The structural analysis software RFEM 6 is the basis of a modular software system. The main program RFEM 6 is used to define structures, materials, and loads of planar and spatial structural systems consisting of plates, walls, shells, and members. The program also allows you to create combined structures as well as to model solid and contact elements.
RSTAB 9 is a powerful analysis and design software for 3D beam, frame, or truss structure calculations, reflecting the current state of the art and helping structural engineers meet requirements in modern civil engineering.
Do you often spend too long calculating cross-sections? Dlubal Software and the RSECTION stand-alone program facilitate your work by determining section properties of various cross-sections and performing a subsequent stress analysis.
Do you always know where the wind is blowing from? From the direction of innovation, of course! With RWIND 2, you have a program at your side that uses a digital wind tunnel for the numerical simulation of wind flows. The program simulates these flows around any building geometry and determines the wind loads on the surfaces.
Are you looking for an overview of snow load zones, wind zones, and seismic zones? Then you are in the right place. Use the Geo-Zone Tool to determine quickly and efficiently snow loads, wind speeds, and seismic data according to ASCE 7‑16 and other international standards.
Would you like to try out the capabilities of the Dlubal Software programs? You have the opportunity to do so! The free 90-day full version allows you to thoroughly test all our programs.
In RFEM, it is possible to define a surface of the Membrane type (see the image). The calculation is then done automatically according to the large deformation analysis.
For the modeling of membrane structures, we recommend the Form-Finding add-on (for RFEM 6) or the RF-FORM-FINDING add-on module (for RFEM 5).
To perform an earthquake analysis, you need a modal analysis and then a load case of the Response Spectrum Analysis type.
After you have performed your modal analysis, create a new load case. Here you will find the usual settings from the previous program generation.
In the Response Spectrum tab, you can define your response spectrum as usual. If you want to use a response spectrum according to the standard, make sure that the desired standard is selected in the general data of Standards II.
In the Selection of Modes tab, you can select the mode shapes and filter them, if necessary.
After the load case has been calculated, you obtain the results.
Masses can be neglected in the modal analysis settings.
It is possible to neglect masses in all fixed nodal supports and line supports, or to create a selection of the individual objects.
Yes, you can also export the response spectra from RFEM 6 and import them into RFEM 5 as a user-defined response spectrum. Please note that export and import via Excel may also have different columns/descriptions due to different versions.
Export your data in RFEM 6 to Excel.
If you want to import this table directly, you will get an error message. RFEM 5 expects a different worksheet description and two columns only.
As soon as you adjust the name in Excel and delete the column with the frequency results, you will be able to edit the response spectrum in RFEM 5.
The ASCE 7-22 standard provides several types of design spectra. In this FAQ, we would like to focus on the following two design spectra:
The two-period spectrum is implemented in the program as usual. However, based on the data available from the standard, only the horizontal design spectrum / MCER spectrum as well as the modification related to the force and displacement can be offered.
For the multi-period design spectrum, discrete numerical values are specified. ASCE 7‑22 states that these values can be queried on the USGS Seismic Design Geodatabase page. In the current state of development, you have the option to create a user-defined response spectrum with a g‑factor (depending on the mass conversion constant) to use the data from the ASCE 7 Hazard Tool [1], for example.
Please proceed as follows:
1) In the material library, set the region to “All” and the material type to “Fabric” in the filter. Select any one of the fabric materials from the list.
2) Activate the “User-defined material” option and specify the user-defined name.
3) Under the Material Values tab, revise the fictitious thickness, density, and so on. The strengths and basis weight (ms) do not affect the calculation and can be disregarded.
4) To specify the modulus of elasticity and shear modulus in terms of force/area, select the Orthotropic Linear Elastic (Surfaces) tab and enter the values there. Note: Changing the thickness in Step 3 affects the values entered in this tab.
To access the user-defined materials and sections for future models, a template can be created. This is shown in FAQ 005109 .
If no angle can be defined in the "Rotation" column, there is an isotropic material model selected for the material, where stiffnesses are identical in all directions and it is not necessary to define an angle.
If you use materials with anisotropic behavior (for example, timber), it is necessary to ensure that the "Orthotropic | Linear Elastic (Surfaces)" material model is selected.
Note: The "Orthotropic | Timber | Linear Elastic (Surfaces)" material model cannot be currently used in combination with the "Layers" thickness type.
As soon as switching to the orthotropic material model, the individual layers can be rotated accordingly.
Both RFEM and RSTAB are ideally suited for modeling and analysis of cable and tensile structures, including substructures. You can decide whether to consider the prestress of cables.
Main Programs RFEM and RSTAB
The main programs RFEM and RSTAB are used to define the model with its properties and actions. In addition to spatial frame and truss structures, you can also use RFEM to model plate, wall, and shell structures. Thus, RFEM proves to be the more versatile option.
Add-ons for Cable Structures
Various add-ons supplement the functionality of the main programs. In the design add-ons Steel Design and Aluminum Design, you can perform the ultimate and serviceability limit state design, as well as the stability analysis according to various standards.
The Form-Finding add-on for RFEM provides you with the option to perform form-finding for cable and membrane systems before the actual design.
In case of any questions about the Dlubal solution for cable and tensile structures, our sales team will be happy to assist you.
The Form-Finding add-on is available for the structural FEA software RFEM, which you can use to search for the shape of a tensile membrane structure before the actual design.
Once you have modeled a supporting structure or a substructure in RFEM and defined membrane surfaces, you can analyze the global model according to the large deformation analysis.
Programs and Add-ons
Use the main program RFEM to define the model, including the properties and actions.
The Form-Finding add-on allows you to determine a shape of the member and surface models subjected to axial forces.
Use the RWIND program to perform simulations in the digital wind tunnel for complex structures and to transfer the generated wind loads to RFEM.
Depending on the design, you can use the add-ons Steel Design and Aluminum Design to design the structure.
If a seismic or vibration analysis is required, the Dynamic Analysis add-ons are the perfect tools for this.
In case of any questions about the Dlubal solution for tensile membrane structures, our sales team will be happy to assist you.