Beam Directions
When you create a straight beam, the software automatically creates
a coordinate system for it. This system defines the axial direction as
well as directions 1 and 2 that are used for viewing beam results. The
axial direction goes from End 1 
of the beam to End 2 
. Directions 1 and 2 are
assigned by the software automatically depending on the section properties.
A number of beam elements are created on the beam.
For curved profiles, the software creates a number of short straight
beams to approximate the geometry. Each beam element has its own directions.
For example, the axial direction for each beam on the swept section shown
below is defined by the straight line connecting its two joints. In the
graphics area, one coordinate system is shown at the middle of the beam.
To view the
coordinate systems of beams:
Run a study with beam mesh (structural members
mesh with beams by default).
Double-click any plot to display it in the graphics
area.
Right-click in the graphics area and select Settings.
In the PropertyManager, under Deformed
Plot Options, select Show beam
directions.
Click 
.
The red arrow shows the positive axial direction,
the green arrow shows the positive direction 1, and the blue arrow shows
the positive direction 2 for each beam.
