Frequently Asked Questions (FAQ)

To make a web request of the Geo-Zone Tool, a URL made up of identity components is required.

→ Contolling WebService (API)

Die Lastarten und Normen werden dabei über den Baustein Language definiert, welcher sich aus 2 Teilen zusammensetzt:

• Der erste Teil des Bausteins bleibt stets unverändert und lautet "language=".
• im Zweiten Teil wird die gewünschte Sprache gewählt. Dabei stehen Ihnen folgende Sprachen zur Verfügung:
  • Deutsch =de
  • Englisch =en-us
  • Französisch =fr
  • Spanisch =es
  • Portugiesisch =pt
  • Italienisch =it
  • Tschechisch =cs
  • Polnisch =pl
  • Russisch =ru
  • Chinesisch =zh

Für die polnische Ausgabe wird somit der Baustein "language=pl verwendet.

To make a web request of the Geo-Zone Tool, a URL made up of identity components is required.

→ Contolling WebService (API)

The load types and standards are defined by the "map" component, which consists of three parts:

• The first part of the component always remains unchanged and is called "map=".
• In the second part, you specify the load category to be requested. The snow/wind/earthquake categories are available for this.
• The third part describes the respective set of rules, which is stored for the analyzed area. For this, this standard, or, if available, the National Annex or a corresponding table is used.

To obtain the load assumptions for snow in Germany, for example, the following component is required:

map=snow-din-en-1991-1-3

In order to carry out a request for a different load type and standard, the corresponding parts must be adjusted. The component for a query about the wind in Italy is as follows:

map=wind-UNI-EN-1991-1-4

A large number of international standards is available for the selection of load zones:

Standards for snow

Standards for wind

Standards for earthquake

No, the SHAPE‑THIN 9 files cannot be used directly in RFEM 6 and RSTAB 9. It is first necessary to convert the files to RSECTION files.

According to EN 1993‑1‑1, 6.3.4 (1), the general method allows for the lateral-torsional and torsional-flexural buckling analysis of individual structural components, which are subjected to loading in their principal plane and include any single-symmetric cross-section, a variable height, and any boundary conditions, as well as the analysis of entire planar structures or partial structures consisting of such components. Therefore, the design of structural components with an asymmetric cross‑section is not possible using the general method. Steel Design reports a failed design and shows the corresponding error message.

The stability analysis may be performed as section design according to EN 1993‑1‑1, 5.2.2 (7) a, provided that a spatial calculation according to the second-order analysis is performed with the global and local imperfections applied. In order to model the lateral-torsional buckling, it is necessary to determine the internal forces according to the geometrically nonlinear torsional buckling analysis with regard to warping torsion. Then, it is only necessary to perform the section design, as all stability effects are covered by the calculation. Therefore, this design method is applicable to all cross‑sections subjected to any loading.
Considering the cross-section warping as an additional degree of freedom is possible using the Warping Torsion add-on.

In order to consider the support of the structure in the soil correctly, it is necessary to excavate the soil accordingly or to provide the solid with a corresponding opening.

• To model the excavation, the solids of the "Intersection" or "Hole" type are suitable for cutting the excavation geometry into the soil solid.
• As an alternative, you can model the excavation manually by modifying the boundary surfaces of the soil solids. When using a soil massif, select the "Soil Solid" type.

For the CSA O86 and NDS, the Modification and Adjustment factors used in the Timber Design add-on in RFEM 6 can be manually adjusted. The factors are listed under the material properties.

To edit them manually, first open the material(s) being used for timber design and then set them to "User-Defined". Once this is done, navigate to the Timber Design tab where the Modification and Adjustment factors can be entered manually.

This is not possible at the moment. The corresponding add-on for the prestressed concrete design is in preparation.

All add-ons are included in the standard installation of RFEM 6 and RSTAB 9. If you have purchased the license for a new add-on, no further installation is required.

Access to the add-on is controlled by login credentials.

You can use the HTML export for the printout report export from RFEM 6 / RSTAB 9 to Microsoft Word or Excel. To do this, proceed as follows:

1. Open the printout report in RFEM 6 / RSTAB 9 and export it as HTML.

2. Open the HTML in Microsoft Word / Microsoft Excel.

Open the "Base Data" dialog box. Right-click the model name in the Project Navigator and select the corresponding entry in the shortcut menu.

Switch to the "Settings and Options" tab.

Select the desired orientation of the Z-axis.

If the orientation is changed subsequently, problems can arise, especially with regard to the applied load. Particular caution is required here.

To find the exact version number of RFEM 6, please proceed as follows:

• Run RFEM 6.
• Click "Help" in the menu.
• Select the "System Information" entry.

The version number of RFEM 6 is displayed in the dialog box that appears. This information is useful to ensure that you are working with the latest version or to specify support requests.

In RFEM 6, you can only design reinforced concrete members and surfaces. To do this, use the Concrete Design add-on. This can perform the ultimate limit state, stability, and serviceability limit state design.

Reinforced concrete solids cannot be designed directly in RFEM 6.

However, it is possible to create solids with the "Concrete" material and determine the stresses within the solid, for example. Optionally, you can add a result beam into the solid, which is used to convert the results of the solid to the member internal forces. You can then design this result beam in the Concrete Design add-on.

When interacting with Mia, our assistant based on generative artificial intelligence, there are a few things you should be aware of to get the best possible answers. To do this, we provide you with some Prompt Engineering rules, which facilitate prompting of Mia and lead to the best answers.

Background: What is a prompt?

The word "prompt" means to hand over a task to be done immediately. For Mia, a prompt is a user input that Mia generates an appropriate answer to.

A text-based prompt to Mia can contain words, letters, special characters, numbers, and links. The prompt can also be a question, a request, or a brief description of the topic. You can have an entire conversation with Mia, where you send her a prompt and she gives you her answers.

The main goal of "prompt engineering" is to create a clear, comprehensive, and effective input that ensures high-quality answers. In the following, you will find some helpful tips and instructions.

Prompting Recommendations for Mia

• Use complete, short, and clear sentences to get to the point.

Mia is not a keyword search, but the AI assistant needs a full prompt. You will receive an answer with keywords, but this may differ significantly from the expected result. To make sure the answer matches what you're looking for, it's best to use complete, short, and clear sentences that Mia can understand. It would also be a big help to Mia if you could be more specific in the prompts and give as clear instructions as possible.

In the attached image, you can see how Mia reacts to a keyword prompt and responds to a detailed question.

• Be as detailed as you can, and make sure it's clear. The more precise, the better.

If you want an answer that refers to certain details from the Dlubal environment (for example, the program family), you should always include these in your prompt. This allows Mia to assess more quickly which answer is correct and thus provide a more reliable and accurate response to your prompt. Accordingly, you should not include information unrelated to your query just to test the limits of Mia.

• Break the task into small, manageable steps. If necessary, ask several questions in one chat.

Since too much input in one prompt may cause Mia to only refer to certain aspects of your prompt and forget others, you can also split your actual prompt into an initial question and follow-up questions. This means that Mia can consider all important aspects in her answer, and thus give you a more accurate answer that actually addresses all aspects of your question.

• Be specific about what is expected. Ask your question as precisely as possible and in context.

Sometimes there are questions that have more than one possible answer. This is because more information is needed to answer the question correctly. You should not withhold these from Mia (if they are available to you), otherwise you will not receive the best possible response from Mia based on the data available and entered. So please include all the information Mia needs to answer your prompt - especially if there are multiple constellations for an answer.

• Give the most important information at the beginning or end.

Mia is often able to better evaluate the information at the beginning or at the end of a prompt and refer to it for her answers. Therefore, you should always place the most important information at the beginning and/or the end of your prompt.

Each license includes the creation time and the expiration time from our server. From time to time, our application checks the model's change log and if it founds out that the change time is not continuous, it logs off.

For this reason, you should make sure that the system times are continuous. If you make major changes to the system time, log out first.

The Calculation for Torsion in the NDS Strength Configuration works together with the torsion limit set to ensure the safety of the member and structure. Below, you find a short explanation for each option:

Check torsional limit only:
The ratio torsion check is compared to the torsion limit. If the ratio is smaller than the limit, then no further calculation is carried out. If the ratio is bigger than the torsion limit, an error will be shown in the design check. The error is then the most governing design check in the graphical and tabular results.

According to Timber Construction Manual:
Torsion design is according to the Timber Construction Manual 4.6, and the result is a typical design ratio based on the calculation.

Ignore torsion:
This setting is very similar to the first option. The ratio is compared from the torsion calculation to the torsion limit. If the ratio is smaller than the limit, then no further calculation is carried out. If the ratio is bigger than the limit, then a warning is shown in the design check. This warning will not be a governing design check in the results tables or graphics and serves only as a warning for safety considerations.

To neglect all torsion for the member design check, the limit value for torsion must be increased.

If you activate the WebService settings in order to use the RFEM 6 interfaces (Revit, Tekla Structures, Rhino/Grasshopper, Excel via Plugin) and you still get the error message, proceed as follows:

Check the server port range used by the interface. The port range must match the one set in the Program Options of RFEM 6.

The error message remains if the default server port range (8081-8089) is otherwise occupied. Set a different server port range in the Program Options in RFEM 6, such as 10001-10009.

It is also necessary to adjust this server port range accordingly for the respective interface.

Revit

Tekla Structures

Rhino/Grasshopper

Excel Plugin

Yes, you can. Move your mouse pointer over the node and wait a moment. A bubble with the node coordinates will appear.

Yes, you can. In RFEM 5 and RSTAB 8, you can use the cross-sections created with SHAPE‑THIN 8 and SHAPE‑THIN 9.

The Dlubal plug-in for Tekla needs to be installed manually. Find the installation information here:
https://www.dlubal.com/en/support-and-learning/support/faq/005375

If you do not see the Dlubal tab after the installation, this is usually caused by the country-specific environments or company templates.

Files and Paths

Dlubal reads out the installation path for the environment from the following registry:
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Trimble\Tekla Structures\2023.0\setup -> "EnvDir"

The "UserDefined.xml" file is then stored in the folder
C:\TeklaStructures\2023.0\Environments\common\system\Commands

and the "DlubalRibbonTab.xml" file in the folder
C:\TeklaStructures\2023.0\Environments\common\system\Ribbons\CustomTabs\Modeling

. These files create and control the Dlubal tabs, the dimensions of the icons, and three additional commands for the import, export, and conversion tables.

Country-Specific Environment or Company Template

Tekla allows you to use your own environments and templates that allow you, for example, to adjust the ribbon. If so, you need to copy the two Dlubal-specific XML files into the folders of the user-defined environment.
This is explained using the example of the Swiss environment. This includes a separate folder for company-specific environments, for example.
C:\TeklaStructures\2024.0\Environments\Switzerland\FirmExample\2024\Firm
The information about using this or any other user-defined folder can be seen in the *.ini file of the corresponding role.

To display the Dlubal tab in Tekla, you need to take the following steps:

• Copy the "DlubalRibbonTab.xml" to the folder

C:\TeklaStructures\2024.0\Environments\Switzerland\FirmExample\2024\Firm\Ribbons\CustomTabs\Modeling

• Create a "Commands" folder in the following folder

C:\TeklaStructures\2024.0\Environments\Switzerland\FirmExample\2024\Firm

• Copy the "UserDefined.xml" to the new folder

C:\TeklaStructures\2024.0\Environments\Switzerland\FirmExample\2024\Firm\Commands

After restarting Tekla, the Dlubal tab should be visible.

The SCIA .xml format is intended for data exchange with RFEM 5. Due to the reprogramming of RFEM 6, the .xml file formats of SCIA and RFEM 6 are not compatible.

A simple solution is to export from SCIA in the SAF 1.0.5 format. This can be imported into RFEM 6.

You can hide the undeformed geometry in the Display tab of the navigator by deactivating the Model check box:

The following programs and add-ons are particularly suitable for structural timber projects.

Main Program

To model your structure and determine the internal forces, you need one of the main programs. Depending on the application area, you can use RFEM 6 or RSTAB 9.

• RSTAB: Analysis of planar or spatial frame & truss structures
• RFEM: Finite element analysis of plate, wall, shell, and member structures

If your model has surface components, such as plates and walls, in addition to membe elements, you need RFEM. This program is the only one with the capability to analyze laminate or cross-laminated timber elements and curved objects.

Timber Design Add-on

Use the Timber Design add-on to design the timber components of your model. The design checks in compliance with specific standards cover both members (bending beams, columns) and surfaces (plates, walls). For columns, the stability analysis according to the equivalent member method or the second order analysis is performed.

You can perform the ultimate and serviceability limit state design checks, as well as the fire resistance design according to the following standards:

• EN 1995 – including National Annexes
• SIA 265
• NTC
• NDS
• CSA O86
• GB 50005
• AS 1720

In the fire resistance design, the charring of a cross-section is taken into account for both the stiffness and the design.

Multilayer Surfaces Add-On

With the Multilayer Surfaces add-on for RFEM, you can analyze laminate and sandwich structures with user-defined layer structures. This allows you to design cross-laminated timber panels, for example.

If certain layers have nonlinear material behavior, you can assign the appropriate properties to them. Furthermore, this add-on allows provides you with the option to analyze curved surfaces.

Additional Add-ons

In case of special requirements for your timber structure, we recommend further add-ons and additional programs to help you solve the task.

If you need to perform seismic or vibration analysis, the dynamic analysis add-ons provide you with powerful tools for your structural analysis and design. The Modal Analysis add-on enables the calculation of natural frequencies, and in combination with the Response Spectrum Analysis add-on, you can also perform seismic analysis according to numerous standards.

If you are designing a building with a complicated shape, so that the determination of wind loads according to the relevant standards reaches its limits, the RWIND RWIND program will help you: Using a CFD analysis, you can determine the wind loads even for highly complex building shapes.

If the construction stages affect the final internal forces in a structure, or if the governing internal forces for the structural design result from certain construction stages, you should consider the modeling using the Construction Stages Analysis add-on. The Building Model add-on allows you to easily enter large multi-story timber structures.

If you receive an RFEM 6 or RSTAB 9 file for further processing, the structures will be displayed in the program using the display settings of the last editor.

If this display does not meet your own requirements, you can simply right-click the free area of the Navigator – Display and select "Dlubal Standard". This returns the settings to the default values.

Please note that the enveloping results are usually shown when displaying the results of design situations or result combinations.

There are three options to graphically display the results of deformations, internal forces, and support forces: Max and Min-values can be displayed separately. To display both envelopes from the extreme values on the model, select Max and Min-values.

Turbulence modeling is a critical aspect of computational fluid dynamics (CFD) that seeks to predict the behavior of turbulent flows. Turbulence models are essential for designing efficient and safe engineering applications, such as wind-structure interaction in order to structural analysis and design. Among the various approaches to turbulence modeling, three popular models are the Reynolds-Averaged Navier-Stokes (RANS), Unsteady Reynolds-Averaged Navier-Stokes (URANS), and Delayed Detached Eddy Simulation (DDES). Each model has its own unique features and applications.

RANS (Reynolds-Averaged Navier-Stokes)

The RANS approach is one of the most common methods used in turbulence modeling. It involves averaging the Navier-Stokes equations over time, which effectively smooths out the fluctuations of turbulence to provide a steady-state solution. This method simplifies the computational requirements significantly and is particularly useful for applications where the flow is steady or mildly unsteady. RANS models are extensively used in industrial applications due to their robustness and low computational cost. However, they can be less accurate in predicting complex flows with significant separation or strong unsteadiness.

URANS (Unsteady Reynolds-Averaged Navier-Stokes)

URANS extends the RANS approach by allowing for time-dependent changes in the flow field, making it capable of capturing unsteady phenomena. It still utilizes the Reynolds averaging of the Navier-Stokes equations but does not average the flow in time as strictly as RANS. This means URANS can model larger-scale transient flow features and oscillatory behaviors, which are typical in many practical engineering systems, such as vortex shedding from building corners. While URANS improves upon RANS in terms of capturing unsteadiness, it still employs eddy-viscosity models that may not adequately resolve finer turbulent structures.

DDES (Delayed Detached Eddy Simulation)

DDES is a hybrid approach that combines RANS and Large Eddy Simulation (LES) methodologies. In regions of the flow where the boundary layer is attached, DDES behaves like a RANS model, providing computational efficiency. In regions where the flow detaches and larger turbulent structures dominate, DDES switches to an LES mode, which resolves these structures more accurately. This method is particularly useful in complex flows involving flow separation, reattachment, and wake regions, such as building edges and corners. DDES offers a good balance between computational expense and accuracy, particularly in simulating high Reynolds number flows with significant unsteady and separated regions.

Conclusion

Choosing the right turbulence model depends largely on the specific requirements of the problem at hand, including the flow characteristics, accuracy needs, and available computational resources. RANS models are suitable for simpler, steady flows, while URANS provides better handling of unsteady phenomena. DDES, although computationally more demanding than RANS or URANS, offers superior accuracy in cases involving complex, unsteady separated flows. Each of these models has contributed significantly to advancements in fluid dynamics simulations, supporting engineers and researchers in developing more effective and efficient technological solutions.

In the standards, no torsion is taken into account in the stability analysis for the equivalent member method or the general method. The warning message is a reminder to the user of this fact.

First of all, the magnitude of the torsional stress or moments should be analyzed. Very small torsional moments in the members to be designed often prevent certain design formats. In order to neglect them and suppress the warning, you can change the limit values in the Ultimate Configuration. There is no normative basis for this limit value and therefore, no general specification. Find more information here:
Neglecting Torsion

In the case of open cross-sections, it can generally be assumed that the acting torsional moments are not transferred by primary torsion, but by secondary (warping) torsion. In RFEM 6 and RSTAB 9, the internal forces are initially only determined with six degrees of freedom without considering warping. For small acting torsional moments, it seems obvious to neglect the torsional stresses in the design. For large torsional moments, however, a calculation should be carried out with seven degrees of freedom in order to also consider the influence of the warping moment and the secondary torsional shear stresses. For this, you can use the Torsional Warping (7 DOF) for RFEM 6 / RSTAB 9 add-on, for example.

We usually release a new version of RFEM 6 / RSTAB 9 every Monday; means, four versions per month.

You are informed about a new version on the Extranet and in the Dlubal Center. There you will also find the links to download the versions.

In RFEM 6 and RSTAB 9, the calculation parameters are no longer managed in a dialog box of the same name, but in the form of Static Analysis Settings in the Load Cases and Combinations category in the navigator.

There are tree analysis types preset:

• Geometrically linear
• Second-order (P-Δ)
• Large deformations

You can adjust the parameters of these analysis types or create more types.

In the "Load Cases & Combinations" dialog box, you can then assign the relevant static analysis setting (SA) to the load cases and load combinations.

The Tower Design add-on is still under development. Therefore, it cannot be activated in the Base Data.

The Glass Design add-on is still under development. Therefore, it cannot be activated in the Base Data.