The selected section is created at a system line.
For beam length and placement, three different object axes types are used:
The standard insertion axis (system line) of a beam lies in the center of gravity.
You can create simple sections by entering a start point and an end point according to the current coordinate system. The current user coordinate system (UCS) determines the position of the section's main axes: the beam web runs in the Z direction of the UCS - the top of the section is in the Z direction.
To create a simple section, use the Section classes flyout on the Beams panel of the Objects tab.
Additionally, you can create custom sections and store them in a library. See User sections.