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  • Answer

    The easiest way to explain the function is with an example. This example file can be downloaded at the end of this FAQ under "Downloads".


    • In load case 1, the following support reaction results for the "actual distribution":

      Image 1

    • Also in Load Case 1, the following distribution results for "Smooth Distribution" (constant):

      Image 2

    • In load case 2, the following distribution results for "Actual":

      Image 3

    The next step is to consider an additive RC with the following definition:
    RC 1 = LC1/s or LC2/s


    If you now look at the "Sum of result combinations" setting, you get the following distribution for RC1:

    LC1 ... smoothed value = 5 kN/m ... here the max value of RC1

    LC2 ... smoothed value = 4 kN/m ... here the min value of RC1


    Now, in the Results navigator, we switch to the max value of RC1 and the actual distribution of the support reactions:


    The mean value of the values shown in the previous figure is no longer 5.0 kN/m, but 5.80 kN/m.


    If you now evaluate the Min value of RC1 with the "Average of the displayed values" option, the result is a value of 3.2 kN/m instead of the 4.0 kN/m described above.


    The setting in the Display navigator thus has an influence on the averaging of the results from additive RCs.

  • Answer

    No, it is not possible to set user-defined values when viewing stress results on a solid. These unfortunately do not work like results on a surface. It is possible to activate the result values on each FE Mesh Node using the settings shown below under Values on Surface. To access the filter settings you must right click on the label "Values on Surfaces."



    You can then also set your results to Solid Point Display under the Results menu. This will help give a better visual on where those results are located graphically.

  • Answer

    Yes, it is. You can keep the results of RWIND Simulation if the FE mesh is deleted. To do this, select the Keep wind simulation results if mesh is deleted option in the RWIND Simulation settings:

    Image 01 - Keeping RWIND Simulation Results if Mesh Deleted

    A new calculation by RWIND Simulation is not required if the material is changed, the support conditions are adjusted, or other changes are made that do not affect the CFD analysis.

    After adjusting the material, the FE mesh is deleted and thus also the RWIND load case. However, you can generate this RWIND load case again in a few seconds by creating the loads again in RFEM using CalculationRWIND Simulation - Calculate All in Background.

    Image 02 - Regenerating Loads After Adjusting Model

    Then, the results are available again.

    Image 03 - Generated Load Case from RWIND Simulation

  • Answer

    A line hinge is nothing more than a line release where an object is released. In the case of a line release, a surface is released, and in the case of a line hinge, this is defined on the line of a surface. Therefore, the released surface is the surface on which the line hinge was defined.

    The forces always act on the original surface, that is, on the non-released surface. In the case of line hinges, this means that the forces act on the surface without a line hinge.

    Now, it is necessary to clarify the sign conventions, that is, in which direction the force acts on the surface. For this, it is necessary to know the local x-axis of the lines as well as the local z-axis of the surface. The internal line hinge coordinate system is to be understood as follows:

    • The axis x' points in the direction of the local x-axis of the line.
    • The axis z' is the normal to the surface on which the line hinge was defined.
    • The axis y' is the tangent to the surface plane, and results from the "right-hand rule."

    For the example shown in Image 01, this means the following:

    Example 1
    The x-axis of the line runs to the right.
    The z-axis of the surface is oriented downwards
    ⇒ The y' axis of the line hinge is oriented away from the original surface (= a surface without a line hinge). Since the value is displayed with a negative sign, the force acts in the direction of the original surface.

    Example 2
    The x-axis of the line runs to the left.
    The z-axis of the surface is oriented downwards
    ⇒ The y' axis of the line hinge is oriented towards the original surface (= a surface without a line hinge). Since the value is displayed with a positive sign, the force acts in the direction of the original surface.

    Example 3
    The x-axis of the line runs to the right.
    The z-axis of the surface is oriented downwards
    ⇒ The y' axis of the line hinge is oriented towards the original surface (= a surface without a line hinge). Since the resulting value is displayed with a positive sign, the force acts in the direction of the original surface because Actio = Reactio.

    Example 1
    The x-axis of the line runs to the left.
    The z-axis of the surface is oriented downwards
    ⇒ The y' axis of the line hinge is oriented away from the original surface (= a surface without a line hinge). Since the resulting value is displayed with a negative sign, the force acts in the direction of the original surface because Actio = Reactio.

    In contrast to the line releases, the axis system cannot be displayed for the line hinges. For the example shown in the image, it is recommended not to arrange the line hinge on the surface, on which the result is to be related, and to orient the x-axis of the line in such a way that its y-axis is oriented in the direction of the desired surface. For this, the coordinate system of the line applies.
  • Answer

    For this, it is first necessary to create a line of the desired shape in the surface at the location where the section is to be created. The section can then be arranged on this line (see Image 01). If no element with a stiffness is connected to this line and no load is applied, you have to first inform the mesh generator that this line should still be meshed (see Image 02). After the calculation, the results can be seen.

    If there are two result diagrams displayed, it is because the result is displayed from both sides of the line. In this case, you can set the smoothing of the internal forces to "Continuous Total." Then, these are smoothed over the lines and only one result diagram remains.
  • Answer

    The deformations of members can be read out by using the "GetMemberDeformations()" function, for example. This function expects a number, the type of the counting method for members (member number/number in the list), and which coordinate system should be used. You can select whether the local axis system, the principal axis system, or the global coordinate system is used:

    Sub test_results_member_axis()

    Dim iApp As RFEM5.Application
    Set iApp = GetObject(, "RFEM5.Application")

    iApp.LockLicense

    Dim iMod As RFEM5.IModel3
    Set iMod = iApp.GetActiveModel


    On Error GoTo e

    'get interface for calculation
    Dim iCalc As RFEM5.ICalculation2
    Set iCalc = iMod.GetCalculation

    'get interface for results
    Dim iRes As RFEM5.IResults2
    Set iRes = iCalc.GetResultsInFeNodes(LoadCaseType, 1)

    'get deformations in local coordinate system
    Dim memDefs_L() As RFEM5.MemberDeformations
    memDefs_L = iRes.GetMemberDeformations(1, AtNo, LocalMemberAxes)

    'get deformations in global coordinate system
    Dim memDefs_G() As RFEM5.MemberDeformations
    memDefs_G = iRes.GetMemberDeformations(1, AtNo, GlobalAxes)

    'get deformations in principal coordinate system
    Dim memDefs_P() As RFEM5.MemberDeformations
    memDefs_P = iRes.GetMemberDeformations(1, AtNo, LocalPrincipalAxes)


    e:

    If Err.Number <> 0 Then MsgBox Err.description, vbCritical, Err.Source

    iMod.GetApplication.UnlockLicense
    Set iMod = Nothing

    End Sub


    The small program reads out the local deformations (memDefs_L) in the member axes and the principal axes (memDefs_P) and the global deformations in the member axes (memDefs_G).

  • Answer

    Contact stresses are not covered by the average regions.

    The average regions only deal with the surface internal forces that are also visible in the dialog box when entering the average region, as well as the stresses that are derived from these surface internal forces.
  • Answer

    After running a calculation, you can view the member internal forces under Table 4.6 Members - Internal Forces. The tools at the top of the table include a filter function. Under the detail setting for the filter, you can turn on/off the internal force values for the start of members, internal points, or end of members. For connection design, the start of members and end of members will be most of interest. This information can additionally be exported to Microsoft Excel with the direct link in the table options.

    For additional information on the filter options, refer to the RFEM Online Manual 11.5.5. Filter Functions.
  • Answer

    The procedure for this is explained on the following example:

    A concrete slab has the bending moments from -103 kNm to +49 kNm.

    The moments from -20 kNm to +20 kNm should not be displayed as the values on surfaces.

    1) Activate the filter for the values between -20 and +20, see Image 01.

    Image 01 - Activating Filter for Displaying Values

    2) Select all the displayed values and deactivate the filter again using the shortcut menu, see Image 02.

    Image 02 - Selecting and Deactivating Filter

    3) Hide the selected values by using the shortcut menu, see Image 03.

    Image 03 - Hide Selection

    Now, the result values of the moments between -20 kNm and +20 kNm are not displayed, see Image 04.

    Image 04 - Display of Desired Values

  • Answer

    Just like all other results, the resultant of a section can be read out via IModel3 → ICalculation2 → IResults2. The interface to the results is provided by the GetResultant function, which then returns the ResultantForce structure when specifying the section number and the type of the result distribution. This structure includes, among other things, the forces and moments as vectors:

    Sub GetResultantSection()
        Dim iApp As RFEM5.Application
        Dim iModel As RFEM5.model
        Set iModel = GetObject(, "RFEM5.Model")

        On Error GoTo e

        '   get interface from model
        Set iApp = iModel.GetApplication
        iApp.LockLicense

        '   get interface from calculation
        Dim iCalc As RFEM5.ICalculation2
        Set iCalc = iModel.GetCalculation

        '   get interface from results from loadcase 1
        Dim iRes As RFEM5.IResults2
        Set iRes = iCalc.GetResultsInFeNodes(LoadCaseType, 1)

        '   get Resultant
        Dim section_resultant As ResultantForce
        section_resultant = iRes.GetResultant(1, AtNo, ConstantDistributionOnElements)

    e:
    If Err.Number <> 0 Then
        MsgBox Err.Number & " " & Err.description
    End If

    If Not iApp Is Nothing Then
        iApp.UnlockLicense
    End If

    End Sub

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Wind Simulation & Wind Load Generation

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