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Frequently Asked Questions (FAQ)
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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 the pictures of members into the printout report.
If this solution is not an option, you can also find the values in 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 the resulting graphics as DXF files. The corresponding button is located below the graphic in window 4.1 (see Figure 01).
After opening the corresponding function, the Windows dialog box "Save As" appears where you can define the name and file path of the DXF file.
RF-/JOINTS is divided into several joint groups. Each of these joint groups requires a separate licence key. If RF-/JOINTS detects a key, the joint group is marked with a green circle (see Figure).
In your case, you have probably selected a joint group that is not licenced. Therefore, please set the joint group that you have purchased. The message about the demo version should then disappear.
DSTV is used to compare existing internal forces with the allowable values of the German guideline DSTV so that you can determine the required joint from typified connections. On the contrary, END‑PLATE is used to recalculate the entire connection.
The connections in END‑PLATE can be extended on both sides and four bolt rows are also possible.
DSTV includes not only bending-resistant end-plates but also hinged end-plate and angle connections.
Thus, the main differences are:
In addition to the rolled sections (I, IPE, HE‑A, HE‑B, HE‑M), the END‑PLATE add-on module allowsw for design of any monosymmetric I-section with axial force (IS- and IU‑sections). In contrast, the DSTV guideline gives only values for the common rolled sections (IPE, HE‑A, HE‑B, HE‑M) and the values calculated are allowed only for bending with shear force, which means that the axial force is not considered in the DSTV guideline.
To design a HD‑section on end-plates, for example, you can use END‑PLATE and replace the HD‑section by an IS-section.
In the case of IS‑sections, you can graphically select the dimensions of the HD‑section. Thus, this IS‑section has the same stiffnesses and can be designed in END‑PLATE.
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