Back to FAQ
Is this page helpful?
144x
005651
Victor Hidalgo, M.Sc.
2025-01-23

Creating Nodal Constraint of Type "Diaphragm" in RFEM 6 | Comparison with RFEM 5

How can I create a nodal constraint of the "Diaphragm" type in RFEM 6, as the function "1.31 – Nodal Constraints" from RFEM 5 is no longer available?

Answer:

In RFEM 5, the modeling option for couplings in the menu “Insert → Model Data → 1.31 Nodal Constraints” (Image 01) has been implemented to model elements with very high in-plane stiffness. This approach is mainly used in building engineering, where massive horizontal components (for example, floor slabs) justify such an assumption.

FAQ 005651 | How can I create a nodal constraint of the "Diaphragm" type in RFEM 6, as the function "1.31 – Nodal Constraints" from RFEM 5 is no longer available?
1 Nodal Coupling in RFEM

Since the “diaphragm” is used almost exclusively in buildings, this function has been transferred to the “Building Model” add-on in RFEM 6. There, you can select from four options to consider the stiffness (Image 02). Thus, the user can choose the model assumptions that best reflect the actual structural system.

Scheme for Floor Modeling
2 Scheme for Floor Modeling

A separate result configuration can be defined for each story. With the options “Rigid Diaphragm” or “Semi-Rigid Diaphragm”, slabs (2D analysis) can be modeled together with columns (nodal supports) and walls (linear supports) in a single model. The “Load Transfer Only” option simplifies the calculation by using only slabs for load transfer.

The building model thus represents an alternative to separate modeling of ceilings, in which the tool “Import Support Reactions as Load” was used beforehand. An initial analysis can be carried out using “Load Transfer Only” to determine global parameters, such as support reactions, stability, and the pre-dimensioning of the vertical main supporting elements.

The image shows the predimensioning of a building with a nodal constraint of the Diaphragm type in RFEM 6.
3 Results for Predimensioning of Building – Story Modeling: Load Transfer Only

Afterwards, you can activate the other functions of the add-on, for example, story modeling, ceiling sets, wall panels, and wall-like beams, om order to perform a more detailed analysis and design of the materials used (Image 04). However, since this advanced model requires more computing and processing power, a step-by-step approach is recommended. In this way, all components of a project can be integrated into just one model.

FAQ 005651 | The diagram shows results from the 2D and global calculation with story modeling and the “diaphragm” nodal constraint type.
4 Results for 2D and Global Calculation with Story Modeling
Author

Mr. Hidalgo is responsible for the development in the field of dynamic analysis.

  • Mia: AI Assistant
  • Latest Knowledge Base
Videos
Models to Download
Knowledge Base Articles
Basic Shapes of Membrane Structures [1]
This paper is focused on the specific aspects of designing membrane structures that have specific requirements, such as form-finding and cutting pattern generation. An integral part of the design of these structures is the process of finding suitable prestressed shapes and generating cutting patterns. The text briefly describes two basic processes in the design of membrane structures. The physical principles are explained and the individual theses illustrated by examples.
KB 001879 | Influence of Bending Stiffness of Cables
This article describes and explains the influence of bending stiffness of cables on their internal forces. Furthermore, the text provides information on how this influence can be reduced.
KB 001848 | Timber Column Design as per 2018 NDS Standard in RFEM 6
Using the Timber Design add-on, timber column design is possible according to the 2018 NDS standard ASD method. Accurately calculating timber member compressive capacity and adjustment factors is important for safety considerations and design. The following article will verify the maximum critical buckling strength calculated by the Timber Design add-on using step-by-step analytical equations as per the NDS 2018 standard including the compressive adjustment factors, adjusted compressive design value, and final design ratio.
RWIND 2 is a program for generating wind loads based on CFD (Computational Fluid Dynamics). The wind flow numerical simulation is generated around any building, including irregular or unique geometry types, to determine the wind loads on surfaces and members. RWIND 2 can be integrated with RFEM/RSTAB for the structural analysis and design or as a stand-alone application.
Screenshots
Product Features
Feature 002423 | Displaying Results in Solids

The results of solid stresses can be displayed as colored 3D points in the finite elements.

Improved Calculation Performance by Optimized Consideration of Nodal Degrees of Freedom in RFEM

The number of degrees of freedom in a node is no longer a global calculation parameter in RFEM (6 degrees of freedom for each mesh node in 3D models, 7 degrees of freedom for the warping torsion analysis). Thus, each node is generally considered with a different number of degrees of freedom, which leads to a variable number of equations in the calculation.

This modification speeds up the calculation, especially for models where a significant reduction of the system could be achieved (for example, trusses and membrane structures).

Extended Display of Surface Strains

Display extended strains of members, surfaces, and solids (for example, the important principal strains, equivalent total strains, and so on) in the Project Navigator - Results in RFEM as well as in Table 4.0.

For example, you can display governing plastic strains when performing the plastic design of connections with surface elements.

Export RFEM or RSTAB Models to *.glb or *.glTF Format

RFEM and RSTAB models can be saved as 3D glTF models (*.glb and *.glTF formats). View the models in 3D in detail with a 3D viewer from Google or Babylon. Take your VR glasses, such as Oculus, to "walk" through the structure.

You can integrate the 3D glTF models into your own websites using JavaScript according to the instructions (as on the Dlubal website Models to Download): "Easily display interactive 3D models on the web & in AR" .

Frequently Asked Questions (FAQ)

Where can I find the update reports for RFEM 5, RSTAB 8, SHAPE-THIN, SHAPE-MASSIVE, RX-TIMBER, CRANEWAY, PLATE-BUCKLING, COMPOSITE-BEAM?

For my NVIDIA graphics card, I need to select between a driver from the "Production Branch" and a "New Feature Branch." Which driver is best suited for RFEM/RSTAB?
Is it possible to quickly evaluate whether the mesh used is fine enough?
Why do the min/max values of the total displacement not match the deformations when working with result combinations?

Why do I get an error message about invalid material when defining timber surfaces?
Does RFEM 5 include a surface contact?
Customer Projects
Recommended Products for You
Display Product Family