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Frequently Asked Questions (FAQ)
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Answer
If the results are to be displayed at a specific location of the crosssection, the element must be divided at this location.
An element can be divided by rightclicking the element and selecting the "Split Element" function in the shortcut menu (Figure 1).
For example, if you want to determine the stress at a distance s = 32.5 mm from the start of element 1, you have to divide element 1 at this point. This is also shown in the video.

Answer
If you want to calculate the stresses in SHAPETHIN, create at least one load case. A new load case can be created by:
 Menu "Insert" → "Load" → "New Load Case"
 Shortcut menu of the "Load Cases" navigator entry
 Input in table "2.1 Load Cases"
Furthermore, internal forces must be defined. Internal forces can be entered via:
 Menu "Insert" → "Loads" → "3.1 Internal Forces" → "Dialog Box"
 Input in table "3.1 Internal Forces"
 Import of internal forces from RSTAB or RFEM in Table "3.1 Internal Forces"
After the calculation, the stresses can be displayed graphically and in tables (Figure 01). This is also shown in the video.

Answer
Yes, it is.
The crosssection created in SHAPE‑THIN 9 (file extension *.du9) should be opened and saved as SHAPE‑THIN 8 crosssection (file extension *.du8) in SHAPE‑THIN 8.In order to open the crosssection in SHAPE‑THIN&nbso;8, set the file type to "All Files."
Figure 03  Opening SHAPETHIN 9 CrossSection in SHAPETHIN 8
Now, you can normally save this crosssection as a SHAPE‑THIN 8 crosssection, and also open it in the previous program versions.

Answer
RF/ALUMINUM checks the symmetry of general crosssections and compares them with the SHAPETHIN evaluation if activating the "Determine symmetry by module and compare with SHAPE‑THIN definition" check box (Figure 01).
Figure 01  Dialog Box Details, Check Box Symmetry
If both methods provide different results, the corresponding error message appears (Figure 02).
Usually, there are small inaccuracies in the SHAPE‑THIN crosssection. Thus, the crosssection Sec‑1.du9 shown in Figure 03 is not absolutely symmetrical to the Z‑axis: The Z‑coordinates of Node 1 and Node 4 as well as Node 55 and Node 60 do not match in the second decimal place.
Figure 03  Different ZCoordinates of CrossSection
SHAPE‑THIN classifies the crosssection as asymmetrical, but RF‑/ALUMINUM as monosymmetric to the z‑axis, so the error message shown in Figure 02 appears.
The SHAPE‑THIN crosssection should be checked for symmetry. When modeling in SHAPE‑THIN, it is useful to only display one side of the crosssection and to create the other half by mirroring. This is also shown in the video.

Answer
If the crosssection consists of several unconnected partial sections, the sum of the moments of inertia is calculated without the parallel axis theorem components. The crosssection shown in Figure 01 consists of two angle sections that are not connected to each other.
Figure 01  CrossSection Consisting of Several Unconnected Partial Sections
The individual angle sections have the following moments of inertia:
I_{y,1,2} = 180.39 cm^{4} (referred to the centroidal axes y, z)
I_{z,1,2} = 65.05 cm^{4} (referred to the centroidal axes y, z)
The moments of inertia of the entire crosssection result in:
I_{y,1+2} = 2 ⋅ I_{y,1,2} = 2 ⋅ 180.39 = 360.78 cm^{4} (referred to the centroidal axes y, z)
I_{z,1+2} = 2 ⋅ I_{z,1,2} = 2 ⋅ 65.05 = 130.11 cm^{4} (referred to the centroidal axes y, z)
If the crosssection consists of several connected partial sections, the sum of the moments of inertia is calculated with the parallel axis theorem components. The crosssection shown in Figure 02 consists of two connected angle sections.
Figure 02  CrossSection Consisting of Several Connected Partial Sections
The individual angle sections have the following crosssection properties:
A_{1,2} = 16.25 cm²
y_{S,0,1,2} = ±2.30 cm (referred to the zero point)
z_{S,0,1,2} = 3.07 cm (referred to the zero point)
I_{y,1,2} = 180.39 cm^{4} (referred to the centroid axes y, z)
I_{z,1,2} = 65.05 cm^{4} (referred to the centroid axes y, z)
The crosssection properties of the entire crosssection result in:
y_{S,0,1+2} = 0.00 cm (referred to the zero point)
z_{S,0,1+2} = 3.07 cm (referred to the zero point)
I_{y,1+2} = 2 ⋅ I_{y,1,2} + 2 ⋅ A_{1,2} ⋅ (z_{S,0,1,2}  z_{S,0,1+2})²
I_{y,1+2} = 2 ⋅ 180.39 + 2 ⋅ 16.25 ⋅ (3.07  3.07)² = 360.78 cm^{4} (referred to the centroidal axes y, z)
I_{z,1+2} = 2 ⋅ I_{z,1,2} + 2 ⋅ A_{1,2} ⋅ (y_{S,0,1,2}  y_{S,0,1+2})²
I_{z,1+2} = 2 ⋅ 65.05 + 2 ⋅ 16.25 ⋅ (2.30  0.00)² = 301.46 cm^{4} (referred to the centroidal axes y, z)

Answer
The "Simulate and Generate Wind Loads" interface application allows you to exchange member, surface, and solid elements in RFEM, and member elements in RSTAB.
To avoid too fine mesh and thus too long calculation time, the program simulates all members with a rectangular crosssection by default. In this case, the size of the rectangular crosssection is selected in such a way that it barely includes the real crosssection geometry.
Figure 02  Pressure Distribution Around Simplified (Optimized) CrossSection Geometry
By deactivating the "Export optimized member topology" option, you can avoid this additional optimization of the model and allow consideration of the real crosssection geometry within the existing crosssection settings.
Figure 01  Pressure Distribution Around Real CrossSection Geometry
If the exact display of the crosssection geometry requires more than 1,000,000 elements, the interface automatically switches to the simplified rectangular crosssection display.

Answer
The shear area is calculated as follows:
${\mathrm A}_{\mathrm y}\;=\;\frac{{\mathrm I}_{\mathrm z}^2}{\int_{\mathrm A^\ast}\left({\displaystyle\frac{{\mathrm S}_{\mathrm z}}{\mathrm t^\ast}}\right)^2\operatorname d\mathrm A^\ast}$
${\mathrm A}_{\mathrm z}\;=\;\frac{{\mathrm I}_{\mathrm y}^2}{\int_{\mathrm A^\ast}\left({\displaystyle\frac{{\mathrm S}_{\mathrm y}}{\mathrm t^\ast}}\right)^2\operatorname d\mathrm A^\ast}$
where
I_{z} or I_{y}is the second moment of area in relation to the axis z or y, S_{z} or S_{y} is the first moment of area in relation to the axis z or y, t* is the effective element thickness for the shear transfer, A*
is the surface area based on the effective shear thickness t*.
The effective element thickness for the shear transfer t* has a significant influence on the shear area. Therefore, the defined effective element thickness for the shear transfer t* (Figure 01) of the elements should be checked.

Answer
Using the FE mesh refinement, it is possible to create an aligned FE mesh in the program. The automatic FE mesh generator can thus be controlled to a certain extent. However, it is not possible to set a specified mesh geometry. 
Answer
In the "c/tParts and Effective CrossSection" tab of the "Calculation Parameters" dialog box, you can define the settings for the automatic creation of c/tparts.
It is also possible to specify an angle from which a support should be created between two elements. In case that the angle for connection of elements is smaller, they are considered as an interconnected c/tpart. Stiffeners (longitudinal ribs, slopes (lips), or bulges, and so on) are not recognized by the program during the automatic generation of the c/tparts. The c/tparts have to be adjusted manually. You can make the changes in Table "1.7 Notional Flat Widths  EN 1993‑1‑3" or in the "Edit Notional Flat Width" dialog box.
The check box for Element is "significant" controls whether a curved element is considered as a c/tpart. If the length of the arc is larger than the diameter entered here, it cannot be neglected.
A corresponding error message appears before the calculation.
The option Element ist "straight" refers to curved elements. The arcs are usually excluded from the determination of the effective widths because the standards do not provide clear specifications. A curved element is assumed to be straight if the ratio of the connecting line (start/end node) to the element length is higher than the specified value. 
Answer
If you need to define different types of lateral intermediate supports, it is necessary to divide the specific member. After that, you can create a set of member and with that done, you can easily define different types of intermediate supports along this set of member, or you can use different nodal supports in the nodes of the set of member.
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First Steps
We provide hints and tips to help you get started with the main programs RFEM and RSTAB.
Wind Simulation & Wind Load Generation
With the standalone 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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