In the Steel Joints add-on, you can classify the joint stiffness.
In addition to the initial stiffness, the table also shows the limit values for hinged and rigid connections for the selected internal forces N, My, and/or Mz. The resulting classification is then displayed in tables as "hinged", "semi-rigid", or "rigid".
Go to Explanatory VideoIn the "Steel Joints" add-on, you can consider preloaded bolts in all components during the calculation. You can easily activate the preloading using the check box in the bolt parameters, and it has an impact on the stress-strain analysis as well as the stiffness analysis.
Preloaded bolts are special bolts used in steel structures to generate a high clamping force between the connected structural components. This clamping force causes friction between the structural components, which allows for the transfer of forces.
Functionality
Preloaded bolts are tightened with a certain torque, causing them to stretch and generate a tensile force. This tensile force is transferred to the connected components and leads to a high clamping force. The clamping force prevents the connection from loosening and ensures safe force transmission.
Advantages
- High load-bearing capacity: Preloaded bolts can transfer large forces.
- Low deformation: They minimize the deformation of the connection.
- Fatigue strength: They are resistant to fatigue.
- Easy assembly: They are relatively easy to assemble and disassemble.
Analysis and Design
The calculation of preloaded bolts is performed in RFEM using the FE analysis model generated by the "Steel Joints" add-on. It takes into account the clamping force, friction between structural components, shear strength of bolts, and load-bearing capacity of the structural components. The design is carried out according to DIN EN 1993‑1‑8 (Eurocode 3) or the US standard ANSI/AISC 360‑16. You can save the created analysis model, including the results, and use it as an independent RFEM model.
In the Steel Joint add-on, you can design the connections of members with composite cross-sections. Furthermore, you can perform joint design checks for almost all thin-walled cross-sections in the RFEM library.
Go to Explanatory VideoIn the Steel Joints add-on, you can design connections according to the American standard ANSI/AISC 360‑16. The following design procedures are integrated:
- Load and Resistance Factor Design (LRFD)
- Allowable Stress Design (ASD)
Complex Connection of Horizontal Beams to Column and Connection of Reinforcing Diagonals
The connection model was modeled using about 50 components. The model was created according to the real example of use in structure.
Steel bolted connections with gusset plates on the canopy structure.
Download the structural analysis model and open it with the finite element program RFEM 6 using Steel Joints Add-on.
In the case of rectangular cross-sections, you can usually achieve a direct connection by using welds. However, you can also connect them to other cross-sections in the same way. Furthermore, other components such as end plates help you to connect the rectangular cross-sections to other structural components.
Design of a frame connection with taper and stiffened members. A stress analysis and a buckling stability analysis were carried out for the connection. To display the buckling results, the connection was converted into a separate model.
- The proposed connection can be applied to all selected nodes in the structure
- The location of the connection can be defined using the 'Main' tab of the Add-on dialog box
- The design is performed for all connections in the structure and after the calculation, the results on all connections can be displayed
- The table shows the results for the individual connections, each connection is designed and can be saved separately
- The design of the connection components is performed according to AISC 360 and Eurocode EN 1993‑1‑8.
- After activating the add-on, it is necessary to activate the design situations for Steel Connections in the "Load Cases and Combinations" dialog box.
- The design of the connection stability (buckling) requires the "Structure Stability" add-on.
- You can run the calculation using the table or the icon in the top bar.
- The steel connections model and the results can be saved as a separate model file
- The resulting stresses and the results of the stability analysis (joint buckling) can be displayed in a separate model
- In the saved model, you can run a deformation animation on the connection
- Connection components are converted to surfaces and members when they are saved
- The results of the connection design can be entered in the printout report
- When creating a new printout report, select the items added from the Steel Joints Add-on
- Use the tool 'Print Graphics to Printout Report' to insert graphics with the results of the connection, including the control panel, into the report
- Printout report contains the specifications of the connection components, design parameters, results and graphics
- For a new connection model, you have to select a node in the RFEM model
- After selecting a node, the members connected to the node are automatically recognized and assigned
- In the window for assigning members, select the ones that will be assigned to the connection
- The members marked by us are displayed in the preview window on the right
- Connections can be modeled for multiple nodes in a structure.
- For member settings, select the ones to be supported
- Many predefined components: Allow easy input of typical connection situations, such as end plates, angles, multi-wall sheets, cleats, fin plates
- Universally applicable basic components (plates, welds, bolts, auxiliary planes) for entering complex connection situations
- Graphical display of the connection geometry that is updated in parallel with the input
- The Steel Joints Template included in the add-on allows you to select from several connection types and, and once selected, it will be applied to your model.
- Wide range of cross-section shapes: Includes I-sections, channel sections, angles, T-sections, built-up cross-sections, RHS (rectangular hollow sections), and thin-walled sections
- The Template covers connections from three general categories: Rigid, Pinned, Truss
- Automatic adaptation of the connection geometry, even if the structural components are subsequently edited, based on the relative relation of the components
- The program performs a plausibility check in parallel with the input to quickly detect missing entries or collisions.
- If an error occurs, an error message appears describing the problem.
For joint components, you can check whether the stability failure is relevant. This requires the Structure Stability add-on for RFEM 6.
In this case, you calculate the critical load factor for all analyzed load combinations and the selected number of mode shapes for the connection model. Compare the smallest critical load factor with the limit value 15 from the standard EN 1993‑1‑1, Clause 5. Furthermore, you can make user-defined adjustment of the limit value. As a result of the stability analysis, the program displays the corresponding mode shapes graphically.
For the stability analysis, RFEM uses the adapted surface model to specifically recognize the local buckling shapes. You can also save and use the model of the stability analysis, including the results, as a separate model file.
- Automatic generation of FE analysis models: The add-on automatically creates a finite element model (FE) of the steel connection in the background.
- Consideration of all internal forces: The calculation and design checks include all internal forces (N, Vy, Vz, My, Mz, MT) and are not limited to planar loading.
- Automatic load transfer: All load combinations are automatically transferred to the FE analysis model of the connection. The loads are transferred directly from RFEM, so manual data input is not necessary.
- Efficient modeling: The add-on saves you time when modeling complex connection situations. You can also save the created FE analysis model and use it further for your own detailed analyses.
- Extensible library: An extensive and extensible library with predefined steel connection templates is available.
- Wide applicability: The add-on is suitable for connections of any type and shape, compatible with almost all rolled, welded, built-up, and thin-walled cross-sections.
- Selection of nodes in the RFEM model, automatic recognition and assignment of the members connected to the node
- Many predefined components available for easy input of typical connection situations (for example, end plates, cleats, fin plates)
- Universally applicable basic components (plates, welds, auxiliary planes) for entering complex connection situations
- No manual editing of the FE model required by the user, the essential calculation settings can be changed via the configuration settings
- Automatic adaptation of the connection geometry, even if the members are subsequently edited, due to the relative relation of the components to each other
- Parallel to the input, a plausibility check is carried out by the program to quickly detect missing input or collisions, for example
- Graphical display of the connection geometry that is updated in parallel with the input
The program supports you: It determines the bolt forces on the basis of the FE analysis model and evaluates them automatically. The add-on performs the standard-compliant design of bolt resistance for failure cases, such as tension, shear, hole bearing, and punching, and clearly displays all required coefficients.
Do you want to perform weld design? The welds are modeled as elastic-plastic surface elements, and their stresses are read out from the FE analysis model. The plasticity criteria is set in the way that they represent failure according to AISC J2-4, J2-5 (strength of welds), and J2-2 (strength of base metal). The design can be performed with the partial safety factors of the selected National Annex of EN 1993‑1‑8.
The plates in the connection are designed plastically by comparing the existing plastic strain to the allowable plastic strain. The default setting is 5% according to EN 1993‑1‑5, Annex C, but can be adjusted by user-defined specifications, as well as 5% for AISC 360.
You can display all essential results on the FE model. In this case, you can filter the results separately according to the respective components.
Furthemore, RFEM delivers you all design checks in a tabular form, including the display of the formulas used. If you wish, you can transfer the result tables to the RFEM printout report.