Loading a new .ifc model into existing simulation -- intense explosions on earthquake motion

[smokhov]

Hello, been experimenting with your simulation setup in Blender... Very nice work!

A question: we tried loading different models of various building shapes to see how well the simulation can handle them. They were exported from various other tools like SketchUp models, or others as .ifc. Most loaded successfully, descritization and running all preprocessing tools appears to work for most models, but some make Blender crash. In the console window there seems to be graph problems or odd edges and some other errors. The models that do complete however, with earthquake motion, appear to "explode" very intensely while your original model nearby appears to fall apart "normally" as per your simulation. This suggests our building material properties imported are not somehow set and may be too "light weight". How to easily configure the material building properties similarly to the multifamily building sample you have? Thanks!

[KaiKostack]

Hello, and thank you :)

Blender crashes should never happen, however, sometimes when you have complicated or malformed meshes in combination with the discretization tool (which uses boolean operations) this might be possible. Also the explosions you are describing speak for a model with self-intersecting geometry or otherwise problematic topology. I would have to have a look at the model to give you a more concrete answer, feel free to send me a test file to kostackstudio@gmx.de and I will check what's wrong.

[smokhov]

• determined the crash happens at Intersection Removal; not doing that step allowed the steps to proceed without a crash. However, some models, especially after resize, did not allow "Build" with "index -1" error. I'll try to capture the relevant screeshots when I can.
• you are probably right about the models; they were exported from some samples found on SketchUp, but it is not obvious in some cases when I look at the wireframe if it self-intersects anywhere, one in particular is a regularly shaped dome...
• deleting your building models (and keeping any of the ones I loaded does not allow build, as it says "No connections found. Probably search distance is too small". Tried playing with the distance at great ranges, same result, only can simulate when your building is present
• will send you the models shortly

[smokhov]

Mail sent with the details... We will continue experimenting in the meantime.

[smokhov]

What would this error mean during Build?

[smokhov]

(BTW, succeeded to properly set materials to one of the dome models and shook it fairly realistically with the Mag 7 earthquake .csv file's data. I've found parts of the problem from what I sent and experimented and read your documentation again...

[KaiKostack]

The models you sent me are indeed extremely bad for use with the BCB. They are all non-manifold, have double faces and other problems like no definitive volume. If you have no volume then the BCB can't compute mass, and without mass nothing will work right. I recommend to model the structure you want yourself with clean geometry from basic primitives, a simple dome isn't hard to make anyway. Here is a test file that took me only a few clicks to create: dome-test.zip

[smokhov]

@KaiKostack -- thanks for the sample dome! :) FYI, yesterday, we got the dome-porous.ifc dome to work actually somewhat realistically; I've uploaded pourous-dome-success.blend into the same location -- it actually withstands Earthquake_mag_7_accel.csv with minor damage and is somewhat remotely reminiscent to the test conducted with a physical dome here -- check it out. We wanted to test some existing models and do not have proper Revit or similar models to play with for this small project. So we had only those "extremely bad" models to do quick tests with.

I've just downloaded your dome-test -- which is indeed a simple way to do so as a half-sphere -- it looked nice and cool, but collapsed in the end under the same Earthquake_mag_7_accel.csv conditions. Its discretization was interesting though.

Otherwise, you are quite right about the models. However, I made some of them work following your guide :-) actually more closely -- such as naming the object pieces properly for element groups and splitting, and then evaluating proper mass etc, as reinforced concrete structures -- so the "explosions" stopped and the models behaved a lot better after that as that porous dome example. I just needed to RTFM a bit better... It has some learning curve for a non-specialist and getting used to it, but now with better understanding it works quite well.

Appreciate your time! And thank you again for this simulation environment! I think this issue can now be closed.

[KaiKostack]

Good to hear that you are making progress. The learning curve is certainly steep but keep trying things out and you'll soon get more familiar with the BCB and Blender. Good luck!