# Frequently Asked Questions (FAQ)

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• ### Within the member or continuous member, the cross-section suddenly twists.What is the cause and how can I fix it?

New FAQ 004221 EN

The cause is the automatic orientation of the local axes in relation to the global axis system. In most cases, it is sufficient to specify a member rotation by means of an angle or a help node. However, if the inclination of the member is reversed, it must be divided and then adjusted by means of the member rotation.

You can find a detailed description of the member rotation angle in RSTAB and RFEM in the links below.
• ### I can no longer select, copy, move, or delete my guidelines. Could you please help me?

New FAQ 004214 EN

Please check if the function "Lock Guidelines" has been activated. You can find this function in the Project Navigator - Data under Guide Objects -> Guidelines. Please right-click a guideline and deactivate this function.
• ### How can I rotate a nodal support?

New FAQ 004213 EN

In the dialog box "Edit Nodal Supports", it is possible to rotate the support's local axis system (Figure 1). First, select the sequence that controls the sequence of the local support axes X ', Y', and Z ', and then specify the rotation angle about the global axes X, Y, and Z in the corresponding text boxes.

The support rotation can also be determined graphically by using the corresponding buttons in the dialog box. The rotation of the support is displayed dynamically in the dialog graphic.

After the calculation, the support reactions of a rotated nodal support can be evaluated in relation to the global axis system as well as to the local one (Figure 2).

• ### I have a surface with complicated geometry and would like to know the surface area. Does RFEM display the surface area anywhere?

New FAQ 004207 EN

You can query the surface area by using the shortcut menu.

Right-click on any surface of the entered structure. In the shortcut menu, you can find the entry "Centroid and Info ..."

In the dialog box that appears, you can find the available information about this surface.

There you can find z. For example, the surface area or the weight.
Optionally, you can also create a node in the centroid of the selected surface. A multiple selection of surfaces is also possible.

• ### When I split a member into surfaces, I get an instability in the calculation. Why?

New FAQ 004202 EN

If a member is divided into surfaces, it is necessary to connect the newly created surfaces to the existing members. This can be done, for example, with a rigid surface (option "Create end plates at member ends" under Settings, see Figure and Video).
• ### How would you best model hold down elements within panels?

New FAQ 004201 EN

In a short overview, creating hold down elements involves modeling rigid links and adding in nodal supports with non-linearity settings that allows the supports to take only tension forces. A line support is added at the bottom of the wall that only takes compression forces. The individual nodal supports connected with rigid members only take tension forces.

A more detailed look on how these elements can be model can be seen in the video below.
• ### How can I create a circular opening in a pipe?

New FAQ 004196 EN

#### Creating the opening by means of an intersection

To create the opening, you have to create a surface with the diameter of the opening through the pipe wall. With the "Create Intersection" function, you can create individual components that you can deactivate afterwards. The procedure is shown in the video.

#### Creating the opening by means of a converted intersection line

It is also possible to convert the found intersection line into a normal line. Then, the intersection can be deleted and an opening can be put into it. The inserted opening then has to be integrated manually into the surface (see the video). Please note, however, that the quality of an intersection is of a higher quality than the converted intersection line. When using the converted intersection line, discontinuities may occur in the rendering or FE mesh, depending on the model.
• ### How can I retroactively change a member via the COM interface?

New FAQ 004195 EN

To modify an existing element, you have to get the interface to the corresponding element, here an example of a member:

Dim iModel As RSTAB8.modelSet iModel = GetObject (, "RSTAB8.Model")iModel.GetApplication.LockLicense    Dim iModData As IModelDataSet iModData = iModel.GetModelData    Dim iMem As RSTAB8.IMemberSet iMem = iModData.GetMember (1, AtNo)

Use this code to get the interface to member 1, which must already be created. Then, you can use the .GetData () method of the interface to get the member data.

If you want to modify data (such as the member rotation here), you can subsequently transfer it to the program within a Prepare-/FinishModification block with the method .SetData ().

Dim mem As RSTAB8.Membermem = iMem.GetData    mem.Rotation.Angle = 0.5mem.Rotation.Type = RSTAB8.Angle   iModData.PrepareModificationiMem.SetData memiModData.FinishModification
• ### Is it possible to completely define a member using a tabular input in RFEM and RSTAB?

New FAQ 004182 EN

Yes, it is possible.

You can enter all the data necessary for:
• Nodes
• Lines
• Materials
• Cross-Sections
• Supports
All of them can be entered in the tables provided for this purpose.

If the cross-section description from the Dlubal cross-section library is known, then this can also be entered directly in column A in Table 1.13. Otherwise, you can use the cell to open the cross-section library.

This is also possible in RSTAB. Here, the input of the line is not needed. It is only necessary in RFEM.
• ### How can I create a result beam by using the COM interface?

New FAQ 004181 EN

First, a result beam is created exactly like a normal member:

    Dim model As RFEM5.model    Set model = GetObject(, "RFEM5.Model")    model.GetApplication.LockLicense    On Error GoTo e    Dim data As IModelData    Set data = model.GetModelData    Dim members(0) As RFEM5.Member        members(0).No = 3    members(0).LineNo = 12    members(0).Type = ResultBeamType        members(0).StartCrossSectionNo = 1    members(0).EndCrossSectionNo = 1        members(0).Comment = "result beam 1"    data.PrepareModification    data.SetMembers members    data.FinishModification

Then, the interface IMember has to be taken from the corresponding member, and the GetExtraData method is used to get the interface to IResultMember. This interface can now be used to read or write the ResultMember data. Please note that a Prepare-/Finishmodification block is required when writing:

    Dim iMem As IMember    Set iMem = data.GetMember(3, AtNo)        Dim iRMem As IResultBeam    Set iRMem = iMem.GetExtraData        Dim RMem As ResultBeam    RMem = iRMem.GetData        RMem.IncludeSurfaces = "1"    RMem.IncludeSolids = "all"        RMem.Integrate = WithinCuboidGeneral        Dim params(0 To 3) As Double        RMem.Parameters = params    RMem.Parameters(0) = 0.5    RMem.Parameters(1) = 0.5    RMem.Parameters(2) = 0.1    RMem.Parameters(3) = 0.1        data.PrepareModification    iRMem.SetData RMem    data.FinishModification

The completed EXCEL macro and the corresponding test file are attached.

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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 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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