KB 001708 | CSA S16:19 Stability Considerations and the New Annex O.2

This article demonstrates how to initiate and conduct the analysis in the software, followed by a short discussion of the underlying concept.

Base plate design according to AISC 360 [1] and ACI 318 [2] is now available in the Steel Joints add-on. This article shows how to model the base plate connection effortlessly and compare the results with an example from AISC Design Guide 1 [3].

The Steel Joints add-on for RFEM 6 has taken a significant step forward by introducing semi-rigid hinges, a feature that dramatically enhances how steel connections are modeled in structural analysis. This new capability enables engineers to go beyond the traditional rigid or hinged connection assumptions, offering a more accurate and flexible way to represent the behavior of joints. With the ability to simulate joint stiffness through advanced initial stiffness analysis, the design process becomes more realistic and optimized, paving the way for safer and more cost-effective projects.

In the Steel Joints add-on, you can classify the joint stiffnesses.

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 Video

In 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.

• "Steel Joints" Add-on
• Explanatory Video: Preloaded Bolts for Steel Joints

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 Member Editor component, you can also select the entire member as the modifying object instead of the individual member plates. This way, you can apply both operations "Notch" and "Chamfer" to several member plates.