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Frequently Asked Questions (FAQ)
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AnswerThe connections in the RF‑/JOINTS Steel - DSTV module are typical steel connections for the transmission or introduction of moments and shear forces.If the note "Wrong geometry" appears, check whether the connection geometry meets the requirements of the typified connections. This can be also caused by inconsistencies in the model input. In the example, a small deviation in the coordinates of the Y‑axis leads to the incorrect model geometry.If the message "Invalid material" appears, check whether the material is provided for the typified connection. For cross-sections and metal sheets, you can select the material S 235 or S 355 for these connections.
AnswerIn addition to geometry input errors, this discrepancy is usually caused by a different calculation basis of both add-on modules.The design of an end plate joint with the RF‑/JOINTS Steel - DSTV add-on module is carried out by comparing the saved ultimate limit states with the design internal forces. The underlying resistances are taken from the current DSTV guidelines.When using the RF‑/JOINTS Steel - Rigid add-on module, the joint resistances of are calculated according to DIN EN 1993‑1‑8 by means of the component method. Thus, you can directly affect the results via the settings you have made.In this case, an elastic distribution of bolt forces is used as a basis by default. By selecting the plastic force distribution in the joint, you can activate additional load capacities. These are already included in the ultimate limit states according to the DSTV guidelines.In order to obtain the comparable results between both add-on modules, it is necessary to apply the plastic force distribution for the calculation. Furthermore, you should pay attention to the correct modeling of the joint geometry.
AnswerIn the current standards, fasteners or connections are always designed in one plane only. The reason for this is that the designs for shear etc. can only be analyzed in the 2D plane. The hole design, for example, is not possible for a failure from the plane.Since internal forces in v y and v z can always occur in a three-dimensional calculation, it has been proven in practice to allow a small proportion of internal forces in secondary direction and not fully utilize the connection. However, if the ratio of shear force in secondary direction is too high, a detailed analysis with an FE simulation might be necessary.
The easiest way to find the internal forces at these nodes is to print graphics of the members in the printout report.
In the event that this solution is not an option, you can also take the values from the result table 4.1 in the printout report. Since the extreme values are only activated by default, it is still necessary to activate nodal values in the selection.
It is usually not reasonable to include the internal forces of all member in the printout report. Therefore, you can only select the members that are relevant to you.
RF-JOINTS performs an idealized design of a steel connection according to the standard, which cannot be easily compared with an exact FE calculation.
Thus, the following conditions must be met:
- Consideration or exclusion of friction/compression/tension within the contact solid (tab 'Solid') as well as for the bolts modelled subsequently
- Consideration of internal forces and deformations within the subsequently modelled end plates or similar, which causes redistribution of bolt forces in the FE calculation (in contrast to the idealized design in RF‑JOINTS)
This can be corrected by rigid connection objects, for example (an end plate as a rigid surface).
- Uniform load introduction into the FE model, for example, by using rigid members or rigid surfaces as described in the article 'FEM Modeling Approaches of Rigid Connections'
In the RF‑/JOINTS add-on module, you can export result graphics as DXF files. The corresponding button is below the graphic in Window 4.1 (see Figure 01).
After you click the button, the Windows dialog box "Save as" appears where you can enter the name and the file path of the DXF file.
RF-/JOINTS is divided into several joint groups. Each of these joint groups requires a separate license key. If RF‑/JOINTS detects a key, the joint group is marked with a green circle.
In your case, you have probably selected a joint group that is not licensed. Therefore, please set the joint group that you have purchased. The message about the demo version should disappear then.
The difference between DSTV and STIRNPL is that DSTV compares existing internal forces with allowable values from the DSTV ring binder according to DIN EN 1993-1-8 and thus determines the required connection from the typed connections. STIRNPL, however, performs a complete recalculation for the connection according to DIN 18800.
The connections in STIRNPL can additionally protrude on both sides. Four bolt rows are also possible.
DSTV not only includes rigid end plates, but also hinged end plate connections and web cleat connections.
In addition to the rolled sections (I, IPE, HE-A, HE-B, HE-M), any single-symmetric I-sections can be designed with axial force in STIRNPL (IS and IU sections). In contrast, the DSTV Guidelines only contain values for the common rolled sections (IPE, HE-A, HE-B, HE-M). Additionally, the values calculated there are only allowable for bending with lateral force; the normal force is not taken into account in the DSTV Guidelines.
To design, for example, end plates on HD sections, you can use STIRNPL while replacing the HD section with an IS section. You can define the dimensions of the HD cross-section for this profile, which then has the same stiffnesses and can be verified in STIRNPL.
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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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