Skip to content

Orientation

An orientation is required for 3D beam elements to indicate how the section is oriented. The orientation object also handles transformation between global and local coordinate systems of beam/truss elements.

For 2D beam elements, the local \(z\)-axis is defined to be the global \(z\)-axis.

Syntax

Text Only
1
2
3
4
5
6
orientation (1) (2) (3) (4) (5)
# (1) int, unique orientation tag
# (2) string, orientation type
# (3) double, x component of local z axis
# (4) double, y component of local z axis
# (5) double, z component of local z axis

Remarks

  1. For type (2), currently only B3DL (stands for linear 3D beam transformation) and B3DC (corotational formulation) available.
  2. The B3DC formulation is based on Crisfield's work with modifications. See de Souza's thesis.
  3. For brevity, the mass distribution does not follow the corotational formulation, implying that the mass matrix is always a constant matrix. This is often sufficient for applications in earthquake engineering. However, it is not recommended for other applications. An energy-reserving corotational formulation is required, see Crisfield's work.