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Frequently Asked Questions (FAQ)
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AnswerIn RF-IMP, you have selected the "Generate Pre-Deformed FE Mesh" option. In this case, the imperfect structure is considered in the calculation via the deformed FE mesh generated in RF-IMP. The results of the CO then refer to the coordinates of the pre-deformed FE mesh and no longer to the original position in the perfect system.To better explain the topic, I exported the coordinates of the pre-deformed FE mesh nodes from RF-IMP to Excel. Based on this information, an imperfect structure was created in a new RFEM file and calculated according to the second-order analysis. The left window shows the deformation of the perfect structure considering RF-STABILITY and RF-IMP, and the right window shows the result of the imperfect structure. The results are identical.
Yes, it is.
The cross-section created in SHAPE‑THIN 9 (file extension *.du9) should be opened and saved as SHAPE‑THIN 8 cross-section (file extension *.du8) in SHAPE‑THIN 8.
In order to open the cross-section in SHAPE‑THIN&nbso;8, set the file type to "All Files."
Now, you can normally save this cross-section as a SHAPE‑THIN 8 cross-section, and also open it in the previous program versions.
In the case of using timber materials in RFEM, a message appears when creating the material, saying that the "isotropic linear elastic" material model is only correct for the calculation with members because the Poisson's ratio is very large. For surfaces, it is necessary to select a different material model.
If you have assigned the material with the orthotropic material model to the surface, it is not possible to use certain orthotropy types. This material cannot be used for ribbed plates.
However, if you have assigned the material to the surface with an isotropic linear elastic material model, you can access all types of orthotropy.
When entering the geometry for the ribbed plate, Error No. 30343 appears due to the incorrectly assigned timber material for the surface: "The computed stiffness matrix is not positive definite."
AnswerThe axis orientation of the surfaces in your model is probably not adjusted. For a circular surface, it is recommended to specify the orientation of the axes for surfaces or the axes for results of the surfaces.You can adjust the axes for each surface. In the "Axes" tab, you can find the subtabs "Axes for Input" and "Axes for Results."The "Axes for Results" tab adjusts the axes of the surface for the results. Here you can specify the orientation of the axes using a point, for example. A great advantage of this method is that the results are not deleted when adjusting the axes.The "Axes for Input" tab adjusts the axes of the surface for the orientation and results. Here you can specify the orientation of the axes on a line, for example.The results of both axis adjustments are the same. For symmetric loading, the expected symmetric results are provided.
The temperature loads as surface loads on general glass cross-sections cannot be considered by modeling them as solid elements in the program. With the default settings, the glass pane is modeled by using 3D solid elements.
However, the 2D calculation allows for modeling temperature loads as surface loads. You can set this in the details of the layer structure, so that the 2D calculation (plate theory) is performed. In this case, it is also possible to consider the shear coupling between the layers, if necessary.
Further details on calculating and using laminated glass can be found in the technical article "Calculation and Use of Laminated Glass."
After the successful calculation, you obtain the results for the respective layer structure. Figure 04 shows the results as an example of a layer structure without shear coupling.
As an alternative to the rectangular cross-section, there is also a "rotated unsymmetric floor beam," which can be created as a cross-section by using the cross-section library.
Subsequently, this cross-section can also be designed in RF‑CONCRETE Members or CONCRETE.
According to DIN EN 1993‑1‑1, 220.127.116.11 (2), the reduction factor χLT can be modified by the f factor for χLT,mod. You can activate or deactivate this option under National Annex Settings.
AnswerThe surfaces are entered as an orthotropic plate. The thickness can be changed in the Constant Thickness tab of the Edit Surface Stiffness dialog box.
The fastest and easiest way to clear the calculated results is to save your model without the results data and printout reports.
To do this, click on the File menu → Save as ... to open the small Select data to save window. In this dialog box, unselect the Results and Printout reports options. Then, click [OK] before you save the model.
AnswerIn this case, it is recommended to use nodal releases. They allow for a transfer of bending moments in the frame plane as a transfer of axial and shear forces to the columns.The nodes to be released are the respective corner nodes with a moment hinge as a member hinge. The released objects are the horizontal members in the frame plane that are connected to the corner nodes.
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Wind Simulation & Wind Load Generation
With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.
The generated wind loads acting on these objects can be imported to RFEM or RSTAB.
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