A Novel Approach to Designing Steel Joints in RFEM 6
One of the innovations in RFEM 6 is the approach to designing steel connections. In contrast to RFEM 5, where the design of steel joints is based on an analytical solution, the Steel Joints add-on in RFEM 6 offers an FE solution for steel connections.
Creation of Steel Joints
Steel joints in RFEM 6 can be created by means of the simple and familiar input of predefined components. The initial data include the selection of nodes in the RFEM model, followed by the automatic recognition and assignment of the connecting members. Several types of predefined components can be selected for typical connection situations (e.g., end plate, cleats, fin plates). Universally applicable basic components (plates, welds, auxiliary planes) are also available for the input of complex connection situations.
The settings of the individual components can be defined and adjusted easily. In addition, modifications in terms of connecting members and plates can be introduced. The set of components defined in this manner can be saved as a template and stored in the user-defined library for further use.
At this point, the design parameters can be defined via the configuration settings. A plausibility check can also be carried out to examine the connection and detect missing data, plate collisions, incorrect welds, etc.
Design of Steel Joints
The advantage of steel joint analysis in RFEM 6 is the automatic generation of an associated FE model in the background. An example of this model is provided in Image 2. This offers the possibility to design any connections with rolled and welded cross-sections. Those currently available are I-sections, U-sections, T-sections, and angles.
In this approach, the loading at the selected nodes is automatically transferred into the FE model and subsequently used for the design checks of the components according to EN 1993-1-8 (including National Annexes). Thus, the bolt forces as well as stresses required for the weld design are determined on the FE model and the design of the bolt resistance and the welds is carried out according to the selected National Annex. The plate design is performed plastically by comparing the existing plastic strain to the allowable plastic strain (5%, according to EN 1993-1-5, Annex C, or user-defined specifications).
Once the design is accomplished, the governing design ratios are available in tabular and graphical form (as shown in Image 3). The results in the joint are accessible via the toolbar and these results can be filtered separately according to the respective components (Image 4).
One of the new features in RFEM 6 is the output of design check details inclusive of the verification formulas used. The formulas provided can also be included in the printout report. An overview of the design check details in terms of steel joint design is shown in Image 5.
In conclusion, the RFEM 6 Steel Joints add-on allows analysis of steel connections using an FE model. The input of different connection situations is possible by means of various components offered by the add-on. The FE model corresponding to the defined connection is automatically generated in the background. The transfer of the loading of all load combinations at the selected nodes is also automatic.
The loads determined on the FE model are subsequently used for the design checks of the components according to EN 1993-1-8 (including National Annexes). The add-on can be used for the design of any connection with the currently available rolled and welded cross sections such as I-sections, U-sections, T-sections, and angles. In addition, there is no restriction on planar loading since all internal forces are considered in the design (N, Vy, Vz, My, Mz, and Mt).
Finally, a detailed insight into the results and the design checks is provided. Both the result tables and the design check details can be transferred to the RFEM printout report. The generated FE model can also be saved and used for further use and analysis.
Irena Kirova, M.Sc.
Marketing & Customer Support
Ms. Kirova is responsible for the creation of technical articles at Dlubal and supports our users in customer support.
Do you have questions or need advice?
Contact our free e-mail, chat, or forum support or find various suggested solutions and useful tips on our FAQ page.
The calculation of complex structures by means of finite element analysis software is generally performed on the entire model. However, the construction of such structures is a process carried out in multiple stages where the final state of the building is achieved by combining the separate structural parts. To avoid errors in the calculation of overall models, the influence of the construction process must be considered. In RFEM 6, this is possible by using the Construction Stages Analysis (CSA) add-on.
Compared to the RF-/STEEL EC3 add-on module (RFEM 5/RSTAB 8), the following new features have been added to the Steel Design add-on for RFEM 6 / RSTAB 9:
- In addition to Eurocode 3, other international standards are integrated (e.g. AISC 360, CSA S16, GB 50017, SP 16.13330)
- Consideration of hot-dip galvanizing (DASt guideline 027) in the fire protection design according to EN 1993-1-2
- Input option for transverse stiffeners that can be taken into account in the shear buckling analysis
- Lateral-torsional buckling can also be checked for hollow sections (e.g. relevant for slender, high rectangular hollow sections)
- Automatic detection of members or member sets valid for the design (e.g. automatic deactivation of members with invalid material or members already contained in a set of members)
- Design settings can be adjusted individually for each member
- Graphical display of the results in the gross section or the effective section
- Output of the used design check formulas (including a reference to the used equation from the standard)
- How can I optimize cross-sections within the steel design?
- Where can I find the materials for the corresponding National Annexes in RFEM 6 and RSTAB 9?
- How do I apply wind load on members of open structures?
- Is it also possible to use RF‑/TOWER Loading without the other TOWER add-on modules?
- I do not want to design a cross-section in the RF‑/STEEL EC3 add-on module. Can I quickly remove this cross-section from the selection?
- I have a roof structure resting on a steel column that runs to the foundations. The column runs through a perimeter wall that supports the false ceiling. A considerable part of the load from the roof is transferred to the wall. I want the steel column to carry all the vertical loads from the roof. How can I do it?
- Are the models and presentations from Info Day 2018 freely available, and can you send them to me?
- I encountered a sharing violation while importing a dxf file into SHAPE-THIN. What is the issue?
- How can I display membrane stresses in the results of RF‑STEEL Surfaces?
- What is the meaning of the superposition according to the CQC rule in a dynamic analysis??
RFEM 6 structural analysis software is the basis of a modular software system. The main RFEM 6 program 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.