For each generic section, a search for symmetries is made, since each symmetry represents an important simplification and checking in the calculation of properties, both inertia and shear/torsion.
Symmetries are recognized in order of importance:
- Bi-axial symmetry.
- Axial symmetry with respect to a principal axis of inertia.
- Central symmetry.
The symbols used to highlight symmetry are:
- for symmetry about an axis;
- for central symmetry.
For example for steel sections the following symmetries (dxf file to import symm.dxf, with units in millimeters):