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Answer
In RFEM, the interface application 'Simulate and Generate Wind Loads' makes it possible to exchange member, surface, and solid elements, and in RSTAB to exchange the bar elements.
To avoid generating a too fine mesh along with a corresponding long calculation time, the program simulates all members with a rectangular crosssection as standard. The size of the rectangular crosssection is selected in such a way that the real crosssection geometry is barely included.
Figure 02  Distribution of Pressure Around Simplified (Optimized) CrossSection Geometry
By deactivating the option 'Export Optimized Member Topology', you can avoid this additional optimization of the model and allow consideration of the real crosssection geometry within existing crosssection settings.
Figure 01  Distribution of Pressure Around Real CrossSection Geometry
If the exact representation of the crosssection geometry requires more than 1000000 elements, the interface automatically changes to the simplified rectangular section display of the crosssections.

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}:second moment of area in relation to the axis z or y S_{z} or S_{y}: first moment of area in relation to the axis z or y t*: effective element thickness for shear transfer A*:
surface area based on effective shear thickness t*
The effective element thickness for shear transfer t* has a significant influence on the shear area. Therefore, the defined effective element thickness for shear transfer t* (Figure 1) of the elements should be checked.

Answer
With the FE mesh refinement, it is also possible to create an aligned FE mesh in the program. Thus, the automatic FE mesh generator can be controlled to a certain extent. However, it is not possible to use it for setting of a specified mesh geometry. 
Answer
In the 'c/tParts and Effective CrossSection' tab of the 'Calculation Parameters' dialog box, you can define 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, etc.) are not recognized by the program during the automatic generation of the c/tParts. The c/tParts have to be adjusted manually. The changes can be made in Table '1.7 CrossSection Parts for Classification' or in the 'Edit c/tPart' dialog box.
The check box with the reference to 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. Arcs are normally 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 connecting line (start/end node) to 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. 
Answer
RSTAB is a pure framework program and only determines internal forces, deformations, and support reactions.On the other hand, stresses are variable depending of the crosssection and are calculated on the stress points of a crosssection. This stress determination is performed in the RF/STEEL addon module by calculating the existing stresses and comparing them with the limit stresses. 
Answer
This kind of result may occur if the limit internal forces of the crosssection cannot be determined. In most cases, the problem lies in a wrongly defined crosssection or in the selection of an unsupported crosssection. Please check if you have selected the crosssection allowed for the aluminum structure in the addon module. These include the rolled crosssections and parametric thinwalled crosssections.The crosssection HK 120/40/5/5/5/5 shown in Figure 01 is not a valid crosssection as it has been selected from the area of solid crosssections (concrete components).
In this case, it is necessary to change the crosssection to TO 120/40/5/5/5/5.In the case of the design in RF‑/ALUMINUM, please note that you have to select the material which also involves thicknesses used for the crosssections. A material that is only allowed up to t=3 mm cannot be used for a crosssection with t=5 mm. 
Answer
The crosssection class is defined according to EN 1993‑1‑1 and EN 1999‑1‑1 by the maximum width/width ratio c/t or b/t of the crosssection parts subjected to compression. EN 1993‑1‑1 or EN 1999‑1‑1 only cover various straight c/t or b/t parts. Therefore, the classification and determination of effective widths is not possible for the curved c/t or b/t sections. 
Answer
This behavior is caused by the detail settings in the RF‑/STEEL addon module. The results of result combinations can be used in many different ways.To use the same maximum internal forces for stress analysis, the settings should be made according to Figure 01.However, this setting is very conservative because not all maximum internal forces can occur at the same time. 
Answer
By default, the computation kernel of the crosssection program SHAPE‑THIN is used in the RF‑/ALUMINUM add‑on module to determine the stresses of the effective crosssection in an iterative procedure. This method is precise as all corners and edges of the crosssection are covered, but can be very timeconsuming in the case of compound crosssections.As an alternative, it is possible to determine the effective crosssection by using the simplified analytical method (see Figure 01), which is significantly faster. In the case of using this approach, the corners, roundings, and others, are neglected and then compensated by a factor. No iterative calculation is performed. Therefore, the effective crosssection values might be higher than with the SHAPE‑THIN calculation.In such a case, it is recommended to carry out the calculation using the analytical method and then to only design the governing structural component with the governing load combination by using the SHAPE‑THIN solution.
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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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