither. I'm using latest v19 of SAP2000.

Thanks in advance for your help.


Are there any known issues with the ggSAPLoadCrvPatch? We are having problems trying to specify different values for Pos1 and Pos2. No matter what we try in regards to positive/negative numbers we can't get the component to do anything else other than apply the loads at 0 and 1 absolute unit location of the frame element.

Can you elaborate more on what the program expects for the A and B inputs of this component or what issues might exist?


Hi JJ T,

Thanks for reporting this, I've traced the code and implemented a fix in the latest builds.

Let me know if this doesn't help.

Cheers,  Jon


I've failed to create a RC beam section property.

ggSAPCreateSectionProp requires the input "Profile" that seems to be related to the steel profile from Bull Ant list.

Could you help me ?

Thanks !


Hi Gery,

Bullant provides some standard shape components, the RHS generates a rectangular profile if wall thickness is zero.  Refer to the attached.

Let me know if that doesn't help.




This fixed it. Thanks!

Hi Jon (or anyone else who is willing to provide an answer),

I've been playing with the Geometry Gym  SAP2000 (v.19) API for about a month and I am having a little trouble figuring out what I'm doing wrong.  I'm trying to set up a simple beam or a simple truss that I can send to SAP...just to see how things work.  However, if I use some of the examples you've uploaded as a reference I get the following error message:   

1. Object reference not set to an instance of an object.    at GGYM.GH.Structure.ggCreateSectionProperty.SolveInstance(IGH_DataAccess DA)

It happens whenever I use the ggSAP Create Frame Properties element and plug in information into the Profile input.  I've tried using the ggIFC CatalogueProfileDef as the name and profile, I've tried using ggAsymmetricIShape and inputting section property info directly...each time I get the same error.  Am I doing something totally wrong or am I on the correct track?

Any help with this would be GREATLY appreciated!








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