Frequently Asked Questions (FAQ) - Search Term: Archivo R...

In the case of the structural analysis of members with a nonlinear material model, an FE mesh is generated on the cross-sectional area and used for the calculation. As of the version RFEM 6.06.0009 and RSTAB 6.06.0009, it is possible to adjust the mesh density for the FE mesh of the cross-sectional area via a refinement factor.

The preset mesh is relatively fine by default, and thus ensures a high degree of accuracy for the calculation results.
However, a coarser FE mesh may be completely sufficient in many cases, reducing the calculation time significantly.

You can adjust the FE mesh refinement factor in the "Edit Section" dialog box, the "FE Mesh" tab. The smaller the value, the finer the mesh.

The effects of the mesh density of the cross-sectional area on the calculation time and internal forces are shown below, using a simple example.

Cross-section: HD 260*54.1
Material: S235
Material model: Isotropic / Plastic (Members)
A vertical distributed load is applied over the entire length of the beam, and it is so large that a plastic hinge is formed above the central support.

Different FE mesh refinement factors between 0.5 and 5.8 will be analyzed. The calculation time as well as the support and sagging moment are evaluated. The relative deviation from the results with an FE mesh refinement factor of 1.0 is shown in brackets.

The table shows that it is reasonable to increase the FE mesh refinement factor for this structural system. In the case of relatively small deviations of internal forces (less than 1%), the calculation time for a structural analysis can be roughly halved.

The most likely cause of the different results is that you have probably not set the same smoothing of the surface internal forces.

This can be set separately in RFEM 6 and in the add-on.

If the smoothing is the same in both settings, the stresses are also the same.

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.

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.

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.

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

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.

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.

No, the module isn't implemented in RFEM 6 / RSTAB 9 just yet. It's still in development right now.

Performance problems may be caused by the Fault Tolerant Heap (FTH). This is a Windows subsystem that is responsible for monitoring application crashes to prevent future application crashes.

To check whether the application (RFEM, RSTAB, RSECTION, and so on) is in the list of the applications to be checked, it is worth taking a look at the Windows registry. You will find the list in the following key:
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\FTH\State

As an alternative, you can also view the entries in the Windows Event Viewer. You will find it in the following path:
Applications and Services Logs → Microsoft → Windows → Fault Tolerant Heap

To reset the list of affected applications, run the command prompt as an administrator and enter the following command:
Rundll32.exe fthsvc.dll,FthSysprepSpecialize

The list should then be cleared and the application can be restarted without restrictions. If the problem occurs frequently, you can disable the FTH completely. The procedure and a summary of the FAQ can be found on the Microsoft Website.

In RFEM 6 or RSTAB 9, you can use plastic hinges to simulate the nonlinear behavior of steel structures subjected to a load. You can model a plastic hinge by arranging a hinge with nonlinear properties on a member end. Proceed as follows:

• Select the member or members to which you want to assign the hinge.
• Open the "Edit Member" dialog box by double-clicking the member or using the member shortcut menu.
• Select the Hinges option in the "Main" tab.
• In the "Hinges" tab, click the button for the member start or the member end, to define a new hinge type.
• In the "New Member Hinge" dialog box, select one of the four plastic options for the relevant degree of freedom in the Nonlinearity list; for example, a plastic hinge according to FEMA 356 or a bilinear hinge according to EN 1998‑3.

• In the second tab, you can specify the yield properties, acceptance criteria, and yield strengths. The parameters are set by default based on the member properties and standards. If necessary, adjust it to describe the behavior of the hinge; for example, the bilinear yield curve including the yielding and hardening regions.

• Click OK to save the hinge.
• Clicking OK again in the "Edit Member" dialog box to assign the hinge to the member end.

If a Rhino surface cannot be created by using the geometry type, it will not be transferred. This is the case, for example, of curved surfaces with more than four boundary lines. In the Rhino command history (_CommandHistory or the F2 key combination), you can find a list of warnings and errors displayed during the transfer process:

Requirements

• RFEM 6 / RSTAB 9 is installed
• You have a valid license of WebServices.
• The Web Services are activated in the settings of RFEM 6 / RSTAB 9.
• IDEA StatiCa is installed.
• The BIM Link to RFEM 6 / RSTAB 9 by IDEA StatiCa is installed (IDEA StatiCa → "BIM" tab → "Activate Your BIM Link" → RFEM 6 / RSTAB 9).

Procedure

1. Create and calculate your RFEM 6 / RSTAB 9 model.
2. Open the shortcut "IDEA StatiCa 2X.X for RFEM 6" or" IDEA StatiCa 2X.X for RSTAB 9".
3. Select joint nodes and connecting member(s) in RFEM 6 / RSTAB 9.
4. Import the geometry into the checkbot via "Import" → "Connections".
5. Transfer the connection or member from the checkbot to IDEA StatiCa.

In RFEM and RSTAB, you can hide certain objects and thus create user-defined visibilities. These hidden objects are displayed in gray in the background.
The intensity of the gray color can be adjusted in the "Program Options & Settings" dialog box under the "Settings" tab.

You can select a value between 0 and 1. The higher the selected value, the darker the inactive objects are displayed.

The following programs and add-ons are perfectly suitable for your reinforced concrete 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.

Concrete Design Add-on

Use the Concrete Design add-on to design the reinforced concrete components of your model. The design checks according to specific standard include not only members (bending beams, columns) and surfaces (plates, walls), but also surfaces susceptible to punching shear. For columns, the stability analysis according to the nominal curvature method is integrated in the add-on.

You can specify user-defined reinforcement or determine it by using the program. With these basic conditions, you can perform the ultimate and serviceability limit state design checks according to one of the following standards:

• EN 1992, including National Annexes
• ACI 318
• CSA A23.3
• SP 63.13330

The add-on also allows for deformation analyses for cracked reinforced concrete surfaces (state II) using the approximation methods described in the standards. Tension stiffening as well as creep and shrinkage can be taken into account.

Additional Add-ons

If you have special requirements for the reinforced concrete structure, we recommend further add-ons and additional programs to help you solve the task.

To use a cross-section that is not included in the extensive cross-section library of RFEM 6 or RSTAB 9, the RSECTION program helps you when modeling the cross-section including reinforcement. You can then design this cross-section as usual in the Concrete Design add-on.

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 concrete structures.

Basic Add-ons

If you design steel structures, you need the following add-ons in addition to RFEM or RSTAB:

• Steel Design
• Stress-Strain Analysis
• Stability
• Steel Joints

The Steel Design add-on allows you to perform stability analysis (lateral-torsional and torsional-flexural buckling) in addition to the normal cross-section design.

The Stress-Strain Analysis add-on calculates not only stresses, but also strains in members, surfaces, and solids.

Steel structures are usually slender structures so the stability plays an important role. Use Structure Stability add-on to calculate the effective lengths and critical load factors for a precise stability analysis.

Model the connections between members precisely and flexibly using the Steel Joints add-on that is based on FEA. The connections need to be loaded not only in the main load-bearing plane. Even if the connection is loaded about the "minor axis", you can dimension the connection using this add-on.

Additional Add-ons

If you have special requirements for steel design checks, there are other add-ons and additional programs available to support you in solving your special tasks.

To use a cross-section that is not included in the extensive cross-section library of RFEM 6 or RSTAB 9, the RSECTION program helps you when modeling the cross-section and calculating the section properties.

If you want to analyze the lateral-torsional buckling with the more accurate and cost-effective method with 7 degrees of freedom, you will need the Torsional Warping (7 DOF) add-on.

If it is necessary to consider the plastification of the material when determining the internal forces, you can use Nonlinear Material Behavior add-on.

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 wind load calculation according to the relevant standards reaches its limits, then the RWIND program will help you: Using a CFD analysis, it can determine wind loads even for the most complicated 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 can model this using the Construction Stages Analysis add-on.

The Building Model add-on allows you to easily enter large multi-story concrete structures.

For your design of lightweight steel structures, containing cables and membranes, the Form-Finding add-on can help you to determine the shape of the structure.

A reason for the calculation time taking a while with little utilization of your computer's processor can be caused by using the Iterative instead of the Direct solver. Both options control the method used for solving the equation system.

The direct solver is a method that uses matrix decomposition techniques, such as the LU decomposition, to solve the system of equations in a single step. This approach is generally more robust and can handle any type of problem, but it may require more memory and computational resources, especially for very large systems.
The iterative solver, such as the Conjugate Gradient method or the GMRES (Generalized Minimal Residual) method, solves the system of equations by iteratively refining the solution.

The solver method that leads to the quicker results depends on the complexity of the model as well as the size of the available main memory amount of RAM in the machine. If resources are not a concern when solving large complex models, then the Direct solver is recommended for a majority of the time and will be the quickest. Make sure to check this under the Static Analysis Settings within RFEM 6.