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Frequently Asked Questions (FAQ)
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AnswerYou have probably forgotten to define "extra bolts" in the upper and lower flange of the beam for the end plate connection. If this function is not activated, JOINTS only allows you to arrange the bolts within both beam flanges.
AnswerIn RF-/JOINTS Steel - Rigid, the design is implemented according to EN 1993‑1‑8, Section 6.2.7, Equation 6.24. If the design axial force exceeds 5% of the plastic resistance Npl, Rd, Equation 6.24 applies.
AnswerThe design of a rigid connection of this type without a web stiffener or an end plate is only possible with the JOINTS Steel - Rigid add-on module. You can find an example under Downloads below.
AnswerThe option to enter a taper on a beam can be activated in the Arrangement section of Window 1.4 Geometry. Here you can model the taper on the bottom or top side of the beam.The plate thicknesses as well as the height of the taper are defined by selecting the cross-section of the taper, since the cut rolled cross-sections are often used, for example. If user-defined plates are used, you can select a parametric T‑section. The length of the taper as well as the material are entered in the same section. The weld thicknesses for connecting the taper to the beam can be defined in the Welds section.If there is a tapered member already used as a beam (entered in the "Nodes and Members" section by specifying different cross-sections and lengths), it is not possible to model an additional taper.
AnswerThe RF-/JOINTS add-on module is divided into several joint groups. For this, see the following FAQ.Therefore, there is no straightforward answer to the special aspects of the design as in this FAQ.In contrast to the RF‑/TIMBER Pro add-on module described in the mentioned FAQ, however, it is obvious that the RF‑/JOINTS add-on modules cannot design EC2, even if manually changing the LDC, for example in the RF‑/JOINTS Timber - Steel to Timber add-on module (see Image 01).Furthermore, this also applies to the add‑on modules RF̩GLASS and RF‑/CONCRETE NL.The reason for this is that there are stiffnesses exported in the program in the case of some joint groups of the RF‑/JOINTS add‑on module. For nonlinear calculations, the superposition with result combinations is not allowed. In the case of the second result combination mentioned above, there is the special feature that the superposition is no longer conservative, even in the case of simple structures. The design cannot be also performed correctly by manually changing the LDC.Nevertheless, if a result combination should be superimposed with constant and alternative additive, it is necessary to split EC2 in the attached file into load combinations as follows.
- RC2*=CO1 or CO2
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.
The geometry depends on the definition of the structural components. In Window "1.2 Nodes and Members," there is the specification of which member is calculated as a column and which one as a beam. The program always recognizes the column as a continuous structural component by default (see Figure 01).In order to make the beam continuous, simply change the status of the individual members (see Figure 02). The actual beam will have the "Column" status and the actual column will be defined as a "Beam."
The designs with our RF-/JOINTS Steel-Rigid module are based on the assumptions and regulations of the EN 1993-1-8 standard. The bending from the main bearing plane is not considered here. This is also displayed as a note during the design.
With RFEM, it is possible to model any rigid joint. All internal forces can be considered there. You can find an example file in the appendix to this FAQ.
In RF-/JOINTS, an idealized design of a steel connection according to the standard is performed, which cannot be easily compared with an exact FE calculation. The results of the numerical and analytical design method differ in particular due to the simplifications and assumptions made.
For example, the following points must be considered when calculating a connection as a surface model:
You can find some webinars and technical articles on this topic on our website (see links below).
- Consideration or exclusion of friction/compression/tension within the contact solid (tab "Solid") as well as for the bolts modeled subsequently
- Consideration of internal forces and deformations within post-modeled end plates or similar, which results in a redistribution of bolt forces in the FE calculation (in contrast to the idealized design in RF-/JOINTS)
- 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"
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Wind Simulation & Wind Load Generation
With the stand -alone program RWIND Simulation, you can simulate wind flows around simple or complex structures 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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