Seismic Analysis error

[hherrera]

I have a building that I have been working on for quite a while now (brought from Revit).  Everything seemed to be working fine for the most part until I used Robot for the seismic analysis.  The determination of the seismic load is correct (I verified by hand calculation), however I recieve a calculation message for all the seismic cases: "There are no nodes in the floor plane.  It is impossible to apply forces for the static seismic analysis case." See attached screen shot

I have tried:

1) Re-meshing walls/floors

2) Running the file in Robot 2014/2015.

3) Turned on "Iterative adjustment of the FE mesh"

Any ideas would be greatly appreciated.

File can be downloaded from: https://SSend.it/goflz9

Thanks!

Henry

[Rafal.Gaweda]

 "There are no nodes in the floor plane.  It is impossible to apply forces for the static seismic analysis case." 

This is the last problem you have in this model.

In general - all results are wrong because you have ignored instabilities type 1.

Instabilities are caused by inaccurate geometry:

- roof panel not connected to node  471  

- nodes  466 468 744to772By2  not located on roof panel edge

- wrongly defined release (on free ends) on bar  202  

[Rafal.Gaweda]

 "There are no nodes in the floor plane.  It is impossible to apply forces for the static seismic analysis case." 

Define correctly stories for calculation purposes:

Corrected file attached

[hherrera]

Thank you for the Reply Rafal.  I have fixed the instabilities 1.  It seems like some of the analytical nodes sometimes shift a bit when going back and forth with Revit on a sloped Roof.   however I am still recieving the same error: "There are no nodes in the floor plane.  It is impossible to apply forces for the static analysis case."   For the seismic.

Attached is the updated file With the fixed instablities:

https://SSend.it/3s4xd7

Thanks,

Henry

[Rafal.Gaweda]

Define properly stories or use my file sent before

[hherrera]

Rafal,

I have updated my model correctly with stories, and I am still recieving the same error.  Even when I try with your corrected model, I have the same error.  I am using Robot 2015.  I have tried to re-mesh the model as well, and no luck.

[hherrera]

Rafal,

I think I understand why this error is occuring.  The Center of Rigidity/Mass have been calculated by robot to be centrally located in some of the large holes I have in the diaphragm.  So there technically is no "floor" there, and no way for the load to transfer into and through the diaphragm, since the seismic load would be applied at that location.  I have come up with this conclusion because I tried infilling the holes I have in my structure with a new floor, and the seismic cases were then able to run, however with false Center of Rigidy/Mass.  I tried also adding a rigid link from the coordinates of the Center of Rigidity, and connecting it to the floor, but that did not work either.  It seems like the program is looking for a floor object in order for this calculation to run.

Is there any other way I can maintain the correct calculated coordinates for Centerof Rigidity/Mass, while still transfering the seismic load to my structure?

[Rafal.Gaweda · Accepted solution]

My way:

[hherrera]

Rafal,

Thanks for the video walkthrough, this ended up working for me.

[tamirzolbayar]

Had the same issue with my building model when running seismic analysis. Followed @Rafal.Gaweda 's video guide and solved the problem. This was very helpful, Thank you! 

[haidangluong.ce]

Thank you.