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.
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RFEM and RSTAB use a variation of the subgrade reaction modulus method. The relation to stiffness modulus ES is not possible.
In RFEM, a multi-parameter foundation model has been implemented. This can be used to carry out a very realistic settlement calculation.
The problem, however, is to find precise values for the parameters Cu,z, Cv,xz, and Cv,yz. For this, you can use the Geotechnical Analysis add-on (for RFEM 6) or the RF-SOILIN add-on module (for RFEM 5): the subgrade parameters are calculated from the loads and the data of the geotechnical report (stiffness modulus or modulus of elasticity and Poisson's ratio, specific weights, layer thicknesses) for each individual finite element using a nonlinear method. These parameters are load-dependent and influence the behavior of the structure. The results of this iterative process are realistic settlements and internal forces in the structure.
The Masonry Design add-on allows you to automatically determine the stiffness of your wall-slab hinge. The diagrams were determined as part of the research project DDmaS - "Digitizing the design of masonry structures" and are derived from the standard.
Define a line hinge on the connection line of both surfaces and activate the slab-wall connection.
You can now enter your parameters in the Slab-Wall Connection tab. Then, click the Regenerate [...] button.
The determined diagrams are displayed subsequently.
There can be many reasons for unstable structural systems. The best way to determine the reason for this message is to use the Structure Stability add-on.
Structure Stability Add-on
This add-on allows you to calculate your structure without loading, and thus to perform an instability analysis using the mode shape.
Therefore, you can display the unstable shape of your structure.
As you can see in our example, the upper steel beams are subjected to lateral deflection.
Upon closer inspection of our modeling, we recognize that we have unconsciously created a hinge chain from couplings of the Rigid-Hinge type. If we remove this hinge chain, we can calculate the load case.
A calculation break‑off due to an unstable system can have different reasons. On one hand, it can indicate a "real" instability due to overloading the structural system; on the other hand, modeling inaccuracies may also be responsible for this error message. In the following text, you can find a possible procedure for finding the cause of the instability.
1. Modeling Check
2. Check of Stiffening
3. Numerical Problems
4. Detecting Causes of Instability
This is not possible in RFEM 5 or the RF‑STAGES add-on module. However, it is possible in the new program generation. In the Construction Stage Analysis add-on for RFEM 6, you can now modify the properties of structural elements.
The warping of a cross-section can be displayed in the "full mode". For this, it is reasonable to increase the display factor for torsional warping in the control panel; see Image 01.
Furthermore, you can select the value of the local deformation ω [1/m] in the Results navigator; see Image 02.
The warping stiffness can be deactivated by cross-section in the "Edit Cross-Section" dialog box; see the image.
Both support forces and loads are assumed for the calculation with warping torsion in the centroid. Accordingly, an asymmetric cross-section would automatically receive torsion; see the image.
After activating Torsional Warping in the Base Data, you can define warping springs and warping restraints. For this, select the Transverse Stiffeners option in the "Edit Member" dialog box; see Image 01.
In the "Transverse Stiffener" tab, you can create several transverse member stiffeners and define the necessary parameters using the "New Transverse Member Stiffener" button. For the "End plate" stiffener type, the resulting warp spring is determined automatically; see Image 02.
In addition to other variants, you can also define a rigid warping restraint or user-defined warping spring stiffness under the "Warping restraint" stiffness type.
As an alternative, you can create member transverse stiffeners using the Data navigator or the menu bar "Insert", "Types for Members", "Member Transverse Stiffeners". In this case, you can use the select function in the "New Member Transverse Stiffness" dialog box to assign them to the corresponding members.