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• ### When calculating a connection with the FRAME-JOINT Pro add-on module, a message appears stating that the value is out the allowable range (provisional value: 160, minimum value 200). What does the mentioned note mean?

New FAQ 003159 EN-US

It is often the case that the member dimensions do not match.
In the example model, the beam has a flange width of 200 mm and the column support of 160 mm.

This joint is not allowed in the add-on module because the flange width of the column should be at least as large as the flange width of the structural element to be connected. As soon as the cross-sections are defined according to this rule, the connection design is also satisfactory.

• ### Is it sufficient to perform the calculation with surface elements or is it better to use the solids elements?

New FAQ 003158 EN-US

When components are calculated with the Finite Element Method (FEM), you can choose between surfaces and solids in RFEM. The big advantage of surfaces is the calculation time, because the FE elements are only defined in the surface plane. The third dimension, that is the thickness, is considered as a physical property in the calculation. Thus, a surface can be considered as a mathematical simplification. In addition, surfaces can be meshed more easily than solids (Jacobi Matrix).

Plate elements are divided into two types of elements. Whereas in the classical thin plate theory (Kirchhoff) shear deformations due to shear forces are neglected, special extended approaches have to be assumed for the thick plate theory (Reissner-Mindlin). For thin plates, the pure bending reaction is dominant. Therefore, the simplified bending theory is also sufficient. As the thickness increases, the proportion of the transversal shear influence on the load bearing capacity increases. Starting at a certain thickness, the error due to neglecting this component is so large that it is absolutely necessary to have the higher theory of the thick plate. Considering a slab as being "thin" or "thick" does not depend on the ratio "dimension to thickness" of the single finite element, but on the conditions in the structural system. Influencing factors include, in addition to the plate thickness, especially the span lengths (length, width, radius), the type of support and the load type as well as their distribution. Due to the multitude of influences, it is not possible to specify a mandatory value.

Figure 01 shows a guideline describing the validity of the corresponding elements. The size "d" is the thickness of the structural component and "L" the length of the structural component or the distance between the supports. The ratio d/L gives an indication of when an element is valid for an analysis. If d/L is large, the shear deformation is a critical parameter and the user should prefer to use solids. If d/L is small, the shear deformation has no decisive influence and surface elements are the most effective choice.

Figure 02 performed calculations with the different elements. A top view is shown so that the deformations can be interpreted on the image plane. For a small d/L ratio of 0.2, the deformations very well match for all three variants. If d/L = 0.4, differences between the thin and thick plate calculations are already noticeable. In the extreme case d/L = 0.7, a difference of the thick plate to the solid is additionally observed. The loads have been selected in such a way that the same deformation is achieved for all solid elements to produce a meaningful printout.

• ### Is it possible to create load combinations manually in RSTAB 8 or RFEM 5?

New FAQ 003157 EN-US

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.

• ### During the calculation, I receive the warning that some elements are connected to the buckling panel, but are not defined like stiffeners (see Figure 1). What can I do?

New FAQ 003156 EN-US

In the cross-section shown in Figure 2, member No. 8 is defined as a buckling stiffener and connected with the zero element No. 5 (thickness t = 0 mm) to the buckling panel. Buckling stiffeners must be connected with the buckling panel with "normal" elements (thickness t > 0 mm). In this case, for example, the element No. 5 can be deleted and the element No. 8 can be connected directly to the buckling surface.

• ### Can I save the load combinations and result combinations and reinsert them in other locations?

New FAQ 003155 EN-US

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.
• ### Why do I receive error message 226 in RF-CONCRETE Surfaces? The check for the crack width is omitted or the design ratio is "0.00".

New FAQ 003154 EN-US

Message No. 226 appears in result dialog boxes 3.1 to 3.3 in RF-CONCRETE Surfaces if the concrete tensile stresses from the defined load for the surface to be designed are smaller than the concrete tensile strength.

In this case, message 226 is displayed with an appropriate message.

By clicking the [i] button, you can open the design details for the respective inconsequential location and display the intermediate values for the determination of the applied tension stress.

• ### During the installation, I receive a message from the Sentinel HASP Run-time installer.What can I do?

New FAQ 003153 EN-US

The cause for this is that a service of the dongle driver is still in use and therefore can not be stopped by the installation.

In this case, you have to manually close the corresponding service, e.g. hasplms.exe or hasplmv.exe, in the Services of the operating system. Afterwards, the installation should be possible without problems.

• ### How to use the Dlubal parameters in the Revit interface?

New FAQ 003152 EN-US

The Dlubal parameters are parameters in Revit that do not exist by default. They are only enabled after the activation ("Add Parameters" -> "Start") in the different dialog boxes.

This information is specific to RSTAB/RFEM and can be stored in Revit. When exporting Revit to Dlubal, you can export and convert this information from RSTAB/RFEM.

"Without Tension"
- to be found in the analytical wall properties
- corresponds to the surface type stiffness "No Tension"

"Surface Support"
- to be found in the analytical slab or plate properties
- creates a surface support with specified spring constants in RFEM

"Dlubal Name (Material)"
- can be found in the user-defined material parameters
- direct assignment of the Dlubal material name possible (without conversion table)

"Dlubal Name (Cross-section)"
- to be found in the model properties of columns or beams
- direct assignment of the Dlubal cross section name possible (without conversion table)

"Member Type Truss/Tension Member"
- to be found in the analytical beam or support properties
- corresponds to the member type Truss or Tension Member in RSTAB/RFEM

• ### When carrying out the fatigue design, I am getting very little or no utilization of my members.What is the reason for this?

New FAQ 003151 EN-US

The RF-STEEL Fatigue Members add-on module requires a stress cycle or a stress range for the fatigue analysis.

To be able to determine them, the input of the load cases to be designed has to be checked.

For example, if only the load cases with the actual operating load have been entered for the design and the self-weight of the structure (here e.g. LC1) was not selected, this effect may occur.

If the load case "Self-Weight" is used for the calculation of the stress cycle, a much higher utilisation may result.

In this context, reference should also be made to result combinations selected for the design, if applicable. They should also be created so that the governing stress cycle in the module can be determined.

• ### Why are the results in RFEM/RSTAB sometimes deleted when the data are exported to Revit?

New FAQ 003150 EN-US

The interface between Dlubal and Revit works internally with so-called Global Unique Identifiers (GUIDs). Revit assigns a GUID to each object. During the import and export, this GUID is transferred via the interface and added to the corresponding Dlubal object (member, surface, etc.). By using GUIDs, you can carry out updates in both directions with only those objects needing to be updated that are affected by changes. Other objects remain unaffected. This results in a better compatibility during the data exchange.

The comparison assumes that each object in Revit has a corresponding counterpart in the Dlubal application. For example, Revit treats each line support individually. If a line support type is assigned to several lines in RFEM, duplicates of the line support type are automatically created when exporting to Revit in RFEM. A line is assigned to each duplicate. Then, a 1:1 comparison is possible (see Figure).

Due to the described functionality of the interface with the resulting modification of the Dlubal model data, it cannot be ruled out that the results will be deleted. Therefore, it is recommended to export the model to Revit before the calculation is made. The results can be transferred retroactively within a second export process.

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