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Hello,
we’re not responsible for OpenSees development, and by our side it’s all fine (all OpenSees tests are working with 3.6.0). You can revert to the previous version of OpenSees or compile a copy by your own – I suspect an installation issue on your pc.regards
Hello,
I understand you need more decimals in the Model data mask.
By now it’s not possible, but we’ll add it in the next minor patch.
regardsHello,
no, the modelling with solid does not mean to have eccentricity – you’re simply using distorted elements. Yes, hexa should have the same size for each dimensions, but modelling a thin plate with solids is not advised; the best is to stay with shell elements.Hi,
thanks for sharing the model – indeed the eccentricity plays an important role, please note that in the static loadcase you have out-of-plane displacements.
As told, we get the same buckling factors with other solvers (we used CalculiX) – you have to consider that you’re using distorted hexa elements: 1 dimension (thickness) is much shorter that the other 2, hence the elements is not in its ideal condition to work properly.Thanks for your comparisons. We corrected buckling on tria, this will be released in the next patch.
As we use OOFEM as default solver, we forwarded your check request to OOFEM team.ps. please upload one model with solid elements just to see your assumption about restraints and loading; other solvers confirm the correctness of OOFEM approach to solid buckling.
Hello,
please upload your non-working models with shells and a sample with solids at the bottom of the Support page.No, the complete versioning cannot be written in the download page, that page always hosts the latest version. You don’t need to use it to upgrade, simply press Updates / Check for minor updates… in the program!
Hello,
please try version 2.3.0.3; the patch for quad elements has been released. For tria, we’re still getting lower results, we’ll get in deep. For quads, we get a good agreement with results you already have. Always use a proper mesh (at least 5 quads per side).You can also run a parametric analysis automatically with Python in this version, please see the sample at https://github.com/NextFEM/API-Python/blob/main/wall_buckling.py
Hello,
we fixed a bug on quad elements that was causing the low factor you got – we’ll release the fix during this week, hopefully.
Regarding the comparison, results depend also on mesh fineness. We suppose you have the same mesh size and load (20kN) on all models. Another thing that affect results is the element formulation: in the built-in solver, tria elements are built by a membrane and plate, while quad elements have MITC4 formulation, which is generally more reliable.
Before releasing the patch we’ll do a parametric test on shell buckling, we’ll let you know when the update will be available.Hello,
have you checked deformed shapes for local buckling modes?
If you’re interested in in-plane buckling modes, you should model the wall in XY plane and set elements as plane stress (Edit / Change element type).
To perform a proper comparison, please make sure the mode is treated the in same way.Hello,
NextFEM Designer works with “.” (dot) as decimal separator. In your screenshot, you have 10,000 as load value, you have to use “10.000”.
Let us know if this solves the problem.Hello,
yes, there are 2 problems:
– all the columns must be beam, otherwise the assembly is obviously labile. Considering for instance node 5, you have all trusses and beams with end releases.
– you must restraint the rotation (torsion of columns) at the base.Please find attached the corrected model.
The rafters and roof ridge then should be beams with end releases for both moments at ends. Don’t apply restraints on the internal nodes, use them only at the base.
Beams with end releases are generally labile, so you have to take care of the assembly. Your model “wooden-house-ALL-RAFTERS-END-RELESED” is correct, except that the side beams is deforming too much (see displacements in case LOAD 1 – 33cm!). In any case, the moment is not transmitted as tou can see in Diagrams view.
Hello,
here we’re discussing about the static scheme to adopt, this is up to you to decide assumptions for your model. Answering your questions:
1. End releases are a constraint inside the beam, while resraints are applied to the nodes. Hence, if you release moments in a simply supported end, this is redundant: use only a simple simple support without end releases, or a fixed support and rotational end release. So yes, it’s just the same behaviour without end releases, but the contemporary presence of both can cause labilities
2. no, constraints tie degrees of freedom of 2 different nodes together, this is not your case.Trusses have only axial response – no releases for them. Only beams can have releases.
I hope this clarifies, regards