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  • Answer

    RF-CONCRETE Columns determines the equivalent moment M0e from the moment M02 at the column head and M01 at the column base according to EN 1992‑1‑1, (2), and performs the design according to the model column method with this equivalent moment M0e.

    Now, it may happen, for example, that a computationally larger required reinforcement area would result from the cross-section design with the moment M01 at the column head.

    To ensure this, message 28) is displayed, according to which the user should perform a standard design with the internal forces according to the linear static analysis. To do this, simply open the RF‑CONCRETE Members add-on module and perform pure design of the internal forces according to the linear static analysis for the member designed in RF‑CONCRETE Columns.

  • Answer

    In the "Edit Load Cases and Combinations" dialog box, you can specify in the bottom right of the "Combination Expressions" tab which method of analysis should be used as the basis for the generated load combinations. By default, the linear calculation according to the geometrically linear analysis is preset for load cases and the nonlinear calculation according to the second-order analysis for load combinations.

    Thus, you can quickly determine whether the load case or the load combination is calculated according to the geometrically linear, second-order, or large deformation analysis. The postcritical analysis option allows you to carry out the stability analysis according to the large deformation analysis with regard to the post-critical failure of the entire structure.

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

    Only the default setting of 1 load increment can be set when a complex nonlinear material model is defined. The reason for this is because the program cannot determine the correct material stiffness for each incremental loading amount. The exact maximum load needs to be applied to the structure in order to determine the state of the material's stress/strain diagram. 

    Figure 01 - Material Model - Nonlinear material defined

    This setting can be found and changed under "Calculation Parameters" as well as under the "Calculation Parameters" in the load cases and combinations dialog box. 

  • Answer

    The following code shows how to get different calculation parameters via the COM interface. It also demonstrates how to specify a setting for deactivating shear stiffness:

        '   get model interface
        Set iApp = iModel.GetApplication()
        '   get calculation interface
        Dim iCalc As RFEM5.ICalculation2
        Set iCalc = iModel.GetCalculation
        '   get surface bending theory
        Dim calc_bend As RFEM5.BendingTheoryType
        calc_bend = iCalc.GetBendingTheory
        '   get settings for nonlinearities
        Dim calc_nl As RFEM5.CalculationNonlinearities
        calc_nl = iCalc.GetNonlinearities
        '   get precision and tolerance settings
        Dim calc_prec As RFEM5.PrecisionAndTolerance
        calc_prec = iCalc.GetPrecisionAndTolerance
        '   get calculation settings
        Dim calc_sets As RFEM5.CalculationSettings
        calc_sets = iCalc.GetSettings
    'get calculate options
        Dim calc_opts As RFEM5.CalculationOptions
        calc_opts = iCalc.GetOptions
        '   set ShearStiffness to false
        calc_opts.ShearStiffness = False
        iCalc.SetOptions calc_opts

    In the annex, there is an EXCEL macro to download.
  • Answer

    In CRANEWAY the internal forces are typically displayed only for max and min locations. If you want to get each internal force on each x-location, then you have to run the detailed calculation and to disable the option "Show only governing results". How to do it, we show you in the short video.
  • Answer

    The difference between both material models is as follows:

    In the Isotropic Nonlinear Elastic 1D material model, no plastic deformations are considered. This means that the material returns to its initial state when the load is released.

    Whereas in the case of the material model Isotropic Plastic 1D, the plastic deformation is considered.

    For both material models, the nonlinear properties are defined in an additional dialog box. When entering data by means of a diagram, it is possible to define a distribution in both models after the last step.

    For the material model Isotropic Nonlinear Elastic 1D, it is possible to enter the stress-strain diagram (different for the positive and negative zone) in an anti-metrical way, whereas for the model Isotropic Plastic 1D, only symmetric input is possible.

  • Answer

    RSTAB is a FEM program that uses trigonometric trial functions for the members. For this reason, members do not have to be subdivided for sufficiently accurate results and the calculation speed is correspondingly higher.

    RSBUCK determines the eigenvalues of the stiffness matrix and can thus linearly calculate the critical load and buckling mode of the structure.

  • Answer

    Both RFEM and RSTAB present a suitable solution. Numerous European and international standards, as well as various add-on modules, are available for both programs, which will facilitate the daily work in steel structures.

    Basic programs RFEM or RSTAB
    The basic programs RFEM or RSTAB define structures, materials, and actions. In addition to creating spatial frame structures, for example, halls, RFEM also provides plate, pane, and shell structures, making it a more diverse option. It pays off if it is necessary to carry out design also in other areas, such as solid construction.

    Available standards
    • EN 1993-1-1 (Eurocode 3),
    • AISC according to ANSI/AISC 360 (US Standard),
    • SIA according to SIA 263:2013 (Swiss Standard),
    • IS according to IS 800:2007 (Indian Standard),
    • BS according to BS 5950-1:2000 (British Standard) or BS EN 1993-1-1 (British Annex),
    • GB according to GB 50017-2003 (Chinese Standard),
    • CSA according to CSA S16-09 and CSA S16-14 (Canadian Standard),
    • AS according to AS 4100-1998 + Annex 1 - 1999 (Australian Standard),
    • NTC-DF according to NTC-RCDF (2004) (Mexican Standard),
    • SP according to SP 16.13330.2011 (Russian Standard),
    • SANS according to SANS 10162-1:2011 (South African Standard),
    • NBR according to ABNT NBR 8800:2008 (Brazilian Standard),
    • HK according to the standard for steel structures 2011 (Buildings Department - Hong Kong)
    • RF-/STEEL - General Stress Designs
    Add-on modules for structural steelwork

    The functionality of the basic programs is supplemented by add-on modules. With RF-/STEEL EC3, for example, it is possible to perform the design for the structure according to Eurocode 3. The add-on module RF-STEEL Warping Torsion supplements this design according to Eurocode 3 with torsional buckling analysis having up to 7 degrees of freedom, provided it doesn´t refer to a standard case of EC3.

    Other more specialized applications such as the plastic design, the stability analysis according to the eigenvalue method or the generation of geometric equivalent imperfections and pre-deformed equivalent models are available. Single modules such as PLATE-BUCKLING provide you with support when designing rigid or stiffened plates. With the SHAPE-THIN add-on module, it is possible to create any thin-walled cross-sections. The cross-section properties are determined and stress analyses or plastic designs can thereby be performed.

    The hinged or rigid connections can be designed by means of the RF-JOINTS add-on modules.

    The stand-alone application CRANWAY is available for the design of craneways.

    Dynamic analysis

    If earthquake calculations or vibration analyses are necessary for the building, the RF-/DYNAM Pro add-on modules provide suitable tools for determining natural frequencies and shapes, analysis of forced vibrations, generation of equivalent loads, or for the nonlinear time history analysis.

    In case of having any further questions about the Dlubal software, contact the sales department, please.

  • Answer

    No, the calculation time is not affected because the data is copied to the local working directory when loading and is not written back until it is saved. Depending on the connection speed to the server, delays may occur during loading and saving.
  • Answer

    Like the 'Forced Vibrations' module, the 'Equivalent Loads' add-on module performs the multimodal response spectrum analysis.

    Contrary to what the name suggests, the simplified response spectrum method is not carried out here, as it is explained, for example, in EN 1998-1. 

    The equivalent loads are determined separately for each direction of excitation according to the following formula:

    $\begin{Bmatrix}{\mathrm F}_{\mathrm X}\\{\mathrm F}_{\mathrm Y}\\{\mathrm F}_{\mathrm Z}\end{Bmatrix}\;=\;\mathrm\Gamma\;\ast\;\begin{Bmatrix}{\mathrm u}_{\mathrm X}\\{\mathrm u}_{\mathrm Y}\\{\mathrm u}_{\mathrm Z}\end{Bmatrix}\;\ast\;{\mathrm S}_{\mathrm a}(\mathrm T)\;\ast\;\begin{Bmatrix}{\mathrm M}_{\mathrm X}\\{\mathrm M}_{\mathrm Y}\\{\mathrm M}_{\mathrm Z}\end{Bmatrix}\;$

    The differences between the two add-on modules are described in this FAQ .

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First Steps

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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