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Frequently Asked Questions (FAQ)
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The setting for the deformation coefficient kdef can already be made in the model data. There, you can specify the deformation coefficient manually or select it based on the service class.
The deformationfactor k def is considered in the load combinations for serviceability in the program (similar to DIN EN 1995-1-1, 2.2.3).
For the design of mixed structures made of timber materials, see FAQ 4325 .
AnswerThe protection can be disabled for the duration of the installation in Windows Security → App & browser control → Reputation-based protection → Check apps and files. After deactivating this check, RX‑TIMBER can be installed now. Then, we recommend to switch on the protection again.
AnswerTapered members must not be designed according to the simplified equivalent member method!For steel structures, the design can be performed by considering the warping torsion or using the General Method. These methods are described in this technical article.For timber structures, the design can also be performed by considering the warping torsion. The method for timber structures is explained in detail in thiswebinar.According to the equivalent member method, the design can be performed if the provisions of the explanations for DIN 1052, Section E8.4.2 (3) for variable cross-sections are met. In various sources of technical literature, this method is adopted for Eurocode 5. An example of this can be found in the document on brettschichtholz.de, page 64 ff.In the RX‑TIMBER program, the design of tapered members is performed according to the equivalent member method. This is briefly explained on a simple example.Structural System (Figure 01):
No stiffening is defined. The lateral-torsional stability becomes governing with 99% (Figure 02) at the x‑location 1.598 m. The cross-section height is 36.8 cm. However, the slenderness ratio is based on the equivalent cross-section height of 60.9 cm (Figure 03).The equivalent cross-section height results at the x-location 5.2 m about 0.65 × 8 m = 5.2 m.If the stiffening is in the middle of the span, for example, the equivalent height for the x‑location changes to 45.3 cm.Since the stiffening is usually applied over the member length, the height must be calculated according to a special algorithm. The supports are always applied as fixed points and the equivalent heights are calculated, based on the x-locations of the designs.For the example, the following results: x0.65 = 0.32 x 4 m + 1.598 m = 2.878 m
- Span length: 8 m
- Beam height right: 80 cm
- Beam height left: 26 cm
- Roof inclination: 3.9°
The cross-sections of members are always related to the centroidal axis in RFEM/RSTAB. The rendering is adjusted accordingly. This has no influence on the calculation.
RFEM allows you to perform structural analysis and design of laminate and sandwich structures. The same applies to cross-laminated timber. Stress and deflection anaylsis of laminate and sandwich surfaces is performed according to the laminate theory, taking into account the shear coupling.
Available Programs and Add-on Modules
- RFEM is the main program where structures, materials, and actions are defined. Planar and spatial plate, slab, shell, and member structures are possible.
- RF-LAMINATE is required for the stress and deflection analysis of laminate surfaces. It is possible to specify user-defined layer structures.
Add-on Module for Timber Structures
- RF-TIMBER Pro performs structural analysis and design according to Eurocode 5, for example, for further supporting elements of the structure.
There are also other add-on modules available for other structures, such as steel or concrete structures.
Data Exchange and BIM
Various interfaces allow for efficient work in exchange with other project participants. In this way, you can also cooperate smoothly in BIM processes.
If it is necessary to perform seismic analysis or vibration designs, the RF‑/DYNAM Pro add-on modules provide special tools for determining natural frequencies and mode shapes, an analysis of forced vibrations, a generation of equivalent loads, or for a nonlinear time history analysis.
If you have any question about the Dlubal Software programs, please do not hesitate to contact our sales department.
In the RF‑/TIMBER Pro add-on module, you can perform the shear force reduction for Eurocode 5 (EN 1995‑1‑1).
The regulations for the reduction are only covered in the following National Annexes:
- DIN EN NCI 6.1.7 (NA.5)
- ÖNORM EN 6.1.7(2)
- SFS EN RIL 205-1-2009, 6.1.7
Therefore, the provisions of DIN EN are used for all other National Annexes by default!
It is possible to determine the width of the support by using the distance from a member start to a support edge ls.
Yes, this is possible with the RF‑/JOINTS Timber - Steel to Timber add-on module. You can design the connection of two diagonals if they are connected with steel plates and dowels, for example. For this, it is reasonable to use the "Main member only" joint type.
After selecting the node in the program, the connection is still marked as insufficiently defined due to the steel bottom flange.
You can now deactivate both steel members to perform the design for the connection of the two diagonals only.
This design is possible in the add-on module.
AnswerYes, the data is freely accessible. You can download the presentations and finished models by the speakers under Downloads below.
For modeling the columns, bottom ribs, top ribs, and so on, you can use members for timber panels covered on one side.
If the timber panel is covered on both sides, it is recommended to replace the members with surfaces. The columns are hinged to the top and the bottom rib. Then, you can define the covering.
For timber surfaces, make sure that the orthotropic material model is used.
When defining supports, you can decide whether they should be linear or nonlinear.
The flexibility of the connection between the covering and the members can be set by using line releases. The springs refer to a length of 1 meter (kN/m/m = kN/m²), which is why the displacement modulus of the fastener must be multiplied by the number of fasteners per linear meter.
In the video, you can see the exact procedure. It shows the results first, and then the modeling.
Yes, it is possible - but only in RFEM . Unfortunately, this function does not exist in RSTAB.
To use the export of stiffnesses, it is necessary to activate the options shown in Figure 01 in Details. Thus, the stiffnesses are exported to RFEM before the calculation and the internal forces are calculated taking into account the flexible connections. However, no further static model is created, but the existing model is modified.
When you start the RF-JOINTS calculation, the eccentricity and connection are transferred to RFEM as member properties, and nodal releases are also generated in RFEM. This information can be found in the RFEM tables "1.14 Member Hinges", "1.15 Member Eccentricities", "1.24 Nodal Releases" and "1.30 Connections". The internal forces for the designs are then determined with the modified model.
There are export options for all members you can define eccentricities and hinges for. If there are already members with hinges or if there are trusses in the model, the additional connection hinges would lead to instabilities in the calculation. Therefore, a corresponding message appears before the dialog box is closed.
In the downloads at the end of this FAQ, you can find an example where the stiffness export is only shown for the eaves node. If you want to consider the flexibility of the fasteners, you should define all connections.
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Wind Simulation & Wind Load Generation
With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.
The generated wind loads acting on these objects can be imported to RFEM or RSTAB.
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