Usually, in case of singularity in IDEA StatiCa Connection analysis, the description of singularities can be found in the Check screen in the Analysis tab. Also, the cause of the singularity is usually possible to see on the 3D screen.
The singularity can be caused by the following:
Unconnected Member or Plate
The simpliest reason for singularity is when one or more components are not connected with to the rest of the structure (missing welds, bolts, or contact operations). The finite elements of this component are not supported anyhow and thus "flies" away.
Singularity on circular hollow sections (CHS)
In IDEA StatiCa Connection, Circular Hollow Section (CHS) members are modeled using plane shell elements. Cutting a CHS or tubular section along its axis with a plate can cause an analysis singularity. A similar singularity warning often occurs when welding a tube along its length. Both issues are driven by the same cause: discretizing a curved surface into flat angular shell elements may create geometric mismatches at the cut or weld line.
To resolve this error, open the Project settings and change the default value of the Division of surface of the biggest circular hollow member from 64 to some lower number, e.g., 40.
Single-bolt connection subjected to bending moment
Applying a moment to a member connected by a single-bolt transforms the joint from a stable connection into a kinematic mechanism, causing an analysis singularity. To prevent this, change the Model type of the connected member to N-Vy-Vz, which restricts moment transfer and ensures the single-bolt joint carries only shear and normal forces.
Too wide gap between connected plates
When modeling a contact or bolted connection between plates, pay attention to the gap distance between them. The operation Bolt grid and Contact can bridge small offsets between items , however, the maximum allowable gap distance is 2 mm. If the gap exceeds 2 mm, the calculation cannot be executed and the analysis will result in singularity.
See also the videos explaining the singularities and how to resolve them.
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