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Frequently Asked Questions (FAQ)
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You can find this setting in the Display navigator.
AnswerIn the graphic, imperfections are always oriented on a support. In the attached model and in Figure 01, the only support of an imperfection is defined at the column head. Therefore, the imperfection is oriented at this point.Since the graphical imperfection is virtually an equivalent load, the display is only of visual relevance in this case. The display is not important for the calculation.In order to orientate the imperfection graphically to the upper column head, you could use a rigid member, for example, and arrange the support there (Figure 02).
According to EN 1991‑1‑3, the snow load must be multiplied by the factor of 0.8 for the snow load on a roof. Therefore, the following load results:
sk = 5 kN/m² × 0.8 = 4 kN/m²
If the load has already been calculated for the roof, you can enter the load completely under the user-defined loads. This is shown in Figure 01 and in the video.
AnswerThe radius of a circle can be adjusted in the "Edit Line" dialog box.Click the button next to the text box to open the shortcut menu, where you can also define the formulas for determining the radius.
AnswerYes, it is possible. Usually, only individual members of a large system are exported to perform detailed analyzes on them. You can find more information about this export in another FAQ (see Downloads below).The export of a member with loads is shown in the attached video.
AnswerIn order to carry out the import in RFEM/RSTAB by using the DSTV interface, the program requires the nodes where the cross-sections can be located.It often happens, that members are only selected in the case of the "Export only selected objects" option (Figure 02). In this case, the nodes are missing in the selection. The model cannot be created.Therefore, you have to select all objects that are necessary for the description of the model by using the "Select" → "Related Objects" option (Figure 03). Then, the import is carried out properly.
RF-/STEEL Cold-Formed Sections is a module extension of RF‑/STEEL EC3. The only thing you need to do is to activate the design for cold-formed cross-sections in the detailed settings of RF‑/STEEL EC3 (Figure 01).
AnswerIn RX‑TIMBER, you can create a user-defined material as a new material in the material library (see the figure), similar to the programs RFEM/RSTAB.In contrast to RFEM/RSTAB, the category is set to "timber" in this case.
AnswerFire resistance design is not implemented in the RF‑LAMINATE add-on module by default.However, you can calculate the charring rates yourself and consider them accordingly in the module. In the following example, this is explained on a simple plate.Structural system (Figure 01):
Factors for fire resistance:
- Span 5 m
- Plate width 2 m
- LC1 (permanent) 1 kN/m² plus dead load
- LC2 (medium) 2.5 kN/m²
- 3 layers
- S1 35 mm C24
- S2 20 mm C24
- S3 35 mm C24
Remaining thickness of Layer 3 = 35 − 26.5 = 8.5 mm > 3 mm → thickness may be applied. (Figure 02)Because of the modified layer thicknesses, a new stiffness matrix results, which is applied in RFEM for accidental combinations with the characteristic stiffness values. For the ultimate limit state, the design values are calculated here (Figure 03).
- Charring rate ß0 = 0.65 mm/min
- Pyrolysis zone k0d0 = 7 mm
- Charring time t = 30 min
- Effective thickness def=t ß0+k0d0=30 min × 0.65 mm/min+7 mm = 26.5 mm
In principle, it is also possible to perform detailed analysis in RF‑LAMINATE. In the case of a very high shear distortion, for example, it can be reasonable to use orthotropic solids for modeling. The video shows a simple modeling and result evaluation of a layer structure by using solids.
A criterion, as of when is the modeling using solids useful, is the shear correction factor. Further information and other criteria can be found in the following FAQ:
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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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