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  • Answer

    This is not possible directly in RFEM, but the RF-/STEEL EC3 add-on module allows you to create a steel profile report. In the Details section of the module, you can set whether the report should be applied to all members or only to members. Then simply carry out the calculation, and the report will be displayed. The report can also be exported to Excel and further edited.
  • Answer

    For correct displaying of loads, it is necessary to carry out some adjustments. If the load is applied in steps, the area load plane may only be defined in sections (per load increment). Otherwise, the load is distributed linearly over the entire area load plane.
  • Answer

    The output of the intermediate values is generally linked to the member division property. Also, member loads defined in sections in RFEM generate further intermediate results. For example, if the member load defined in sections extends from member start to member end, intermediate results are obtained at the member end nodes.

  • Answer

    In the Dlubal programs, all values are stored internally based on SI units. When a user changes the units in the program to metric or imperial, SI units are still used internally and only the value displayed in the interface is modified. Therefore, all values set in the time diagram function also default to SI units unless the user clarifies an alternative unit.

    Let's look at a simple example shown in Figure 1 where the parameter x = 1 ft has been set in RFEM.

    In RF-DYNAM PRO - Forced Vibrations, the time diagram function is defined as k(t) = 1*x where 1 is the multiplier (1/ft) to convert x to a dimensionless value. You can see in Figure 2, because all values default to SI units, the Multiplier column produces values of 0.305 instead of the correct value of 1.000.  

    In order to correct the issue, the user only needs to specify the units of the multiplier as (1/ft) in the function equation. This can be done with the formula modification k(t) = 1/1[ft]*x as shown in Figure 3. Notice the Multiplier column now shows the correct values of 1.000.

    In summary, when using units in the program other than SI units, coefficients or multipliers in the time diagram function should be accompanied with alternative units defined in brackets.

  • Answer

    To calculate only certain load cases, load combinations, or result combinations, just like the "To Calculate ..." command (see Figure 01), you can use the CalculateBatch method of the ICalculation interface. When transferring data, the method expects a field with the loading type. Loading includes the number of the loading and the type (e.g. load combination):

    Sub batch_test ()
    '   get interface from the opened model and lock the licence/program
        Dim iModel As RFEM5.IModel3
        Set iModel = GetObject(, "RFEM5.Model")

    On Error GoTo e
    'get interface for calculation
    Dim iCalc As ICalculation2
        Set iCalc = iModel.GetCalculation
    'create array with loading types
    Dim loadings (3) As Loading
    loadings (0) .no = 1
    loadings (0) .Type = LoadCaseType
    loadings (1) .no = 4
    loadings (1) .Type = LoadCaseType
    loadings (2) .no = 4
    loadings (2) .Type = LoadCombinationType
    'calculate all loadings from the array at once
    iCalc.CalculateBatch loadings

    e: If Err.Number <> 0 Then MsgBox Err.description,, Err.Source
        Set iModelData = Nothing
        Set iModel = Nothing

    End Sub
  • Answer

    In the 'Load Cases and Combinations' window, you can specify in the bottom right of the 'Combination Expressions' tab which calculation type should be used as the basis for the generated load combinations. Presetting of load cases refers to the linear calculation according to first order theory, presetting of load combinations to the nonlinear calculation according to second order theory.

    Thus, you can quickly determine whether the load case or the load combination is calculated according to I., II., or III. order theory. Select the option of post-critical analysis to carry out a stability analysis according to the large deformation analysis under consideration of the post-critical failure of the entire structure.

    If the model includes cable members, the calculation according to the large deformation analysis is preset in all cases.
  • Answer

    If the add-on module PLATE-BUCKLING is not opened as a stand-alone version, but via RSTAB or RFEM, the panels (c/t parts of a member cross-section), as well as the respective load cases in PLATE-BUCKLING of the RSTAB or RFEM Models, can be loaded (see picture).

    In case that no suitable cross-sections of PLATE-BUCKLING will be found in the model file of RFEM/RSTAB, the field for importing the buckling fields remains inactive.
  • Answer

    When using the COM interface (RS-COM or RF-COM), it is possible to create a comment through the guide object interface (IGuideObjects). The following is an example program that sets a comment:

    Sub test_comment()

    '   get interface from the opened model and lock the licence/program
        Dim iModel As RFEM5.IModel3
        Set iModel = GetObject(, "RFEM5.Model")

    On Error GoTo e
        Dim iModelData As RFEM5.IModelData2
        Set iModelData = iModel.GetModelData
        Dim iGuiObj As RFEM5.IGuideObjects
        Set iGuiObj = iModel.GetGuideObjects
        Dim comm As RFEM5.Comment
        '   set frame type
        comm.Frame = CircularFrameType
        '   set reference object type
        comm.ObjectType = GeneralObjectType
        comm.ObjectNo = 1
        '   set point if GeneralObjectType is choosen
        comm.Point.X = 2
        comm.Point.Y = 4
        comm.Point.Z = 6
        '   set offset from reference object
        comm.Offset.X = 0.5
        comm.Offset.Y = 1
        comm.Offset.Z = 1.5
        comm.Rotation = 1
        '   set text of comment
        comm.Text = "testcomment"
        '   transfer object to program
        iGuiObj.SetComment comm
    e:  If Err.Number <> 0 Then MsgBox Err.description, , Err.Source
        Set iModelData = Nothing
        Set iModel = Nothing

    End Sub

    The selection of the reference or the element to which the comment is considered to be attached to is first defined by the type (ObjectType). Here, it is possible to select e.g. a member, a node or any point in space. Next, the number of the reference object is specified via ObjectNo (e.g. member 1). If a free point has been selected, it is set by Point.
    Finally, an offset can be specified, which results from the reference object.
  • Answer

    In RFEM and RSTAB, the simplified designs from [1] Chapter 2.2.3 have been implemented for the automatic load combinations. This means that strictly speaking, only structures concerning the final deformation may be analyzed, in which materials with identical creep behavior occur since the creep deformations are considered in a simplified way on the load side. If the structure is a mixed structure made of wood with different creep properties or in combination with steel, the final deformations must be determined according to [2] Amendment to 2.2.3 as follows:

    '(4) If a structure consists of structural components or components with different creep properties, the long-term deformations should be calculated according to (1) due to the quasi-permanent combination of actions with the final values of the mean values of the corresponding elasticity, shear, and displacement modules. The final deformation ufin is then calculated by superposition of the initial deformation due to the difference of the characteristic and quasi-permanent combinations of actions with the long-term deformation.'

    However, this requires a superposition of results from different load combinations, which cannot be implemented automatically in RFEM and RSTAB.

    If the different creep properties are to be taken into account, the load combinations must be created manually, and the stiffness must be reduced according to the creep coefficient.
    The procedure is described using the example of a timber-concrete composite floor presented on the Info Day 2017. Below this FAQ, you can find the link for this.

  • Answer

    Please check the definition of the scissor hinges in the RSTAB 8 file.

    To properly consider the function of the scissor hinge, the scissor hinge of the same type must be specified on the member ends of both members ‘touching’ at a node. If this is not the case, you receive the described error message.

    Figure 01 - Note Regarding Incorrectly Defined Scissor Hinges

    If you have got this error message displayed when opening an RSTAB 8 file in RFEM 5, this may lead to problems in the calculation, for example, the structure becomes unstable due to incorrect hinge definition (already in RSTAB 8).

    The problem should, therefore, be adjusted either already in the RSTAB 8 file or the RFEM model after import.

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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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