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• ### How can I change the calculation parameters of a load case using the COM interface?

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The calculation parameters of a load case cannot initially be set when creating it, but only afterwards by using the interface of the existing load case. To get the interface of a load case, you have to get the interfaces 'IModel' and 'ILoads' first:

Sub test_analysis_parameters()Dim iApp As RFEM5.ApplicationSet iApp = GetObject(, "RFEM5.Application")iApp.LockLicenseDim iMod As RFEM5.IModel3Set iMod = iApp.GetActiveModelOn Error GoTo e' get interface of loadsDim iLds As RFEM5.iLoadsSet iLds = iMod.GetLoads' get interface of load caseDim iLc As RFEM5.ILoadCaseSet iLc = iLds.GetLoadCase(1, AtNo)' get analysis parametersDim param_analy As RFEM5.AnalysisParametersparam_analy = iLc.GetAnalysisParameters' change analysis parametersparam_analy.Method = Postcriticalparam_analy.ModifyLoadingByFactor = Trueparam_analy.LoadingFactor = 1.5' ...' set new analysis parametersiLds.PrepareModificationiLc.SetAnalysisParameters param_analyiLds.FinishModificatione:If Err.Number <> 0 Then MsgBox Err.description, vbCritical, Err.SourceiMod.GetApplication.UnlockLicenseSet iMod = NothingEnd Sub

Use 'ILoads.GetLoadcase' to get the interface for a specific load case. This interface provides the functions 'GetAnalysisParameters' and 'SetAnalysisparameters' that you can then use to read out and write the parameters.

The same procedure also applies for load combinations.

• ### When calculating a cross-section in SHAPE‑THIN, I get the error message that Fy is not positive.

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Please define a yield strength and limit stresses in Window "1.2 Materials."

The yield strength is required to determine the plastic cross-section properties if the "Plastic cross-section properties" check box is selected in General Data.

The limit stresses are required to compare the calculated stresses with the limit stresses.

• ### In the current program version of RFEM, the calculation does not converge anymore. I have already calculated the model in different RFEM versions:RFEM 5.21.02 - Calculation convergesRFEM 5.23.02 - Calculation does not convergeRFEM 5.24.01 - Calculation does not converge

In RFEM 5.23, changes have been made to the calculation kernel, which lead to a slightly different, more "sensitive" behavior of the nonlinear supports.

In this case, it is helpful to slightly adjust the diagrams for the nonlinear supports: Instead of applying the stop directly, you could define a slightly "smoother" transition.

On our website, you can find a list of the update reports of our programs.

• ### How can I increase the maximum number of iterations in RFEM/RSTAB?

The maximum number of iterations can be set within the global calculation parameters (menu "Calculation" → "Calculation Parameters", tab "Global Calculation Parameters", see the image).

• ### I have the program version 5.24 and the calculation takes longer time than in the previous versions for the same model. What is the reason for this?

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In the version 5.23, the option to calculate the maximum strain was added, which searches for the largest total strain (and also plastic strain in the case of nonlinear materials) for members, surfaces, and solids. The calculation of the maximum values of strains is activated by default. If you disable this option, the calculation should speed up.
• ### Why does the deformation of a modeled single-span beam not correspond to the manual calculation?

The shear stiffness was probably not considered in the manual calculation or it was assumed as infinite. In RFEM/RSTAB, this is taken into account according to reality by default, so that the deformation is more unfavorable than in the manual calculation, which only includes the deformation component from bending.

The shear stiffness can be deactivated under the global calculation parameters (menu "Calculation" → "Calculation Parameters"), see the figure.

• ### The calculation of a file runs smoothly for my colleagues, but I get the message "Calculation stopped" for the same file. What should I do?

It is highly probable that the software is blocked by an antivirus program.

We recommend to add the Dlubal Software programs, including the working directory, to the exceptions of all existing antivirus programs.

You can find the path of the working directory in the menu "Options" → "Program Options," tab "Data Files" → category "Working Directory," see the figure.

• ### How can I modify the FE mesh settings via the COM interface?

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The general FE mesh settings can be modified using the IFeMeshSettings interface. This interface is located under IModel > IModelData > ICalculation. Figure 01 shows which elements can be modified / displayed.

Here is a code example where the target length of the FE elements is set to 100 mm. Furthermore, the division of the members with the same element size is activated and the minimum division is set to 3 elements:

Sub mesh_params()Dim iApp As RFEM5.Application'   get interface for model dataDim iModel As RFEM5.modelSet iModel = GetObject(, "RFEM5.Model")On Error GoTo eIf Not iModel Is Nothing Then        '   get interface for application and lock licence    Set iApp = iModel.GetApplication()    iApp.LockLicense        '   get interface for model dat    Dim iModdata As RFEM5.IModelData2    Set iModdata = iModel.GetModelData        '   get interface for calculation    Dim iCalc As RFEM5.ICalculation2    Set iCalc = iModel.GetCalculation()        '   get interface for mesh settings    Dim iMeshSet As RFEM5.IFeMeshSettings    Set iMeshSet = iCalc.GetFeMeshSettings        '   get general mesh settings    Dim meshGen As RFEM5.FeMeshGeneralSettings    meshGen = iMeshSet.GetGeneral        meshGen.ElementLength = 0.1        '   set new general mesh settings    iModdata.PrepareModification    iMeshSet.SetGeneral meshGen    iModdata.FinishModification        '   get mesh member settings    Dim meshMem As RFEM5.FeMeshMembersSettings    meshMem = iMeshSet.GetMembers        meshMem.DivideStraightMembers = True    meshMem.ElementLength = 0.1    meshMem.MinStraightMemberDivisions = 3        '   set new mesh member settings    iModdata.PrepareModification    iMeshSet.SetMembers meshMem    iModdata.FinishModification            iApp.UnlockLicenseEnd Ife:  If Err.Number <> 0 Then    MsgBox Err.description, , Err.Source    End If    iApp.UnlockLicense    Set iApp = Nothing    Set iModel = NothingEnd Sub

The subroutine is also completed by an error interceptio routine (On Error GoTo e) and the Prepare-/FinishModification block is required as in the case of modifying other elements. Here, the block is created via the IFeMeshSettings interface.

• ### When starting the calculation, a message appears saying that the maximum number of 9,999 load cases and combinations has been exceeded. What can I do?

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The number of load cases and combinations calculated at one time is limited to 9,999. This limitation can be avoided by using the "To Calculate" option, which allows you to select the cases to be calculated. Thus, load cases and load combinations can be divided into several groups with a smaller number of cases.
• ### Why is it not possible to change the solving method for the equation system of my model?

Basically, there are six methods available for solving the nonlinear algebraic system of equations. If your model does not include any nonlinearities (that is, you have created a purely linear system), the access of this selection field is blocked.

As soon as you define a nonlinearity in the model, the selection field for the solving methods is activated, and you can select the desired solving method.

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Wind Simulation & Wind Load Generation

With the stand -alone program RWIND Simulation, you can simulate wind flows around simple or complex structures 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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