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  • Answer

    You have probably selected the "Absolute extreme value for result combinations" option in the results navigator. Thus, only the absolute largest value of both is displayed.

  • Answer

    This warning appears in the case of the following result combination definitions when the load cases/load combinations are analyzed according to a nonlinear analysis such as second-order or large deformation analysis.

    Case 1:  RC = LC1/CO1 + LC2/CO2

    For Case 1, load cases/load combinations cannot be superimposed together in a result combination when each case/combination is ran according to a nonlinear analysis such as a second-order (P-Delta, p-delta) or large deformation analysis.  Deformations in both load cases are based on different structural systems and will result in incorrect results as P-Delta effects cannot be simply added together. 

    The solution for this case is to either run the load cases/load combinations according to a geometrically linear analysis where the results can be superimposed together in a result combination, or the consideration of the combined load cases must only be considered under the Load Combinations tab and evaluated individually rather than in a result combination.   

    Keep in mind, this same warning will appear when creating a result combination in a model where geometric nonlinearities are also defined.  An example includes a slab foundation where a nonlinear surface support is defined to fail in the case of uplift.   Geometric nonlinearities can accurately be considered in load combinations opposed to result combinations which may yield incorrect summary results.

    Case 2:  RC = factor* LC1/CO1 or factor* LC2/CO2

    For Case 2, if a load case/load combination is calculated according to a nonlinear analysis, it is not possible to additionally apply a factor to the result combination.  The factor would not only be applied to the defined loads on the structure, but also to the nonlinear effects such as P-Delta which is incorrect.    

    The solution for this case is to either run the load cases/load combinations according to a geometrically linear analysis where the factor can be applied to the result combination, or the factor can be considered under the Load Combinations tab where it will be applied directly to load cases only according to a geometrically linear analysis without consideration to the second-order effects

  • Answer

    If you want to create the load combinations or result combinations manually, you first have to define it in General Data of Model (see Figure 1). By deactivating the button "Create Combinations Automatically", all load combinations have to be created manually.

    After that, you can use the dialog box "Edit Load Cases and Combinations" to superimpose all load combinations including the partial safety factors with each other (see Figure 2). In the "Result Combinations" tab, you can subsequently create a result envelope from these load combinations, if necessary.

  • Answer

    Yes, this is possible with a combination scheme. This can be used to create user-defined templates.

    The Combination Schema dialog box can be accessed via the "Tools" menu. A scheme defined there can be used as template for your load data. You can create a combination scheme in any model and access it from any model.

    In a combination scheme, you specify the load cases, load and result combinations to be created with the relevant key data and the basic settings. In addition to the number of load cases, load combinations and result combinations, you can also define the factors and the type of superposition in a combination scheme.

    Then, when creating a new model, you can quickly access these settings so that you only have to enter the contents of the load cases (member loads, etc.). If you have already created several schemes, you can select one of them from the pull-down list.

    Click the [New Scheme] button to create another combination scheme. In doing so, you can copy the existing load cases and combinations of the current model.

    The button [Create Load Cases, Load Combinations, and Result Combinations Defined in Tables] transfers the current combination scheme to the model.

    The combination diagrams can also be exported to Excel and reimported.

    The user-defined combination diagrams are stored in the KombinSchema.dat file, which is located in the master data folder "C:\ProgramData\Dlubal\Global\Root File" by default. If you copy this file to another computer, you can also use the combination diagrams there.
  • Answer

    This behavior is caused by the detail settings in the RF-/STEEL add-on module. The results of result combinations can be used in many different ways.

    To use the same maximum internal forces for stress analysis, the settings should be made according to Figure 01.

    However, this setting is very conservative because not all maximum internal forces can occur at the same time.

  • Answer

    Basically, you should select the design load for the verification which relates to the design situation to be analyzed for the design conduct. For example “ULS” or “SLS”.

    Now, it is important that the add-on modules in RFEM or RSTAB do not automatically generate these design load cases. That is, it is not sufficient to select only the load cases in the add-on modules. Before starting the design process, you have to either create or generate load combinations or result combinations in the add-on modules.

    Afterward, these load or result combinations can be applied for the design in the add-on modules.

    However, if you want to explicitly carry out the design in an add-on module for a specific load case, you can select it for the design. If several single load cases are selected for design, the design is performed consecutively by load cases.

  • Answer

    To do this, open the “General Data” dialog box of the current model. Right-click the model description in the Data navigator.

    Figure 01 - Opening the General Data by Using the Shortcut Menu of the File

    Alternatively, you can open the “General Data” dialog box with the “Edit” menu.

    In the “General Data” dialog box, you can first select the standard according to which the combinatorics is to be carried out, or if load combinations (CO) or result combinations (RC) should be created. 

    If CO or RC are already available in the existing file, a query appears asking if the program should delete or keep the existing combinations.

  • Answer

    The RF-CONCRETE add-on module Deflect is available for the calculation of state II deformations in RF-CONCRETE Surfaces.

    For the analytical calculation of deformations in state II, RF-CONCRETE Deflect requires a unique load situation, which is given only by using the load combinations (CO). Result combinations do not provide an explicit load situation, no matter if an additive or an enveloped OR-combination. Therefore, when applying the RC for the calculation of deformations in RF-CONCRETE Surfaces by RF-CONCRETE Deflect, you receive the mentioned error message. See Figure 01.

    To avoid this problem, you can simply generate load combinations (CO) instead of result combinations (RC). If you still want to perform the ultimate limit state design with RC's, you can manually create a LC in addition to the existing RCs for which you want to calculate the deformations by means of RF-CONCRETE Deflect. See Figure 02.

    It is important that RF-CONCRETE Surfaces calculates the loads from the quasi-permanent design situation by default for the calculation of the deformations. See Figure 03. This means that the LC for which the deformations are to be calculated must be defined as “Quasi-permanent”. Alternatively, the check boxes for the settings of the design situations (see Figure 03) can be user-defined.

  • Answer

    It is correct that no corresponding load cases are displayed in Table 4.13 "Surfaces - Local Deformations".

    However, you can find them in Table 4.4 "Members - Local Deformations", for example. See Figure 01.

    If you want to see the corresponding load cases for the max. deformations of a RC on a certain surface, it is possible to integrate a member into this surface. In order that this member does not influence the surface stiffness, it is recommended, for example, to use a very small cross-section.

    If the member has been integrated or cross-linked correctly in the surface, the table shown in Figure 01 is obtained. Figure 02 shows the corresponding deformation in the surface component.

    Optionally, right-click the row containing the desired result (for example, max uz ) in Table 4.4. In the shortcut menu, you can now use the option "Generate CO Acc. Selected Row" which can be used to generate a CO that contains the load cases belonging to the selected value. See Figure 03.

    When having executed this command, you receive a CO from the RC with the corresponding load cases. See Figure 04 with the results of the generated CO and the max. deformations in the considered field.

  • Answer

    Check if you entered "Nonlinearities" in your structure. For example, "Ineffective Supports", "Members with Nonlinearities (Compression or Tension Members)" or "Nonlinear Material Behavior" (see Figure 01).

    This warning appears when trying to add load cases through result-combinations in such structures (see Figure 02).

    When adding load cases of the result combination (RC), only the results of the individual load cases are added. This means that the "Nonlinearities" does not have to be displayed correctly because a member could fail e.g. in one load case, but does not in another load case. When using RC's, you would thus add up the results from different structural systems. This leads to incorrect results.

    Please, use the load combinations (COs) in such situations. In this case, a large load case (load combination) will be created and this load situation calculated in a summarized form. This should enable a correct representation of nonlinearities in the structure.

    As an alternative - if a calculation with the RCs is required due to the calculation time - you can consider whether the nonlinearities will be absolutely necessary.

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